CELL SELECTIONRESELECTION

K S Madanpuri

madanpuri_ksyahoocom

1

Cell selectionreselection are processes which are

performed by a GSM mobile station in idle mode

The MS uses the cell selection algorithm to look for a cell

(of the chosen PLMN) where it can camp on (camping on a

cell)

If the MS looses coverage of that cell (caused for example

by moving out of the cell) it will look for the most suitable

alternative cell (of the selected PLMN) and it will camp on

that cell This is called cell reselection

In case of normal cell selection the MS has no prior knowledge on

which GSM 900 or DCS 1800 frequencies are BCCH carriers

Therefore the MS has to search in the beginning all RF carriers of the

corresponding system (124 carriers for P-GSM 174 carriers for E-

GSM and 374 carriers for DCS 1800) and has to measure the signal

strength on each RF carrier The MS takes 5 measurement samples

per RF carrier which are averaged

AV_RXLEV = 15 x (RXLEV1 + RXLEV2 + + RXLEV5)

A multi band MS searches all carriers within its band of operation

The number of carriers searched corresponds to the sum of carriers

on each band of operation

Based on these measurements samples over a period of 3 to 5

seconds the MS can estimate whether a cell will be an

appropriate serving cell from the radio propagation point of

view ie whether there will be a sufficient rdquolink qualityrdquo

C1 Criterion for Cell Selection

C1 = AV_RXLEV - RXLEV_ACCESS_MIN - max (0

MS_TXPWR_MAX_CCH - P )

RXLEV_ACCESS_MIN minimum received level at the MS

required for access to the system

MS_TXPWR_MAX_CCH maximum allowed MS transmit

power on RACH

P is the maximum RF output power of the MS usually 33dBm for

a handheld GSM900 and 30dBm for a handheld GSM1800 MS

Often the latter term in C1 equals 0 and equation can be simplified

to

C1 = A = AV_RXLEV minus RX_ACCESS_MIN

For example if the minimum allowed level to gain access to a

cell is minus100dBm and the received average level at the cellrsquos

BCCH frequency is -80 dBm MS calculates C1 as +20 for that

particular cell MS camps to the cell with the highest C1

value

There is an exception to the standard procedure described

above When MS evaluates C1 values for cells belonging to a

different Location Area (LA) it subtracts a parameter called

CELL_RESELECT_HYSTERESIS from the C1 value which means

that those cells are given a negative offset

The reason for this is that changing LA requires a Location

Update (LU) procedure that consumes network signaling

capacity Thus by assigning a negative offset to C1

unnecessary LUs caused by slow fading can be reduced MS

receives information of the cell dependent

CELL_RESELECT_HYSTERESIS values through BCCH

During cell selection procedure the MS will select only those

cells which have C1 gt 0

C1 Examples

For a system where the minimum access level is -104 then

C1 has a minimum value of 0 but you will sometimes see a

minimum of 1 - this is due to the mobile functionality since a value

of 0 actually would mean NO signal and no detection should have

occurred

bull screen 31 on pocket TEMS

C1c31 18-26 displayed

cell reselection hystresis =6 is displayed

bull Beside the C1 radio criterion there are some other criteria

(administrative and traffic control) for a cell to be suitable

A Suitable Cell is defined as a cell which

1048698 is part of the selected PLMN

1048698 is unbarred (parameter CELL_BAR_ACCESS = 0)

1048698 has a value C1 gt 0

1048698 is not in a location area forbidden for national roaming

To allow eg emergency calls the conditions for a serving cell

are less restrictive

Suitable Cell

An Acceptable Cell is defined as a cell which

1048698 is unbarred

1048698 has a parameter C1 gt 0

The general strategy for cell selection is to find the rdquosuitable

cellrdquo with the highest C1 (best estimated link quality) If no

suitable cell can be found an rdquoacceptable cellrdquo is selected

Cell Selection with Stored BCCH Information

Optionally the MS may store information on

received level on BCCH carriers when switched

off

When switched on the MS first performs

measurements on these carriers If cell selection

for the corresponding cells is not successful

normal cell selection is carried out

Phase 2 Cell reselection criterion C2 is defined as

C2 = C1 + CELL_RESELECT_OFFSET minus TEMPORARY_OFFSET

If CELL RESELECT PARAM IND = TRUE then

If the counter T lt PENALTY TIME

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY OFFSET

If the counter T gt= PENALTY TIME

C2 = C1 + CELL_RESELECT_OFFSET

13

If the neighbour is the last serving cell

T = PENALTY TIME and

C2 = C1 + CELL_RESELECT_OFFSET

The timer T is started separately for each cell in the list of the six

strongest cells immediately after it is placed on the list MS camps

in the cell with the highest C2 value

15

The criterion C2 is applied in hierarchical cell structures to keep fast

moving MS in an upper layer and slow moving MS in micro cells It is

assumed that a fast moving MS passes through the micro cell before

PENALTY_TIME is reached This efficiently prevents unnecessary LUs and

thus saves network signaling capacity As in the case of C1 MS receives

the C2 parameter information through BCCH A parameter called

CELL_RESELECT_PARAM_IND informs MS about which reselection

criterion (C1 or C2) is used in the cell It is broadcast on the BCCH

The following actions are performed by the MS to detect whether or not a

cell reselection is necessary

Detection of a Downlink Signaling Failure ndash The downlink signaling failure counter DSC is a counter running in the

MS The starting value of this counter is called DSC0 and is set by the

MS to the following value

DSC0 = round(90 BS_PA_MFRMS)

The value of BS_PA_MFRMS is broadcasted in the system informations on

the BCCH of the serving cell Each BS_PA_MFRMS the MS attempts to

decode the messages on its paging sub-channel Depending on whether or

not this decoding is successful the value of the downlink signaling failure

counter DSC is modified in the following way

successful decoding DSC new = DSC old + 1

if DSC new + 1 gt DSC0 rarr DSC new = DSC old

unsuccessful decoding DSC new = DSC old ndash 4

If DSC lt 0 the MS has detected a downlink signaling

failure

Minimum decoding

Monitoring of all BCCH carriers given in the BCCH allocation

(neighbor cells) of the serving cell

Taking at least 5 samples of the received level from the serving cell

(on paging sub-channel) as well as from the neighbor cells

=gt AV_RXLEV(serving cell) and AV_RXLEV (neighbor cell)

Decoding of full BCCH data of the serving cell at least every 30 sec

Decoding of BCCH data of the 6 strongest neighbor cells at least

every 5 minutes

From the radio propagation point of view it is

worth to select a new (neighbor) cell if the

received level from that neighbor cell exceeds the

received level of the current serving cell For

phase 1 MS this is expressed using the C1

criterion

C1 (neighbor cell) gt C1 (serving cell)

For phase 2 MS a modified path loss criterion the C2 criterion

is usedThe C2 criterion depends on the value of a timer T

which is called PENALTY_TIMERThe timer T is started in the MS

for each cell in the list of the 6 strongest neighbor cells as soon

as it is placed on the list Timer T is reset to 0 if the cell is

removed from the list

During penalty time

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

After penalty time

C2 = C1 + CELL_RESELECT_OFFSET

For penalty time = 31 the whole time

C2 = C1 - CELL_RESELECT_OFFSET

CELL_RESELECT_OFFSET TEMPORARY_OFFSET and

PENALTY_TIME are cell reselection parameters which

are broadcasted on the BCCH of the cell in the

system informations if CELL_RESLECT_PARAM_IND

(Cell Reselection Parameter Indication) is set to 1

A negative TEMPORARY_OFFSET reduces the

priority of a cell in the list of strongest neighbor

cells

A positive CELL_RESELECT_OFFSET increases the

priority of a cell in the list of strongest neighbor

cells

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells

When a mobile reaches the coverage area of a (neighbor) micro cell given

by the C1 criterion this cell becomes effectively excluded from reselection

during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell be-fore PENALTY_TIME is reached and hence the micro cell is not

selected

In contrast a slow moving mobile is assumed to be still within the coverage

area of the micro cell when PENALTY_TIME has expired

Applying the positive CELL_RESELECT_OFFSET this cell is selected with

preference

Triggers for Cell Reselection

Cell reselection is triggered by the following conditions

1 C1 lt 0 for the serving cell for a period of 5 s

2 MS detects a downlink signaling failure

3 Serving cell becomes barred

Phase 1 MS

C1 (serving cell) lt C1 (suitable neighbor cell) if the suitable neighbor cell is

in the same location area

C1 (serving cell) + CELL_RESELECT_HYSTERESIS lt C1 (suitable

neighbor cell) if the suitable neighbor cell is in another location area for a

period of 5 sec

Phase 2 MS

C2 (serving cell) lt C2 (suitable neighbor cell) if the suitable neighbor cell is in

the same location area

C2 (serving cell) + CELL_RESELECT_HYSTERESIS lt C2 (suitable neighbor

cell) if the suitable neighbor cell is in another location area for a period of 5

sec

A random access attempt is unsuccessful even after the maximum number

of repetitions

For phase 2 there is the additional trigger

A location update request has been rejected with cause rdquolocation area not

allowedrdquo

PARAMETERS SETTING

BA (BCCH) - BCCH Allocation broadcasted on BCCH

In each cell the absolute radio frequency carrier number

BCCH_ARFCN_NC(n) of each of its neighbor cell n has to be

known This information is broadcasted as the so-called BCCH

Allocation to all MS in the respective cell On the

corresponding frequencies the MS take measurement samples

of the received level used for cell selection reselection

Furthermore the BCCH of neighbor cells has to be decoded by

the MS (at least every 5 min) to know the current values of the

control parameters for the reselection algorithm

PARAMETERS SETTING

Object DB Name Range Step Size

Unit ADJC BCCHFREQ 01023 1

PARAMETERS SETTING

CELL_BAR_ACCESS - Cell Barred for Access

A mobile station cannot camp on a barred cell ie a barred cell is not

selected by the cell selectionreselection procedure

Mobile stations which camp on a cell while it becomes barred initialize the

reselection procedure to find a new (unbarred) cell ie traffic load is

distributed to neighbor cells

This means that eg neither a call nor a location update can start in a

barred cell

However a cell barred for access is not barred for incoming handovers To

barr a cell completely eg for maintenance reasons also incoming

handovers have to be avoided

To reduce overload in a certain cell more moderately without distributing

the overload to neighbor cells barring of access classes has to be used

Barring access for an access class does not trigger a cell reselection for

MSs of that class

Object DB Name Range

BTS CELLBARR FALSETRUE

RXLEV_ACCESS_MIN - Minimum Downlink Received Level for Cell to be

selected

The parameter RXLEV_ACCESS_MIN determines the cell border for a MS in idle

mode by means of the C1 or C2 criterion respectively

Choosing a high value reduces the risk of a handover immediately after call

setup

On the other hand the value has to be low enough to achieve a sufficient overlap

between adjacent cells (especially if they belong to different location areas)

It has to be observed that the overlap may be different for mobiles of different

power classes (refer to MS_TXPWR_MAX_CCH)

In any case RXLEV_ACCESS_MIN has to be above the MS receiver sensitivity level

(-100 dBm for DCS1800 -102 dBm for GSM handhelds -104 dBm for other GSM

MS)

Furthermore it has to harmonize with the

handover thresholds (RXLEV_MIN L_RXLEV_HO)

Object DB Name Range Step Size Unit

BTS RXLEVAMI 063 1

RXLEV

MS_TXPWR_MAX_CCH - Maximum allowed MS Transmit

Power on RACH

The transmit power level the MS uses for the access on the

Random Access Channel is given by the minimum of two

values

the maximum possible transmit power of the MS (given by

the power class P of the MS) the maximum allowed power

for access within the respective cell

(given by MS_TXP WR_MAX_CCH)

This parameter affects the

the random access procedure

the cell selection procedure

Random access

If there is a collision of channel requests on the random access

channel the one with the higher received level has a good chance

to be decoded and to get a response by the BTS

Hence MS with higher output power are preferred This imbalance

can be avoided by choosing a low maximum allowed transmit power

PARAMETERS SETTING

Cell Selection

To be selected by the cell selection procedure a cell has to fulfill the

C1 criterion

C1 gt 0 where

C1 = AV_RXLEV - RXLEV_ACCESS_MIN - Max(0

MS_TXPWR_MAX_CCH - P )

Choosing for example MS_TXPWR_MAX_CCH = Pmin where Pmin is

the output power level for the minimum power class 5 (29 dBm)

the C1 criterion reduces to AV_RXLEV gt RXLEV_ACCESS_MIN

for MSs of all power classes Hence the same idle mode cell border

is seen by each mobile

Choosing for example MS_TXPWR_MAX_CCH = Pmax where Pmax is

the output power level for the maximum power class 1 (43 dBm)

the C1 criterion reduces to

AV_RXLEV gt RXLEV_ACCESS_MIN + ( MS_TXPWR_MAX_CCH - P )

for MSs of all power classes Hence a larger cell radius is seen by a

mobile of higher output power than by a mobile of lower output

power On the other hand one can ensure by this mechanism that a

certain uplink received level is exceeded by each MS independent of

its power class

Object DB Name Range Step Size Unit

BTS MSTXPMAXCH 031 1 2 dB

MS_TXPWR_MAX_CCH - Maximum allowed MS transmit power on RACH

default 2

MS GSM900 MS GSM900 MS DCS1800

Phase 1 Phase 2

0 = 43 dBm 0 = 39 dBm 0 = 30 dBm

1 = 41 dBm 1 = 39 dBm 1 = 28 dBm

2 = 39 dBm 2 = 39 dBm 2 = 26 dBm

3 = 37 dBm 3 = 37 dBm 3 = 24 dBm

15 = 13dBm 19 = 5 dBm 15 = 0 dBm

16-31 = 13 dBm 20-31 = 5 dBm 16-31 = 0 dBm

POWER_OFFSET - Additional Parameter for Class 3

DCS1800 MS

The parameter POWER_OFFSET is only used by class 3

DCS1800 MS to calculate the C1-criterion described as

follows

C1 = AV_RXLEV - RXLEV_ACCESS_MIN -

Max(0MS_TXPWR_MAX_CCH + POWER_OFFSET- P)

Object DB Name Range Step Size Unit

BTS PWROFS 03 1 2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for Reselection of a Cell

from another Location Area

In idle mode the MS selects a new (neighbor) cell if the received level of the

neighbor cell exceeds the received level of the current cell in order to be

served by the cell with the expected best link quality However due to

fading effects the propagation conditions may change rapidly and

therefore a reselection may occur very frequently

If the cells involved in the reselection process belong to the same location

area frequent cell reselection does not have an effect on the network

performance

But if the involved cells belong to different location area the reselection of

a new cell triggers a location update procedure which causes signaling

load (eg on the SDCCH) and involves all network elements

To avoid unnecessary signaling load by forward and backward reselection due to fading

a hysteresis given by the parameter CELL_RESELECT_HYSTERESIS is introduced ie

a cell from another location area is selected only if the corresponding received level

exceeds the level of the current serving cell by the value of this parameter This is

expressed in terms of the C1 (phase 1) or C2 (phase 2) criterion

C1 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C1 (suitable neighbor cell)

or

C2 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C2 (suitable neighbor cell)

respectively

The adjustment of CELL_RESELECT_HYSTERESES should be a compromise between

reduction of unnecessary location updates (high value) and

selection of the cell with best reception quality (low value)

Object DB Name Range Step Size Unit

BTS CELLRESH 07 1

2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for

reselection of a cell from another location area

default 2

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter

Indication

CELL_RESELECT_PARAM_IND=1

The cell reselection parameters CELL_RESELECT_OFFSET

TEMPORARY_OFFSET and PENALTY_TIME used for the C2 criterion as well as

the parameter CELL_BAR_QUALIFY are broadcasted on the BCCH These

parameters are taken into account by phase 2 MS but are ignored by

phase 1 MS

CELL_RESELECT_PARAM_IND = 0

The cell reselection parameters and CELL_BAR_QUALIFY are not

broadcasted on the BCCH

A phase 2 MS then uses the value 0 for all these parameters ie C1 = C2

Object DB Name Range

BTS CRESPARI 01

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter Indication default 1

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

Cell selectionreselection are processes which are

performed by a GSM mobile station in idle mode

The MS uses the cell selection algorithm to look for a cell

(of the chosen PLMN) where it can camp on (camping on a

cell)

If the MS looses coverage of that cell (caused for example

by moving out of the cell) it will look for the most suitable

alternative cell (of the selected PLMN) and it will camp on

that cell This is called cell reselection

In case of normal cell selection the MS has no prior knowledge on

which GSM 900 or DCS 1800 frequencies are BCCH carriers

Therefore the MS has to search in the beginning all RF carriers of the

corresponding system (124 carriers for P-GSM 174 carriers for E-

GSM and 374 carriers for DCS 1800) and has to measure the signal

strength on each RF carrier The MS takes 5 measurement samples

per RF carrier which are averaged

AV_RXLEV = 15 x (RXLEV1 + RXLEV2 + + RXLEV5)

A multi band MS searches all carriers within its band of operation

The number of carriers searched corresponds to the sum of carriers

on each band of operation

Based on these measurements samples over a period of 3 to 5

seconds the MS can estimate whether a cell will be an

appropriate serving cell from the radio propagation point of

view ie whether there will be a sufficient rdquolink qualityrdquo

C1 Criterion for Cell Selection

C1 = AV_RXLEV - RXLEV_ACCESS_MIN - max (0

MS_TXPWR_MAX_CCH - P )

RXLEV_ACCESS_MIN minimum received level at the MS

required for access to the system

MS_TXPWR_MAX_CCH maximum allowed MS transmit

power on RACH

P is the maximum RF output power of the MS usually 33dBm for

a handheld GSM900 and 30dBm for a handheld GSM1800 MS

Often the latter term in C1 equals 0 and equation can be simplified

to

C1 = A = AV_RXLEV minus RX_ACCESS_MIN

For example if the minimum allowed level to gain access to a

cell is minus100dBm and the received average level at the cellrsquos

BCCH frequency is -80 dBm MS calculates C1 as +20 for that

particular cell MS camps to the cell with the highest C1

value

There is an exception to the standard procedure described

above When MS evaluates C1 values for cells belonging to a

different Location Area (LA) it subtracts a parameter called

CELL_RESELECT_HYSTERESIS from the C1 value which means

that those cells are given a negative offset

The reason for this is that changing LA requires a Location

Update (LU) procedure that consumes network signaling

capacity Thus by assigning a negative offset to C1

unnecessary LUs caused by slow fading can be reduced MS

receives information of the cell dependent

CELL_RESELECT_HYSTERESIS values through BCCH

During cell selection procedure the MS will select only those

cells which have C1 gt 0

C1 Examples

For a system where the minimum access level is -104 then

C1 has a minimum value of 0 but you will sometimes see a

minimum of 1 - this is due to the mobile functionality since a value

of 0 actually would mean NO signal and no detection should have

occurred

bull screen 31 on pocket TEMS

C1c31 18-26 displayed

cell reselection hystresis =6 is displayed

bull Beside the C1 radio criterion there are some other criteria

(administrative and traffic control) for a cell to be suitable

A Suitable Cell is defined as a cell which

1048698 is part of the selected PLMN

1048698 is unbarred (parameter CELL_BAR_ACCESS = 0)

1048698 has a value C1 gt 0

1048698 is not in a location area forbidden for national roaming

To allow eg emergency calls the conditions for a serving cell

are less restrictive

Suitable Cell

An Acceptable Cell is defined as a cell which

1048698 is unbarred

1048698 has a parameter C1 gt 0

The general strategy for cell selection is to find the rdquosuitable

cellrdquo with the highest C1 (best estimated link quality) If no

suitable cell can be found an rdquoacceptable cellrdquo is selected

Cell Selection with Stored BCCH Information

Optionally the MS may store information on

received level on BCCH carriers when switched

off

When switched on the MS first performs

measurements on these carriers If cell selection

for the corresponding cells is not successful

normal cell selection is carried out

Phase 2 Cell reselection criterion C2 is defined as

C2 = C1 + CELL_RESELECT_OFFSET minus TEMPORARY_OFFSET

If CELL RESELECT PARAM IND = TRUE then

If the counter T lt PENALTY TIME

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY OFFSET

If the counter T gt= PENALTY TIME

C2 = C1 + CELL_RESELECT_OFFSET

13

If the neighbour is the last serving cell

T = PENALTY TIME and

C2 = C1 + CELL_RESELECT_OFFSET

The timer T is started separately for each cell in the list of the six

strongest cells immediately after it is placed on the list MS camps

in the cell with the highest C2 value

15

The criterion C2 is applied in hierarchical cell structures to keep fast

moving MS in an upper layer and slow moving MS in micro cells It is

assumed that a fast moving MS passes through the micro cell before

PENALTY_TIME is reached This efficiently prevents unnecessary LUs and

thus saves network signaling capacity As in the case of C1 MS receives

the C2 parameter information through BCCH A parameter called

CELL_RESELECT_PARAM_IND informs MS about which reselection

criterion (C1 or C2) is used in the cell It is broadcast on the BCCH

The following actions are performed by the MS to detect whether or not a

cell reselection is necessary

Detection of a Downlink Signaling Failure ndash The downlink signaling failure counter DSC is a counter running in the

MS The starting value of this counter is called DSC0 and is set by the

MS to the following value

DSC0 = round(90 BS_PA_MFRMS)

The value of BS_PA_MFRMS is broadcasted in the system informations on

the BCCH of the serving cell Each BS_PA_MFRMS the MS attempts to

decode the messages on its paging sub-channel Depending on whether or

not this decoding is successful the value of the downlink signaling failure

counter DSC is modified in the following way

successful decoding DSC new = DSC old + 1

if DSC new + 1 gt DSC0 rarr DSC new = DSC old

unsuccessful decoding DSC new = DSC old ndash 4

If DSC lt 0 the MS has detected a downlink signaling

failure

Minimum decoding

Monitoring of all BCCH carriers given in the BCCH allocation

(neighbor cells) of the serving cell

Taking at least 5 samples of the received level from the serving cell

(on paging sub-channel) as well as from the neighbor cells

=gt AV_RXLEV(serving cell) and AV_RXLEV (neighbor cell)

Decoding of full BCCH data of the serving cell at least every 30 sec

Decoding of BCCH data of the 6 strongest neighbor cells at least

every 5 minutes

From the radio propagation point of view it is

worth to select a new (neighbor) cell if the

received level from that neighbor cell exceeds the

received level of the current serving cell For

phase 1 MS this is expressed using the C1

criterion

C1 (neighbor cell) gt C1 (serving cell)

For phase 2 MS a modified path loss criterion the C2 criterion

is usedThe C2 criterion depends on the value of a timer T

which is called PENALTY_TIMERThe timer T is started in the MS

for each cell in the list of the 6 strongest neighbor cells as soon

as it is placed on the list Timer T is reset to 0 if the cell is

removed from the list

During penalty time

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

After penalty time

C2 = C1 + CELL_RESELECT_OFFSET

For penalty time = 31 the whole time

C2 = C1 - CELL_RESELECT_OFFSET

CELL_RESELECT_OFFSET TEMPORARY_OFFSET and

PENALTY_TIME are cell reselection parameters which

are broadcasted on the BCCH of the cell in the

system informations if CELL_RESLECT_PARAM_IND

(Cell Reselection Parameter Indication) is set to 1

A negative TEMPORARY_OFFSET reduces the

priority of a cell in the list of strongest neighbor

cells

A positive CELL_RESELECT_OFFSET increases the

priority of a cell in the list of strongest neighbor

cells

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells

When a mobile reaches the coverage area of a (neighbor) micro cell given

by the C1 criterion this cell becomes effectively excluded from reselection

during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell be-fore PENALTY_TIME is reached and hence the micro cell is not

selected

In contrast a slow moving mobile is assumed to be still within the coverage

area of the micro cell when PENALTY_TIME has expired

Applying the positive CELL_RESELECT_OFFSET this cell is selected with

preference

Triggers for Cell Reselection

Cell reselection is triggered by the following conditions

1 C1 lt 0 for the serving cell for a period of 5 s

2 MS detects a downlink signaling failure

3 Serving cell becomes barred

Phase 1 MS

C1 (serving cell) lt C1 (suitable neighbor cell) if the suitable neighbor cell is

in the same location area

C1 (serving cell) + CELL_RESELECT_HYSTERESIS lt C1 (suitable

neighbor cell) if the suitable neighbor cell is in another location area for a

period of 5 sec

Phase 2 MS

C2 (serving cell) lt C2 (suitable neighbor cell) if the suitable neighbor cell is in

the same location area

C2 (serving cell) + CELL_RESELECT_HYSTERESIS lt C2 (suitable neighbor

cell) if the suitable neighbor cell is in another location area for a period of 5

sec

A random access attempt is unsuccessful even after the maximum number

of repetitions

For phase 2 there is the additional trigger

A location update request has been rejected with cause rdquolocation area not

allowedrdquo

PARAMETERS SETTING

BA (BCCH) - BCCH Allocation broadcasted on BCCH

In each cell the absolute radio frequency carrier number

BCCH_ARFCN_NC(n) of each of its neighbor cell n has to be

known This information is broadcasted as the so-called BCCH

Allocation to all MS in the respective cell On the

corresponding frequencies the MS take measurement samples

of the received level used for cell selection reselection

Furthermore the BCCH of neighbor cells has to be decoded by

the MS (at least every 5 min) to know the current values of the

control parameters for the reselection algorithm

PARAMETERS SETTING

Object DB Name Range Step Size

Unit ADJC BCCHFREQ 01023 1

PARAMETERS SETTING

CELL_BAR_ACCESS - Cell Barred for Access

A mobile station cannot camp on a barred cell ie a barred cell is not

selected by the cell selectionreselection procedure

Mobile stations which camp on a cell while it becomes barred initialize the

reselection procedure to find a new (unbarred) cell ie traffic load is

distributed to neighbor cells

This means that eg neither a call nor a location update can start in a

barred cell

However a cell barred for access is not barred for incoming handovers To

barr a cell completely eg for maintenance reasons also incoming

handovers have to be avoided

To reduce overload in a certain cell more moderately without distributing

the overload to neighbor cells barring of access classes has to be used

Barring access for an access class does not trigger a cell reselection for

MSs of that class

Object DB Name Range

BTS CELLBARR FALSETRUE

RXLEV_ACCESS_MIN - Minimum Downlink Received Level for Cell to be

selected

The parameter RXLEV_ACCESS_MIN determines the cell border for a MS in idle

mode by means of the C1 or C2 criterion respectively

Choosing a high value reduces the risk of a handover immediately after call

setup

On the other hand the value has to be low enough to achieve a sufficient overlap

between adjacent cells (especially if they belong to different location areas)

It has to be observed that the overlap may be different for mobiles of different

power classes (refer to MS_TXPWR_MAX_CCH)

In any case RXLEV_ACCESS_MIN has to be above the MS receiver sensitivity level

(-100 dBm for DCS1800 -102 dBm for GSM handhelds -104 dBm for other GSM

MS)

Furthermore it has to harmonize with the

handover thresholds (RXLEV_MIN L_RXLEV_HO)

Object DB Name Range Step Size Unit

BTS RXLEVAMI 063 1

RXLEV

MS_TXPWR_MAX_CCH - Maximum allowed MS Transmit

Power on RACH

The transmit power level the MS uses for the access on the

Random Access Channel is given by the minimum of two

values

the maximum possible transmit power of the MS (given by

the power class P of the MS) the maximum allowed power

for access within the respective cell

(given by MS_TXP WR_MAX_CCH)

This parameter affects the

the random access procedure

the cell selection procedure

Random access

If there is a collision of channel requests on the random access

channel the one with the higher received level has a good chance

to be decoded and to get a response by the BTS

Hence MS with higher output power are preferred This imbalance

can be avoided by choosing a low maximum allowed transmit power

PARAMETERS SETTING

Cell Selection

To be selected by the cell selection procedure a cell has to fulfill the

C1 criterion

C1 gt 0 where

C1 = AV_RXLEV - RXLEV_ACCESS_MIN - Max(0

MS_TXPWR_MAX_CCH - P )

Choosing for example MS_TXPWR_MAX_CCH = Pmin where Pmin is

the output power level for the minimum power class 5 (29 dBm)

the C1 criterion reduces to AV_RXLEV gt RXLEV_ACCESS_MIN

for MSs of all power classes Hence the same idle mode cell border

is seen by each mobile

Choosing for example MS_TXPWR_MAX_CCH = Pmax where Pmax is

the output power level for the maximum power class 1 (43 dBm)

the C1 criterion reduces to

AV_RXLEV gt RXLEV_ACCESS_MIN + ( MS_TXPWR_MAX_CCH - P )

for MSs of all power classes Hence a larger cell radius is seen by a

mobile of higher output power than by a mobile of lower output

power On the other hand one can ensure by this mechanism that a

certain uplink received level is exceeded by each MS independent of

its power class

Object DB Name Range Step Size Unit

BTS MSTXPMAXCH 031 1 2 dB

MS_TXPWR_MAX_CCH - Maximum allowed MS transmit power on RACH

default 2

MS GSM900 MS GSM900 MS DCS1800

Phase 1 Phase 2

0 = 43 dBm 0 = 39 dBm 0 = 30 dBm

1 = 41 dBm 1 = 39 dBm 1 = 28 dBm

2 = 39 dBm 2 = 39 dBm 2 = 26 dBm

3 = 37 dBm 3 = 37 dBm 3 = 24 dBm

15 = 13dBm 19 = 5 dBm 15 = 0 dBm

16-31 = 13 dBm 20-31 = 5 dBm 16-31 = 0 dBm

POWER_OFFSET - Additional Parameter for Class 3

DCS1800 MS

The parameter POWER_OFFSET is only used by class 3

DCS1800 MS to calculate the C1-criterion described as

follows

C1 = AV_RXLEV - RXLEV_ACCESS_MIN -

Max(0MS_TXPWR_MAX_CCH + POWER_OFFSET- P)

Object DB Name Range Step Size Unit

BTS PWROFS 03 1 2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for Reselection of a Cell

from another Location Area

In idle mode the MS selects a new (neighbor) cell if the received level of the

neighbor cell exceeds the received level of the current cell in order to be

served by the cell with the expected best link quality However due to

fading effects the propagation conditions may change rapidly and

therefore a reselection may occur very frequently

If the cells involved in the reselection process belong to the same location

area frequent cell reselection does not have an effect on the network

performance

But if the involved cells belong to different location area the reselection of

a new cell triggers a location update procedure which causes signaling

load (eg on the SDCCH) and involves all network elements

To avoid unnecessary signaling load by forward and backward reselection due to fading

a hysteresis given by the parameter CELL_RESELECT_HYSTERESIS is introduced ie

a cell from another location area is selected only if the corresponding received level

exceeds the level of the current serving cell by the value of this parameter This is

expressed in terms of the C1 (phase 1) or C2 (phase 2) criterion

C1 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C1 (suitable neighbor cell)

or

C2 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C2 (suitable neighbor cell)

respectively

The adjustment of CELL_RESELECT_HYSTERESES should be a compromise between

reduction of unnecessary location updates (high value) and

selection of the cell with best reception quality (low value)

Object DB Name Range Step Size Unit

BTS CELLRESH 07 1

2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for

reselection of a cell from another location area

default 2

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter

Indication

CELL_RESELECT_PARAM_IND=1

The cell reselection parameters CELL_RESELECT_OFFSET

TEMPORARY_OFFSET and PENALTY_TIME used for the C2 criterion as well as

the parameter CELL_BAR_QUALIFY are broadcasted on the BCCH These

parameters are taken into account by phase 2 MS but are ignored by

phase 1 MS

CELL_RESELECT_PARAM_IND = 0

The cell reselection parameters and CELL_BAR_QUALIFY are not

broadcasted on the BCCH

A phase 2 MS then uses the value 0 for all these parameters ie C1 = C2

Object DB Name Range

BTS CRESPARI 01

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter Indication default 1

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

In case of normal cell selection the MS has no prior knowledge on

which GSM 900 or DCS 1800 frequencies are BCCH carriers

Therefore the MS has to search in the beginning all RF carriers of the

corresponding system (124 carriers for P-GSM 174 carriers for E-

GSM and 374 carriers for DCS 1800) and has to measure the signal

strength on each RF carrier The MS takes 5 measurement samples

per RF carrier which are averaged

AV_RXLEV = 15 x (RXLEV1 + RXLEV2 + + RXLEV5)

A multi band MS searches all carriers within its band of operation

The number of carriers searched corresponds to the sum of carriers

on each band of operation

Based on these measurements samples over a period of 3 to 5

seconds the MS can estimate whether a cell will be an

appropriate serving cell from the radio propagation point of

view ie whether there will be a sufficient rdquolink qualityrdquo

C1 Criterion for Cell Selection

C1 = AV_RXLEV - RXLEV_ACCESS_MIN - max (0

MS_TXPWR_MAX_CCH - P )

RXLEV_ACCESS_MIN minimum received level at the MS

required for access to the system

MS_TXPWR_MAX_CCH maximum allowed MS transmit

power on RACH

P is the maximum RF output power of the MS usually 33dBm for

a handheld GSM900 and 30dBm for a handheld GSM1800 MS

Often the latter term in C1 equals 0 and equation can be simplified

to

C1 = A = AV_RXLEV minus RX_ACCESS_MIN

For example if the minimum allowed level to gain access to a

cell is minus100dBm and the received average level at the cellrsquos

BCCH frequency is -80 dBm MS calculates C1 as +20 for that

particular cell MS camps to the cell with the highest C1

value

There is an exception to the standard procedure described

above When MS evaluates C1 values for cells belonging to a

different Location Area (LA) it subtracts a parameter called

CELL_RESELECT_HYSTERESIS from the C1 value which means

that those cells are given a negative offset

The reason for this is that changing LA requires a Location

Update (LU) procedure that consumes network signaling

capacity Thus by assigning a negative offset to C1

unnecessary LUs caused by slow fading can be reduced MS

receives information of the cell dependent

CELL_RESELECT_HYSTERESIS values through BCCH

During cell selection procedure the MS will select only those

cells which have C1 gt 0

C1 Examples

For a system where the minimum access level is -104 then

C1 has a minimum value of 0 but you will sometimes see a

minimum of 1 - this is due to the mobile functionality since a value

of 0 actually would mean NO signal and no detection should have

occurred

bull screen 31 on pocket TEMS

C1c31 18-26 displayed

cell reselection hystresis =6 is displayed

bull Beside the C1 radio criterion there are some other criteria

(administrative and traffic control) for a cell to be suitable

A Suitable Cell is defined as a cell which

1048698 is part of the selected PLMN

1048698 is unbarred (parameter CELL_BAR_ACCESS = 0)

1048698 has a value C1 gt 0

1048698 is not in a location area forbidden for national roaming

To allow eg emergency calls the conditions for a serving cell

are less restrictive

Suitable Cell

An Acceptable Cell is defined as a cell which

1048698 is unbarred

1048698 has a parameter C1 gt 0

The general strategy for cell selection is to find the rdquosuitable

cellrdquo with the highest C1 (best estimated link quality) If no

suitable cell can be found an rdquoacceptable cellrdquo is selected

Cell Selection with Stored BCCH Information

Optionally the MS may store information on

received level on BCCH carriers when switched

off

When switched on the MS first performs

measurements on these carriers If cell selection

for the corresponding cells is not successful

normal cell selection is carried out

Phase 2 Cell reselection criterion C2 is defined as

C2 = C1 + CELL_RESELECT_OFFSET minus TEMPORARY_OFFSET

If CELL RESELECT PARAM IND = TRUE then

If the counter T lt PENALTY TIME

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY OFFSET

If the counter T gt= PENALTY TIME

C2 = C1 + CELL_RESELECT_OFFSET

13

If the neighbour is the last serving cell

T = PENALTY TIME and

C2 = C1 + CELL_RESELECT_OFFSET

The timer T is started separately for each cell in the list of the six

strongest cells immediately after it is placed on the list MS camps

in the cell with the highest C2 value

15

The criterion C2 is applied in hierarchical cell structures to keep fast

moving MS in an upper layer and slow moving MS in micro cells It is

assumed that a fast moving MS passes through the micro cell before

PENALTY_TIME is reached This efficiently prevents unnecessary LUs and

thus saves network signaling capacity As in the case of C1 MS receives

the C2 parameter information through BCCH A parameter called

CELL_RESELECT_PARAM_IND informs MS about which reselection

criterion (C1 or C2) is used in the cell It is broadcast on the BCCH

The following actions are performed by the MS to detect whether or not a

cell reselection is necessary

Detection of a Downlink Signaling Failure ndash The downlink signaling failure counter DSC is a counter running in the

MS The starting value of this counter is called DSC0 and is set by the

MS to the following value

DSC0 = round(90 BS_PA_MFRMS)

The value of BS_PA_MFRMS is broadcasted in the system informations on

the BCCH of the serving cell Each BS_PA_MFRMS the MS attempts to

decode the messages on its paging sub-channel Depending on whether or

not this decoding is successful the value of the downlink signaling failure

counter DSC is modified in the following way

successful decoding DSC new = DSC old + 1

if DSC new + 1 gt DSC0 rarr DSC new = DSC old

unsuccessful decoding DSC new = DSC old ndash 4

If DSC lt 0 the MS has detected a downlink signaling

failure

Minimum decoding

Monitoring of all BCCH carriers given in the BCCH allocation

(neighbor cells) of the serving cell

Taking at least 5 samples of the received level from the serving cell

(on paging sub-channel) as well as from the neighbor cells

=gt AV_RXLEV(serving cell) and AV_RXLEV (neighbor cell)

Decoding of full BCCH data of the serving cell at least every 30 sec

Decoding of BCCH data of the 6 strongest neighbor cells at least

every 5 minutes

From the radio propagation point of view it is

worth to select a new (neighbor) cell if the

received level from that neighbor cell exceeds the

received level of the current serving cell For

phase 1 MS this is expressed using the C1

criterion

C1 (neighbor cell) gt C1 (serving cell)

For phase 2 MS a modified path loss criterion the C2 criterion

is usedThe C2 criterion depends on the value of a timer T

which is called PENALTY_TIMERThe timer T is started in the MS

for each cell in the list of the 6 strongest neighbor cells as soon

as it is placed on the list Timer T is reset to 0 if the cell is

removed from the list

During penalty time

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

After penalty time

C2 = C1 + CELL_RESELECT_OFFSET

For penalty time = 31 the whole time

C2 = C1 - CELL_RESELECT_OFFSET

CELL_RESELECT_OFFSET TEMPORARY_OFFSET and

PENALTY_TIME are cell reselection parameters which

are broadcasted on the BCCH of the cell in the

system informations if CELL_RESLECT_PARAM_IND

(Cell Reselection Parameter Indication) is set to 1

A negative TEMPORARY_OFFSET reduces the

priority of a cell in the list of strongest neighbor

cells

A positive CELL_RESELECT_OFFSET increases the

priority of a cell in the list of strongest neighbor

cells

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells

When a mobile reaches the coverage area of a (neighbor) micro cell given

by the C1 criterion this cell becomes effectively excluded from reselection

during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell be-fore PENALTY_TIME is reached and hence the micro cell is not

selected

In contrast a slow moving mobile is assumed to be still within the coverage

area of the micro cell when PENALTY_TIME has expired

Applying the positive CELL_RESELECT_OFFSET this cell is selected with

preference

Triggers for Cell Reselection

Cell reselection is triggered by the following conditions

1 C1 lt 0 for the serving cell for a period of 5 s

2 MS detects a downlink signaling failure

3 Serving cell becomes barred

Phase 1 MS

C1 (serving cell) lt C1 (suitable neighbor cell) if the suitable neighbor cell is

in the same location area

C1 (serving cell) + CELL_RESELECT_HYSTERESIS lt C1 (suitable

neighbor cell) if the suitable neighbor cell is in another location area for a

period of 5 sec

Phase 2 MS

C2 (serving cell) lt C2 (suitable neighbor cell) if the suitable neighbor cell is in

the same location area

C2 (serving cell) + CELL_RESELECT_HYSTERESIS lt C2 (suitable neighbor

cell) if the suitable neighbor cell is in another location area for a period of 5

sec

A random access attempt is unsuccessful even after the maximum number

of repetitions

For phase 2 there is the additional trigger

A location update request has been rejected with cause rdquolocation area not

allowedrdquo

PARAMETERS SETTING

BA (BCCH) - BCCH Allocation broadcasted on BCCH

In each cell the absolute radio frequency carrier number

BCCH_ARFCN_NC(n) of each of its neighbor cell n has to be

known This information is broadcasted as the so-called BCCH

Allocation to all MS in the respective cell On the

corresponding frequencies the MS take measurement samples

of the received level used for cell selection reselection

Furthermore the BCCH of neighbor cells has to be decoded by

the MS (at least every 5 min) to know the current values of the

control parameters for the reselection algorithm

PARAMETERS SETTING

Object DB Name Range Step Size

Unit ADJC BCCHFREQ 01023 1

PARAMETERS SETTING

CELL_BAR_ACCESS - Cell Barred for Access

A mobile station cannot camp on a barred cell ie a barred cell is not

selected by the cell selectionreselection procedure

Mobile stations which camp on a cell while it becomes barred initialize the

reselection procedure to find a new (unbarred) cell ie traffic load is

distributed to neighbor cells

This means that eg neither a call nor a location update can start in a

barred cell

However a cell barred for access is not barred for incoming handovers To

barr a cell completely eg for maintenance reasons also incoming

handovers have to be avoided

To reduce overload in a certain cell more moderately without distributing

the overload to neighbor cells barring of access classes has to be used

Barring access for an access class does not trigger a cell reselection for

MSs of that class

Object DB Name Range

BTS CELLBARR FALSETRUE

RXLEV_ACCESS_MIN - Minimum Downlink Received Level for Cell to be

selected

The parameter RXLEV_ACCESS_MIN determines the cell border for a MS in idle

mode by means of the C1 or C2 criterion respectively

Choosing a high value reduces the risk of a handover immediately after call

setup

On the other hand the value has to be low enough to achieve a sufficient overlap

between adjacent cells (especially if they belong to different location areas)

It has to be observed that the overlap may be different for mobiles of different

power classes (refer to MS_TXPWR_MAX_CCH)

In any case RXLEV_ACCESS_MIN has to be above the MS receiver sensitivity level

(-100 dBm for DCS1800 -102 dBm for GSM handhelds -104 dBm for other GSM

MS)

Furthermore it has to harmonize with the

handover thresholds (RXLEV_MIN L_RXLEV_HO)

Object DB Name Range Step Size Unit

BTS RXLEVAMI 063 1

RXLEV

MS_TXPWR_MAX_CCH - Maximum allowed MS Transmit

Power on RACH

The transmit power level the MS uses for the access on the

Random Access Channel is given by the minimum of two

values

the maximum possible transmit power of the MS (given by

the power class P of the MS) the maximum allowed power

for access within the respective cell

(given by MS_TXP WR_MAX_CCH)

This parameter affects the

the random access procedure

the cell selection procedure

Random access

If there is a collision of channel requests on the random access

channel the one with the higher received level has a good chance

to be decoded and to get a response by the BTS

Hence MS with higher output power are preferred This imbalance

can be avoided by choosing a low maximum allowed transmit power

PARAMETERS SETTING

Cell Selection

To be selected by the cell selection procedure a cell has to fulfill the

C1 criterion

C1 gt 0 where

C1 = AV_RXLEV - RXLEV_ACCESS_MIN - Max(0

MS_TXPWR_MAX_CCH - P )

Choosing for example MS_TXPWR_MAX_CCH = Pmin where Pmin is

the output power level for the minimum power class 5 (29 dBm)

the C1 criterion reduces to AV_RXLEV gt RXLEV_ACCESS_MIN

for MSs of all power classes Hence the same idle mode cell border

is seen by each mobile

Choosing for example MS_TXPWR_MAX_CCH = Pmax where Pmax is

the output power level for the maximum power class 1 (43 dBm)

the C1 criterion reduces to

AV_RXLEV gt RXLEV_ACCESS_MIN + ( MS_TXPWR_MAX_CCH - P )

for MSs of all power classes Hence a larger cell radius is seen by a

mobile of higher output power than by a mobile of lower output

power On the other hand one can ensure by this mechanism that a

certain uplink received level is exceeded by each MS independent of

its power class

Object DB Name Range Step Size Unit

BTS MSTXPMAXCH 031 1 2 dB

MS_TXPWR_MAX_CCH - Maximum allowed MS transmit power on RACH

default 2

MS GSM900 MS GSM900 MS DCS1800

Phase 1 Phase 2

0 = 43 dBm 0 = 39 dBm 0 = 30 dBm

1 = 41 dBm 1 = 39 dBm 1 = 28 dBm

2 = 39 dBm 2 = 39 dBm 2 = 26 dBm

3 = 37 dBm 3 = 37 dBm 3 = 24 dBm

15 = 13dBm 19 = 5 dBm 15 = 0 dBm

16-31 = 13 dBm 20-31 = 5 dBm 16-31 = 0 dBm

POWER_OFFSET - Additional Parameter for Class 3

DCS1800 MS

The parameter POWER_OFFSET is only used by class 3

DCS1800 MS to calculate the C1-criterion described as

follows

C1 = AV_RXLEV - RXLEV_ACCESS_MIN -

Max(0MS_TXPWR_MAX_CCH + POWER_OFFSET- P)

Object DB Name Range Step Size Unit

BTS PWROFS 03 1 2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for Reselection of a Cell

from another Location Area

In idle mode the MS selects a new (neighbor) cell if the received level of the

neighbor cell exceeds the received level of the current cell in order to be

served by the cell with the expected best link quality However due to

fading effects the propagation conditions may change rapidly and

therefore a reselection may occur very frequently

If the cells involved in the reselection process belong to the same location

area frequent cell reselection does not have an effect on the network

performance

But if the involved cells belong to different location area the reselection of

a new cell triggers a location update procedure which causes signaling

load (eg on the SDCCH) and involves all network elements

To avoid unnecessary signaling load by forward and backward reselection due to fading

a hysteresis given by the parameter CELL_RESELECT_HYSTERESIS is introduced ie

a cell from another location area is selected only if the corresponding received level

exceeds the level of the current serving cell by the value of this parameter This is

expressed in terms of the C1 (phase 1) or C2 (phase 2) criterion

C1 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C1 (suitable neighbor cell)

or

C2 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C2 (suitable neighbor cell)

respectively

The adjustment of CELL_RESELECT_HYSTERESES should be a compromise between

reduction of unnecessary location updates (high value) and

selection of the cell with best reception quality (low value)

Object DB Name Range Step Size Unit

BTS CELLRESH 07 1

2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for

reselection of a cell from another location area

default 2

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter

Indication

CELL_RESELECT_PARAM_IND=1

The cell reselection parameters CELL_RESELECT_OFFSET

TEMPORARY_OFFSET and PENALTY_TIME used for the C2 criterion as well as

the parameter CELL_BAR_QUALIFY are broadcasted on the BCCH These

parameters are taken into account by phase 2 MS but are ignored by

phase 1 MS

CELL_RESELECT_PARAM_IND = 0

The cell reselection parameters and CELL_BAR_QUALIFY are not

broadcasted on the BCCH

A phase 2 MS then uses the value 0 for all these parameters ie C1 = C2

Object DB Name Range

BTS CRESPARI 01

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter Indication default 1

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

Based on these measurements samples over a period of 3 to 5

seconds the MS can estimate whether a cell will be an

appropriate serving cell from the radio propagation point of

view ie whether there will be a sufficient rdquolink qualityrdquo

C1 Criterion for Cell Selection

C1 = AV_RXLEV - RXLEV_ACCESS_MIN - max (0

MS_TXPWR_MAX_CCH - P )

RXLEV_ACCESS_MIN minimum received level at the MS

required for access to the system

MS_TXPWR_MAX_CCH maximum allowed MS transmit

power on RACH

P is the maximum RF output power of the MS usually 33dBm for

a handheld GSM900 and 30dBm for a handheld GSM1800 MS

Often the latter term in C1 equals 0 and equation can be simplified

to

C1 = A = AV_RXLEV minus RX_ACCESS_MIN

For example if the minimum allowed level to gain access to a

cell is minus100dBm and the received average level at the cellrsquos

BCCH frequency is -80 dBm MS calculates C1 as +20 for that

particular cell MS camps to the cell with the highest C1

value

There is an exception to the standard procedure described

above When MS evaluates C1 values for cells belonging to a

different Location Area (LA) it subtracts a parameter called

CELL_RESELECT_HYSTERESIS from the C1 value which means

that those cells are given a negative offset

The reason for this is that changing LA requires a Location

Update (LU) procedure that consumes network signaling

capacity Thus by assigning a negative offset to C1

unnecessary LUs caused by slow fading can be reduced MS

receives information of the cell dependent

CELL_RESELECT_HYSTERESIS values through BCCH

During cell selection procedure the MS will select only those

cells which have C1 gt 0

C1 Examples

For a system where the minimum access level is -104 then

C1 has a minimum value of 0 but you will sometimes see a

minimum of 1 - this is due to the mobile functionality since a value

of 0 actually would mean NO signal and no detection should have

occurred

bull screen 31 on pocket TEMS

C1c31 18-26 displayed

cell reselection hystresis =6 is displayed

bull Beside the C1 radio criterion there are some other criteria

(administrative and traffic control) for a cell to be suitable

A Suitable Cell is defined as a cell which

1048698 is part of the selected PLMN

1048698 is unbarred (parameter CELL_BAR_ACCESS = 0)

1048698 has a value C1 gt 0

1048698 is not in a location area forbidden for national roaming

To allow eg emergency calls the conditions for a serving cell

are less restrictive

Suitable Cell

An Acceptable Cell is defined as a cell which

1048698 is unbarred

1048698 has a parameter C1 gt 0

The general strategy for cell selection is to find the rdquosuitable

cellrdquo with the highest C1 (best estimated link quality) If no

suitable cell can be found an rdquoacceptable cellrdquo is selected

Cell Selection with Stored BCCH Information

Optionally the MS may store information on

received level on BCCH carriers when switched

off

When switched on the MS first performs

measurements on these carriers If cell selection

for the corresponding cells is not successful

normal cell selection is carried out

Phase 2 Cell reselection criterion C2 is defined as

C2 = C1 + CELL_RESELECT_OFFSET minus TEMPORARY_OFFSET

If CELL RESELECT PARAM IND = TRUE then

If the counter T lt PENALTY TIME

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY OFFSET

If the counter T gt= PENALTY TIME

C2 = C1 + CELL_RESELECT_OFFSET

13

If the neighbour is the last serving cell

T = PENALTY TIME and

C2 = C1 + CELL_RESELECT_OFFSET

The timer T is started separately for each cell in the list of the six

strongest cells immediately after it is placed on the list MS camps

in the cell with the highest C2 value

15

The criterion C2 is applied in hierarchical cell structures to keep fast

moving MS in an upper layer and slow moving MS in micro cells It is

assumed that a fast moving MS passes through the micro cell before

PENALTY_TIME is reached This efficiently prevents unnecessary LUs and

thus saves network signaling capacity As in the case of C1 MS receives

the C2 parameter information through BCCH A parameter called

CELL_RESELECT_PARAM_IND informs MS about which reselection

criterion (C1 or C2) is used in the cell It is broadcast on the BCCH

The following actions are performed by the MS to detect whether or not a

cell reselection is necessary

Detection of a Downlink Signaling Failure ndash The downlink signaling failure counter DSC is a counter running in the

MS The starting value of this counter is called DSC0 and is set by the

MS to the following value

DSC0 = round(90 BS_PA_MFRMS)

The value of BS_PA_MFRMS is broadcasted in the system informations on

the BCCH of the serving cell Each BS_PA_MFRMS the MS attempts to

decode the messages on its paging sub-channel Depending on whether or

not this decoding is successful the value of the downlink signaling failure

counter DSC is modified in the following way

successful decoding DSC new = DSC old + 1

if DSC new + 1 gt DSC0 rarr DSC new = DSC old

unsuccessful decoding DSC new = DSC old ndash 4

If DSC lt 0 the MS has detected a downlink signaling

failure

Minimum decoding

Monitoring of all BCCH carriers given in the BCCH allocation

(neighbor cells) of the serving cell

Taking at least 5 samples of the received level from the serving cell

(on paging sub-channel) as well as from the neighbor cells

=gt AV_RXLEV(serving cell) and AV_RXLEV (neighbor cell)

Decoding of full BCCH data of the serving cell at least every 30 sec

Decoding of BCCH data of the 6 strongest neighbor cells at least

every 5 minutes

From the radio propagation point of view it is

worth to select a new (neighbor) cell if the

received level from that neighbor cell exceeds the

received level of the current serving cell For

phase 1 MS this is expressed using the C1

criterion

C1 (neighbor cell) gt C1 (serving cell)

For phase 2 MS a modified path loss criterion the C2 criterion

is usedThe C2 criterion depends on the value of a timer T

which is called PENALTY_TIMERThe timer T is started in the MS

for each cell in the list of the 6 strongest neighbor cells as soon

as it is placed on the list Timer T is reset to 0 if the cell is

removed from the list

During penalty time

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

After penalty time

C2 = C1 + CELL_RESELECT_OFFSET

For penalty time = 31 the whole time

C2 = C1 - CELL_RESELECT_OFFSET

CELL_RESELECT_OFFSET TEMPORARY_OFFSET and

PENALTY_TIME are cell reselection parameters which

are broadcasted on the BCCH of the cell in the

system informations if CELL_RESLECT_PARAM_IND

(Cell Reselection Parameter Indication) is set to 1

A negative TEMPORARY_OFFSET reduces the

priority of a cell in the list of strongest neighbor

cells

A positive CELL_RESELECT_OFFSET increases the

priority of a cell in the list of strongest neighbor

cells

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells

When a mobile reaches the coverage area of a (neighbor) micro cell given

by the C1 criterion this cell becomes effectively excluded from reselection

during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell be-fore PENALTY_TIME is reached and hence the micro cell is not

selected

In contrast a slow moving mobile is assumed to be still within the coverage

area of the micro cell when PENALTY_TIME has expired

Applying the positive CELL_RESELECT_OFFSET this cell is selected with

preference

Triggers for Cell Reselection

Cell reselection is triggered by the following conditions

1 C1 lt 0 for the serving cell for a period of 5 s

2 MS detects a downlink signaling failure

3 Serving cell becomes barred

Phase 1 MS

C1 (serving cell) lt C1 (suitable neighbor cell) if the suitable neighbor cell is

in the same location area

C1 (serving cell) + CELL_RESELECT_HYSTERESIS lt C1 (suitable

neighbor cell) if the suitable neighbor cell is in another location area for a

period of 5 sec

Phase 2 MS

C2 (serving cell) lt C2 (suitable neighbor cell) if the suitable neighbor cell is in

the same location area

C2 (serving cell) + CELL_RESELECT_HYSTERESIS lt C2 (suitable neighbor

cell) if the suitable neighbor cell is in another location area for a period of 5

sec

A random access attempt is unsuccessful even after the maximum number

of repetitions

For phase 2 there is the additional trigger

A location update request has been rejected with cause rdquolocation area not

allowedrdquo

PARAMETERS SETTING

BA (BCCH) - BCCH Allocation broadcasted on BCCH

In each cell the absolute radio frequency carrier number

BCCH_ARFCN_NC(n) of each of its neighbor cell n has to be

known This information is broadcasted as the so-called BCCH

Allocation to all MS in the respective cell On the

corresponding frequencies the MS take measurement samples

of the received level used for cell selection reselection

Furthermore the BCCH of neighbor cells has to be decoded by

the MS (at least every 5 min) to know the current values of the

control parameters for the reselection algorithm

PARAMETERS SETTING

Object DB Name Range Step Size

Unit ADJC BCCHFREQ 01023 1

PARAMETERS SETTING

CELL_BAR_ACCESS - Cell Barred for Access

A mobile station cannot camp on a barred cell ie a barred cell is not

selected by the cell selectionreselection procedure

Mobile stations which camp on a cell while it becomes barred initialize the

reselection procedure to find a new (unbarred) cell ie traffic load is

distributed to neighbor cells

This means that eg neither a call nor a location update can start in a

barred cell

However a cell barred for access is not barred for incoming handovers To

barr a cell completely eg for maintenance reasons also incoming

handovers have to be avoided

To reduce overload in a certain cell more moderately without distributing

the overload to neighbor cells barring of access classes has to be used

Barring access for an access class does not trigger a cell reselection for

MSs of that class

Object DB Name Range

BTS CELLBARR FALSETRUE

RXLEV_ACCESS_MIN - Minimum Downlink Received Level for Cell to be

selected

The parameter RXLEV_ACCESS_MIN determines the cell border for a MS in idle

mode by means of the C1 or C2 criterion respectively

Choosing a high value reduces the risk of a handover immediately after call

setup

On the other hand the value has to be low enough to achieve a sufficient overlap

between adjacent cells (especially if they belong to different location areas)

It has to be observed that the overlap may be different for mobiles of different

power classes (refer to MS_TXPWR_MAX_CCH)

In any case RXLEV_ACCESS_MIN has to be above the MS receiver sensitivity level

(-100 dBm for DCS1800 -102 dBm for GSM handhelds -104 dBm for other GSM

MS)

Furthermore it has to harmonize with the

handover thresholds (RXLEV_MIN L_RXLEV_HO)

Object DB Name Range Step Size Unit

BTS RXLEVAMI 063 1

RXLEV

MS_TXPWR_MAX_CCH - Maximum allowed MS Transmit

Power on RACH

The transmit power level the MS uses for the access on the

Random Access Channel is given by the minimum of two

values

the maximum possible transmit power of the MS (given by

the power class P of the MS) the maximum allowed power

for access within the respective cell

(given by MS_TXP WR_MAX_CCH)

This parameter affects the

the random access procedure

the cell selection procedure

Random access

If there is a collision of channel requests on the random access

channel the one with the higher received level has a good chance

to be decoded and to get a response by the BTS

Hence MS with higher output power are preferred This imbalance

can be avoided by choosing a low maximum allowed transmit power

PARAMETERS SETTING

Cell Selection

To be selected by the cell selection procedure a cell has to fulfill the

C1 criterion

C1 gt 0 where

C1 = AV_RXLEV - RXLEV_ACCESS_MIN - Max(0

MS_TXPWR_MAX_CCH - P )

Choosing for example MS_TXPWR_MAX_CCH = Pmin where Pmin is

the output power level for the minimum power class 5 (29 dBm)

the C1 criterion reduces to AV_RXLEV gt RXLEV_ACCESS_MIN

for MSs of all power classes Hence the same idle mode cell border

is seen by each mobile

Choosing for example MS_TXPWR_MAX_CCH = Pmax where Pmax is

the output power level for the maximum power class 1 (43 dBm)

the C1 criterion reduces to

AV_RXLEV gt RXLEV_ACCESS_MIN + ( MS_TXPWR_MAX_CCH - P )

for MSs of all power classes Hence a larger cell radius is seen by a

mobile of higher output power than by a mobile of lower output

power On the other hand one can ensure by this mechanism that a

certain uplink received level is exceeded by each MS independent of

its power class

Object DB Name Range Step Size Unit

BTS MSTXPMAXCH 031 1 2 dB

MS_TXPWR_MAX_CCH - Maximum allowed MS transmit power on RACH

default 2

MS GSM900 MS GSM900 MS DCS1800

Phase 1 Phase 2

0 = 43 dBm 0 = 39 dBm 0 = 30 dBm

1 = 41 dBm 1 = 39 dBm 1 = 28 dBm

2 = 39 dBm 2 = 39 dBm 2 = 26 dBm

3 = 37 dBm 3 = 37 dBm 3 = 24 dBm

15 = 13dBm 19 = 5 dBm 15 = 0 dBm

16-31 = 13 dBm 20-31 = 5 dBm 16-31 = 0 dBm

POWER_OFFSET - Additional Parameter for Class 3

DCS1800 MS

The parameter POWER_OFFSET is only used by class 3

DCS1800 MS to calculate the C1-criterion described as

follows

C1 = AV_RXLEV - RXLEV_ACCESS_MIN -

Max(0MS_TXPWR_MAX_CCH + POWER_OFFSET- P)

Object DB Name Range Step Size Unit

BTS PWROFS 03 1 2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for Reselection of a Cell

from another Location Area

In idle mode the MS selects a new (neighbor) cell if the received level of the

neighbor cell exceeds the received level of the current cell in order to be

served by the cell with the expected best link quality However due to

fading effects the propagation conditions may change rapidly and

therefore a reselection may occur very frequently

If the cells involved in the reselection process belong to the same location

area frequent cell reselection does not have an effect on the network

performance

But if the involved cells belong to different location area the reselection of

a new cell triggers a location update procedure which causes signaling

load (eg on the SDCCH) and involves all network elements

To avoid unnecessary signaling load by forward and backward reselection due to fading

a hysteresis given by the parameter CELL_RESELECT_HYSTERESIS is introduced ie

a cell from another location area is selected only if the corresponding received level

exceeds the level of the current serving cell by the value of this parameter This is

expressed in terms of the C1 (phase 1) or C2 (phase 2) criterion

C1 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C1 (suitable neighbor cell)

or

C2 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C2 (suitable neighbor cell)

respectively

The adjustment of CELL_RESELECT_HYSTERESES should be a compromise between

reduction of unnecessary location updates (high value) and

selection of the cell with best reception quality (low value)

Object DB Name Range Step Size Unit

BTS CELLRESH 07 1

2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for

reselection of a cell from another location area

default 2

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter

Indication

CELL_RESELECT_PARAM_IND=1

The cell reselection parameters CELL_RESELECT_OFFSET

TEMPORARY_OFFSET and PENALTY_TIME used for the C2 criterion as well as

the parameter CELL_BAR_QUALIFY are broadcasted on the BCCH These

parameters are taken into account by phase 2 MS but are ignored by

phase 1 MS

CELL_RESELECT_PARAM_IND = 0

The cell reselection parameters and CELL_BAR_QUALIFY are not

broadcasted on the BCCH

A phase 2 MS then uses the value 0 for all these parameters ie C1 = C2

Object DB Name Range

BTS CRESPARI 01

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter Indication default 1

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

RXLEV_ACCESS_MIN minimum received level at the MS

required for access to the system

MS_TXPWR_MAX_CCH maximum allowed MS transmit

power on RACH

P is the maximum RF output power of the MS usually 33dBm for

a handheld GSM900 and 30dBm for a handheld GSM1800 MS

Often the latter term in C1 equals 0 and equation can be simplified

to

C1 = A = AV_RXLEV minus RX_ACCESS_MIN

For example if the minimum allowed level to gain access to a

cell is minus100dBm and the received average level at the cellrsquos

BCCH frequency is -80 dBm MS calculates C1 as +20 for that

particular cell MS camps to the cell with the highest C1

value

There is an exception to the standard procedure described

above When MS evaluates C1 values for cells belonging to a

different Location Area (LA) it subtracts a parameter called

CELL_RESELECT_HYSTERESIS from the C1 value which means

that those cells are given a negative offset

The reason for this is that changing LA requires a Location

Update (LU) procedure that consumes network signaling

capacity Thus by assigning a negative offset to C1

unnecessary LUs caused by slow fading can be reduced MS

receives information of the cell dependent

CELL_RESELECT_HYSTERESIS values through BCCH

During cell selection procedure the MS will select only those

cells which have C1 gt 0

C1 Examples

For a system where the minimum access level is -104 then

C1 has a minimum value of 0 but you will sometimes see a

minimum of 1 - this is due to the mobile functionality since a value

of 0 actually would mean NO signal and no detection should have

occurred

bull screen 31 on pocket TEMS

C1c31 18-26 displayed

cell reselection hystresis =6 is displayed

bull Beside the C1 radio criterion there are some other criteria

(administrative and traffic control) for a cell to be suitable

A Suitable Cell is defined as a cell which

1048698 is part of the selected PLMN

1048698 is unbarred (parameter CELL_BAR_ACCESS = 0)

1048698 has a value C1 gt 0

1048698 is not in a location area forbidden for national roaming

To allow eg emergency calls the conditions for a serving cell

are less restrictive

Suitable Cell

An Acceptable Cell is defined as a cell which

1048698 is unbarred

1048698 has a parameter C1 gt 0

The general strategy for cell selection is to find the rdquosuitable

cellrdquo with the highest C1 (best estimated link quality) If no

suitable cell can be found an rdquoacceptable cellrdquo is selected

Cell Selection with Stored BCCH Information

Optionally the MS may store information on

received level on BCCH carriers when switched

off

When switched on the MS first performs

measurements on these carriers If cell selection

for the corresponding cells is not successful

normal cell selection is carried out

Phase 2 Cell reselection criterion C2 is defined as

C2 = C1 + CELL_RESELECT_OFFSET minus TEMPORARY_OFFSET

If CELL RESELECT PARAM IND = TRUE then

If the counter T lt PENALTY TIME

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY OFFSET

If the counter T gt= PENALTY TIME

C2 = C1 + CELL_RESELECT_OFFSET

13

If the neighbour is the last serving cell

T = PENALTY TIME and

C2 = C1 + CELL_RESELECT_OFFSET

The timer T is started separately for each cell in the list of the six

strongest cells immediately after it is placed on the list MS camps

in the cell with the highest C2 value

15

The criterion C2 is applied in hierarchical cell structures to keep fast

moving MS in an upper layer and slow moving MS in micro cells It is

assumed that a fast moving MS passes through the micro cell before

PENALTY_TIME is reached This efficiently prevents unnecessary LUs and

thus saves network signaling capacity As in the case of C1 MS receives

the C2 parameter information through BCCH A parameter called

CELL_RESELECT_PARAM_IND informs MS about which reselection

criterion (C1 or C2) is used in the cell It is broadcast on the BCCH

The following actions are performed by the MS to detect whether or not a

cell reselection is necessary

Detection of a Downlink Signaling Failure ndash The downlink signaling failure counter DSC is a counter running in the

MS The starting value of this counter is called DSC0 and is set by the

MS to the following value

DSC0 = round(90 BS_PA_MFRMS)

The value of BS_PA_MFRMS is broadcasted in the system informations on

the BCCH of the serving cell Each BS_PA_MFRMS the MS attempts to

decode the messages on its paging sub-channel Depending on whether or

not this decoding is successful the value of the downlink signaling failure

counter DSC is modified in the following way

successful decoding DSC new = DSC old + 1

if DSC new + 1 gt DSC0 rarr DSC new = DSC old

unsuccessful decoding DSC new = DSC old ndash 4

If DSC lt 0 the MS has detected a downlink signaling

failure

Minimum decoding

Monitoring of all BCCH carriers given in the BCCH allocation

(neighbor cells) of the serving cell

Taking at least 5 samples of the received level from the serving cell

(on paging sub-channel) as well as from the neighbor cells

=gt AV_RXLEV(serving cell) and AV_RXLEV (neighbor cell)

Decoding of full BCCH data of the serving cell at least every 30 sec

Decoding of BCCH data of the 6 strongest neighbor cells at least

every 5 minutes

From the radio propagation point of view it is

worth to select a new (neighbor) cell if the

received level from that neighbor cell exceeds the

received level of the current serving cell For

phase 1 MS this is expressed using the C1

criterion

C1 (neighbor cell) gt C1 (serving cell)

For phase 2 MS a modified path loss criterion the C2 criterion

is usedThe C2 criterion depends on the value of a timer T

which is called PENALTY_TIMERThe timer T is started in the MS

for each cell in the list of the 6 strongest neighbor cells as soon

as it is placed on the list Timer T is reset to 0 if the cell is

removed from the list

During penalty time

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

After penalty time

C2 = C1 + CELL_RESELECT_OFFSET

For penalty time = 31 the whole time

C2 = C1 - CELL_RESELECT_OFFSET

CELL_RESELECT_OFFSET TEMPORARY_OFFSET and

PENALTY_TIME are cell reselection parameters which

are broadcasted on the BCCH of the cell in the

system informations if CELL_RESLECT_PARAM_IND

(Cell Reselection Parameter Indication) is set to 1

A negative TEMPORARY_OFFSET reduces the

priority of a cell in the list of strongest neighbor

cells

A positive CELL_RESELECT_OFFSET increases the

priority of a cell in the list of strongest neighbor

cells

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells

When a mobile reaches the coverage area of a (neighbor) micro cell given

by the C1 criterion this cell becomes effectively excluded from reselection

during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell be-fore PENALTY_TIME is reached and hence the micro cell is not

selected

In contrast a slow moving mobile is assumed to be still within the coverage

area of the micro cell when PENALTY_TIME has expired

Applying the positive CELL_RESELECT_OFFSET this cell is selected with

preference

Triggers for Cell Reselection

Cell reselection is triggered by the following conditions

1 C1 lt 0 for the serving cell for a period of 5 s

2 MS detects a downlink signaling failure

3 Serving cell becomes barred

Phase 1 MS

C1 (serving cell) lt C1 (suitable neighbor cell) if the suitable neighbor cell is

in the same location area

C1 (serving cell) + CELL_RESELECT_HYSTERESIS lt C1 (suitable

neighbor cell) if the suitable neighbor cell is in another location area for a

period of 5 sec

Phase 2 MS

C2 (serving cell) lt C2 (suitable neighbor cell) if the suitable neighbor cell is in

the same location area

C2 (serving cell) + CELL_RESELECT_HYSTERESIS lt C2 (suitable neighbor

cell) if the suitable neighbor cell is in another location area for a period of 5

sec

A random access attempt is unsuccessful even after the maximum number

of repetitions

For phase 2 there is the additional trigger

A location update request has been rejected with cause rdquolocation area not

allowedrdquo

PARAMETERS SETTING

BA (BCCH) - BCCH Allocation broadcasted on BCCH

In each cell the absolute radio frequency carrier number

BCCH_ARFCN_NC(n) of each of its neighbor cell n has to be

known This information is broadcasted as the so-called BCCH

Allocation to all MS in the respective cell On the

corresponding frequencies the MS take measurement samples

of the received level used for cell selection reselection

Furthermore the BCCH of neighbor cells has to be decoded by

the MS (at least every 5 min) to know the current values of the

control parameters for the reselection algorithm

PARAMETERS SETTING

Object DB Name Range Step Size

Unit ADJC BCCHFREQ 01023 1

PARAMETERS SETTING

CELL_BAR_ACCESS - Cell Barred for Access

A mobile station cannot camp on a barred cell ie a barred cell is not

selected by the cell selectionreselection procedure

Mobile stations which camp on a cell while it becomes barred initialize the

reselection procedure to find a new (unbarred) cell ie traffic load is

distributed to neighbor cells

This means that eg neither a call nor a location update can start in a

barred cell

However a cell barred for access is not barred for incoming handovers To

barr a cell completely eg for maintenance reasons also incoming

handovers have to be avoided

To reduce overload in a certain cell more moderately without distributing

the overload to neighbor cells barring of access classes has to be used

Barring access for an access class does not trigger a cell reselection for

MSs of that class

Object DB Name Range

BTS CELLBARR FALSETRUE

RXLEV_ACCESS_MIN - Minimum Downlink Received Level for Cell to be

selected

The parameter RXLEV_ACCESS_MIN determines the cell border for a MS in idle

mode by means of the C1 or C2 criterion respectively

Choosing a high value reduces the risk of a handover immediately after call

setup

On the other hand the value has to be low enough to achieve a sufficient overlap

between adjacent cells (especially if they belong to different location areas)

It has to be observed that the overlap may be different for mobiles of different

power classes (refer to MS_TXPWR_MAX_CCH)

In any case RXLEV_ACCESS_MIN has to be above the MS receiver sensitivity level

(-100 dBm for DCS1800 -102 dBm for GSM handhelds -104 dBm for other GSM

MS)

Furthermore it has to harmonize with the

handover thresholds (RXLEV_MIN L_RXLEV_HO)

Object DB Name Range Step Size Unit

BTS RXLEVAMI 063 1

RXLEV

MS_TXPWR_MAX_CCH - Maximum allowed MS Transmit

Power on RACH

The transmit power level the MS uses for the access on the

Random Access Channel is given by the minimum of two

values

the maximum possible transmit power of the MS (given by

the power class P of the MS) the maximum allowed power

for access within the respective cell

(given by MS_TXP WR_MAX_CCH)

This parameter affects the

the random access procedure

the cell selection procedure

Random access

If there is a collision of channel requests on the random access

channel the one with the higher received level has a good chance

to be decoded and to get a response by the BTS

Hence MS with higher output power are preferred This imbalance

can be avoided by choosing a low maximum allowed transmit power

PARAMETERS SETTING

Cell Selection

To be selected by the cell selection procedure a cell has to fulfill the

C1 criterion

C1 gt 0 where

C1 = AV_RXLEV - RXLEV_ACCESS_MIN - Max(0

MS_TXPWR_MAX_CCH - P )

Choosing for example MS_TXPWR_MAX_CCH = Pmin where Pmin is

the output power level for the minimum power class 5 (29 dBm)

the C1 criterion reduces to AV_RXLEV gt RXLEV_ACCESS_MIN

for MSs of all power classes Hence the same idle mode cell border

is seen by each mobile

Choosing for example MS_TXPWR_MAX_CCH = Pmax where Pmax is

the output power level for the maximum power class 1 (43 dBm)

the C1 criterion reduces to

AV_RXLEV gt RXLEV_ACCESS_MIN + ( MS_TXPWR_MAX_CCH - P )

for MSs of all power classes Hence a larger cell radius is seen by a

mobile of higher output power than by a mobile of lower output

power On the other hand one can ensure by this mechanism that a

certain uplink received level is exceeded by each MS independent of

its power class

Object DB Name Range Step Size Unit

BTS MSTXPMAXCH 031 1 2 dB

MS_TXPWR_MAX_CCH - Maximum allowed MS transmit power on RACH

default 2

MS GSM900 MS GSM900 MS DCS1800

Phase 1 Phase 2

0 = 43 dBm 0 = 39 dBm 0 = 30 dBm

1 = 41 dBm 1 = 39 dBm 1 = 28 dBm

2 = 39 dBm 2 = 39 dBm 2 = 26 dBm

3 = 37 dBm 3 = 37 dBm 3 = 24 dBm

15 = 13dBm 19 = 5 dBm 15 = 0 dBm

16-31 = 13 dBm 20-31 = 5 dBm 16-31 = 0 dBm

POWER_OFFSET - Additional Parameter for Class 3

DCS1800 MS

The parameter POWER_OFFSET is only used by class 3

DCS1800 MS to calculate the C1-criterion described as

follows

C1 = AV_RXLEV - RXLEV_ACCESS_MIN -

Max(0MS_TXPWR_MAX_CCH + POWER_OFFSET- P)

Object DB Name Range Step Size Unit

BTS PWROFS 03 1 2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for Reselection of a Cell

from another Location Area

In idle mode the MS selects a new (neighbor) cell if the received level of the

neighbor cell exceeds the received level of the current cell in order to be

served by the cell with the expected best link quality However due to

fading effects the propagation conditions may change rapidly and

therefore a reselection may occur very frequently

If the cells involved in the reselection process belong to the same location

area frequent cell reselection does not have an effect on the network

performance

But if the involved cells belong to different location area the reselection of

a new cell triggers a location update procedure which causes signaling

load (eg on the SDCCH) and involves all network elements

To avoid unnecessary signaling load by forward and backward reselection due to fading

a hysteresis given by the parameter CELL_RESELECT_HYSTERESIS is introduced ie

a cell from another location area is selected only if the corresponding received level

exceeds the level of the current serving cell by the value of this parameter This is

expressed in terms of the C1 (phase 1) or C2 (phase 2) criterion

C1 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C1 (suitable neighbor cell)

or

C2 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C2 (suitable neighbor cell)

respectively

The adjustment of CELL_RESELECT_HYSTERESES should be a compromise between

reduction of unnecessary location updates (high value) and

selection of the cell with best reception quality (low value)

Object DB Name Range Step Size Unit

BTS CELLRESH 07 1

2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for

reselection of a cell from another location area

default 2

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter

Indication

CELL_RESELECT_PARAM_IND=1

The cell reselection parameters CELL_RESELECT_OFFSET

TEMPORARY_OFFSET and PENALTY_TIME used for the C2 criterion as well as

the parameter CELL_BAR_QUALIFY are broadcasted on the BCCH These

parameters are taken into account by phase 2 MS but are ignored by

phase 1 MS

CELL_RESELECT_PARAM_IND = 0

The cell reselection parameters and CELL_BAR_QUALIFY are not

broadcasted on the BCCH

A phase 2 MS then uses the value 0 for all these parameters ie C1 = C2

Object DB Name Range

BTS CRESPARI 01

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter Indication default 1

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

For example if the minimum allowed level to gain access to a

cell is minus100dBm and the received average level at the cellrsquos

BCCH frequency is -80 dBm MS calculates C1 as +20 for that

particular cell MS camps to the cell with the highest C1

value

There is an exception to the standard procedure described

above When MS evaluates C1 values for cells belonging to a

different Location Area (LA) it subtracts a parameter called

CELL_RESELECT_HYSTERESIS from the C1 value which means

that those cells are given a negative offset

The reason for this is that changing LA requires a Location

Update (LU) procedure that consumes network signaling

capacity Thus by assigning a negative offset to C1

unnecessary LUs caused by slow fading can be reduced MS

receives information of the cell dependent

CELL_RESELECT_HYSTERESIS values through BCCH

During cell selection procedure the MS will select only those

cells which have C1 gt 0

C1 Examples

For a system where the minimum access level is -104 then

C1 has a minimum value of 0 but you will sometimes see a

minimum of 1 - this is due to the mobile functionality since a value

of 0 actually would mean NO signal and no detection should have

occurred

bull screen 31 on pocket TEMS

C1c31 18-26 displayed

cell reselection hystresis =6 is displayed

bull Beside the C1 radio criterion there are some other criteria

(administrative and traffic control) for a cell to be suitable

A Suitable Cell is defined as a cell which

1048698 is part of the selected PLMN

1048698 is unbarred (parameter CELL_BAR_ACCESS = 0)

1048698 has a value C1 gt 0

1048698 is not in a location area forbidden for national roaming

To allow eg emergency calls the conditions for a serving cell

are less restrictive

Suitable Cell

An Acceptable Cell is defined as a cell which

1048698 is unbarred

1048698 has a parameter C1 gt 0

The general strategy for cell selection is to find the rdquosuitable

cellrdquo with the highest C1 (best estimated link quality) If no

suitable cell can be found an rdquoacceptable cellrdquo is selected

Cell Selection with Stored BCCH Information

Optionally the MS may store information on

received level on BCCH carriers when switched

off

When switched on the MS first performs

measurements on these carriers If cell selection

for the corresponding cells is not successful

normal cell selection is carried out

Phase 2 Cell reselection criterion C2 is defined as

C2 = C1 + CELL_RESELECT_OFFSET minus TEMPORARY_OFFSET

If CELL RESELECT PARAM IND = TRUE then

If the counter T lt PENALTY TIME

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY OFFSET

If the counter T gt= PENALTY TIME

C2 = C1 + CELL_RESELECT_OFFSET

13

If the neighbour is the last serving cell

T = PENALTY TIME and

C2 = C1 + CELL_RESELECT_OFFSET

The timer T is started separately for each cell in the list of the six

strongest cells immediately after it is placed on the list MS camps

in the cell with the highest C2 value

15

The criterion C2 is applied in hierarchical cell structures to keep fast

moving MS in an upper layer and slow moving MS in micro cells It is

assumed that a fast moving MS passes through the micro cell before

PENALTY_TIME is reached This efficiently prevents unnecessary LUs and

thus saves network signaling capacity As in the case of C1 MS receives

the C2 parameter information through BCCH A parameter called

CELL_RESELECT_PARAM_IND informs MS about which reselection

criterion (C1 or C2) is used in the cell It is broadcast on the BCCH

The following actions are performed by the MS to detect whether or not a

cell reselection is necessary

Detection of a Downlink Signaling Failure ndash The downlink signaling failure counter DSC is a counter running in the

MS The starting value of this counter is called DSC0 and is set by the

MS to the following value

DSC0 = round(90 BS_PA_MFRMS)

The value of BS_PA_MFRMS is broadcasted in the system informations on

the BCCH of the serving cell Each BS_PA_MFRMS the MS attempts to

decode the messages on its paging sub-channel Depending on whether or

not this decoding is successful the value of the downlink signaling failure

counter DSC is modified in the following way

successful decoding DSC new = DSC old + 1

if DSC new + 1 gt DSC0 rarr DSC new = DSC old

unsuccessful decoding DSC new = DSC old ndash 4

If DSC lt 0 the MS has detected a downlink signaling

failure

Minimum decoding

Monitoring of all BCCH carriers given in the BCCH allocation

(neighbor cells) of the serving cell

Taking at least 5 samples of the received level from the serving cell

(on paging sub-channel) as well as from the neighbor cells

=gt AV_RXLEV(serving cell) and AV_RXLEV (neighbor cell)

Decoding of full BCCH data of the serving cell at least every 30 sec

Decoding of BCCH data of the 6 strongest neighbor cells at least

every 5 minutes

From the radio propagation point of view it is

worth to select a new (neighbor) cell if the

received level from that neighbor cell exceeds the

received level of the current serving cell For

phase 1 MS this is expressed using the C1

criterion

C1 (neighbor cell) gt C1 (serving cell)

For phase 2 MS a modified path loss criterion the C2 criterion

is usedThe C2 criterion depends on the value of a timer T

which is called PENALTY_TIMERThe timer T is started in the MS

for each cell in the list of the 6 strongest neighbor cells as soon

as it is placed on the list Timer T is reset to 0 if the cell is

removed from the list

During penalty time

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

After penalty time

C2 = C1 + CELL_RESELECT_OFFSET

For penalty time = 31 the whole time

C2 = C1 - CELL_RESELECT_OFFSET

CELL_RESELECT_OFFSET TEMPORARY_OFFSET and

PENALTY_TIME are cell reselection parameters which

are broadcasted on the BCCH of the cell in the

system informations if CELL_RESLECT_PARAM_IND

(Cell Reselection Parameter Indication) is set to 1

A negative TEMPORARY_OFFSET reduces the

priority of a cell in the list of strongest neighbor

cells

A positive CELL_RESELECT_OFFSET increases the

priority of a cell in the list of strongest neighbor

cells

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells

When a mobile reaches the coverage area of a (neighbor) micro cell given

by the C1 criterion this cell becomes effectively excluded from reselection

during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell be-fore PENALTY_TIME is reached and hence the micro cell is not

selected

In contrast a slow moving mobile is assumed to be still within the coverage

area of the micro cell when PENALTY_TIME has expired

Applying the positive CELL_RESELECT_OFFSET this cell is selected with

preference

Triggers for Cell Reselection

Cell reselection is triggered by the following conditions

1 C1 lt 0 for the serving cell for a period of 5 s

2 MS detects a downlink signaling failure

3 Serving cell becomes barred

Phase 1 MS

C1 (serving cell) lt C1 (suitable neighbor cell) if the suitable neighbor cell is

in the same location area

C1 (serving cell) + CELL_RESELECT_HYSTERESIS lt C1 (suitable

neighbor cell) if the suitable neighbor cell is in another location area for a

period of 5 sec

Phase 2 MS

C2 (serving cell) lt C2 (suitable neighbor cell) if the suitable neighbor cell is in

the same location area

C2 (serving cell) + CELL_RESELECT_HYSTERESIS lt C2 (suitable neighbor

cell) if the suitable neighbor cell is in another location area for a period of 5

sec

A random access attempt is unsuccessful even after the maximum number

of repetitions

For phase 2 there is the additional trigger

A location update request has been rejected with cause rdquolocation area not

allowedrdquo

PARAMETERS SETTING

BA (BCCH) - BCCH Allocation broadcasted on BCCH

In each cell the absolute radio frequency carrier number

BCCH_ARFCN_NC(n) of each of its neighbor cell n has to be

known This information is broadcasted as the so-called BCCH

Allocation to all MS in the respective cell On the

corresponding frequencies the MS take measurement samples

of the received level used for cell selection reselection

Furthermore the BCCH of neighbor cells has to be decoded by

the MS (at least every 5 min) to know the current values of the

control parameters for the reselection algorithm

PARAMETERS SETTING

Object DB Name Range Step Size

Unit ADJC BCCHFREQ 01023 1

PARAMETERS SETTING

CELL_BAR_ACCESS - Cell Barred for Access

A mobile station cannot camp on a barred cell ie a barred cell is not

selected by the cell selectionreselection procedure

Mobile stations which camp on a cell while it becomes barred initialize the

reselection procedure to find a new (unbarred) cell ie traffic load is

distributed to neighbor cells

This means that eg neither a call nor a location update can start in a

barred cell

However a cell barred for access is not barred for incoming handovers To

barr a cell completely eg for maintenance reasons also incoming

handovers have to be avoided

To reduce overload in a certain cell more moderately without distributing

the overload to neighbor cells barring of access classes has to be used

Barring access for an access class does not trigger a cell reselection for

MSs of that class

Object DB Name Range

BTS CELLBARR FALSETRUE

RXLEV_ACCESS_MIN - Minimum Downlink Received Level for Cell to be

selected

The parameter RXLEV_ACCESS_MIN determines the cell border for a MS in idle

mode by means of the C1 or C2 criterion respectively

Choosing a high value reduces the risk of a handover immediately after call

setup

On the other hand the value has to be low enough to achieve a sufficient overlap

between adjacent cells (especially if they belong to different location areas)

It has to be observed that the overlap may be different for mobiles of different

power classes (refer to MS_TXPWR_MAX_CCH)

In any case RXLEV_ACCESS_MIN has to be above the MS receiver sensitivity level

(-100 dBm for DCS1800 -102 dBm for GSM handhelds -104 dBm for other GSM

MS)

Furthermore it has to harmonize with the

handover thresholds (RXLEV_MIN L_RXLEV_HO)

Object DB Name Range Step Size Unit

BTS RXLEVAMI 063 1

RXLEV

MS_TXPWR_MAX_CCH - Maximum allowed MS Transmit

Power on RACH

The transmit power level the MS uses for the access on the

Random Access Channel is given by the minimum of two

values

the maximum possible transmit power of the MS (given by

the power class P of the MS) the maximum allowed power

for access within the respective cell

(given by MS_TXP WR_MAX_CCH)

This parameter affects the

the random access procedure

the cell selection procedure

Random access

If there is a collision of channel requests on the random access

channel the one with the higher received level has a good chance

to be decoded and to get a response by the BTS

Hence MS with higher output power are preferred This imbalance

can be avoided by choosing a low maximum allowed transmit power

PARAMETERS SETTING

Cell Selection

To be selected by the cell selection procedure a cell has to fulfill the

C1 criterion

C1 gt 0 where

C1 = AV_RXLEV - RXLEV_ACCESS_MIN - Max(0

MS_TXPWR_MAX_CCH - P )

Choosing for example MS_TXPWR_MAX_CCH = Pmin where Pmin is

the output power level for the minimum power class 5 (29 dBm)

the C1 criterion reduces to AV_RXLEV gt RXLEV_ACCESS_MIN

for MSs of all power classes Hence the same idle mode cell border

is seen by each mobile

Choosing for example MS_TXPWR_MAX_CCH = Pmax where Pmax is

the output power level for the maximum power class 1 (43 dBm)

the C1 criterion reduces to

AV_RXLEV gt RXLEV_ACCESS_MIN + ( MS_TXPWR_MAX_CCH - P )

for MSs of all power classes Hence a larger cell radius is seen by a

mobile of higher output power than by a mobile of lower output

power On the other hand one can ensure by this mechanism that a

certain uplink received level is exceeded by each MS independent of

its power class

Object DB Name Range Step Size Unit

BTS MSTXPMAXCH 031 1 2 dB

MS_TXPWR_MAX_CCH - Maximum allowed MS transmit power on RACH

default 2

MS GSM900 MS GSM900 MS DCS1800

Phase 1 Phase 2

0 = 43 dBm 0 = 39 dBm 0 = 30 dBm

1 = 41 dBm 1 = 39 dBm 1 = 28 dBm

2 = 39 dBm 2 = 39 dBm 2 = 26 dBm

3 = 37 dBm 3 = 37 dBm 3 = 24 dBm

15 = 13dBm 19 = 5 dBm 15 = 0 dBm

16-31 = 13 dBm 20-31 = 5 dBm 16-31 = 0 dBm

POWER_OFFSET - Additional Parameter for Class 3

DCS1800 MS

The parameter POWER_OFFSET is only used by class 3

DCS1800 MS to calculate the C1-criterion described as

follows

C1 = AV_RXLEV - RXLEV_ACCESS_MIN -

Max(0MS_TXPWR_MAX_CCH + POWER_OFFSET- P)

Object DB Name Range Step Size Unit

BTS PWROFS 03 1 2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for Reselection of a Cell

from another Location Area

In idle mode the MS selects a new (neighbor) cell if the received level of the

neighbor cell exceeds the received level of the current cell in order to be

served by the cell with the expected best link quality However due to

fading effects the propagation conditions may change rapidly and

therefore a reselection may occur very frequently

If the cells involved in the reselection process belong to the same location

area frequent cell reselection does not have an effect on the network

performance

But if the involved cells belong to different location area the reselection of

a new cell triggers a location update procedure which causes signaling

load (eg on the SDCCH) and involves all network elements

To avoid unnecessary signaling load by forward and backward reselection due to fading

a hysteresis given by the parameter CELL_RESELECT_HYSTERESIS is introduced ie

a cell from another location area is selected only if the corresponding received level

exceeds the level of the current serving cell by the value of this parameter This is

expressed in terms of the C1 (phase 1) or C2 (phase 2) criterion

C1 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C1 (suitable neighbor cell)

or

C2 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C2 (suitable neighbor cell)

respectively

The adjustment of CELL_RESELECT_HYSTERESES should be a compromise between

reduction of unnecessary location updates (high value) and

selection of the cell with best reception quality (low value)

Object DB Name Range Step Size Unit

BTS CELLRESH 07 1

2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for

reselection of a cell from another location area

default 2

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter

Indication

CELL_RESELECT_PARAM_IND=1

The cell reselection parameters CELL_RESELECT_OFFSET

TEMPORARY_OFFSET and PENALTY_TIME used for the C2 criterion as well as

the parameter CELL_BAR_QUALIFY are broadcasted on the BCCH These

parameters are taken into account by phase 2 MS but are ignored by

phase 1 MS

CELL_RESELECT_PARAM_IND = 0

The cell reselection parameters and CELL_BAR_QUALIFY are not

broadcasted on the BCCH

A phase 2 MS then uses the value 0 for all these parameters ie C1 = C2

Object DB Name Range

BTS CRESPARI 01

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter Indication default 1

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

The reason for this is that changing LA requires a Location

Update (LU) procedure that consumes network signaling

capacity Thus by assigning a negative offset to C1

unnecessary LUs caused by slow fading can be reduced MS

receives information of the cell dependent

CELL_RESELECT_HYSTERESIS values through BCCH

During cell selection procedure the MS will select only those

cells which have C1 gt 0

C1 Examples

For a system where the minimum access level is -104 then

C1 has a minimum value of 0 but you will sometimes see a

minimum of 1 - this is due to the mobile functionality since a value

of 0 actually would mean NO signal and no detection should have

occurred

bull screen 31 on pocket TEMS

C1c31 18-26 displayed

cell reselection hystresis =6 is displayed

bull Beside the C1 radio criterion there are some other criteria

(administrative and traffic control) for a cell to be suitable

A Suitable Cell is defined as a cell which

1048698 is part of the selected PLMN

1048698 is unbarred (parameter CELL_BAR_ACCESS = 0)

1048698 has a value C1 gt 0

1048698 is not in a location area forbidden for national roaming

To allow eg emergency calls the conditions for a serving cell

are less restrictive

Suitable Cell

An Acceptable Cell is defined as a cell which

1048698 is unbarred

1048698 has a parameter C1 gt 0

The general strategy for cell selection is to find the rdquosuitable

cellrdquo with the highest C1 (best estimated link quality) If no

suitable cell can be found an rdquoacceptable cellrdquo is selected

Cell Selection with Stored BCCH Information

Optionally the MS may store information on

received level on BCCH carriers when switched

off

When switched on the MS first performs

measurements on these carriers If cell selection

for the corresponding cells is not successful

normal cell selection is carried out

Phase 2 Cell reselection criterion C2 is defined as

C2 = C1 + CELL_RESELECT_OFFSET minus TEMPORARY_OFFSET

If CELL RESELECT PARAM IND = TRUE then

If the counter T lt PENALTY TIME

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY OFFSET

If the counter T gt= PENALTY TIME

C2 = C1 + CELL_RESELECT_OFFSET

13

If the neighbour is the last serving cell

T = PENALTY TIME and

C2 = C1 + CELL_RESELECT_OFFSET

The timer T is started separately for each cell in the list of the six

strongest cells immediately after it is placed on the list MS camps

in the cell with the highest C2 value

15

The criterion C2 is applied in hierarchical cell structures to keep fast

moving MS in an upper layer and slow moving MS in micro cells It is

assumed that a fast moving MS passes through the micro cell before

PENALTY_TIME is reached This efficiently prevents unnecessary LUs and

thus saves network signaling capacity As in the case of C1 MS receives

the C2 parameter information through BCCH A parameter called

CELL_RESELECT_PARAM_IND informs MS about which reselection

criterion (C1 or C2) is used in the cell It is broadcast on the BCCH

The following actions are performed by the MS to detect whether or not a

cell reselection is necessary

Detection of a Downlink Signaling Failure ndash The downlink signaling failure counter DSC is a counter running in the

MS The starting value of this counter is called DSC0 and is set by the

MS to the following value

DSC0 = round(90 BS_PA_MFRMS)

The value of BS_PA_MFRMS is broadcasted in the system informations on

the BCCH of the serving cell Each BS_PA_MFRMS the MS attempts to

decode the messages on its paging sub-channel Depending on whether or

not this decoding is successful the value of the downlink signaling failure

counter DSC is modified in the following way

successful decoding DSC new = DSC old + 1

if DSC new + 1 gt DSC0 rarr DSC new = DSC old

unsuccessful decoding DSC new = DSC old ndash 4

If DSC lt 0 the MS has detected a downlink signaling

failure

Minimum decoding

Monitoring of all BCCH carriers given in the BCCH allocation

(neighbor cells) of the serving cell

Taking at least 5 samples of the received level from the serving cell

(on paging sub-channel) as well as from the neighbor cells

=gt AV_RXLEV(serving cell) and AV_RXLEV (neighbor cell)

Decoding of full BCCH data of the serving cell at least every 30 sec

Decoding of BCCH data of the 6 strongest neighbor cells at least

every 5 minutes

From the radio propagation point of view it is

worth to select a new (neighbor) cell if the

received level from that neighbor cell exceeds the

received level of the current serving cell For

phase 1 MS this is expressed using the C1

criterion

C1 (neighbor cell) gt C1 (serving cell)

For phase 2 MS a modified path loss criterion the C2 criterion

is usedThe C2 criterion depends on the value of a timer T

which is called PENALTY_TIMERThe timer T is started in the MS

for each cell in the list of the 6 strongest neighbor cells as soon

as it is placed on the list Timer T is reset to 0 if the cell is

removed from the list

During penalty time

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

After penalty time

C2 = C1 + CELL_RESELECT_OFFSET

For penalty time = 31 the whole time

C2 = C1 - CELL_RESELECT_OFFSET

CELL_RESELECT_OFFSET TEMPORARY_OFFSET and

PENALTY_TIME are cell reselection parameters which

are broadcasted on the BCCH of the cell in the

system informations if CELL_RESLECT_PARAM_IND

(Cell Reselection Parameter Indication) is set to 1

A negative TEMPORARY_OFFSET reduces the

priority of a cell in the list of strongest neighbor

cells

A positive CELL_RESELECT_OFFSET increases the

priority of a cell in the list of strongest neighbor

cells

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells

When a mobile reaches the coverage area of a (neighbor) micro cell given

by the C1 criterion this cell becomes effectively excluded from reselection

during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell be-fore PENALTY_TIME is reached and hence the micro cell is not

selected

In contrast a slow moving mobile is assumed to be still within the coverage

area of the micro cell when PENALTY_TIME has expired

Applying the positive CELL_RESELECT_OFFSET this cell is selected with

preference

Triggers for Cell Reselection

Cell reselection is triggered by the following conditions

1 C1 lt 0 for the serving cell for a period of 5 s

2 MS detects a downlink signaling failure

3 Serving cell becomes barred

Phase 1 MS

C1 (serving cell) lt C1 (suitable neighbor cell) if the suitable neighbor cell is

in the same location area

C1 (serving cell) + CELL_RESELECT_HYSTERESIS lt C1 (suitable

neighbor cell) if the suitable neighbor cell is in another location area for a

period of 5 sec

Phase 2 MS

C2 (serving cell) lt C2 (suitable neighbor cell) if the suitable neighbor cell is in

the same location area

C2 (serving cell) + CELL_RESELECT_HYSTERESIS lt C2 (suitable neighbor

cell) if the suitable neighbor cell is in another location area for a period of 5

sec

A random access attempt is unsuccessful even after the maximum number

of repetitions

For phase 2 there is the additional trigger

A location update request has been rejected with cause rdquolocation area not

allowedrdquo

PARAMETERS SETTING

BA (BCCH) - BCCH Allocation broadcasted on BCCH

In each cell the absolute radio frequency carrier number

BCCH_ARFCN_NC(n) of each of its neighbor cell n has to be

known This information is broadcasted as the so-called BCCH

Allocation to all MS in the respective cell On the

corresponding frequencies the MS take measurement samples

of the received level used for cell selection reselection

Furthermore the BCCH of neighbor cells has to be decoded by

the MS (at least every 5 min) to know the current values of the

control parameters for the reselection algorithm

PARAMETERS SETTING

Object DB Name Range Step Size

Unit ADJC BCCHFREQ 01023 1

PARAMETERS SETTING

CELL_BAR_ACCESS - Cell Barred for Access

A mobile station cannot camp on a barred cell ie a barred cell is not

selected by the cell selectionreselection procedure

Mobile stations which camp on a cell while it becomes barred initialize the

reselection procedure to find a new (unbarred) cell ie traffic load is

distributed to neighbor cells

This means that eg neither a call nor a location update can start in a

barred cell

However a cell barred for access is not barred for incoming handovers To

barr a cell completely eg for maintenance reasons also incoming

handovers have to be avoided

To reduce overload in a certain cell more moderately without distributing

the overload to neighbor cells barring of access classes has to be used

Barring access for an access class does not trigger a cell reselection for

MSs of that class

Object DB Name Range

BTS CELLBARR FALSETRUE

RXLEV_ACCESS_MIN - Minimum Downlink Received Level for Cell to be

selected

The parameter RXLEV_ACCESS_MIN determines the cell border for a MS in idle

mode by means of the C1 or C2 criterion respectively

Choosing a high value reduces the risk of a handover immediately after call

setup

On the other hand the value has to be low enough to achieve a sufficient overlap

between adjacent cells (especially if they belong to different location areas)

It has to be observed that the overlap may be different for mobiles of different

power classes (refer to MS_TXPWR_MAX_CCH)

In any case RXLEV_ACCESS_MIN has to be above the MS receiver sensitivity level

(-100 dBm for DCS1800 -102 dBm for GSM handhelds -104 dBm for other GSM

MS)

Furthermore it has to harmonize with the

handover thresholds (RXLEV_MIN L_RXLEV_HO)

Object DB Name Range Step Size Unit

BTS RXLEVAMI 063 1

RXLEV

MS_TXPWR_MAX_CCH - Maximum allowed MS Transmit

Power on RACH

The transmit power level the MS uses for the access on the

Random Access Channel is given by the minimum of two

values

the maximum possible transmit power of the MS (given by

the power class P of the MS) the maximum allowed power

for access within the respective cell

(given by MS_TXP WR_MAX_CCH)

This parameter affects the

the random access procedure

the cell selection procedure

Random access

If there is a collision of channel requests on the random access

channel the one with the higher received level has a good chance

to be decoded and to get a response by the BTS

Hence MS with higher output power are preferred This imbalance

can be avoided by choosing a low maximum allowed transmit power

PARAMETERS SETTING

Cell Selection

To be selected by the cell selection procedure a cell has to fulfill the

C1 criterion

C1 gt 0 where

C1 = AV_RXLEV - RXLEV_ACCESS_MIN - Max(0

MS_TXPWR_MAX_CCH - P )

Choosing for example MS_TXPWR_MAX_CCH = Pmin where Pmin is

the output power level for the minimum power class 5 (29 dBm)

the C1 criterion reduces to AV_RXLEV gt RXLEV_ACCESS_MIN

for MSs of all power classes Hence the same idle mode cell border

is seen by each mobile

Choosing for example MS_TXPWR_MAX_CCH = Pmax where Pmax is

the output power level for the maximum power class 1 (43 dBm)

the C1 criterion reduces to

AV_RXLEV gt RXLEV_ACCESS_MIN + ( MS_TXPWR_MAX_CCH - P )

for MSs of all power classes Hence a larger cell radius is seen by a

mobile of higher output power than by a mobile of lower output

power On the other hand one can ensure by this mechanism that a

certain uplink received level is exceeded by each MS independent of

its power class

Object DB Name Range Step Size Unit

BTS MSTXPMAXCH 031 1 2 dB

MS_TXPWR_MAX_CCH - Maximum allowed MS transmit power on RACH

default 2

MS GSM900 MS GSM900 MS DCS1800

Phase 1 Phase 2

0 = 43 dBm 0 = 39 dBm 0 = 30 dBm

1 = 41 dBm 1 = 39 dBm 1 = 28 dBm

2 = 39 dBm 2 = 39 dBm 2 = 26 dBm

3 = 37 dBm 3 = 37 dBm 3 = 24 dBm

15 = 13dBm 19 = 5 dBm 15 = 0 dBm

16-31 = 13 dBm 20-31 = 5 dBm 16-31 = 0 dBm

POWER_OFFSET - Additional Parameter for Class 3

DCS1800 MS

The parameter POWER_OFFSET is only used by class 3

DCS1800 MS to calculate the C1-criterion described as

follows

C1 = AV_RXLEV - RXLEV_ACCESS_MIN -

Max(0MS_TXPWR_MAX_CCH + POWER_OFFSET- P)

Object DB Name Range Step Size Unit

BTS PWROFS 03 1 2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for Reselection of a Cell

from another Location Area

In idle mode the MS selects a new (neighbor) cell if the received level of the

neighbor cell exceeds the received level of the current cell in order to be

served by the cell with the expected best link quality However due to

fading effects the propagation conditions may change rapidly and

therefore a reselection may occur very frequently

If the cells involved in the reselection process belong to the same location

area frequent cell reselection does not have an effect on the network

performance

But if the involved cells belong to different location area the reselection of

a new cell triggers a location update procedure which causes signaling

load (eg on the SDCCH) and involves all network elements

To avoid unnecessary signaling load by forward and backward reselection due to fading

a hysteresis given by the parameter CELL_RESELECT_HYSTERESIS is introduced ie

a cell from another location area is selected only if the corresponding received level

exceeds the level of the current serving cell by the value of this parameter This is

expressed in terms of the C1 (phase 1) or C2 (phase 2) criterion

C1 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C1 (suitable neighbor cell)

or

C2 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C2 (suitable neighbor cell)

respectively

The adjustment of CELL_RESELECT_HYSTERESES should be a compromise between

reduction of unnecessary location updates (high value) and

selection of the cell with best reception quality (low value)

Object DB Name Range Step Size Unit

BTS CELLRESH 07 1

2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for

reselection of a cell from another location area

default 2

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter

Indication

CELL_RESELECT_PARAM_IND=1

The cell reselection parameters CELL_RESELECT_OFFSET

TEMPORARY_OFFSET and PENALTY_TIME used for the C2 criterion as well as

the parameter CELL_BAR_QUALIFY are broadcasted on the BCCH These

parameters are taken into account by phase 2 MS but are ignored by

phase 1 MS

CELL_RESELECT_PARAM_IND = 0

The cell reselection parameters and CELL_BAR_QUALIFY are not

broadcasted on the BCCH

A phase 2 MS then uses the value 0 for all these parameters ie C1 = C2

Object DB Name Range

BTS CRESPARI 01

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter Indication default 1

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

C1 Examples

For a system where the minimum access level is -104 then

C1 has a minimum value of 0 but you will sometimes see a

minimum of 1 - this is due to the mobile functionality since a value

of 0 actually would mean NO signal and no detection should have

occurred

bull screen 31 on pocket TEMS

C1c31 18-26 displayed

cell reselection hystresis =6 is displayed

bull Beside the C1 radio criterion there are some other criteria

(administrative and traffic control) for a cell to be suitable

A Suitable Cell is defined as a cell which

1048698 is part of the selected PLMN

1048698 is unbarred (parameter CELL_BAR_ACCESS = 0)

1048698 has a value C1 gt 0

1048698 is not in a location area forbidden for national roaming

To allow eg emergency calls the conditions for a serving cell

are less restrictive

Suitable Cell

An Acceptable Cell is defined as a cell which

1048698 is unbarred

1048698 has a parameter C1 gt 0

The general strategy for cell selection is to find the rdquosuitable

cellrdquo with the highest C1 (best estimated link quality) If no

suitable cell can be found an rdquoacceptable cellrdquo is selected

Cell Selection with Stored BCCH Information

Optionally the MS may store information on

received level on BCCH carriers when switched

off

When switched on the MS first performs

measurements on these carriers If cell selection

for the corresponding cells is not successful

normal cell selection is carried out

Phase 2 Cell reselection criterion C2 is defined as

C2 = C1 + CELL_RESELECT_OFFSET minus TEMPORARY_OFFSET

If CELL RESELECT PARAM IND = TRUE then

If the counter T lt PENALTY TIME

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY OFFSET

If the counter T gt= PENALTY TIME

C2 = C1 + CELL_RESELECT_OFFSET

13

If the neighbour is the last serving cell

T = PENALTY TIME and

C2 = C1 + CELL_RESELECT_OFFSET

The timer T is started separately for each cell in the list of the six

strongest cells immediately after it is placed on the list MS camps

in the cell with the highest C2 value

15

The criterion C2 is applied in hierarchical cell structures to keep fast

moving MS in an upper layer and slow moving MS in micro cells It is

assumed that a fast moving MS passes through the micro cell before

PENALTY_TIME is reached This efficiently prevents unnecessary LUs and

thus saves network signaling capacity As in the case of C1 MS receives

the C2 parameter information through BCCH A parameter called

CELL_RESELECT_PARAM_IND informs MS about which reselection

criterion (C1 or C2) is used in the cell It is broadcast on the BCCH

The following actions are performed by the MS to detect whether or not a

cell reselection is necessary

Detection of a Downlink Signaling Failure ndash The downlink signaling failure counter DSC is a counter running in the

MS The starting value of this counter is called DSC0 and is set by the

MS to the following value

DSC0 = round(90 BS_PA_MFRMS)

The value of BS_PA_MFRMS is broadcasted in the system informations on

the BCCH of the serving cell Each BS_PA_MFRMS the MS attempts to

decode the messages on its paging sub-channel Depending on whether or

not this decoding is successful the value of the downlink signaling failure

counter DSC is modified in the following way

successful decoding DSC new = DSC old + 1

if DSC new + 1 gt DSC0 rarr DSC new = DSC old

unsuccessful decoding DSC new = DSC old ndash 4

If DSC lt 0 the MS has detected a downlink signaling

failure

Minimum decoding

Monitoring of all BCCH carriers given in the BCCH allocation

(neighbor cells) of the serving cell

Taking at least 5 samples of the received level from the serving cell

(on paging sub-channel) as well as from the neighbor cells

=gt AV_RXLEV(serving cell) and AV_RXLEV (neighbor cell)

Decoding of full BCCH data of the serving cell at least every 30 sec

Decoding of BCCH data of the 6 strongest neighbor cells at least

every 5 minutes

From the radio propagation point of view it is

worth to select a new (neighbor) cell if the

received level from that neighbor cell exceeds the

received level of the current serving cell For

phase 1 MS this is expressed using the C1

criterion

C1 (neighbor cell) gt C1 (serving cell)

For phase 2 MS a modified path loss criterion the C2 criterion

is usedThe C2 criterion depends on the value of a timer T

which is called PENALTY_TIMERThe timer T is started in the MS

for each cell in the list of the 6 strongest neighbor cells as soon

as it is placed on the list Timer T is reset to 0 if the cell is

removed from the list

During penalty time

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

After penalty time

C2 = C1 + CELL_RESELECT_OFFSET

For penalty time = 31 the whole time

C2 = C1 - CELL_RESELECT_OFFSET

CELL_RESELECT_OFFSET TEMPORARY_OFFSET and

PENALTY_TIME are cell reselection parameters which

are broadcasted on the BCCH of the cell in the

system informations if CELL_RESLECT_PARAM_IND

(Cell Reselection Parameter Indication) is set to 1

A negative TEMPORARY_OFFSET reduces the

priority of a cell in the list of strongest neighbor

cells

A positive CELL_RESELECT_OFFSET increases the

priority of a cell in the list of strongest neighbor

cells

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells

When a mobile reaches the coverage area of a (neighbor) micro cell given

by the C1 criterion this cell becomes effectively excluded from reselection

during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell be-fore PENALTY_TIME is reached and hence the micro cell is not

selected

In contrast a slow moving mobile is assumed to be still within the coverage

area of the micro cell when PENALTY_TIME has expired

Applying the positive CELL_RESELECT_OFFSET this cell is selected with

preference

Triggers for Cell Reselection

Cell reselection is triggered by the following conditions

1 C1 lt 0 for the serving cell for a period of 5 s

2 MS detects a downlink signaling failure

3 Serving cell becomes barred

Phase 1 MS

C1 (serving cell) lt C1 (suitable neighbor cell) if the suitable neighbor cell is

in the same location area

C1 (serving cell) + CELL_RESELECT_HYSTERESIS lt C1 (suitable

neighbor cell) if the suitable neighbor cell is in another location area for a

period of 5 sec

Phase 2 MS

C2 (serving cell) lt C2 (suitable neighbor cell) if the suitable neighbor cell is in

the same location area

C2 (serving cell) + CELL_RESELECT_HYSTERESIS lt C2 (suitable neighbor

cell) if the suitable neighbor cell is in another location area for a period of 5

sec

A random access attempt is unsuccessful even after the maximum number

of repetitions

For phase 2 there is the additional trigger

A location update request has been rejected with cause rdquolocation area not

allowedrdquo

PARAMETERS SETTING

BA (BCCH) - BCCH Allocation broadcasted on BCCH

In each cell the absolute radio frequency carrier number

BCCH_ARFCN_NC(n) of each of its neighbor cell n has to be

known This information is broadcasted as the so-called BCCH

Allocation to all MS in the respective cell On the

corresponding frequencies the MS take measurement samples

of the received level used for cell selection reselection

Furthermore the BCCH of neighbor cells has to be decoded by

the MS (at least every 5 min) to know the current values of the

control parameters for the reselection algorithm

PARAMETERS SETTING

Object DB Name Range Step Size

Unit ADJC BCCHFREQ 01023 1

PARAMETERS SETTING

CELL_BAR_ACCESS - Cell Barred for Access

A mobile station cannot camp on a barred cell ie a barred cell is not

selected by the cell selectionreselection procedure

Mobile stations which camp on a cell while it becomes barred initialize the

reselection procedure to find a new (unbarred) cell ie traffic load is

distributed to neighbor cells

This means that eg neither a call nor a location update can start in a

barred cell

However a cell barred for access is not barred for incoming handovers To

barr a cell completely eg for maintenance reasons also incoming

handovers have to be avoided

To reduce overload in a certain cell more moderately without distributing

the overload to neighbor cells barring of access classes has to be used

Barring access for an access class does not trigger a cell reselection for

MSs of that class

Object DB Name Range

BTS CELLBARR FALSETRUE

RXLEV_ACCESS_MIN - Minimum Downlink Received Level for Cell to be

selected

The parameter RXLEV_ACCESS_MIN determines the cell border for a MS in idle

mode by means of the C1 or C2 criterion respectively

Choosing a high value reduces the risk of a handover immediately after call

setup

On the other hand the value has to be low enough to achieve a sufficient overlap

between adjacent cells (especially if they belong to different location areas)

It has to be observed that the overlap may be different for mobiles of different

power classes (refer to MS_TXPWR_MAX_CCH)

In any case RXLEV_ACCESS_MIN has to be above the MS receiver sensitivity level

(-100 dBm for DCS1800 -102 dBm for GSM handhelds -104 dBm for other GSM

MS)

Furthermore it has to harmonize with the

handover thresholds (RXLEV_MIN L_RXLEV_HO)

Object DB Name Range Step Size Unit

BTS RXLEVAMI 063 1

RXLEV

MS_TXPWR_MAX_CCH - Maximum allowed MS Transmit

Power on RACH

The transmit power level the MS uses for the access on the

Random Access Channel is given by the minimum of two

values

the maximum possible transmit power of the MS (given by

the power class P of the MS) the maximum allowed power

for access within the respective cell

(given by MS_TXP WR_MAX_CCH)

This parameter affects the

the random access procedure

the cell selection procedure

Random access

If there is a collision of channel requests on the random access

channel the one with the higher received level has a good chance

to be decoded and to get a response by the BTS

Hence MS with higher output power are preferred This imbalance

can be avoided by choosing a low maximum allowed transmit power

PARAMETERS SETTING

Cell Selection

To be selected by the cell selection procedure a cell has to fulfill the

C1 criterion

C1 gt 0 where

C1 = AV_RXLEV - RXLEV_ACCESS_MIN - Max(0

MS_TXPWR_MAX_CCH - P )

Choosing for example MS_TXPWR_MAX_CCH = Pmin where Pmin is

the output power level for the minimum power class 5 (29 dBm)

the C1 criterion reduces to AV_RXLEV gt RXLEV_ACCESS_MIN

for MSs of all power classes Hence the same idle mode cell border

is seen by each mobile

Choosing for example MS_TXPWR_MAX_CCH = Pmax where Pmax is

the output power level for the maximum power class 1 (43 dBm)

the C1 criterion reduces to

AV_RXLEV gt RXLEV_ACCESS_MIN + ( MS_TXPWR_MAX_CCH - P )

for MSs of all power classes Hence a larger cell radius is seen by a

mobile of higher output power than by a mobile of lower output

power On the other hand one can ensure by this mechanism that a

certain uplink received level is exceeded by each MS independent of

its power class

Object DB Name Range Step Size Unit

BTS MSTXPMAXCH 031 1 2 dB

MS_TXPWR_MAX_CCH - Maximum allowed MS transmit power on RACH

default 2

MS GSM900 MS GSM900 MS DCS1800

Phase 1 Phase 2

0 = 43 dBm 0 = 39 dBm 0 = 30 dBm

1 = 41 dBm 1 = 39 dBm 1 = 28 dBm

2 = 39 dBm 2 = 39 dBm 2 = 26 dBm

3 = 37 dBm 3 = 37 dBm 3 = 24 dBm

15 = 13dBm 19 = 5 dBm 15 = 0 dBm

16-31 = 13 dBm 20-31 = 5 dBm 16-31 = 0 dBm

POWER_OFFSET - Additional Parameter for Class 3

DCS1800 MS

The parameter POWER_OFFSET is only used by class 3

DCS1800 MS to calculate the C1-criterion described as

follows

C1 = AV_RXLEV - RXLEV_ACCESS_MIN -

Max(0MS_TXPWR_MAX_CCH + POWER_OFFSET- P)

Object DB Name Range Step Size Unit

BTS PWROFS 03 1 2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for Reselection of a Cell

from another Location Area

In idle mode the MS selects a new (neighbor) cell if the received level of the

neighbor cell exceeds the received level of the current cell in order to be

served by the cell with the expected best link quality However due to

fading effects the propagation conditions may change rapidly and

therefore a reselection may occur very frequently

If the cells involved in the reselection process belong to the same location

area frequent cell reselection does not have an effect on the network

performance

But if the involved cells belong to different location area the reselection of

a new cell triggers a location update procedure which causes signaling

load (eg on the SDCCH) and involves all network elements

To avoid unnecessary signaling load by forward and backward reselection due to fading

a hysteresis given by the parameter CELL_RESELECT_HYSTERESIS is introduced ie

a cell from another location area is selected only if the corresponding received level

exceeds the level of the current serving cell by the value of this parameter This is

expressed in terms of the C1 (phase 1) or C2 (phase 2) criterion

C1 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C1 (suitable neighbor cell)

or

C2 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C2 (suitable neighbor cell)

respectively

The adjustment of CELL_RESELECT_HYSTERESES should be a compromise between

reduction of unnecessary location updates (high value) and

selection of the cell with best reception quality (low value)

Object DB Name Range Step Size Unit

BTS CELLRESH 07 1

2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for

reselection of a cell from another location area

default 2

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter

Indication

CELL_RESELECT_PARAM_IND=1

The cell reselection parameters CELL_RESELECT_OFFSET

TEMPORARY_OFFSET and PENALTY_TIME used for the C2 criterion as well as

the parameter CELL_BAR_QUALIFY are broadcasted on the BCCH These

parameters are taken into account by phase 2 MS but are ignored by

phase 1 MS

CELL_RESELECT_PARAM_IND = 0

The cell reselection parameters and CELL_BAR_QUALIFY are not

broadcasted on the BCCH

A phase 2 MS then uses the value 0 for all these parameters ie C1 = C2

Object DB Name Range

BTS CRESPARI 01

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter Indication default 1

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

bull screen 31 on pocket TEMS

C1c31 18-26 displayed

cell reselection hystresis =6 is displayed

bull Beside the C1 radio criterion there are some other criteria

(administrative and traffic control) for a cell to be suitable

A Suitable Cell is defined as a cell which

1048698 is part of the selected PLMN

1048698 is unbarred (parameter CELL_BAR_ACCESS = 0)

1048698 has a value C1 gt 0

1048698 is not in a location area forbidden for national roaming

To allow eg emergency calls the conditions for a serving cell

are less restrictive

Suitable Cell

An Acceptable Cell is defined as a cell which

1048698 is unbarred

1048698 has a parameter C1 gt 0

The general strategy for cell selection is to find the rdquosuitable

cellrdquo with the highest C1 (best estimated link quality) If no

suitable cell can be found an rdquoacceptable cellrdquo is selected

Cell Selection with Stored BCCH Information

Optionally the MS may store information on

received level on BCCH carriers when switched

off

When switched on the MS first performs

measurements on these carriers If cell selection

for the corresponding cells is not successful

normal cell selection is carried out

Phase 2 Cell reselection criterion C2 is defined as

C2 = C1 + CELL_RESELECT_OFFSET minus TEMPORARY_OFFSET

If CELL RESELECT PARAM IND = TRUE then

If the counter T lt PENALTY TIME

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY OFFSET

If the counter T gt= PENALTY TIME

C2 = C1 + CELL_RESELECT_OFFSET

13

If the neighbour is the last serving cell

T = PENALTY TIME and

C2 = C1 + CELL_RESELECT_OFFSET

The timer T is started separately for each cell in the list of the six

strongest cells immediately after it is placed on the list MS camps

in the cell with the highest C2 value

15

The criterion C2 is applied in hierarchical cell structures to keep fast

moving MS in an upper layer and slow moving MS in micro cells It is

assumed that a fast moving MS passes through the micro cell before

PENALTY_TIME is reached This efficiently prevents unnecessary LUs and

thus saves network signaling capacity As in the case of C1 MS receives

the C2 parameter information through BCCH A parameter called

CELL_RESELECT_PARAM_IND informs MS about which reselection

criterion (C1 or C2) is used in the cell It is broadcast on the BCCH

The following actions are performed by the MS to detect whether or not a

cell reselection is necessary

Detection of a Downlink Signaling Failure ndash The downlink signaling failure counter DSC is a counter running in the

MS The starting value of this counter is called DSC0 and is set by the

MS to the following value

DSC0 = round(90 BS_PA_MFRMS)

The value of BS_PA_MFRMS is broadcasted in the system informations on

the BCCH of the serving cell Each BS_PA_MFRMS the MS attempts to

decode the messages on its paging sub-channel Depending on whether or

not this decoding is successful the value of the downlink signaling failure

counter DSC is modified in the following way

successful decoding DSC new = DSC old + 1

if DSC new + 1 gt DSC0 rarr DSC new = DSC old

unsuccessful decoding DSC new = DSC old ndash 4

If DSC lt 0 the MS has detected a downlink signaling

failure

Minimum decoding

Monitoring of all BCCH carriers given in the BCCH allocation

(neighbor cells) of the serving cell

Taking at least 5 samples of the received level from the serving cell

(on paging sub-channel) as well as from the neighbor cells

=gt AV_RXLEV(serving cell) and AV_RXLEV (neighbor cell)

Decoding of full BCCH data of the serving cell at least every 30 sec

Decoding of BCCH data of the 6 strongest neighbor cells at least

every 5 minutes

From the radio propagation point of view it is

worth to select a new (neighbor) cell if the

received level from that neighbor cell exceeds the

received level of the current serving cell For

phase 1 MS this is expressed using the C1

criterion

C1 (neighbor cell) gt C1 (serving cell)

For phase 2 MS a modified path loss criterion the C2 criterion

is usedThe C2 criterion depends on the value of a timer T

which is called PENALTY_TIMERThe timer T is started in the MS

for each cell in the list of the 6 strongest neighbor cells as soon

as it is placed on the list Timer T is reset to 0 if the cell is

removed from the list

During penalty time

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

After penalty time

C2 = C1 + CELL_RESELECT_OFFSET

For penalty time = 31 the whole time

C2 = C1 - CELL_RESELECT_OFFSET

CELL_RESELECT_OFFSET TEMPORARY_OFFSET and

PENALTY_TIME are cell reselection parameters which

are broadcasted on the BCCH of the cell in the

system informations if CELL_RESLECT_PARAM_IND

(Cell Reselection Parameter Indication) is set to 1

A negative TEMPORARY_OFFSET reduces the

priority of a cell in the list of strongest neighbor

cells

A positive CELL_RESELECT_OFFSET increases the

priority of a cell in the list of strongest neighbor

cells

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells

When a mobile reaches the coverage area of a (neighbor) micro cell given

by the C1 criterion this cell becomes effectively excluded from reselection

during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell be-fore PENALTY_TIME is reached and hence the micro cell is not

selected

In contrast a slow moving mobile is assumed to be still within the coverage

area of the micro cell when PENALTY_TIME has expired

Applying the positive CELL_RESELECT_OFFSET this cell is selected with

preference

Triggers for Cell Reselection

Cell reselection is triggered by the following conditions

1 C1 lt 0 for the serving cell for a period of 5 s

2 MS detects a downlink signaling failure

3 Serving cell becomes barred

Phase 1 MS

C1 (serving cell) lt C1 (suitable neighbor cell) if the suitable neighbor cell is

in the same location area

C1 (serving cell) + CELL_RESELECT_HYSTERESIS lt C1 (suitable

neighbor cell) if the suitable neighbor cell is in another location area for a

period of 5 sec

Phase 2 MS

C2 (serving cell) lt C2 (suitable neighbor cell) if the suitable neighbor cell is in

the same location area

C2 (serving cell) + CELL_RESELECT_HYSTERESIS lt C2 (suitable neighbor

cell) if the suitable neighbor cell is in another location area for a period of 5

sec

A random access attempt is unsuccessful even after the maximum number

of repetitions

For phase 2 there is the additional trigger

A location update request has been rejected with cause rdquolocation area not

allowedrdquo

PARAMETERS SETTING

BA (BCCH) - BCCH Allocation broadcasted on BCCH

In each cell the absolute radio frequency carrier number

BCCH_ARFCN_NC(n) of each of its neighbor cell n has to be

known This information is broadcasted as the so-called BCCH

Allocation to all MS in the respective cell On the

corresponding frequencies the MS take measurement samples

of the received level used for cell selection reselection

Furthermore the BCCH of neighbor cells has to be decoded by

the MS (at least every 5 min) to know the current values of the

control parameters for the reselection algorithm

PARAMETERS SETTING

Object DB Name Range Step Size

Unit ADJC BCCHFREQ 01023 1

PARAMETERS SETTING

CELL_BAR_ACCESS - Cell Barred for Access

A mobile station cannot camp on a barred cell ie a barred cell is not

selected by the cell selectionreselection procedure

Mobile stations which camp on a cell while it becomes barred initialize the

reselection procedure to find a new (unbarred) cell ie traffic load is

distributed to neighbor cells

This means that eg neither a call nor a location update can start in a

barred cell

However a cell barred for access is not barred for incoming handovers To

barr a cell completely eg for maintenance reasons also incoming

handovers have to be avoided

To reduce overload in a certain cell more moderately without distributing

the overload to neighbor cells barring of access classes has to be used

Barring access for an access class does not trigger a cell reselection for

MSs of that class

Object DB Name Range

BTS CELLBARR FALSETRUE

RXLEV_ACCESS_MIN - Minimum Downlink Received Level for Cell to be

selected

The parameter RXLEV_ACCESS_MIN determines the cell border for a MS in idle

mode by means of the C1 or C2 criterion respectively

Choosing a high value reduces the risk of a handover immediately after call

setup

On the other hand the value has to be low enough to achieve a sufficient overlap

between adjacent cells (especially if they belong to different location areas)

It has to be observed that the overlap may be different for mobiles of different

power classes (refer to MS_TXPWR_MAX_CCH)

In any case RXLEV_ACCESS_MIN has to be above the MS receiver sensitivity level

(-100 dBm for DCS1800 -102 dBm for GSM handhelds -104 dBm for other GSM

MS)

Furthermore it has to harmonize with the

handover thresholds (RXLEV_MIN L_RXLEV_HO)

Object DB Name Range Step Size Unit

BTS RXLEVAMI 063 1

RXLEV

MS_TXPWR_MAX_CCH - Maximum allowed MS Transmit

Power on RACH

The transmit power level the MS uses for the access on the

Random Access Channel is given by the minimum of two

values

the maximum possible transmit power of the MS (given by

the power class P of the MS) the maximum allowed power

for access within the respective cell

(given by MS_TXP WR_MAX_CCH)

This parameter affects the

the random access procedure

the cell selection procedure

Random access

If there is a collision of channel requests on the random access

channel the one with the higher received level has a good chance

to be decoded and to get a response by the BTS

Hence MS with higher output power are preferred This imbalance

can be avoided by choosing a low maximum allowed transmit power

PARAMETERS SETTING

Cell Selection

To be selected by the cell selection procedure a cell has to fulfill the

C1 criterion

C1 gt 0 where

C1 = AV_RXLEV - RXLEV_ACCESS_MIN - Max(0

MS_TXPWR_MAX_CCH - P )

Choosing for example MS_TXPWR_MAX_CCH = Pmin where Pmin is

the output power level for the minimum power class 5 (29 dBm)

the C1 criterion reduces to AV_RXLEV gt RXLEV_ACCESS_MIN

for MSs of all power classes Hence the same idle mode cell border

is seen by each mobile

Choosing for example MS_TXPWR_MAX_CCH = Pmax where Pmax is

the output power level for the maximum power class 1 (43 dBm)

the C1 criterion reduces to

AV_RXLEV gt RXLEV_ACCESS_MIN + ( MS_TXPWR_MAX_CCH - P )

for MSs of all power classes Hence a larger cell radius is seen by a

mobile of higher output power than by a mobile of lower output

power On the other hand one can ensure by this mechanism that a

certain uplink received level is exceeded by each MS independent of

its power class

Object DB Name Range Step Size Unit

BTS MSTXPMAXCH 031 1 2 dB

MS_TXPWR_MAX_CCH - Maximum allowed MS transmit power on RACH

default 2

MS GSM900 MS GSM900 MS DCS1800

Phase 1 Phase 2

0 = 43 dBm 0 = 39 dBm 0 = 30 dBm

1 = 41 dBm 1 = 39 dBm 1 = 28 dBm

2 = 39 dBm 2 = 39 dBm 2 = 26 dBm

3 = 37 dBm 3 = 37 dBm 3 = 24 dBm

15 = 13dBm 19 = 5 dBm 15 = 0 dBm

16-31 = 13 dBm 20-31 = 5 dBm 16-31 = 0 dBm

POWER_OFFSET - Additional Parameter for Class 3

DCS1800 MS

The parameter POWER_OFFSET is only used by class 3

DCS1800 MS to calculate the C1-criterion described as

follows

C1 = AV_RXLEV - RXLEV_ACCESS_MIN -

Max(0MS_TXPWR_MAX_CCH + POWER_OFFSET- P)

Object DB Name Range Step Size Unit

BTS PWROFS 03 1 2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for Reselection of a Cell

from another Location Area

In idle mode the MS selects a new (neighbor) cell if the received level of the

neighbor cell exceeds the received level of the current cell in order to be

served by the cell with the expected best link quality However due to

fading effects the propagation conditions may change rapidly and

therefore a reselection may occur very frequently

If the cells involved in the reselection process belong to the same location

area frequent cell reselection does not have an effect on the network

performance

But if the involved cells belong to different location area the reselection of

a new cell triggers a location update procedure which causes signaling

load (eg on the SDCCH) and involves all network elements

To avoid unnecessary signaling load by forward and backward reselection due to fading

a hysteresis given by the parameter CELL_RESELECT_HYSTERESIS is introduced ie

a cell from another location area is selected only if the corresponding received level

exceeds the level of the current serving cell by the value of this parameter This is

expressed in terms of the C1 (phase 1) or C2 (phase 2) criterion

C1 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C1 (suitable neighbor cell)

or

C2 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C2 (suitable neighbor cell)

respectively

The adjustment of CELL_RESELECT_HYSTERESES should be a compromise between

reduction of unnecessary location updates (high value) and

selection of the cell with best reception quality (low value)

Object DB Name Range Step Size Unit

BTS CELLRESH 07 1

2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for

reselection of a cell from another location area

default 2

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter

Indication

CELL_RESELECT_PARAM_IND=1

The cell reselection parameters CELL_RESELECT_OFFSET

TEMPORARY_OFFSET and PENALTY_TIME used for the C2 criterion as well as

the parameter CELL_BAR_QUALIFY are broadcasted on the BCCH These

parameters are taken into account by phase 2 MS but are ignored by

phase 1 MS

CELL_RESELECT_PARAM_IND = 0

The cell reselection parameters and CELL_BAR_QUALIFY are not

broadcasted on the BCCH

A phase 2 MS then uses the value 0 for all these parameters ie C1 = C2

Object DB Name Range

BTS CRESPARI 01

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter Indication default 1

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

bull Beside the C1 radio criterion there are some other criteria

(administrative and traffic control) for a cell to be suitable

A Suitable Cell is defined as a cell which

1048698 is part of the selected PLMN

1048698 is unbarred (parameter CELL_BAR_ACCESS = 0)

1048698 has a value C1 gt 0

1048698 is not in a location area forbidden for national roaming

To allow eg emergency calls the conditions for a serving cell

are less restrictive

Suitable Cell

An Acceptable Cell is defined as a cell which

1048698 is unbarred

1048698 has a parameter C1 gt 0

The general strategy for cell selection is to find the rdquosuitable

cellrdquo with the highest C1 (best estimated link quality) If no

suitable cell can be found an rdquoacceptable cellrdquo is selected

Cell Selection with Stored BCCH Information

Optionally the MS may store information on

received level on BCCH carriers when switched

off

When switched on the MS first performs

measurements on these carriers If cell selection

for the corresponding cells is not successful

normal cell selection is carried out

Phase 2 Cell reselection criterion C2 is defined as

C2 = C1 + CELL_RESELECT_OFFSET minus TEMPORARY_OFFSET

If CELL RESELECT PARAM IND = TRUE then

If the counter T lt PENALTY TIME

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY OFFSET

If the counter T gt= PENALTY TIME

C2 = C1 + CELL_RESELECT_OFFSET

13

If the neighbour is the last serving cell

T = PENALTY TIME and

C2 = C1 + CELL_RESELECT_OFFSET

The timer T is started separately for each cell in the list of the six

strongest cells immediately after it is placed on the list MS camps

in the cell with the highest C2 value

15

The criterion C2 is applied in hierarchical cell structures to keep fast

moving MS in an upper layer and slow moving MS in micro cells It is

assumed that a fast moving MS passes through the micro cell before

PENALTY_TIME is reached This efficiently prevents unnecessary LUs and

thus saves network signaling capacity As in the case of C1 MS receives

the C2 parameter information through BCCH A parameter called

CELL_RESELECT_PARAM_IND informs MS about which reselection

criterion (C1 or C2) is used in the cell It is broadcast on the BCCH

The following actions are performed by the MS to detect whether or not a

cell reselection is necessary

Detection of a Downlink Signaling Failure ndash The downlink signaling failure counter DSC is a counter running in the

MS The starting value of this counter is called DSC0 and is set by the

MS to the following value

DSC0 = round(90 BS_PA_MFRMS)

The value of BS_PA_MFRMS is broadcasted in the system informations on

the BCCH of the serving cell Each BS_PA_MFRMS the MS attempts to

decode the messages on its paging sub-channel Depending on whether or

not this decoding is successful the value of the downlink signaling failure

counter DSC is modified in the following way

successful decoding DSC new = DSC old + 1

if DSC new + 1 gt DSC0 rarr DSC new = DSC old

unsuccessful decoding DSC new = DSC old ndash 4

If DSC lt 0 the MS has detected a downlink signaling

failure

Minimum decoding

Monitoring of all BCCH carriers given in the BCCH allocation

(neighbor cells) of the serving cell

Taking at least 5 samples of the received level from the serving cell

(on paging sub-channel) as well as from the neighbor cells

=gt AV_RXLEV(serving cell) and AV_RXLEV (neighbor cell)

Decoding of full BCCH data of the serving cell at least every 30 sec

Decoding of BCCH data of the 6 strongest neighbor cells at least

every 5 minutes

From the radio propagation point of view it is

worth to select a new (neighbor) cell if the

received level from that neighbor cell exceeds the

received level of the current serving cell For

phase 1 MS this is expressed using the C1

criterion

C1 (neighbor cell) gt C1 (serving cell)

For phase 2 MS a modified path loss criterion the C2 criterion

is usedThe C2 criterion depends on the value of a timer T

which is called PENALTY_TIMERThe timer T is started in the MS

for each cell in the list of the 6 strongest neighbor cells as soon

as it is placed on the list Timer T is reset to 0 if the cell is

removed from the list

During penalty time

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

After penalty time

C2 = C1 + CELL_RESELECT_OFFSET

For penalty time = 31 the whole time

C2 = C1 - CELL_RESELECT_OFFSET

CELL_RESELECT_OFFSET TEMPORARY_OFFSET and

PENALTY_TIME are cell reselection parameters which

are broadcasted on the BCCH of the cell in the

system informations if CELL_RESLECT_PARAM_IND

(Cell Reselection Parameter Indication) is set to 1

A negative TEMPORARY_OFFSET reduces the

priority of a cell in the list of strongest neighbor

cells

A positive CELL_RESELECT_OFFSET increases the

priority of a cell in the list of strongest neighbor

cells

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells

When a mobile reaches the coverage area of a (neighbor) micro cell given

by the C1 criterion this cell becomes effectively excluded from reselection

during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell be-fore PENALTY_TIME is reached and hence the micro cell is not

selected

In contrast a slow moving mobile is assumed to be still within the coverage

area of the micro cell when PENALTY_TIME has expired

Applying the positive CELL_RESELECT_OFFSET this cell is selected with

preference

Triggers for Cell Reselection

Cell reselection is triggered by the following conditions

1 C1 lt 0 for the serving cell for a period of 5 s

2 MS detects a downlink signaling failure

3 Serving cell becomes barred

Phase 1 MS

C1 (serving cell) lt C1 (suitable neighbor cell) if the suitable neighbor cell is

in the same location area

C1 (serving cell) + CELL_RESELECT_HYSTERESIS lt C1 (suitable

neighbor cell) if the suitable neighbor cell is in another location area for a

period of 5 sec

Phase 2 MS

C2 (serving cell) lt C2 (suitable neighbor cell) if the suitable neighbor cell is in

the same location area

C2 (serving cell) + CELL_RESELECT_HYSTERESIS lt C2 (suitable neighbor

cell) if the suitable neighbor cell is in another location area for a period of 5

sec

A random access attempt is unsuccessful even after the maximum number

of repetitions

For phase 2 there is the additional trigger

A location update request has been rejected with cause rdquolocation area not

allowedrdquo

PARAMETERS SETTING

BA (BCCH) - BCCH Allocation broadcasted on BCCH

In each cell the absolute radio frequency carrier number

BCCH_ARFCN_NC(n) of each of its neighbor cell n has to be

known This information is broadcasted as the so-called BCCH

Allocation to all MS in the respective cell On the

corresponding frequencies the MS take measurement samples

of the received level used for cell selection reselection

Furthermore the BCCH of neighbor cells has to be decoded by

the MS (at least every 5 min) to know the current values of the

control parameters for the reselection algorithm

PARAMETERS SETTING

Object DB Name Range Step Size

Unit ADJC BCCHFREQ 01023 1

PARAMETERS SETTING

CELL_BAR_ACCESS - Cell Barred for Access

A mobile station cannot camp on a barred cell ie a barred cell is not

selected by the cell selectionreselection procedure

Mobile stations which camp on a cell while it becomes barred initialize the

reselection procedure to find a new (unbarred) cell ie traffic load is

distributed to neighbor cells

This means that eg neither a call nor a location update can start in a

barred cell

However a cell barred for access is not barred for incoming handovers To

barr a cell completely eg for maintenance reasons also incoming

handovers have to be avoided

To reduce overload in a certain cell more moderately without distributing

the overload to neighbor cells barring of access classes has to be used

Barring access for an access class does not trigger a cell reselection for

MSs of that class

Object DB Name Range

BTS CELLBARR FALSETRUE

RXLEV_ACCESS_MIN - Minimum Downlink Received Level for Cell to be

selected

The parameter RXLEV_ACCESS_MIN determines the cell border for a MS in idle

mode by means of the C1 or C2 criterion respectively

Choosing a high value reduces the risk of a handover immediately after call

setup

On the other hand the value has to be low enough to achieve a sufficient overlap

between adjacent cells (especially if they belong to different location areas)

It has to be observed that the overlap may be different for mobiles of different

power classes (refer to MS_TXPWR_MAX_CCH)

In any case RXLEV_ACCESS_MIN has to be above the MS receiver sensitivity level

(-100 dBm for DCS1800 -102 dBm for GSM handhelds -104 dBm for other GSM

MS)

Furthermore it has to harmonize with the

handover thresholds (RXLEV_MIN L_RXLEV_HO)

Object DB Name Range Step Size Unit

BTS RXLEVAMI 063 1

RXLEV

MS_TXPWR_MAX_CCH - Maximum allowed MS Transmit

Power on RACH

The transmit power level the MS uses for the access on the

Random Access Channel is given by the minimum of two

values

the maximum possible transmit power of the MS (given by

the power class P of the MS) the maximum allowed power

for access within the respective cell

(given by MS_TXP WR_MAX_CCH)

This parameter affects the

the random access procedure

the cell selection procedure

Random access

If there is a collision of channel requests on the random access

channel the one with the higher received level has a good chance

to be decoded and to get a response by the BTS

Hence MS with higher output power are preferred This imbalance

can be avoided by choosing a low maximum allowed transmit power

PARAMETERS SETTING

Cell Selection

To be selected by the cell selection procedure a cell has to fulfill the

C1 criterion

C1 gt 0 where

C1 = AV_RXLEV - RXLEV_ACCESS_MIN - Max(0

MS_TXPWR_MAX_CCH - P )

Choosing for example MS_TXPWR_MAX_CCH = Pmin where Pmin is

the output power level for the minimum power class 5 (29 dBm)

the C1 criterion reduces to AV_RXLEV gt RXLEV_ACCESS_MIN

for MSs of all power classes Hence the same idle mode cell border

is seen by each mobile

Choosing for example MS_TXPWR_MAX_CCH = Pmax where Pmax is

the output power level for the maximum power class 1 (43 dBm)

the C1 criterion reduces to

AV_RXLEV gt RXLEV_ACCESS_MIN + ( MS_TXPWR_MAX_CCH - P )

for MSs of all power classes Hence a larger cell radius is seen by a

mobile of higher output power than by a mobile of lower output

power On the other hand one can ensure by this mechanism that a

certain uplink received level is exceeded by each MS independent of

its power class

Object DB Name Range Step Size Unit

BTS MSTXPMAXCH 031 1 2 dB

MS_TXPWR_MAX_CCH - Maximum allowed MS transmit power on RACH

default 2

MS GSM900 MS GSM900 MS DCS1800

Phase 1 Phase 2

0 = 43 dBm 0 = 39 dBm 0 = 30 dBm

1 = 41 dBm 1 = 39 dBm 1 = 28 dBm

2 = 39 dBm 2 = 39 dBm 2 = 26 dBm

3 = 37 dBm 3 = 37 dBm 3 = 24 dBm

15 = 13dBm 19 = 5 dBm 15 = 0 dBm

16-31 = 13 dBm 20-31 = 5 dBm 16-31 = 0 dBm

POWER_OFFSET - Additional Parameter for Class 3

DCS1800 MS

The parameter POWER_OFFSET is only used by class 3

DCS1800 MS to calculate the C1-criterion described as

follows

C1 = AV_RXLEV - RXLEV_ACCESS_MIN -

Max(0MS_TXPWR_MAX_CCH + POWER_OFFSET- P)

Object DB Name Range Step Size Unit

BTS PWROFS 03 1 2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for Reselection of a Cell

from another Location Area

In idle mode the MS selects a new (neighbor) cell if the received level of the

neighbor cell exceeds the received level of the current cell in order to be

served by the cell with the expected best link quality However due to

fading effects the propagation conditions may change rapidly and

therefore a reselection may occur very frequently

If the cells involved in the reselection process belong to the same location

area frequent cell reselection does not have an effect on the network

performance

But if the involved cells belong to different location area the reselection of

a new cell triggers a location update procedure which causes signaling

load (eg on the SDCCH) and involves all network elements

To avoid unnecessary signaling load by forward and backward reselection due to fading

a hysteresis given by the parameter CELL_RESELECT_HYSTERESIS is introduced ie

a cell from another location area is selected only if the corresponding received level

exceeds the level of the current serving cell by the value of this parameter This is

expressed in terms of the C1 (phase 1) or C2 (phase 2) criterion

C1 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C1 (suitable neighbor cell)

or

C2 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C2 (suitable neighbor cell)

respectively

The adjustment of CELL_RESELECT_HYSTERESES should be a compromise between

reduction of unnecessary location updates (high value) and

selection of the cell with best reception quality (low value)

Object DB Name Range Step Size Unit

BTS CELLRESH 07 1

2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for

reselection of a cell from another location area

default 2

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter

Indication

CELL_RESELECT_PARAM_IND=1

The cell reselection parameters CELL_RESELECT_OFFSET

TEMPORARY_OFFSET and PENALTY_TIME used for the C2 criterion as well as

the parameter CELL_BAR_QUALIFY are broadcasted on the BCCH These

parameters are taken into account by phase 2 MS but are ignored by

phase 1 MS

CELL_RESELECT_PARAM_IND = 0

The cell reselection parameters and CELL_BAR_QUALIFY are not

broadcasted on the BCCH

A phase 2 MS then uses the value 0 for all these parameters ie C1 = C2

Object DB Name Range

BTS CRESPARI 01

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter Indication default 1

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

An Acceptable Cell is defined as a cell which

1048698 is unbarred

1048698 has a parameter C1 gt 0

The general strategy for cell selection is to find the rdquosuitable

cellrdquo with the highest C1 (best estimated link quality) If no

suitable cell can be found an rdquoacceptable cellrdquo is selected

Cell Selection with Stored BCCH Information

Optionally the MS may store information on

received level on BCCH carriers when switched

off

When switched on the MS first performs

measurements on these carriers If cell selection

for the corresponding cells is not successful

normal cell selection is carried out

Phase 2 Cell reselection criterion C2 is defined as

C2 = C1 + CELL_RESELECT_OFFSET minus TEMPORARY_OFFSET

If CELL RESELECT PARAM IND = TRUE then

If the counter T lt PENALTY TIME

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY OFFSET

If the counter T gt= PENALTY TIME

C2 = C1 + CELL_RESELECT_OFFSET

13

If the neighbour is the last serving cell

T = PENALTY TIME and

C2 = C1 + CELL_RESELECT_OFFSET

The timer T is started separately for each cell in the list of the six

strongest cells immediately after it is placed on the list MS camps

in the cell with the highest C2 value

15

The criterion C2 is applied in hierarchical cell structures to keep fast

moving MS in an upper layer and slow moving MS in micro cells It is

assumed that a fast moving MS passes through the micro cell before

PENALTY_TIME is reached This efficiently prevents unnecessary LUs and

thus saves network signaling capacity As in the case of C1 MS receives

the C2 parameter information through BCCH A parameter called

CELL_RESELECT_PARAM_IND informs MS about which reselection

criterion (C1 or C2) is used in the cell It is broadcast on the BCCH

The following actions are performed by the MS to detect whether or not a

cell reselection is necessary

Detection of a Downlink Signaling Failure ndash The downlink signaling failure counter DSC is a counter running in the

MS The starting value of this counter is called DSC0 and is set by the

MS to the following value

DSC0 = round(90 BS_PA_MFRMS)

The value of BS_PA_MFRMS is broadcasted in the system informations on

the BCCH of the serving cell Each BS_PA_MFRMS the MS attempts to

decode the messages on its paging sub-channel Depending on whether or

not this decoding is successful the value of the downlink signaling failure

counter DSC is modified in the following way

successful decoding DSC new = DSC old + 1

if DSC new + 1 gt DSC0 rarr DSC new = DSC old

unsuccessful decoding DSC new = DSC old ndash 4

If DSC lt 0 the MS has detected a downlink signaling

failure

Minimum decoding

Monitoring of all BCCH carriers given in the BCCH allocation

(neighbor cells) of the serving cell

Taking at least 5 samples of the received level from the serving cell

(on paging sub-channel) as well as from the neighbor cells

=gt AV_RXLEV(serving cell) and AV_RXLEV (neighbor cell)

Decoding of full BCCH data of the serving cell at least every 30 sec

Decoding of BCCH data of the 6 strongest neighbor cells at least

every 5 minutes

From the radio propagation point of view it is

worth to select a new (neighbor) cell if the

received level from that neighbor cell exceeds the

received level of the current serving cell For

phase 1 MS this is expressed using the C1

criterion

C1 (neighbor cell) gt C1 (serving cell)

For phase 2 MS a modified path loss criterion the C2 criterion

is usedThe C2 criterion depends on the value of a timer T

which is called PENALTY_TIMERThe timer T is started in the MS

for each cell in the list of the 6 strongest neighbor cells as soon

as it is placed on the list Timer T is reset to 0 if the cell is

removed from the list

During penalty time

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

After penalty time

C2 = C1 + CELL_RESELECT_OFFSET

For penalty time = 31 the whole time

C2 = C1 - CELL_RESELECT_OFFSET

CELL_RESELECT_OFFSET TEMPORARY_OFFSET and

PENALTY_TIME are cell reselection parameters which

are broadcasted on the BCCH of the cell in the

system informations if CELL_RESLECT_PARAM_IND

(Cell Reselection Parameter Indication) is set to 1

A negative TEMPORARY_OFFSET reduces the

priority of a cell in the list of strongest neighbor

cells

A positive CELL_RESELECT_OFFSET increases the

priority of a cell in the list of strongest neighbor

cells

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells

When a mobile reaches the coverage area of a (neighbor) micro cell given

by the C1 criterion this cell becomes effectively excluded from reselection

during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell be-fore PENALTY_TIME is reached and hence the micro cell is not

selected

In contrast a slow moving mobile is assumed to be still within the coverage

area of the micro cell when PENALTY_TIME has expired

Applying the positive CELL_RESELECT_OFFSET this cell is selected with

preference

Triggers for Cell Reselection

Cell reselection is triggered by the following conditions

1 C1 lt 0 for the serving cell for a period of 5 s

2 MS detects a downlink signaling failure

3 Serving cell becomes barred

Phase 1 MS

C1 (serving cell) lt C1 (suitable neighbor cell) if the suitable neighbor cell is

in the same location area

C1 (serving cell) + CELL_RESELECT_HYSTERESIS lt C1 (suitable

neighbor cell) if the suitable neighbor cell is in another location area for a

period of 5 sec

Phase 2 MS

C2 (serving cell) lt C2 (suitable neighbor cell) if the suitable neighbor cell is in

the same location area

C2 (serving cell) + CELL_RESELECT_HYSTERESIS lt C2 (suitable neighbor

cell) if the suitable neighbor cell is in another location area for a period of 5

sec

A random access attempt is unsuccessful even after the maximum number

of repetitions

For phase 2 there is the additional trigger

A location update request has been rejected with cause rdquolocation area not

allowedrdquo

PARAMETERS SETTING

BA (BCCH) - BCCH Allocation broadcasted on BCCH

In each cell the absolute radio frequency carrier number

BCCH_ARFCN_NC(n) of each of its neighbor cell n has to be

known This information is broadcasted as the so-called BCCH

Allocation to all MS in the respective cell On the

corresponding frequencies the MS take measurement samples

of the received level used for cell selection reselection

Furthermore the BCCH of neighbor cells has to be decoded by

the MS (at least every 5 min) to know the current values of the

control parameters for the reselection algorithm

PARAMETERS SETTING

Object DB Name Range Step Size

Unit ADJC BCCHFREQ 01023 1

PARAMETERS SETTING

CELL_BAR_ACCESS - Cell Barred for Access

A mobile station cannot camp on a barred cell ie a barred cell is not

selected by the cell selectionreselection procedure

Mobile stations which camp on a cell while it becomes barred initialize the

reselection procedure to find a new (unbarred) cell ie traffic load is

distributed to neighbor cells

This means that eg neither a call nor a location update can start in a

barred cell

However a cell barred for access is not barred for incoming handovers To

barr a cell completely eg for maintenance reasons also incoming

handovers have to be avoided

To reduce overload in a certain cell more moderately without distributing

the overload to neighbor cells barring of access classes has to be used

Barring access for an access class does not trigger a cell reselection for

MSs of that class

Object DB Name Range

BTS CELLBARR FALSETRUE

RXLEV_ACCESS_MIN - Minimum Downlink Received Level for Cell to be

selected

The parameter RXLEV_ACCESS_MIN determines the cell border for a MS in idle

mode by means of the C1 or C2 criterion respectively

Choosing a high value reduces the risk of a handover immediately after call

setup

On the other hand the value has to be low enough to achieve a sufficient overlap

between adjacent cells (especially if they belong to different location areas)

It has to be observed that the overlap may be different for mobiles of different

power classes (refer to MS_TXPWR_MAX_CCH)

In any case RXLEV_ACCESS_MIN has to be above the MS receiver sensitivity level

(-100 dBm for DCS1800 -102 dBm for GSM handhelds -104 dBm for other GSM

MS)

Furthermore it has to harmonize with the

handover thresholds (RXLEV_MIN L_RXLEV_HO)

Object DB Name Range Step Size Unit

BTS RXLEVAMI 063 1

RXLEV

MS_TXPWR_MAX_CCH - Maximum allowed MS Transmit

Power on RACH

The transmit power level the MS uses for the access on the

Random Access Channel is given by the minimum of two

values

the maximum possible transmit power of the MS (given by

the power class P of the MS) the maximum allowed power

for access within the respective cell

(given by MS_TXP WR_MAX_CCH)

This parameter affects the

the random access procedure

the cell selection procedure

Random access

If there is a collision of channel requests on the random access

channel the one with the higher received level has a good chance

to be decoded and to get a response by the BTS

Hence MS with higher output power are preferred This imbalance

can be avoided by choosing a low maximum allowed transmit power

PARAMETERS SETTING

Cell Selection

To be selected by the cell selection procedure a cell has to fulfill the

C1 criterion

C1 gt 0 where

C1 = AV_RXLEV - RXLEV_ACCESS_MIN - Max(0

MS_TXPWR_MAX_CCH - P )

Choosing for example MS_TXPWR_MAX_CCH = Pmin where Pmin is

the output power level for the minimum power class 5 (29 dBm)

the C1 criterion reduces to AV_RXLEV gt RXLEV_ACCESS_MIN

for MSs of all power classes Hence the same idle mode cell border

is seen by each mobile

Choosing for example MS_TXPWR_MAX_CCH = Pmax where Pmax is

the output power level for the maximum power class 1 (43 dBm)

the C1 criterion reduces to

AV_RXLEV gt RXLEV_ACCESS_MIN + ( MS_TXPWR_MAX_CCH - P )

for MSs of all power classes Hence a larger cell radius is seen by a

mobile of higher output power than by a mobile of lower output

power On the other hand one can ensure by this mechanism that a

certain uplink received level is exceeded by each MS independent of

its power class

Object DB Name Range Step Size Unit

BTS MSTXPMAXCH 031 1 2 dB

MS_TXPWR_MAX_CCH - Maximum allowed MS transmit power on RACH

default 2

MS GSM900 MS GSM900 MS DCS1800

Phase 1 Phase 2

0 = 43 dBm 0 = 39 dBm 0 = 30 dBm

1 = 41 dBm 1 = 39 dBm 1 = 28 dBm

2 = 39 dBm 2 = 39 dBm 2 = 26 dBm

3 = 37 dBm 3 = 37 dBm 3 = 24 dBm

15 = 13dBm 19 = 5 dBm 15 = 0 dBm

16-31 = 13 dBm 20-31 = 5 dBm 16-31 = 0 dBm

POWER_OFFSET - Additional Parameter for Class 3

DCS1800 MS

The parameter POWER_OFFSET is only used by class 3

DCS1800 MS to calculate the C1-criterion described as

follows

C1 = AV_RXLEV - RXLEV_ACCESS_MIN -

Max(0MS_TXPWR_MAX_CCH + POWER_OFFSET- P)

Object DB Name Range Step Size Unit

BTS PWROFS 03 1 2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for Reselection of a Cell

from another Location Area

In idle mode the MS selects a new (neighbor) cell if the received level of the

neighbor cell exceeds the received level of the current cell in order to be

served by the cell with the expected best link quality However due to

fading effects the propagation conditions may change rapidly and

therefore a reselection may occur very frequently

If the cells involved in the reselection process belong to the same location

area frequent cell reselection does not have an effect on the network

performance

But if the involved cells belong to different location area the reselection of

a new cell triggers a location update procedure which causes signaling

load (eg on the SDCCH) and involves all network elements

To avoid unnecessary signaling load by forward and backward reselection due to fading

a hysteresis given by the parameter CELL_RESELECT_HYSTERESIS is introduced ie

a cell from another location area is selected only if the corresponding received level

exceeds the level of the current serving cell by the value of this parameter This is

expressed in terms of the C1 (phase 1) or C2 (phase 2) criterion

C1 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C1 (suitable neighbor cell)

or

C2 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C2 (suitable neighbor cell)

respectively

The adjustment of CELL_RESELECT_HYSTERESES should be a compromise between

reduction of unnecessary location updates (high value) and

selection of the cell with best reception quality (low value)

Object DB Name Range Step Size Unit

BTS CELLRESH 07 1

2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for

reselection of a cell from another location area

default 2

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter

Indication

CELL_RESELECT_PARAM_IND=1

The cell reselection parameters CELL_RESELECT_OFFSET

TEMPORARY_OFFSET and PENALTY_TIME used for the C2 criterion as well as

the parameter CELL_BAR_QUALIFY are broadcasted on the BCCH These

parameters are taken into account by phase 2 MS but are ignored by

phase 1 MS

CELL_RESELECT_PARAM_IND = 0

The cell reselection parameters and CELL_BAR_QUALIFY are not

broadcasted on the BCCH

A phase 2 MS then uses the value 0 for all these parameters ie C1 = C2

Object DB Name Range

BTS CRESPARI 01

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter Indication default 1

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

Cell Selection with Stored BCCH Information

Optionally the MS may store information on

received level on BCCH carriers when switched

off

When switched on the MS first performs

measurements on these carriers If cell selection

for the corresponding cells is not successful

normal cell selection is carried out

Phase 2 Cell reselection criterion C2 is defined as

C2 = C1 + CELL_RESELECT_OFFSET minus TEMPORARY_OFFSET

If CELL RESELECT PARAM IND = TRUE then

If the counter T lt PENALTY TIME

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY OFFSET

If the counter T gt= PENALTY TIME

C2 = C1 + CELL_RESELECT_OFFSET

13

If the neighbour is the last serving cell

T = PENALTY TIME and

C2 = C1 + CELL_RESELECT_OFFSET

The timer T is started separately for each cell in the list of the six

strongest cells immediately after it is placed on the list MS camps

in the cell with the highest C2 value

15

The criterion C2 is applied in hierarchical cell structures to keep fast

moving MS in an upper layer and slow moving MS in micro cells It is

assumed that a fast moving MS passes through the micro cell before

PENALTY_TIME is reached This efficiently prevents unnecessary LUs and

thus saves network signaling capacity As in the case of C1 MS receives

the C2 parameter information through BCCH A parameter called

CELL_RESELECT_PARAM_IND informs MS about which reselection

criterion (C1 or C2) is used in the cell It is broadcast on the BCCH

The following actions are performed by the MS to detect whether or not a

cell reselection is necessary

Detection of a Downlink Signaling Failure ndash The downlink signaling failure counter DSC is a counter running in the

MS The starting value of this counter is called DSC0 and is set by the

MS to the following value

DSC0 = round(90 BS_PA_MFRMS)

The value of BS_PA_MFRMS is broadcasted in the system informations on

the BCCH of the serving cell Each BS_PA_MFRMS the MS attempts to

decode the messages on its paging sub-channel Depending on whether or

not this decoding is successful the value of the downlink signaling failure

counter DSC is modified in the following way

successful decoding DSC new = DSC old + 1

if DSC new + 1 gt DSC0 rarr DSC new = DSC old

unsuccessful decoding DSC new = DSC old ndash 4

If DSC lt 0 the MS has detected a downlink signaling

failure

Minimum decoding

Monitoring of all BCCH carriers given in the BCCH allocation

(neighbor cells) of the serving cell

Taking at least 5 samples of the received level from the serving cell

(on paging sub-channel) as well as from the neighbor cells

=gt AV_RXLEV(serving cell) and AV_RXLEV (neighbor cell)

Decoding of full BCCH data of the serving cell at least every 30 sec

Decoding of BCCH data of the 6 strongest neighbor cells at least

every 5 minutes

From the radio propagation point of view it is

worth to select a new (neighbor) cell if the

received level from that neighbor cell exceeds the

received level of the current serving cell For

phase 1 MS this is expressed using the C1

criterion

C1 (neighbor cell) gt C1 (serving cell)

For phase 2 MS a modified path loss criterion the C2 criterion

is usedThe C2 criterion depends on the value of a timer T

which is called PENALTY_TIMERThe timer T is started in the MS

for each cell in the list of the 6 strongest neighbor cells as soon

as it is placed on the list Timer T is reset to 0 if the cell is

removed from the list

During penalty time

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

After penalty time

C2 = C1 + CELL_RESELECT_OFFSET

For penalty time = 31 the whole time

C2 = C1 - CELL_RESELECT_OFFSET

CELL_RESELECT_OFFSET TEMPORARY_OFFSET and

PENALTY_TIME are cell reselection parameters which

are broadcasted on the BCCH of the cell in the

system informations if CELL_RESLECT_PARAM_IND

(Cell Reselection Parameter Indication) is set to 1

A negative TEMPORARY_OFFSET reduces the

priority of a cell in the list of strongest neighbor

cells

A positive CELL_RESELECT_OFFSET increases the

priority of a cell in the list of strongest neighbor

cells

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells

When a mobile reaches the coverage area of a (neighbor) micro cell given

by the C1 criterion this cell becomes effectively excluded from reselection

during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell be-fore PENALTY_TIME is reached and hence the micro cell is not

selected

In contrast a slow moving mobile is assumed to be still within the coverage

area of the micro cell when PENALTY_TIME has expired

Applying the positive CELL_RESELECT_OFFSET this cell is selected with

preference

Triggers for Cell Reselection

Cell reselection is triggered by the following conditions

1 C1 lt 0 for the serving cell for a period of 5 s

2 MS detects a downlink signaling failure

3 Serving cell becomes barred

Phase 1 MS

C1 (serving cell) lt C1 (suitable neighbor cell) if the suitable neighbor cell is

in the same location area

C1 (serving cell) + CELL_RESELECT_HYSTERESIS lt C1 (suitable

neighbor cell) if the suitable neighbor cell is in another location area for a

period of 5 sec

Phase 2 MS

C2 (serving cell) lt C2 (suitable neighbor cell) if the suitable neighbor cell is in

the same location area

C2 (serving cell) + CELL_RESELECT_HYSTERESIS lt C2 (suitable neighbor

cell) if the suitable neighbor cell is in another location area for a period of 5

sec

A random access attempt is unsuccessful even after the maximum number

of repetitions

For phase 2 there is the additional trigger

A location update request has been rejected with cause rdquolocation area not

allowedrdquo

PARAMETERS SETTING

BA (BCCH) - BCCH Allocation broadcasted on BCCH

In each cell the absolute radio frequency carrier number

BCCH_ARFCN_NC(n) of each of its neighbor cell n has to be

known This information is broadcasted as the so-called BCCH

Allocation to all MS in the respective cell On the

corresponding frequencies the MS take measurement samples

of the received level used for cell selection reselection

Furthermore the BCCH of neighbor cells has to be decoded by

the MS (at least every 5 min) to know the current values of the

control parameters for the reselection algorithm

PARAMETERS SETTING

Object DB Name Range Step Size

Unit ADJC BCCHFREQ 01023 1

PARAMETERS SETTING

CELL_BAR_ACCESS - Cell Barred for Access

A mobile station cannot camp on a barred cell ie a barred cell is not

selected by the cell selectionreselection procedure

Mobile stations which camp on a cell while it becomes barred initialize the

reselection procedure to find a new (unbarred) cell ie traffic load is

distributed to neighbor cells

This means that eg neither a call nor a location update can start in a

barred cell

However a cell barred for access is not barred for incoming handovers To

barr a cell completely eg for maintenance reasons also incoming

handovers have to be avoided

To reduce overload in a certain cell more moderately without distributing

the overload to neighbor cells barring of access classes has to be used

Barring access for an access class does not trigger a cell reselection for

MSs of that class

Object DB Name Range

BTS CELLBARR FALSETRUE

RXLEV_ACCESS_MIN - Minimum Downlink Received Level for Cell to be

selected

The parameter RXLEV_ACCESS_MIN determines the cell border for a MS in idle

mode by means of the C1 or C2 criterion respectively

Choosing a high value reduces the risk of a handover immediately after call

setup

On the other hand the value has to be low enough to achieve a sufficient overlap

between adjacent cells (especially if they belong to different location areas)

It has to be observed that the overlap may be different for mobiles of different

power classes (refer to MS_TXPWR_MAX_CCH)

In any case RXLEV_ACCESS_MIN has to be above the MS receiver sensitivity level

(-100 dBm for DCS1800 -102 dBm for GSM handhelds -104 dBm for other GSM

MS)

Furthermore it has to harmonize with the

handover thresholds (RXLEV_MIN L_RXLEV_HO)

Object DB Name Range Step Size Unit

BTS RXLEVAMI 063 1

RXLEV

MS_TXPWR_MAX_CCH - Maximum allowed MS Transmit

Power on RACH

The transmit power level the MS uses for the access on the

Random Access Channel is given by the minimum of two

values

the maximum possible transmit power of the MS (given by

the power class P of the MS) the maximum allowed power

for access within the respective cell

(given by MS_TXP WR_MAX_CCH)

This parameter affects the

the random access procedure

the cell selection procedure

Random access

If there is a collision of channel requests on the random access

channel the one with the higher received level has a good chance

to be decoded and to get a response by the BTS

Hence MS with higher output power are preferred This imbalance

can be avoided by choosing a low maximum allowed transmit power

PARAMETERS SETTING

Cell Selection

To be selected by the cell selection procedure a cell has to fulfill the

C1 criterion

C1 gt 0 where

C1 = AV_RXLEV - RXLEV_ACCESS_MIN - Max(0

MS_TXPWR_MAX_CCH - P )

Choosing for example MS_TXPWR_MAX_CCH = Pmin where Pmin is

the output power level for the minimum power class 5 (29 dBm)

the C1 criterion reduces to AV_RXLEV gt RXLEV_ACCESS_MIN

for MSs of all power classes Hence the same idle mode cell border

is seen by each mobile

Choosing for example MS_TXPWR_MAX_CCH = Pmax where Pmax is

the output power level for the maximum power class 1 (43 dBm)

the C1 criterion reduces to

AV_RXLEV gt RXLEV_ACCESS_MIN + ( MS_TXPWR_MAX_CCH - P )

for MSs of all power classes Hence a larger cell radius is seen by a

mobile of higher output power than by a mobile of lower output

power On the other hand one can ensure by this mechanism that a

certain uplink received level is exceeded by each MS independent of

its power class

Object DB Name Range Step Size Unit

BTS MSTXPMAXCH 031 1 2 dB

MS_TXPWR_MAX_CCH - Maximum allowed MS transmit power on RACH

default 2

MS GSM900 MS GSM900 MS DCS1800

Phase 1 Phase 2

0 = 43 dBm 0 = 39 dBm 0 = 30 dBm

1 = 41 dBm 1 = 39 dBm 1 = 28 dBm

2 = 39 dBm 2 = 39 dBm 2 = 26 dBm

3 = 37 dBm 3 = 37 dBm 3 = 24 dBm

15 = 13dBm 19 = 5 dBm 15 = 0 dBm

16-31 = 13 dBm 20-31 = 5 dBm 16-31 = 0 dBm

POWER_OFFSET - Additional Parameter for Class 3

DCS1800 MS

The parameter POWER_OFFSET is only used by class 3

DCS1800 MS to calculate the C1-criterion described as

follows

C1 = AV_RXLEV - RXLEV_ACCESS_MIN -

Max(0MS_TXPWR_MAX_CCH + POWER_OFFSET- P)

Object DB Name Range Step Size Unit

BTS PWROFS 03 1 2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for Reselection of a Cell

from another Location Area

In idle mode the MS selects a new (neighbor) cell if the received level of the

neighbor cell exceeds the received level of the current cell in order to be

served by the cell with the expected best link quality However due to

fading effects the propagation conditions may change rapidly and

therefore a reselection may occur very frequently

If the cells involved in the reselection process belong to the same location

area frequent cell reselection does not have an effect on the network

performance

But if the involved cells belong to different location area the reselection of

a new cell triggers a location update procedure which causes signaling

load (eg on the SDCCH) and involves all network elements

To avoid unnecessary signaling load by forward and backward reselection due to fading

a hysteresis given by the parameter CELL_RESELECT_HYSTERESIS is introduced ie

a cell from another location area is selected only if the corresponding received level

exceeds the level of the current serving cell by the value of this parameter This is

expressed in terms of the C1 (phase 1) or C2 (phase 2) criterion

C1 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C1 (suitable neighbor cell)

or

C2 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C2 (suitable neighbor cell)

respectively

The adjustment of CELL_RESELECT_HYSTERESES should be a compromise between

reduction of unnecessary location updates (high value) and

selection of the cell with best reception quality (low value)

Object DB Name Range Step Size Unit

BTS CELLRESH 07 1

2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for

reselection of a cell from another location area

default 2

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter

Indication

CELL_RESELECT_PARAM_IND=1

The cell reselection parameters CELL_RESELECT_OFFSET

TEMPORARY_OFFSET and PENALTY_TIME used for the C2 criterion as well as

the parameter CELL_BAR_QUALIFY are broadcasted on the BCCH These

parameters are taken into account by phase 2 MS but are ignored by

phase 1 MS

CELL_RESELECT_PARAM_IND = 0

The cell reselection parameters and CELL_BAR_QUALIFY are not

broadcasted on the BCCH

A phase 2 MS then uses the value 0 for all these parameters ie C1 = C2

Object DB Name Range

BTS CRESPARI 01

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter Indication default 1

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

Phase 2 Cell reselection criterion C2 is defined as

C2 = C1 + CELL_RESELECT_OFFSET minus TEMPORARY_OFFSET

If CELL RESELECT PARAM IND = TRUE then

If the counter T lt PENALTY TIME

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY OFFSET

If the counter T gt= PENALTY TIME

C2 = C1 + CELL_RESELECT_OFFSET

13

If the neighbour is the last serving cell

T = PENALTY TIME and

C2 = C1 + CELL_RESELECT_OFFSET

The timer T is started separately for each cell in the list of the six

strongest cells immediately after it is placed on the list MS camps

in the cell with the highest C2 value

15

The criterion C2 is applied in hierarchical cell structures to keep fast

moving MS in an upper layer and slow moving MS in micro cells It is

assumed that a fast moving MS passes through the micro cell before

PENALTY_TIME is reached This efficiently prevents unnecessary LUs and

thus saves network signaling capacity As in the case of C1 MS receives

the C2 parameter information through BCCH A parameter called

CELL_RESELECT_PARAM_IND informs MS about which reselection

criterion (C1 or C2) is used in the cell It is broadcast on the BCCH

The following actions are performed by the MS to detect whether or not a

cell reselection is necessary

Detection of a Downlink Signaling Failure ndash The downlink signaling failure counter DSC is a counter running in the

MS The starting value of this counter is called DSC0 and is set by the

MS to the following value

DSC0 = round(90 BS_PA_MFRMS)

The value of BS_PA_MFRMS is broadcasted in the system informations on

the BCCH of the serving cell Each BS_PA_MFRMS the MS attempts to

decode the messages on its paging sub-channel Depending on whether or

not this decoding is successful the value of the downlink signaling failure

counter DSC is modified in the following way

successful decoding DSC new = DSC old + 1

if DSC new + 1 gt DSC0 rarr DSC new = DSC old

unsuccessful decoding DSC new = DSC old ndash 4

If DSC lt 0 the MS has detected a downlink signaling

failure

Minimum decoding

Monitoring of all BCCH carriers given in the BCCH allocation

(neighbor cells) of the serving cell

Taking at least 5 samples of the received level from the serving cell

(on paging sub-channel) as well as from the neighbor cells

=gt AV_RXLEV(serving cell) and AV_RXLEV (neighbor cell)

Decoding of full BCCH data of the serving cell at least every 30 sec

Decoding of BCCH data of the 6 strongest neighbor cells at least

every 5 minutes

From the radio propagation point of view it is

worth to select a new (neighbor) cell if the

received level from that neighbor cell exceeds the

received level of the current serving cell For

phase 1 MS this is expressed using the C1

criterion

C1 (neighbor cell) gt C1 (serving cell)

For phase 2 MS a modified path loss criterion the C2 criterion

is usedThe C2 criterion depends on the value of a timer T

which is called PENALTY_TIMERThe timer T is started in the MS

for each cell in the list of the 6 strongest neighbor cells as soon

as it is placed on the list Timer T is reset to 0 if the cell is

removed from the list

During penalty time

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

After penalty time

C2 = C1 + CELL_RESELECT_OFFSET

For penalty time = 31 the whole time

C2 = C1 - CELL_RESELECT_OFFSET

CELL_RESELECT_OFFSET TEMPORARY_OFFSET and

PENALTY_TIME are cell reselection parameters which

are broadcasted on the BCCH of the cell in the

system informations if CELL_RESLECT_PARAM_IND

(Cell Reselection Parameter Indication) is set to 1

A negative TEMPORARY_OFFSET reduces the

priority of a cell in the list of strongest neighbor

cells

A positive CELL_RESELECT_OFFSET increases the

priority of a cell in the list of strongest neighbor

cells

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells

When a mobile reaches the coverage area of a (neighbor) micro cell given

by the C1 criterion this cell becomes effectively excluded from reselection

during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell be-fore PENALTY_TIME is reached and hence the micro cell is not

selected

In contrast a slow moving mobile is assumed to be still within the coverage

area of the micro cell when PENALTY_TIME has expired

Applying the positive CELL_RESELECT_OFFSET this cell is selected with

preference

Triggers for Cell Reselection

Cell reselection is triggered by the following conditions

1 C1 lt 0 for the serving cell for a period of 5 s

2 MS detects a downlink signaling failure

3 Serving cell becomes barred

Phase 1 MS

C1 (serving cell) lt C1 (suitable neighbor cell) if the suitable neighbor cell is

in the same location area

C1 (serving cell) + CELL_RESELECT_HYSTERESIS lt C1 (suitable

neighbor cell) if the suitable neighbor cell is in another location area for a

period of 5 sec

Phase 2 MS

C2 (serving cell) lt C2 (suitable neighbor cell) if the suitable neighbor cell is in

the same location area

C2 (serving cell) + CELL_RESELECT_HYSTERESIS lt C2 (suitable neighbor

cell) if the suitable neighbor cell is in another location area for a period of 5

sec

A random access attempt is unsuccessful even after the maximum number

of repetitions

For phase 2 there is the additional trigger

A location update request has been rejected with cause rdquolocation area not

allowedrdquo

PARAMETERS SETTING

BA (BCCH) - BCCH Allocation broadcasted on BCCH

In each cell the absolute radio frequency carrier number

BCCH_ARFCN_NC(n) of each of its neighbor cell n has to be

known This information is broadcasted as the so-called BCCH

Allocation to all MS in the respective cell On the

corresponding frequencies the MS take measurement samples

of the received level used for cell selection reselection

Furthermore the BCCH of neighbor cells has to be decoded by

the MS (at least every 5 min) to know the current values of the

control parameters for the reselection algorithm

PARAMETERS SETTING

Object DB Name Range Step Size

Unit ADJC BCCHFREQ 01023 1

PARAMETERS SETTING

CELL_BAR_ACCESS - Cell Barred for Access

A mobile station cannot camp on a barred cell ie a barred cell is not

selected by the cell selectionreselection procedure

Mobile stations which camp on a cell while it becomes barred initialize the

reselection procedure to find a new (unbarred) cell ie traffic load is

distributed to neighbor cells

This means that eg neither a call nor a location update can start in a

barred cell

However a cell barred for access is not barred for incoming handovers To

barr a cell completely eg for maintenance reasons also incoming

handovers have to be avoided

To reduce overload in a certain cell more moderately without distributing

the overload to neighbor cells barring of access classes has to be used

Barring access for an access class does not trigger a cell reselection for

MSs of that class

Object DB Name Range

BTS CELLBARR FALSETRUE

RXLEV_ACCESS_MIN - Minimum Downlink Received Level for Cell to be

selected

The parameter RXLEV_ACCESS_MIN determines the cell border for a MS in idle

mode by means of the C1 or C2 criterion respectively

Choosing a high value reduces the risk of a handover immediately after call

setup

On the other hand the value has to be low enough to achieve a sufficient overlap

between adjacent cells (especially if they belong to different location areas)

It has to be observed that the overlap may be different for mobiles of different

power classes (refer to MS_TXPWR_MAX_CCH)

In any case RXLEV_ACCESS_MIN has to be above the MS receiver sensitivity level

(-100 dBm for DCS1800 -102 dBm for GSM handhelds -104 dBm for other GSM

MS)

Furthermore it has to harmonize with the

handover thresholds (RXLEV_MIN L_RXLEV_HO)

Object DB Name Range Step Size Unit

BTS RXLEVAMI 063 1

RXLEV

MS_TXPWR_MAX_CCH - Maximum allowed MS Transmit

Power on RACH

The transmit power level the MS uses for the access on the

Random Access Channel is given by the minimum of two

values

the maximum possible transmit power of the MS (given by

the power class P of the MS) the maximum allowed power

for access within the respective cell

(given by MS_TXP WR_MAX_CCH)

This parameter affects the

the random access procedure

the cell selection procedure

Random access

If there is a collision of channel requests on the random access

channel the one with the higher received level has a good chance

to be decoded and to get a response by the BTS

Hence MS with higher output power are preferred This imbalance

can be avoided by choosing a low maximum allowed transmit power

PARAMETERS SETTING

Cell Selection

To be selected by the cell selection procedure a cell has to fulfill the

C1 criterion

C1 gt 0 where

C1 = AV_RXLEV - RXLEV_ACCESS_MIN - Max(0

MS_TXPWR_MAX_CCH - P )

Choosing for example MS_TXPWR_MAX_CCH = Pmin where Pmin is

the output power level for the minimum power class 5 (29 dBm)

the C1 criterion reduces to AV_RXLEV gt RXLEV_ACCESS_MIN

for MSs of all power classes Hence the same idle mode cell border

is seen by each mobile

Choosing for example MS_TXPWR_MAX_CCH = Pmax where Pmax is

the output power level for the maximum power class 1 (43 dBm)

the C1 criterion reduces to

AV_RXLEV gt RXLEV_ACCESS_MIN + ( MS_TXPWR_MAX_CCH - P )

for MSs of all power classes Hence a larger cell radius is seen by a

mobile of higher output power than by a mobile of lower output

power On the other hand one can ensure by this mechanism that a

certain uplink received level is exceeded by each MS independent of

its power class

Object DB Name Range Step Size Unit

BTS MSTXPMAXCH 031 1 2 dB

MS_TXPWR_MAX_CCH - Maximum allowed MS transmit power on RACH

default 2

MS GSM900 MS GSM900 MS DCS1800

Phase 1 Phase 2

0 = 43 dBm 0 = 39 dBm 0 = 30 dBm

1 = 41 dBm 1 = 39 dBm 1 = 28 dBm

2 = 39 dBm 2 = 39 dBm 2 = 26 dBm

3 = 37 dBm 3 = 37 dBm 3 = 24 dBm

15 = 13dBm 19 = 5 dBm 15 = 0 dBm

16-31 = 13 dBm 20-31 = 5 dBm 16-31 = 0 dBm

POWER_OFFSET - Additional Parameter for Class 3

DCS1800 MS

The parameter POWER_OFFSET is only used by class 3

DCS1800 MS to calculate the C1-criterion described as

follows

C1 = AV_RXLEV - RXLEV_ACCESS_MIN -

Max(0MS_TXPWR_MAX_CCH + POWER_OFFSET- P)

Object DB Name Range Step Size Unit

BTS PWROFS 03 1 2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for Reselection of a Cell

from another Location Area

In idle mode the MS selects a new (neighbor) cell if the received level of the

neighbor cell exceeds the received level of the current cell in order to be

served by the cell with the expected best link quality However due to

fading effects the propagation conditions may change rapidly and

therefore a reselection may occur very frequently

If the cells involved in the reselection process belong to the same location

area frequent cell reselection does not have an effect on the network

performance

But if the involved cells belong to different location area the reselection of

a new cell triggers a location update procedure which causes signaling

load (eg on the SDCCH) and involves all network elements

To avoid unnecessary signaling load by forward and backward reselection due to fading

a hysteresis given by the parameter CELL_RESELECT_HYSTERESIS is introduced ie

a cell from another location area is selected only if the corresponding received level

exceeds the level of the current serving cell by the value of this parameter This is

expressed in terms of the C1 (phase 1) or C2 (phase 2) criterion

C1 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C1 (suitable neighbor cell)

or

C2 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C2 (suitable neighbor cell)

respectively

The adjustment of CELL_RESELECT_HYSTERESES should be a compromise between

reduction of unnecessary location updates (high value) and

selection of the cell with best reception quality (low value)

Object DB Name Range Step Size Unit

BTS CELLRESH 07 1

2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for

reselection of a cell from another location area

default 2

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter

Indication

CELL_RESELECT_PARAM_IND=1

The cell reselection parameters CELL_RESELECT_OFFSET

TEMPORARY_OFFSET and PENALTY_TIME used for the C2 criterion as well as

the parameter CELL_BAR_QUALIFY are broadcasted on the BCCH These

parameters are taken into account by phase 2 MS but are ignored by

phase 1 MS

CELL_RESELECT_PARAM_IND = 0

The cell reselection parameters and CELL_BAR_QUALIFY are not

broadcasted on the BCCH

A phase 2 MS then uses the value 0 for all these parameters ie C1 = C2

Object DB Name Range

BTS CRESPARI 01

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter Indication default 1

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

If the neighbour is the last serving cell

T = PENALTY TIME and

C2 = C1 + CELL_RESELECT_OFFSET

The timer T is started separately for each cell in the list of the six

strongest cells immediately after it is placed on the list MS camps

in the cell with the highest C2 value

15

The criterion C2 is applied in hierarchical cell structures to keep fast

moving MS in an upper layer and slow moving MS in micro cells It is

assumed that a fast moving MS passes through the micro cell before

PENALTY_TIME is reached This efficiently prevents unnecessary LUs and

thus saves network signaling capacity As in the case of C1 MS receives

the C2 parameter information through BCCH A parameter called

CELL_RESELECT_PARAM_IND informs MS about which reselection

criterion (C1 or C2) is used in the cell It is broadcast on the BCCH

The following actions are performed by the MS to detect whether or not a

cell reselection is necessary

Detection of a Downlink Signaling Failure ndash The downlink signaling failure counter DSC is a counter running in the

MS The starting value of this counter is called DSC0 and is set by the

MS to the following value

DSC0 = round(90 BS_PA_MFRMS)

The value of BS_PA_MFRMS is broadcasted in the system informations on

the BCCH of the serving cell Each BS_PA_MFRMS the MS attempts to

decode the messages on its paging sub-channel Depending on whether or

not this decoding is successful the value of the downlink signaling failure

counter DSC is modified in the following way

successful decoding DSC new = DSC old + 1

if DSC new + 1 gt DSC0 rarr DSC new = DSC old

unsuccessful decoding DSC new = DSC old ndash 4

If DSC lt 0 the MS has detected a downlink signaling

failure

Minimum decoding

Monitoring of all BCCH carriers given in the BCCH allocation

(neighbor cells) of the serving cell

Taking at least 5 samples of the received level from the serving cell

(on paging sub-channel) as well as from the neighbor cells

=gt AV_RXLEV(serving cell) and AV_RXLEV (neighbor cell)

Decoding of full BCCH data of the serving cell at least every 30 sec

Decoding of BCCH data of the 6 strongest neighbor cells at least

every 5 minutes

From the radio propagation point of view it is

worth to select a new (neighbor) cell if the

received level from that neighbor cell exceeds the

received level of the current serving cell For

phase 1 MS this is expressed using the C1

criterion

C1 (neighbor cell) gt C1 (serving cell)

For phase 2 MS a modified path loss criterion the C2 criterion

is usedThe C2 criterion depends on the value of a timer T

which is called PENALTY_TIMERThe timer T is started in the MS

for each cell in the list of the 6 strongest neighbor cells as soon

as it is placed on the list Timer T is reset to 0 if the cell is

removed from the list

During penalty time

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

After penalty time

C2 = C1 + CELL_RESELECT_OFFSET

For penalty time = 31 the whole time

C2 = C1 - CELL_RESELECT_OFFSET

CELL_RESELECT_OFFSET TEMPORARY_OFFSET and

PENALTY_TIME are cell reselection parameters which

are broadcasted on the BCCH of the cell in the

system informations if CELL_RESLECT_PARAM_IND

(Cell Reselection Parameter Indication) is set to 1

A negative TEMPORARY_OFFSET reduces the

priority of a cell in the list of strongest neighbor

cells

A positive CELL_RESELECT_OFFSET increases the

priority of a cell in the list of strongest neighbor

cells

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells

When a mobile reaches the coverage area of a (neighbor) micro cell given

by the C1 criterion this cell becomes effectively excluded from reselection

during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell be-fore PENALTY_TIME is reached and hence the micro cell is not

selected

In contrast a slow moving mobile is assumed to be still within the coverage

area of the micro cell when PENALTY_TIME has expired

Applying the positive CELL_RESELECT_OFFSET this cell is selected with

preference

Triggers for Cell Reselection

Cell reselection is triggered by the following conditions

1 C1 lt 0 for the serving cell for a period of 5 s

2 MS detects a downlink signaling failure

3 Serving cell becomes barred

Phase 1 MS

C1 (serving cell) lt C1 (suitable neighbor cell) if the suitable neighbor cell is

in the same location area

C1 (serving cell) + CELL_RESELECT_HYSTERESIS lt C1 (suitable

neighbor cell) if the suitable neighbor cell is in another location area for a

period of 5 sec

Phase 2 MS

C2 (serving cell) lt C2 (suitable neighbor cell) if the suitable neighbor cell is in

the same location area

C2 (serving cell) + CELL_RESELECT_HYSTERESIS lt C2 (suitable neighbor

cell) if the suitable neighbor cell is in another location area for a period of 5

sec

A random access attempt is unsuccessful even after the maximum number

of repetitions

For phase 2 there is the additional trigger

A location update request has been rejected with cause rdquolocation area not

allowedrdquo

PARAMETERS SETTING

BA (BCCH) - BCCH Allocation broadcasted on BCCH

In each cell the absolute radio frequency carrier number

BCCH_ARFCN_NC(n) of each of its neighbor cell n has to be

known This information is broadcasted as the so-called BCCH

Allocation to all MS in the respective cell On the

corresponding frequencies the MS take measurement samples

of the received level used for cell selection reselection

Furthermore the BCCH of neighbor cells has to be decoded by

the MS (at least every 5 min) to know the current values of the

control parameters for the reselection algorithm

PARAMETERS SETTING

Object DB Name Range Step Size

Unit ADJC BCCHFREQ 01023 1

PARAMETERS SETTING

CELL_BAR_ACCESS - Cell Barred for Access

A mobile station cannot camp on a barred cell ie a barred cell is not

selected by the cell selectionreselection procedure

Mobile stations which camp on a cell while it becomes barred initialize the

reselection procedure to find a new (unbarred) cell ie traffic load is

distributed to neighbor cells

This means that eg neither a call nor a location update can start in a

barred cell

However a cell barred for access is not barred for incoming handovers To

barr a cell completely eg for maintenance reasons also incoming

handovers have to be avoided

To reduce overload in a certain cell more moderately without distributing

the overload to neighbor cells barring of access classes has to be used

Barring access for an access class does not trigger a cell reselection for

MSs of that class

Object DB Name Range

BTS CELLBARR FALSETRUE

RXLEV_ACCESS_MIN - Minimum Downlink Received Level for Cell to be

selected

The parameter RXLEV_ACCESS_MIN determines the cell border for a MS in idle

mode by means of the C1 or C2 criterion respectively

Choosing a high value reduces the risk of a handover immediately after call

setup

On the other hand the value has to be low enough to achieve a sufficient overlap

between adjacent cells (especially if they belong to different location areas)

It has to be observed that the overlap may be different for mobiles of different

power classes (refer to MS_TXPWR_MAX_CCH)

In any case RXLEV_ACCESS_MIN has to be above the MS receiver sensitivity level

(-100 dBm for DCS1800 -102 dBm for GSM handhelds -104 dBm for other GSM

MS)

Furthermore it has to harmonize with the

handover thresholds (RXLEV_MIN L_RXLEV_HO)

Object DB Name Range Step Size Unit

BTS RXLEVAMI 063 1

RXLEV

MS_TXPWR_MAX_CCH - Maximum allowed MS Transmit

Power on RACH

The transmit power level the MS uses for the access on the

Random Access Channel is given by the minimum of two

values

the maximum possible transmit power of the MS (given by

the power class P of the MS) the maximum allowed power

for access within the respective cell

(given by MS_TXP WR_MAX_CCH)

This parameter affects the

the random access procedure

the cell selection procedure

Random access

If there is a collision of channel requests on the random access

channel the one with the higher received level has a good chance

to be decoded and to get a response by the BTS

Hence MS with higher output power are preferred This imbalance

can be avoided by choosing a low maximum allowed transmit power

PARAMETERS SETTING

Cell Selection

To be selected by the cell selection procedure a cell has to fulfill the

C1 criterion

C1 gt 0 where

C1 = AV_RXLEV - RXLEV_ACCESS_MIN - Max(0

MS_TXPWR_MAX_CCH - P )

Choosing for example MS_TXPWR_MAX_CCH = Pmin where Pmin is

the output power level for the minimum power class 5 (29 dBm)

the C1 criterion reduces to AV_RXLEV gt RXLEV_ACCESS_MIN

for MSs of all power classes Hence the same idle mode cell border

is seen by each mobile

Choosing for example MS_TXPWR_MAX_CCH = Pmax where Pmax is

the output power level for the maximum power class 1 (43 dBm)

the C1 criterion reduces to

AV_RXLEV gt RXLEV_ACCESS_MIN + ( MS_TXPWR_MAX_CCH - P )

for MSs of all power classes Hence a larger cell radius is seen by a

mobile of higher output power than by a mobile of lower output

power On the other hand one can ensure by this mechanism that a

certain uplink received level is exceeded by each MS independent of

its power class

Object DB Name Range Step Size Unit

BTS MSTXPMAXCH 031 1 2 dB

MS_TXPWR_MAX_CCH - Maximum allowed MS transmit power on RACH

default 2

MS GSM900 MS GSM900 MS DCS1800

Phase 1 Phase 2

0 = 43 dBm 0 = 39 dBm 0 = 30 dBm

1 = 41 dBm 1 = 39 dBm 1 = 28 dBm

2 = 39 dBm 2 = 39 dBm 2 = 26 dBm

3 = 37 dBm 3 = 37 dBm 3 = 24 dBm

15 = 13dBm 19 = 5 dBm 15 = 0 dBm

16-31 = 13 dBm 20-31 = 5 dBm 16-31 = 0 dBm

POWER_OFFSET - Additional Parameter for Class 3

DCS1800 MS

The parameter POWER_OFFSET is only used by class 3

DCS1800 MS to calculate the C1-criterion described as

follows

C1 = AV_RXLEV - RXLEV_ACCESS_MIN -

Max(0MS_TXPWR_MAX_CCH + POWER_OFFSET- P)

Object DB Name Range Step Size Unit

BTS PWROFS 03 1 2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for Reselection of a Cell

from another Location Area

In idle mode the MS selects a new (neighbor) cell if the received level of the

neighbor cell exceeds the received level of the current cell in order to be

served by the cell with the expected best link quality However due to

fading effects the propagation conditions may change rapidly and

therefore a reselection may occur very frequently

If the cells involved in the reselection process belong to the same location

area frequent cell reselection does not have an effect on the network

performance

But if the involved cells belong to different location area the reselection of

a new cell triggers a location update procedure which causes signaling

load (eg on the SDCCH) and involves all network elements

To avoid unnecessary signaling load by forward and backward reselection due to fading

a hysteresis given by the parameter CELL_RESELECT_HYSTERESIS is introduced ie

a cell from another location area is selected only if the corresponding received level

exceeds the level of the current serving cell by the value of this parameter This is

expressed in terms of the C1 (phase 1) or C2 (phase 2) criterion

C1 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C1 (suitable neighbor cell)

or

C2 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C2 (suitable neighbor cell)

respectively

The adjustment of CELL_RESELECT_HYSTERESES should be a compromise between

reduction of unnecessary location updates (high value) and

selection of the cell with best reception quality (low value)

Object DB Name Range Step Size Unit

BTS CELLRESH 07 1

2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for

reselection of a cell from another location area

default 2

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter

Indication

CELL_RESELECT_PARAM_IND=1

The cell reselection parameters CELL_RESELECT_OFFSET

TEMPORARY_OFFSET and PENALTY_TIME used for the C2 criterion as well as

the parameter CELL_BAR_QUALIFY are broadcasted on the BCCH These

parameters are taken into account by phase 2 MS but are ignored by

phase 1 MS

CELL_RESELECT_PARAM_IND = 0

The cell reselection parameters and CELL_BAR_QUALIFY are not

broadcasted on the BCCH

A phase 2 MS then uses the value 0 for all these parameters ie C1 = C2

Object DB Name Range

BTS CRESPARI 01

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter Indication default 1

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

15

The criterion C2 is applied in hierarchical cell structures to keep fast

moving MS in an upper layer and slow moving MS in micro cells It is

assumed that a fast moving MS passes through the micro cell before

PENALTY_TIME is reached This efficiently prevents unnecessary LUs and

thus saves network signaling capacity As in the case of C1 MS receives

the C2 parameter information through BCCH A parameter called

CELL_RESELECT_PARAM_IND informs MS about which reselection

criterion (C1 or C2) is used in the cell It is broadcast on the BCCH

The following actions are performed by the MS to detect whether or not a

cell reselection is necessary

Detection of a Downlink Signaling Failure ndash The downlink signaling failure counter DSC is a counter running in the

MS The starting value of this counter is called DSC0 and is set by the

MS to the following value

DSC0 = round(90 BS_PA_MFRMS)

The value of BS_PA_MFRMS is broadcasted in the system informations on

the BCCH of the serving cell Each BS_PA_MFRMS the MS attempts to

decode the messages on its paging sub-channel Depending on whether or

not this decoding is successful the value of the downlink signaling failure

counter DSC is modified in the following way

successful decoding DSC new = DSC old + 1

if DSC new + 1 gt DSC0 rarr DSC new = DSC old

unsuccessful decoding DSC new = DSC old ndash 4

If DSC lt 0 the MS has detected a downlink signaling

failure

Minimum decoding

Monitoring of all BCCH carriers given in the BCCH allocation

(neighbor cells) of the serving cell

Taking at least 5 samples of the received level from the serving cell

(on paging sub-channel) as well as from the neighbor cells

=gt AV_RXLEV(serving cell) and AV_RXLEV (neighbor cell)

Decoding of full BCCH data of the serving cell at least every 30 sec

Decoding of BCCH data of the 6 strongest neighbor cells at least

every 5 minutes

From the radio propagation point of view it is

worth to select a new (neighbor) cell if the

received level from that neighbor cell exceeds the

received level of the current serving cell For

phase 1 MS this is expressed using the C1

criterion

C1 (neighbor cell) gt C1 (serving cell)

For phase 2 MS a modified path loss criterion the C2 criterion

is usedThe C2 criterion depends on the value of a timer T

which is called PENALTY_TIMERThe timer T is started in the MS

for each cell in the list of the 6 strongest neighbor cells as soon

as it is placed on the list Timer T is reset to 0 if the cell is

removed from the list

During penalty time

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

After penalty time

C2 = C1 + CELL_RESELECT_OFFSET

For penalty time = 31 the whole time

C2 = C1 - CELL_RESELECT_OFFSET

CELL_RESELECT_OFFSET TEMPORARY_OFFSET and

PENALTY_TIME are cell reselection parameters which

are broadcasted on the BCCH of the cell in the

system informations if CELL_RESLECT_PARAM_IND

(Cell Reselection Parameter Indication) is set to 1

A negative TEMPORARY_OFFSET reduces the

priority of a cell in the list of strongest neighbor

cells

A positive CELL_RESELECT_OFFSET increases the

priority of a cell in the list of strongest neighbor

cells

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells

When a mobile reaches the coverage area of a (neighbor) micro cell given

by the C1 criterion this cell becomes effectively excluded from reselection

during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell be-fore PENALTY_TIME is reached and hence the micro cell is not

selected

In contrast a slow moving mobile is assumed to be still within the coverage

area of the micro cell when PENALTY_TIME has expired

Applying the positive CELL_RESELECT_OFFSET this cell is selected with

preference

Triggers for Cell Reselection

Cell reselection is triggered by the following conditions

1 C1 lt 0 for the serving cell for a period of 5 s

2 MS detects a downlink signaling failure

3 Serving cell becomes barred

Phase 1 MS

C1 (serving cell) lt C1 (suitable neighbor cell) if the suitable neighbor cell is

in the same location area

C1 (serving cell) + CELL_RESELECT_HYSTERESIS lt C1 (suitable

neighbor cell) if the suitable neighbor cell is in another location area for a

period of 5 sec

Phase 2 MS

C2 (serving cell) lt C2 (suitable neighbor cell) if the suitable neighbor cell is in

the same location area

C2 (serving cell) + CELL_RESELECT_HYSTERESIS lt C2 (suitable neighbor

cell) if the suitable neighbor cell is in another location area for a period of 5

sec

A random access attempt is unsuccessful even after the maximum number

of repetitions

For phase 2 there is the additional trigger

A location update request has been rejected with cause rdquolocation area not

allowedrdquo

PARAMETERS SETTING

BA (BCCH) - BCCH Allocation broadcasted on BCCH

In each cell the absolute radio frequency carrier number

BCCH_ARFCN_NC(n) of each of its neighbor cell n has to be

known This information is broadcasted as the so-called BCCH

Allocation to all MS in the respective cell On the

corresponding frequencies the MS take measurement samples

of the received level used for cell selection reselection

Furthermore the BCCH of neighbor cells has to be decoded by

the MS (at least every 5 min) to know the current values of the

control parameters for the reselection algorithm

PARAMETERS SETTING

Object DB Name Range Step Size

Unit ADJC BCCHFREQ 01023 1

PARAMETERS SETTING

CELL_BAR_ACCESS - Cell Barred for Access

A mobile station cannot camp on a barred cell ie a barred cell is not

selected by the cell selectionreselection procedure

Mobile stations which camp on a cell while it becomes barred initialize the

reselection procedure to find a new (unbarred) cell ie traffic load is

distributed to neighbor cells

This means that eg neither a call nor a location update can start in a

barred cell

However a cell barred for access is not barred for incoming handovers To

barr a cell completely eg for maintenance reasons also incoming

handovers have to be avoided

To reduce overload in a certain cell more moderately without distributing

the overload to neighbor cells barring of access classes has to be used

Barring access for an access class does not trigger a cell reselection for

MSs of that class

Object DB Name Range

BTS CELLBARR FALSETRUE

RXLEV_ACCESS_MIN - Minimum Downlink Received Level for Cell to be

selected

The parameter RXLEV_ACCESS_MIN determines the cell border for a MS in idle

mode by means of the C1 or C2 criterion respectively

Choosing a high value reduces the risk of a handover immediately after call

setup

On the other hand the value has to be low enough to achieve a sufficient overlap

between adjacent cells (especially if they belong to different location areas)

It has to be observed that the overlap may be different for mobiles of different

power classes (refer to MS_TXPWR_MAX_CCH)

In any case RXLEV_ACCESS_MIN has to be above the MS receiver sensitivity level

(-100 dBm for DCS1800 -102 dBm for GSM handhelds -104 dBm for other GSM

MS)

Furthermore it has to harmonize with the

handover thresholds (RXLEV_MIN L_RXLEV_HO)

Object DB Name Range Step Size Unit

BTS RXLEVAMI 063 1

RXLEV

MS_TXPWR_MAX_CCH - Maximum allowed MS Transmit

Power on RACH

The transmit power level the MS uses for the access on the

Random Access Channel is given by the minimum of two

values

the maximum possible transmit power of the MS (given by

the power class P of the MS) the maximum allowed power

for access within the respective cell

(given by MS_TXP WR_MAX_CCH)

This parameter affects the

the random access procedure

the cell selection procedure

Random access

If there is a collision of channel requests on the random access

channel the one with the higher received level has a good chance

to be decoded and to get a response by the BTS

Hence MS with higher output power are preferred This imbalance

can be avoided by choosing a low maximum allowed transmit power

PARAMETERS SETTING

Cell Selection

To be selected by the cell selection procedure a cell has to fulfill the

C1 criterion

C1 gt 0 where

C1 = AV_RXLEV - RXLEV_ACCESS_MIN - Max(0

MS_TXPWR_MAX_CCH - P )

Choosing for example MS_TXPWR_MAX_CCH = Pmin where Pmin is

the output power level for the minimum power class 5 (29 dBm)

the C1 criterion reduces to AV_RXLEV gt RXLEV_ACCESS_MIN

for MSs of all power classes Hence the same idle mode cell border

is seen by each mobile

Choosing for example MS_TXPWR_MAX_CCH = Pmax where Pmax is

the output power level for the maximum power class 1 (43 dBm)

the C1 criterion reduces to

AV_RXLEV gt RXLEV_ACCESS_MIN + ( MS_TXPWR_MAX_CCH - P )

for MSs of all power classes Hence a larger cell radius is seen by a

mobile of higher output power than by a mobile of lower output

power On the other hand one can ensure by this mechanism that a

certain uplink received level is exceeded by each MS independent of

its power class

Object DB Name Range Step Size Unit

BTS MSTXPMAXCH 031 1 2 dB

MS_TXPWR_MAX_CCH - Maximum allowed MS transmit power on RACH

default 2

MS GSM900 MS GSM900 MS DCS1800

Phase 1 Phase 2

0 = 43 dBm 0 = 39 dBm 0 = 30 dBm

1 = 41 dBm 1 = 39 dBm 1 = 28 dBm

2 = 39 dBm 2 = 39 dBm 2 = 26 dBm

3 = 37 dBm 3 = 37 dBm 3 = 24 dBm

15 = 13dBm 19 = 5 dBm 15 = 0 dBm

16-31 = 13 dBm 20-31 = 5 dBm 16-31 = 0 dBm

POWER_OFFSET - Additional Parameter for Class 3

DCS1800 MS

The parameter POWER_OFFSET is only used by class 3

DCS1800 MS to calculate the C1-criterion described as

follows

C1 = AV_RXLEV - RXLEV_ACCESS_MIN -

Max(0MS_TXPWR_MAX_CCH + POWER_OFFSET- P)

Object DB Name Range Step Size Unit

BTS PWROFS 03 1 2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for Reselection of a Cell

from another Location Area

In idle mode the MS selects a new (neighbor) cell if the received level of the

neighbor cell exceeds the received level of the current cell in order to be

served by the cell with the expected best link quality However due to

fading effects the propagation conditions may change rapidly and

therefore a reselection may occur very frequently

If the cells involved in the reselection process belong to the same location

area frequent cell reselection does not have an effect on the network

performance

But if the involved cells belong to different location area the reselection of

a new cell triggers a location update procedure which causes signaling

load (eg on the SDCCH) and involves all network elements

To avoid unnecessary signaling load by forward and backward reselection due to fading

a hysteresis given by the parameter CELL_RESELECT_HYSTERESIS is introduced ie

a cell from another location area is selected only if the corresponding received level

exceeds the level of the current serving cell by the value of this parameter This is

expressed in terms of the C1 (phase 1) or C2 (phase 2) criterion

C1 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C1 (suitable neighbor cell)

or

C2 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C2 (suitable neighbor cell)

respectively

The adjustment of CELL_RESELECT_HYSTERESES should be a compromise between

reduction of unnecessary location updates (high value) and

selection of the cell with best reception quality (low value)

Object DB Name Range Step Size Unit

BTS CELLRESH 07 1

2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for

reselection of a cell from another location area

default 2

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter

Indication

CELL_RESELECT_PARAM_IND=1

The cell reselection parameters CELL_RESELECT_OFFSET

TEMPORARY_OFFSET and PENALTY_TIME used for the C2 criterion as well as

the parameter CELL_BAR_QUALIFY are broadcasted on the BCCH These

parameters are taken into account by phase 2 MS but are ignored by

phase 1 MS

CELL_RESELECT_PARAM_IND = 0

The cell reselection parameters and CELL_BAR_QUALIFY are not

broadcasted on the BCCH

A phase 2 MS then uses the value 0 for all these parameters ie C1 = C2

Object DB Name Range

BTS CRESPARI 01

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter Indication default 1

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

The following actions are performed by the MS to detect whether or not a

cell reselection is necessary

Detection of a Downlink Signaling Failure ndash The downlink signaling failure counter DSC is a counter running in the

MS The starting value of this counter is called DSC0 and is set by the

MS to the following value

DSC0 = round(90 BS_PA_MFRMS)

The value of BS_PA_MFRMS is broadcasted in the system informations on

the BCCH of the serving cell Each BS_PA_MFRMS the MS attempts to

decode the messages on its paging sub-channel Depending on whether or

not this decoding is successful the value of the downlink signaling failure

counter DSC is modified in the following way

successful decoding DSC new = DSC old + 1

if DSC new + 1 gt DSC0 rarr DSC new = DSC old

unsuccessful decoding DSC new = DSC old ndash 4

If DSC lt 0 the MS has detected a downlink signaling

failure

Minimum decoding

Monitoring of all BCCH carriers given in the BCCH allocation

(neighbor cells) of the serving cell

Taking at least 5 samples of the received level from the serving cell

(on paging sub-channel) as well as from the neighbor cells

=gt AV_RXLEV(serving cell) and AV_RXLEV (neighbor cell)

Decoding of full BCCH data of the serving cell at least every 30 sec

Decoding of BCCH data of the 6 strongest neighbor cells at least

every 5 minutes

From the radio propagation point of view it is

worth to select a new (neighbor) cell if the

received level from that neighbor cell exceeds the

received level of the current serving cell For

phase 1 MS this is expressed using the C1

criterion

C1 (neighbor cell) gt C1 (serving cell)

For phase 2 MS a modified path loss criterion the C2 criterion

is usedThe C2 criterion depends on the value of a timer T

which is called PENALTY_TIMERThe timer T is started in the MS

for each cell in the list of the 6 strongest neighbor cells as soon

as it is placed on the list Timer T is reset to 0 if the cell is

removed from the list

During penalty time

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

After penalty time

C2 = C1 + CELL_RESELECT_OFFSET

For penalty time = 31 the whole time

C2 = C1 - CELL_RESELECT_OFFSET

CELL_RESELECT_OFFSET TEMPORARY_OFFSET and

PENALTY_TIME are cell reselection parameters which

are broadcasted on the BCCH of the cell in the

system informations if CELL_RESLECT_PARAM_IND

(Cell Reselection Parameter Indication) is set to 1

A negative TEMPORARY_OFFSET reduces the

priority of a cell in the list of strongest neighbor

cells

A positive CELL_RESELECT_OFFSET increases the

priority of a cell in the list of strongest neighbor

cells

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells

When a mobile reaches the coverage area of a (neighbor) micro cell given

by the C1 criterion this cell becomes effectively excluded from reselection

during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell be-fore PENALTY_TIME is reached and hence the micro cell is not

selected

In contrast a slow moving mobile is assumed to be still within the coverage

area of the micro cell when PENALTY_TIME has expired

Applying the positive CELL_RESELECT_OFFSET this cell is selected with

preference

Triggers for Cell Reselection

Cell reselection is triggered by the following conditions

1 C1 lt 0 for the serving cell for a period of 5 s

2 MS detects a downlink signaling failure

3 Serving cell becomes barred

Phase 1 MS

C1 (serving cell) lt C1 (suitable neighbor cell) if the suitable neighbor cell is

in the same location area

C1 (serving cell) + CELL_RESELECT_HYSTERESIS lt C1 (suitable

neighbor cell) if the suitable neighbor cell is in another location area for a

period of 5 sec

Phase 2 MS

C2 (serving cell) lt C2 (suitable neighbor cell) if the suitable neighbor cell is in

the same location area

C2 (serving cell) + CELL_RESELECT_HYSTERESIS lt C2 (suitable neighbor

cell) if the suitable neighbor cell is in another location area for a period of 5

sec

A random access attempt is unsuccessful even after the maximum number

of repetitions

For phase 2 there is the additional trigger

A location update request has been rejected with cause rdquolocation area not

allowedrdquo

PARAMETERS SETTING

BA (BCCH) - BCCH Allocation broadcasted on BCCH

In each cell the absolute radio frequency carrier number

BCCH_ARFCN_NC(n) of each of its neighbor cell n has to be

known This information is broadcasted as the so-called BCCH

Allocation to all MS in the respective cell On the

corresponding frequencies the MS take measurement samples

of the received level used for cell selection reselection

Furthermore the BCCH of neighbor cells has to be decoded by

the MS (at least every 5 min) to know the current values of the

control parameters for the reselection algorithm

PARAMETERS SETTING

Object DB Name Range Step Size

Unit ADJC BCCHFREQ 01023 1

PARAMETERS SETTING

CELL_BAR_ACCESS - Cell Barred for Access

A mobile station cannot camp on a barred cell ie a barred cell is not

selected by the cell selectionreselection procedure

Mobile stations which camp on a cell while it becomes barred initialize the

reselection procedure to find a new (unbarred) cell ie traffic load is

distributed to neighbor cells

This means that eg neither a call nor a location update can start in a

barred cell

However a cell barred for access is not barred for incoming handovers To

barr a cell completely eg for maintenance reasons also incoming

handovers have to be avoided

To reduce overload in a certain cell more moderately without distributing

the overload to neighbor cells barring of access classes has to be used

Barring access for an access class does not trigger a cell reselection for

MSs of that class

Object DB Name Range

BTS CELLBARR FALSETRUE

RXLEV_ACCESS_MIN - Minimum Downlink Received Level for Cell to be

selected

The parameter RXLEV_ACCESS_MIN determines the cell border for a MS in idle

mode by means of the C1 or C2 criterion respectively

Choosing a high value reduces the risk of a handover immediately after call

setup

On the other hand the value has to be low enough to achieve a sufficient overlap

between adjacent cells (especially if they belong to different location areas)

It has to be observed that the overlap may be different for mobiles of different

power classes (refer to MS_TXPWR_MAX_CCH)

In any case RXLEV_ACCESS_MIN has to be above the MS receiver sensitivity level

(-100 dBm for DCS1800 -102 dBm for GSM handhelds -104 dBm for other GSM

MS)

Furthermore it has to harmonize with the

handover thresholds (RXLEV_MIN L_RXLEV_HO)

Object DB Name Range Step Size Unit

BTS RXLEVAMI 063 1

RXLEV

MS_TXPWR_MAX_CCH - Maximum allowed MS Transmit

Power on RACH

The transmit power level the MS uses for the access on the

Random Access Channel is given by the minimum of two

values

the maximum possible transmit power of the MS (given by

the power class P of the MS) the maximum allowed power

for access within the respective cell

(given by MS_TXP WR_MAX_CCH)

This parameter affects the

the random access procedure

the cell selection procedure

Random access

If there is a collision of channel requests on the random access

channel the one with the higher received level has a good chance

to be decoded and to get a response by the BTS

Hence MS with higher output power are preferred This imbalance

can be avoided by choosing a low maximum allowed transmit power

PARAMETERS SETTING

Cell Selection

To be selected by the cell selection procedure a cell has to fulfill the

C1 criterion

C1 gt 0 where

C1 = AV_RXLEV - RXLEV_ACCESS_MIN - Max(0

MS_TXPWR_MAX_CCH - P )

Choosing for example MS_TXPWR_MAX_CCH = Pmin where Pmin is

the output power level for the minimum power class 5 (29 dBm)

the C1 criterion reduces to AV_RXLEV gt RXLEV_ACCESS_MIN

for MSs of all power classes Hence the same idle mode cell border

is seen by each mobile

Choosing for example MS_TXPWR_MAX_CCH = Pmax where Pmax is

the output power level for the maximum power class 1 (43 dBm)

the C1 criterion reduces to

AV_RXLEV gt RXLEV_ACCESS_MIN + ( MS_TXPWR_MAX_CCH - P )

for MSs of all power classes Hence a larger cell radius is seen by a

mobile of higher output power than by a mobile of lower output

power On the other hand one can ensure by this mechanism that a

certain uplink received level is exceeded by each MS independent of

its power class

Object DB Name Range Step Size Unit

BTS MSTXPMAXCH 031 1 2 dB

MS_TXPWR_MAX_CCH - Maximum allowed MS transmit power on RACH

default 2

MS GSM900 MS GSM900 MS DCS1800

Phase 1 Phase 2

0 = 43 dBm 0 = 39 dBm 0 = 30 dBm

1 = 41 dBm 1 = 39 dBm 1 = 28 dBm

2 = 39 dBm 2 = 39 dBm 2 = 26 dBm

3 = 37 dBm 3 = 37 dBm 3 = 24 dBm

15 = 13dBm 19 = 5 dBm 15 = 0 dBm

16-31 = 13 dBm 20-31 = 5 dBm 16-31 = 0 dBm

POWER_OFFSET - Additional Parameter for Class 3

DCS1800 MS

The parameter POWER_OFFSET is only used by class 3

DCS1800 MS to calculate the C1-criterion described as

follows

C1 = AV_RXLEV - RXLEV_ACCESS_MIN -

Max(0MS_TXPWR_MAX_CCH + POWER_OFFSET- P)

Object DB Name Range Step Size Unit

BTS PWROFS 03 1 2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for Reselection of a Cell

from another Location Area

In idle mode the MS selects a new (neighbor) cell if the received level of the

neighbor cell exceeds the received level of the current cell in order to be

served by the cell with the expected best link quality However due to

fading effects the propagation conditions may change rapidly and

therefore a reselection may occur very frequently

If the cells involved in the reselection process belong to the same location

area frequent cell reselection does not have an effect on the network

performance

But if the involved cells belong to different location area the reselection of

a new cell triggers a location update procedure which causes signaling

load (eg on the SDCCH) and involves all network elements

To avoid unnecessary signaling load by forward and backward reselection due to fading

a hysteresis given by the parameter CELL_RESELECT_HYSTERESIS is introduced ie

a cell from another location area is selected only if the corresponding received level

exceeds the level of the current serving cell by the value of this parameter This is

expressed in terms of the C1 (phase 1) or C2 (phase 2) criterion

C1 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C1 (suitable neighbor cell)

or

C2 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C2 (suitable neighbor cell)

respectively

The adjustment of CELL_RESELECT_HYSTERESES should be a compromise between

reduction of unnecessary location updates (high value) and

selection of the cell with best reception quality (low value)

Object DB Name Range Step Size Unit

BTS CELLRESH 07 1

2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for

reselection of a cell from another location area

default 2

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter

Indication

CELL_RESELECT_PARAM_IND=1

The cell reselection parameters CELL_RESELECT_OFFSET

TEMPORARY_OFFSET and PENALTY_TIME used for the C2 criterion as well as

the parameter CELL_BAR_QUALIFY are broadcasted on the BCCH These

parameters are taken into account by phase 2 MS but are ignored by

phase 1 MS

CELL_RESELECT_PARAM_IND = 0

The cell reselection parameters and CELL_BAR_QUALIFY are not

broadcasted on the BCCH

A phase 2 MS then uses the value 0 for all these parameters ie C1 = C2

Object DB Name Range

BTS CRESPARI 01

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter Indication default 1

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

successful decoding DSC new = DSC old + 1

if DSC new + 1 gt DSC0 rarr DSC new = DSC old

unsuccessful decoding DSC new = DSC old ndash 4

If DSC lt 0 the MS has detected a downlink signaling

failure

Minimum decoding

Monitoring of all BCCH carriers given in the BCCH allocation

(neighbor cells) of the serving cell

Taking at least 5 samples of the received level from the serving cell

(on paging sub-channel) as well as from the neighbor cells

=gt AV_RXLEV(serving cell) and AV_RXLEV (neighbor cell)

Decoding of full BCCH data of the serving cell at least every 30 sec

Decoding of BCCH data of the 6 strongest neighbor cells at least

every 5 minutes

From the radio propagation point of view it is

worth to select a new (neighbor) cell if the

received level from that neighbor cell exceeds the

received level of the current serving cell For

phase 1 MS this is expressed using the C1

criterion

C1 (neighbor cell) gt C1 (serving cell)

For phase 2 MS a modified path loss criterion the C2 criterion

is usedThe C2 criterion depends on the value of a timer T

which is called PENALTY_TIMERThe timer T is started in the MS

for each cell in the list of the 6 strongest neighbor cells as soon

as it is placed on the list Timer T is reset to 0 if the cell is

removed from the list

During penalty time

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

After penalty time

C2 = C1 + CELL_RESELECT_OFFSET

For penalty time = 31 the whole time

C2 = C1 - CELL_RESELECT_OFFSET

CELL_RESELECT_OFFSET TEMPORARY_OFFSET and

PENALTY_TIME are cell reselection parameters which

are broadcasted on the BCCH of the cell in the

system informations if CELL_RESLECT_PARAM_IND

(Cell Reselection Parameter Indication) is set to 1

A negative TEMPORARY_OFFSET reduces the

priority of a cell in the list of strongest neighbor

cells

A positive CELL_RESELECT_OFFSET increases the

priority of a cell in the list of strongest neighbor

cells

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells

When a mobile reaches the coverage area of a (neighbor) micro cell given

by the C1 criterion this cell becomes effectively excluded from reselection

during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell be-fore PENALTY_TIME is reached and hence the micro cell is not

selected

In contrast a slow moving mobile is assumed to be still within the coverage

area of the micro cell when PENALTY_TIME has expired

Applying the positive CELL_RESELECT_OFFSET this cell is selected with

preference

Triggers for Cell Reselection

Cell reselection is triggered by the following conditions

1 C1 lt 0 for the serving cell for a period of 5 s

2 MS detects a downlink signaling failure

3 Serving cell becomes barred

Phase 1 MS

C1 (serving cell) lt C1 (suitable neighbor cell) if the suitable neighbor cell is

in the same location area

C1 (serving cell) + CELL_RESELECT_HYSTERESIS lt C1 (suitable

neighbor cell) if the suitable neighbor cell is in another location area for a

period of 5 sec

Phase 2 MS

C2 (serving cell) lt C2 (suitable neighbor cell) if the suitable neighbor cell is in

the same location area

C2 (serving cell) + CELL_RESELECT_HYSTERESIS lt C2 (suitable neighbor

cell) if the suitable neighbor cell is in another location area for a period of 5

sec

A random access attempt is unsuccessful even after the maximum number

of repetitions

For phase 2 there is the additional trigger

A location update request has been rejected with cause rdquolocation area not

allowedrdquo

PARAMETERS SETTING

BA (BCCH) - BCCH Allocation broadcasted on BCCH

In each cell the absolute radio frequency carrier number

BCCH_ARFCN_NC(n) of each of its neighbor cell n has to be

known This information is broadcasted as the so-called BCCH

Allocation to all MS in the respective cell On the

corresponding frequencies the MS take measurement samples

of the received level used for cell selection reselection

Furthermore the BCCH of neighbor cells has to be decoded by

the MS (at least every 5 min) to know the current values of the

control parameters for the reselection algorithm

PARAMETERS SETTING

Object DB Name Range Step Size

Unit ADJC BCCHFREQ 01023 1

PARAMETERS SETTING

CELL_BAR_ACCESS - Cell Barred for Access

A mobile station cannot camp on a barred cell ie a barred cell is not

selected by the cell selectionreselection procedure

Mobile stations which camp on a cell while it becomes barred initialize the

reselection procedure to find a new (unbarred) cell ie traffic load is

distributed to neighbor cells

This means that eg neither a call nor a location update can start in a

barred cell

However a cell barred for access is not barred for incoming handovers To

barr a cell completely eg for maintenance reasons also incoming

handovers have to be avoided

To reduce overload in a certain cell more moderately without distributing

the overload to neighbor cells barring of access classes has to be used

Barring access for an access class does not trigger a cell reselection for

MSs of that class

Object DB Name Range

BTS CELLBARR FALSETRUE

RXLEV_ACCESS_MIN - Minimum Downlink Received Level for Cell to be

selected

The parameter RXLEV_ACCESS_MIN determines the cell border for a MS in idle

mode by means of the C1 or C2 criterion respectively

Choosing a high value reduces the risk of a handover immediately after call

setup

On the other hand the value has to be low enough to achieve a sufficient overlap

between adjacent cells (especially if they belong to different location areas)

It has to be observed that the overlap may be different for mobiles of different

power classes (refer to MS_TXPWR_MAX_CCH)

In any case RXLEV_ACCESS_MIN has to be above the MS receiver sensitivity level

(-100 dBm for DCS1800 -102 dBm for GSM handhelds -104 dBm for other GSM

MS)

Furthermore it has to harmonize with the

handover thresholds (RXLEV_MIN L_RXLEV_HO)

Object DB Name Range Step Size Unit

BTS RXLEVAMI 063 1

RXLEV

MS_TXPWR_MAX_CCH - Maximum allowed MS Transmit

Power on RACH

The transmit power level the MS uses for the access on the

Random Access Channel is given by the minimum of two

values

the maximum possible transmit power of the MS (given by

the power class P of the MS) the maximum allowed power

for access within the respective cell

(given by MS_TXP WR_MAX_CCH)

This parameter affects the

the random access procedure

the cell selection procedure

Random access

If there is a collision of channel requests on the random access

channel the one with the higher received level has a good chance

to be decoded and to get a response by the BTS

Hence MS with higher output power are preferred This imbalance

can be avoided by choosing a low maximum allowed transmit power

PARAMETERS SETTING

Cell Selection

To be selected by the cell selection procedure a cell has to fulfill the

C1 criterion

C1 gt 0 where

C1 = AV_RXLEV - RXLEV_ACCESS_MIN - Max(0

MS_TXPWR_MAX_CCH - P )

Choosing for example MS_TXPWR_MAX_CCH = Pmin where Pmin is

the output power level for the minimum power class 5 (29 dBm)

the C1 criterion reduces to AV_RXLEV gt RXLEV_ACCESS_MIN

for MSs of all power classes Hence the same idle mode cell border

is seen by each mobile

Choosing for example MS_TXPWR_MAX_CCH = Pmax where Pmax is

the output power level for the maximum power class 1 (43 dBm)

the C1 criterion reduces to

AV_RXLEV gt RXLEV_ACCESS_MIN + ( MS_TXPWR_MAX_CCH - P )

for MSs of all power classes Hence a larger cell radius is seen by a

mobile of higher output power than by a mobile of lower output

power On the other hand one can ensure by this mechanism that a

certain uplink received level is exceeded by each MS independent of

its power class

Object DB Name Range Step Size Unit

BTS MSTXPMAXCH 031 1 2 dB

MS_TXPWR_MAX_CCH - Maximum allowed MS transmit power on RACH

default 2

MS GSM900 MS GSM900 MS DCS1800

Phase 1 Phase 2

0 = 43 dBm 0 = 39 dBm 0 = 30 dBm

1 = 41 dBm 1 = 39 dBm 1 = 28 dBm

2 = 39 dBm 2 = 39 dBm 2 = 26 dBm

3 = 37 dBm 3 = 37 dBm 3 = 24 dBm

15 = 13dBm 19 = 5 dBm 15 = 0 dBm

16-31 = 13 dBm 20-31 = 5 dBm 16-31 = 0 dBm

POWER_OFFSET - Additional Parameter for Class 3

DCS1800 MS

The parameter POWER_OFFSET is only used by class 3

DCS1800 MS to calculate the C1-criterion described as

follows

C1 = AV_RXLEV - RXLEV_ACCESS_MIN -

Max(0MS_TXPWR_MAX_CCH + POWER_OFFSET- P)

Object DB Name Range Step Size Unit

BTS PWROFS 03 1 2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for Reselection of a Cell

from another Location Area

In idle mode the MS selects a new (neighbor) cell if the received level of the

neighbor cell exceeds the received level of the current cell in order to be

served by the cell with the expected best link quality However due to

fading effects the propagation conditions may change rapidly and

therefore a reselection may occur very frequently

If the cells involved in the reselection process belong to the same location

area frequent cell reselection does not have an effect on the network

performance

But if the involved cells belong to different location area the reselection of

a new cell triggers a location update procedure which causes signaling

load (eg on the SDCCH) and involves all network elements

To avoid unnecessary signaling load by forward and backward reselection due to fading

a hysteresis given by the parameter CELL_RESELECT_HYSTERESIS is introduced ie

a cell from another location area is selected only if the corresponding received level

exceeds the level of the current serving cell by the value of this parameter This is

expressed in terms of the C1 (phase 1) or C2 (phase 2) criterion

C1 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C1 (suitable neighbor cell)

or

C2 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C2 (suitable neighbor cell)

respectively

The adjustment of CELL_RESELECT_HYSTERESES should be a compromise between

reduction of unnecessary location updates (high value) and

selection of the cell with best reception quality (low value)

Object DB Name Range Step Size Unit

BTS CELLRESH 07 1

2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for

reselection of a cell from another location area

default 2

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter

Indication

CELL_RESELECT_PARAM_IND=1

The cell reselection parameters CELL_RESELECT_OFFSET

TEMPORARY_OFFSET and PENALTY_TIME used for the C2 criterion as well as

the parameter CELL_BAR_QUALIFY are broadcasted on the BCCH These

parameters are taken into account by phase 2 MS but are ignored by

phase 1 MS

CELL_RESELECT_PARAM_IND = 0

The cell reselection parameters and CELL_BAR_QUALIFY are not

broadcasted on the BCCH

A phase 2 MS then uses the value 0 for all these parameters ie C1 = C2

Object DB Name Range

BTS CRESPARI 01

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter Indication default 1

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

Minimum decoding

Monitoring of all BCCH carriers given in the BCCH allocation

(neighbor cells) of the serving cell

Taking at least 5 samples of the received level from the serving cell

(on paging sub-channel) as well as from the neighbor cells

=gt AV_RXLEV(serving cell) and AV_RXLEV (neighbor cell)

Decoding of full BCCH data of the serving cell at least every 30 sec

Decoding of BCCH data of the 6 strongest neighbor cells at least

every 5 minutes

From the radio propagation point of view it is

worth to select a new (neighbor) cell if the

received level from that neighbor cell exceeds the

received level of the current serving cell For

phase 1 MS this is expressed using the C1

criterion

C1 (neighbor cell) gt C1 (serving cell)

For phase 2 MS a modified path loss criterion the C2 criterion

is usedThe C2 criterion depends on the value of a timer T

which is called PENALTY_TIMERThe timer T is started in the MS

for each cell in the list of the 6 strongest neighbor cells as soon

as it is placed on the list Timer T is reset to 0 if the cell is

removed from the list

During penalty time

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

After penalty time

C2 = C1 + CELL_RESELECT_OFFSET

For penalty time = 31 the whole time

C2 = C1 - CELL_RESELECT_OFFSET

CELL_RESELECT_OFFSET TEMPORARY_OFFSET and

PENALTY_TIME are cell reselection parameters which

are broadcasted on the BCCH of the cell in the

system informations if CELL_RESLECT_PARAM_IND

(Cell Reselection Parameter Indication) is set to 1

A negative TEMPORARY_OFFSET reduces the

priority of a cell in the list of strongest neighbor

cells

A positive CELL_RESELECT_OFFSET increases the

priority of a cell in the list of strongest neighbor

cells

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells

When a mobile reaches the coverage area of a (neighbor) micro cell given

by the C1 criterion this cell becomes effectively excluded from reselection

during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell be-fore PENALTY_TIME is reached and hence the micro cell is not

selected

In contrast a slow moving mobile is assumed to be still within the coverage

area of the micro cell when PENALTY_TIME has expired

Applying the positive CELL_RESELECT_OFFSET this cell is selected with

preference

Triggers for Cell Reselection

Cell reselection is triggered by the following conditions

1 C1 lt 0 for the serving cell for a period of 5 s

2 MS detects a downlink signaling failure

3 Serving cell becomes barred

Phase 1 MS

C1 (serving cell) lt C1 (suitable neighbor cell) if the suitable neighbor cell is

in the same location area

C1 (serving cell) + CELL_RESELECT_HYSTERESIS lt C1 (suitable

neighbor cell) if the suitable neighbor cell is in another location area for a

period of 5 sec

Phase 2 MS

C2 (serving cell) lt C2 (suitable neighbor cell) if the suitable neighbor cell is in

the same location area

C2 (serving cell) + CELL_RESELECT_HYSTERESIS lt C2 (suitable neighbor

cell) if the suitable neighbor cell is in another location area for a period of 5

sec

A random access attempt is unsuccessful even after the maximum number

of repetitions

For phase 2 there is the additional trigger

A location update request has been rejected with cause rdquolocation area not

allowedrdquo

PARAMETERS SETTING

BA (BCCH) - BCCH Allocation broadcasted on BCCH

In each cell the absolute radio frequency carrier number

BCCH_ARFCN_NC(n) of each of its neighbor cell n has to be

known This information is broadcasted as the so-called BCCH

Allocation to all MS in the respective cell On the

corresponding frequencies the MS take measurement samples

of the received level used for cell selection reselection

Furthermore the BCCH of neighbor cells has to be decoded by

the MS (at least every 5 min) to know the current values of the

control parameters for the reselection algorithm

PARAMETERS SETTING

Object DB Name Range Step Size

Unit ADJC BCCHFREQ 01023 1

PARAMETERS SETTING

CELL_BAR_ACCESS - Cell Barred for Access

A mobile station cannot camp on a barred cell ie a barred cell is not

selected by the cell selectionreselection procedure

Mobile stations which camp on a cell while it becomes barred initialize the

reselection procedure to find a new (unbarred) cell ie traffic load is

distributed to neighbor cells

This means that eg neither a call nor a location update can start in a

barred cell

However a cell barred for access is not barred for incoming handovers To

barr a cell completely eg for maintenance reasons also incoming

handovers have to be avoided

To reduce overload in a certain cell more moderately without distributing

the overload to neighbor cells barring of access classes has to be used

Barring access for an access class does not trigger a cell reselection for

MSs of that class

Object DB Name Range

BTS CELLBARR FALSETRUE

RXLEV_ACCESS_MIN - Minimum Downlink Received Level for Cell to be

selected

The parameter RXLEV_ACCESS_MIN determines the cell border for a MS in idle

mode by means of the C1 or C2 criterion respectively

Choosing a high value reduces the risk of a handover immediately after call

setup

On the other hand the value has to be low enough to achieve a sufficient overlap

between adjacent cells (especially if they belong to different location areas)

It has to be observed that the overlap may be different for mobiles of different

power classes (refer to MS_TXPWR_MAX_CCH)

In any case RXLEV_ACCESS_MIN has to be above the MS receiver sensitivity level

(-100 dBm for DCS1800 -102 dBm for GSM handhelds -104 dBm for other GSM

MS)

Furthermore it has to harmonize with the

handover thresholds (RXLEV_MIN L_RXLEV_HO)

Object DB Name Range Step Size Unit

BTS RXLEVAMI 063 1

RXLEV

MS_TXPWR_MAX_CCH - Maximum allowed MS Transmit

Power on RACH

The transmit power level the MS uses for the access on the

Random Access Channel is given by the minimum of two

values

the maximum possible transmit power of the MS (given by

the power class P of the MS) the maximum allowed power

for access within the respective cell

(given by MS_TXP WR_MAX_CCH)

This parameter affects the

the random access procedure

the cell selection procedure

Random access

If there is a collision of channel requests on the random access

channel the one with the higher received level has a good chance

to be decoded and to get a response by the BTS

Hence MS with higher output power are preferred This imbalance

can be avoided by choosing a low maximum allowed transmit power

PARAMETERS SETTING

Cell Selection

To be selected by the cell selection procedure a cell has to fulfill the

C1 criterion

C1 gt 0 where

C1 = AV_RXLEV - RXLEV_ACCESS_MIN - Max(0

MS_TXPWR_MAX_CCH - P )

Choosing for example MS_TXPWR_MAX_CCH = Pmin where Pmin is

the output power level for the minimum power class 5 (29 dBm)

the C1 criterion reduces to AV_RXLEV gt RXLEV_ACCESS_MIN

for MSs of all power classes Hence the same idle mode cell border

is seen by each mobile

Choosing for example MS_TXPWR_MAX_CCH = Pmax where Pmax is

the output power level for the maximum power class 1 (43 dBm)

the C1 criterion reduces to

AV_RXLEV gt RXLEV_ACCESS_MIN + ( MS_TXPWR_MAX_CCH - P )

for MSs of all power classes Hence a larger cell radius is seen by a

mobile of higher output power than by a mobile of lower output

power On the other hand one can ensure by this mechanism that a

certain uplink received level is exceeded by each MS independent of

its power class

Object DB Name Range Step Size Unit

BTS MSTXPMAXCH 031 1 2 dB

MS_TXPWR_MAX_CCH - Maximum allowed MS transmit power on RACH

default 2

MS GSM900 MS GSM900 MS DCS1800

Phase 1 Phase 2

0 = 43 dBm 0 = 39 dBm 0 = 30 dBm

1 = 41 dBm 1 = 39 dBm 1 = 28 dBm

2 = 39 dBm 2 = 39 dBm 2 = 26 dBm

3 = 37 dBm 3 = 37 dBm 3 = 24 dBm

15 = 13dBm 19 = 5 dBm 15 = 0 dBm

16-31 = 13 dBm 20-31 = 5 dBm 16-31 = 0 dBm

POWER_OFFSET - Additional Parameter for Class 3

DCS1800 MS

The parameter POWER_OFFSET is only used by class 3

DCS1800 MS to calculate the C1-criterion described as

follows

C1 = AV_RXLEV - RXLEV_ACCESS_MIN -

Max(0MS_TXPWR_MAX_CCH + POWER_OFFSET- P)

Object DB Name Range Step Size Unit

BTS PWROFS 03 1 2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for Reselection of a Cell

from another Location Area

In idle mode the MS selects a new (neighbor) cell if the received level of the

neighbor cell exceeds the received level of the current cell in order to be

served by the cell with the expected best link quality However due to

fading effects the propagation conditions may change rapidly and

therefore a reselection may occur very frequently

If the cells involved in the reselection process belong to the same location

area frequent cell reselection does not have an effect on the network

performance

But if the involved cells belong to different location area the reselection of

a new cell triggers a location update procedure which causes signaling

load (eg on the SDCCH) and involves all network elements

To avoid unnecessary signaling load by forward and backward reselection due to fading

a hysteresis given by the parameter CELL_RESELECT_HYSTERESIS is introduced ie

a cell from another location area is selected only if the corresponding received level

exceeds the level of the current serving cell by the value of this parameter This is

expressed in terms of the C1 (phase 1) or C2 (phase 2) criterion

C1 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C1 (suitable neighbor cell)

or

C2 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C2 (suitable neighbor cell)

respectively

The adjustment of CELL_RESELECT_HYSTERESES should be a compromise between

reduction of unnecessary location updates (high value) and

selection of the cell with best reception quality (low value)

Object DB Name Range Step Size Unit

BTS CELLRESH 07 1

2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for

reselection of a cell from another location area

default 2

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter

Indication

CELL_RESELECT_PARAM_IND=1

The cell reselection parameters CELL_RESELECT_OFFSET

TEMPORARY_OFFSET and PENALTY_TIME used for the C2 criterion as well as

the parameter CELL_BAR_QUALIFY are broadcasted on the BCCH These

parameters are taken into account by phase 2 MS but are ignored by

phase 1 MS

CELL_RESELECT_PARAM_IND = 0

The cell reselection parameters and CELL_BAR_QUALIFY are not

broadcasted on the BCCH

A phase 2 MS then uses the value 0 for all these parameters ie C1 = C2

Object DB Name Range

BTS CRESPARI 01

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter Indication default 1

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

From the radio propagation point of view it is

worth to select a new (neighbor) cell if the

received level from that neighbor cell exceeds the

received level of the current serving cell For

phase 1 MS this is expressed using the C1

criterion

C1 (neighbor cell) gt C1 (serving cell)

For phase 2 MS a modified path loss criterion the C2 criterion

is usedThe C2 criterion depends on the value of a timer T

which is called PENALTY_TIMERThe timer T is started in the MS

for each cell in the list of the 6 strongest neighbor cells as soon

as it is placed on the list Timer T is reset to 0 if the cell is

removed from the list

During penalty time

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

After penalty time

C2 = C1 + CELL_RESELECT_OFFSET

For penalty time = 31 the whole time

C2 = C1 - CELL_RESELECT_OFFSET

CELL_RESELECT_OFFSET TEMPORARY_OFFSET and

PENALTY_TIME are cell reselection parameters which

are broadcasted on the BCCH of the cell in the

system informations if CELL_RESLECT_PARAM_IND

(Cell Reselection Parameter Indication) is set to 1

A negative TEMPORARY_OFFSET reduces the

priority of a cell in the list of strongest neighbor

cells

A positive CELL_RESELECT_OFFSET increases the

priority of a cell in the list of strongest neighbor

cells

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells

When a mobile reaches the coverage area of a (neighbor) micro cell given

by the C1 criterion this cell becomes effectively excluded from reselection

during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell be-fore PENALTY_TIME is reached and hence the micro cell is not

selected

In contrast a slow moving mobile is assumed to be still within the coverage

area of the micro cell when PENALTY_TIME has expired

Applying the positive CELL_RESELECT_OFFSET this cell is selected with

preference

Triggers for Cell Reselection

Cell reselection is triggered by the following conditions

1 C1 lt 0 for the serving cell for a period of 5 s

2 MS detects a downlink signaling failure

3 Serving cell becomes barred

Phase 1 MS

C1 (serving cell) lt C1 (suitable neighbor cell) if the suitable neighbor cell is

in the same location area

C1 (serving cell) + CELL_RESELECT_HYSTERESIS lt C1 (suitable

neighbor cell) if the suitable neighbor cell is in another location area for a

period of 5 sec

Phase 2 MS

C2 (serving cell) lt C2 (suitable neighbor cell) if the suitable neighbor cell is in

the same location area

C2 (serving cell) + CELL_RESELECT_HYSTERESIS lt C2 (suitable neighbor

cell) if the suitable neighbor cell is in another location area for a period of 5

sec

A random access attempt is unsuccessful even after the maximum number

of repetitions

For phase 2 there is the additional trigger

A location update request has been rejected with cause rdquolocation area not

allowedrdquo

PARAMETERS SETTING

BA (BCCH) - BCCH Allocation broadcasted on BCCH

In each cell the absolute radio frequency carrier number

BCCH_ARFCN_NC(n) of each of its neighbor cell n has to be

known This information is broadcasted as the so-called BCCH

Allocation to all MS in the respective cell On the

corresponding frequencies the MS take measurement samples

of the received level used for cell selection reselection

Furthermore the BCCH of neighbor cells has to be decoded by

the MS (at least every 5 min) to know the current values of the

control parameters for the reselection algorithm

PARAMETERS SETTING

Object DB Name Range Step Size

Unit ADJC BCCHFREQ 01023 1

PARAMETERS SETTING

CELL_BAR_ACCESS - Cell Barred for Access

A mobile station cannot camp on a barred cell ie a barred cell is not

selected by the cell selectionreselection procedure

Mobile stations which camp on a cell while it becomes barred initialize the

reselection procedure to find a new (unbarred) cell ie traffic load is

distributed to neighbor cells

This means that eg neither a call nor a location update can start in a

barred cell

However a cell barred for access is not barred for incoming handovers To

barr a cell completely eg for maintenance reasons also incoming

handovers have to be avoided

To reduce overload in a certain cell more moderately without distributing

the overload to neighbor cells barring of access classes has to be used

Barring access for an access class does not trigger a cell reselection for

MSs of that class

Object DB Name Range

BTS CELLBARR FALSETRUE

RXLEV_ACCESS_MIN - Minimum Downlink Received Level for Cell to be

selected

The parameter RXLEV_ACCESS_MIN determines the cell border for a MS in idle

mode by means of the C1 or C2 criterion respectively

Choosing a high value reduces the risk of a handover immediately after call

setup

On the other hand the value has to be low enough to achieve a sufficient overlap

between adjacent cells (especially if they belong to different location areas)

It has to be observed that the overlap may be different for mobiles of different

power classes (refer to MS_TXPWR_MAX_CCH)

In any case RXLEV_ACCESS_MIN has to be above the MS receiver sensitivity level

(-100 dBm for DCS1800 -102 dBm for GSM handhelds -104 dBm for other GSM

MS)

Furthermore it has to harmonize with the

handover thresholds (RXLEV_MIN L_RXLEV_HO)

Object DB Name Range Step Size Unit

BTS RXLEVAMI 063 1

RXLEV

MS_TXPWR_MAX_CCH - Maximum allowed MS Transmit

Power on RACH

The transmit power level the MS uses for the access on the

Random Access Channel is given by the minimum of two

values

the maximum possible transmit power of the MS (given by

the power class P of the MS) the maximum allowed power

for access within the respective cell

(given by MS_TXP WR_MAX_CCH)

This parameter affects the

the random access procedure

the cell selection procedure

Random access

If there is a collision of channel requests on the random access

channel the one with the higher received level has a good chance

to be decoded and to get a response by the BTS

Hence MS with higher output power are preferred This imbalance

can be avoided by choosing a low maximum allowed transmit power

PARAMETERS SETTING

Cell Selection

To be selected by the cell selection procedure a cell has to fulfill the

C1 criterion

C1 gt 0 where

C1 = AV_RXLEV - RXLEV_ACCESS_MIN - Max(0

MS_TXPWR_MAX_CCH - P )

Choosing for example MS_TXPWR_MAX_CCH = Pmin where Pmin is

the output power level for the minimum power class 5 (29 dBm)

the C1 criterion reduces to AV_RXLEV gt RXLEV_ACCESS_MIN

for MSs of all power classes Hence the same idle mode cell border

is seen by each mobile

Choosing for example MS_TXPWR_MAX_CCH = Pmax where Pmax is

the output power level for the maximum power class 1 (43 dBm)

the C1 criterion reduces to

AV_RXLEV gt RXLEV_ACCESS_MIN + ( MS_TXPWR_MAX_CCH - P )

for MSs of all power classes Hence a larger cell radius is seen by a

mobile of higher output power than by a mobile of lower output

power On the other hand one can ensure by this mechanism that a

certain uplink received level is exceeded by each MS independent of

its power class

Object DB Name Range Step Size Unit

BTS MSTXPMAXCH 031 1 2 dB

MS_TXPWR_MAX_CCH - Maximum allowed MS transmit power on RACH

default 2

MS GSM900 MS GSM900 MS DCS1800

Phase 1 Phase 2

0 = 43 dBm 0 = 39 dBm 0 = 30 dBm

1 = 41 dBm 1 = 39 dBm 1 = 28 dBm

2 = 39 dBm 2 = 39 dBm 2 = 26 dBm

3 = 37 dBm 3 = 37 dBm 3 = 24 dBm

15 = 13dBm 19 = 5 dBm 15 = 0 dBm

16-31 = 13 dBm 20-31 = 5 dBm 16-31 = 0 dBm

POWER_OFFSET - Additional Parameter for Class 3

DCS1800 MS

The parameter POWER_OFFSET is only used by class 3

DCS1800 MS to calculate the C1-criterion described as

follows

C1 = AV_RXLEV - RXLEV_ACCESS_MIN -

Max(0MS_TXPWR_MAX_CCH + POWER_OFFSET- P)

Object DB Name Range Step Size Unit

BTS PWROFS 03 1 2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for Reselection of a Cell

from another Location Area

In idle mode the MS selects a new (neighbor) cell if the received level of the

neighbor cell exceeds the received level of the current cell in order to be

served by the cell with the expected best link quality However due to

fading effects the propagation conditions may change rapidly and

therefore a reselection may occur very frequently

If the cells involved in the reselection process belong to the same location

area frequent cell reselection does not have an effect on the network

performance

But if the involved cells belong to different location area the reselection of

a new cell triggers a location update procedure which causes signaling

load (eg on the SDCCH) and involves all network elements

To avoid unnecessary signaling load by forward and backward reselection due to fading

a hysteresis given by the parameter CELL_RESELECT_HYSTERESIS is introduced ie

a cell from another location area is selected only if the corresponding received level

exceeds the level of the current serving cell by the value of this parameter This is

expressed in terms of the C1 (phase 1) or C2 (phase 2) criterion

C1 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C1 (suitable neighbor cell)

or

C2 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C2 (suitable neighbor cell)

respectively

The adjustment of CELL_RESELECT_HYSTERESES should be a compromise between

reduction of unnecessary location updates (high value) and

selection of the cell with best reception quality (low value)

Object DB Name Range Step Size Unit

BTS CELLRESH 07 1

2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for

reselection of a cell from another location area

default 2

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter

Indication

CELL_RESELECT_PARAM_IND=1

The cell reselection parameters CELL_RESELECT_OFFSET

TEMPORARY_OFFSET and PENALTY_TIME used for the C2 criterion as well as

the parameter CELL_BAR_QUALIFY are broadcasted on the BCCH These

parameters are taken into account by phase 2 MS but are ignored by

phase 1 MS

CELL_RESELECT_PARAM_IND = 0

The cell reselection parameters and CELL_BAR_QUALIFY are not

broadcasted on the BCCH

A phase 2 MS then uses the value 0 for all these parameters ie C1 = C2

Object DB Name Range

BTS CRESPARI 01

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter Indication default 1

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

For phase 2 MS a modified path loss criterion the C2 criterion

is usedThe C2 criterion depends on the value of a timer T

which is called PENALTY_TIMERThe timer T is started in the MS

for each cell in the list of the 6 strongest neighbor cells as soon

as it is placed on the list Timer T is reset to 0 if the cell is

removed from the list

During penalty time

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

After penalty time

C2 = C1 + CELL_RESELECT_OFFSET

For penalty time = 31 the whole time

C2 = C1 - CELL_RESELECT_OFFSET

CELL_RESELECT_OFFSET TEMPORARY_OFFSET and

PENALTY_TIME are cell reselection parameters which

are broadcasted on the BCCH of the cell in the

system informations if CELL_RESLECT_PARAM_IND

(Cell Reselection Parameter Indication) is set to 1

A negative TEMPORARY_OFFSET reduces the

priority of a cell in the list of strongest neighbor

cells

A positive CELL_RESELECT_OFFSET increases the

priority of a cell in the list of strongest neighbor

cells

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells

When a mobile reaches the coverage area of a (neighbor) micro cell given

by the C1 criterion this cell becomes effectively excluded from reselection

during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell be-fore PENALTY_TIME is reached and hence the micro cell is not

selected

In contrast a slow moving mobile is assumed to be still within the coverage

area of the micro cell when PENALTY_TIME has expired

Applying the positive CELL_RESELECT_OFFSET this cell is selected with

preference

Triggers for Cell Reselection

Cell reselection is triggered by the following conditions

1 C1 lt 0 for the serving cell for a period of 5 s

2 MS detects a downlink signaling failure

3 Serving cell becomes barred

Phase 1 MS

C1 (serving cell) lt C1 (suitable neighbor cell) if the suitable neighbor cell is

in the same location area

C1 (serving cell) + CELL_RESELECT_HYSTERESIS lt C1 (suitable

neighbor cell) if the suitable neighbor cell is in another location area for a

period of 5 sec

Phase 2 MS

C2 (serving cell) lt C2 (suitable neighbor cell) if the suitable neighbor cell is in

the same location area

C2 (serving cell) + CELL_RESELECT_HYSTERESIS lt C2 (suitable neighbor

cell) if the suitable neighbor cell is in another location area for a period of 5

sec

A random access attempt is unsuccessful even after the maximum number

of repetitions

For phase 2 there is the additional trigger

A location update request has been rejected with cause rdquolocation area not

allowedrdquo

PARAMETERS SETTING

BA (BCCH) - BCCH Allocation broadcasted on BCCH

In each cell the absolute radio frequency carrier number

BCCH_ARFCN_NC(n) of each of its neighbor cell n has to be

known This information is broadcasted as the so-called BCCH

Allocation to all MS in the respective cell On the

corresponding frequencies the MS take measurement samples

of the received level used for cell selection reselection

Furthermore the BCCH of neighbor cells has to be decoded by

the MS (at least every 5 min) to know the current values of the

control parameters for the reselection algorithm

PARAMETERS SETTING

Object DB Name Range Step Size

Unit ADJC BCCHFREQ 01023 1

PARAMETERS SETTING

CELL_BAR_ACCESS - Cell Barred for Access

A mobile station cannot camp on a barred cell ie a barred cell is not

selected by the cell selectionreselection procedure

Mobile stations which camp on a cell while it becomes barred initialize the

reselection procedure to find a new (unbarred) cell ie traffic load is

distributed to neighbor cells

This means that eg neither a call nor a location update can start in a

barred cell

However a cell barred for access is not barred for incoming handovers To

barr a cell completely eg for maintenance reasons also incoming

handovers have to be avoided

To reduce overload in a certain cell more moderately without distributing

the overload to neighbor cells barring of access classes has to be used

Barring access for an access class does not trigger a cell reselection for

MSs of that class

Object DB Name Range

BTS CELLBARR FALSETRUE

RXLEV_ACCESS_MIN - Minimum Downlink Received Level for Cell to be

selected

The parameter RXLEV_ACCESS_MIN determines the cell border for a MS in idle

mode by means of the C1 or C2 criterion respectively

Choosing a high value reduces the risk of a handover immediately after call

setup

On the other hand the value has to be low enough to achieve a sufficient overlap

between adjacent cells (especially if they belong to different location areas)

It has to be observed that the overlap may be different for mobiles of different

power classes (refer to MS_TXPWR_MAX_CCH)

In any case RXLEV_ACCESS_MIN has to be above the MS receiver sensitivity level

(-100 dBm for DCS1800 -102 dBm for GSM handhelds -104 dBm for other GSM

MS)

Furthermore it has to harmonize with the

handover thresholds (RXLEV_MIN L_RXLEV_HO)

Object DB Name Range Step Size Unit

BTS RXLEVAMI 063 1

RXLEV

MS_TXPWR_MAX_CCH - Maximum allowed MS Transmit

Power on RACH

The transmit power level the MS uses for the access on the

Random Access Channel is given by the minimum of two

values

the maximum possible transmit power of the MS (given by

the power class P of the MS) the maximum allowed power

for access within the respective cell

(given by MS_TXP WR_MAX_CCH)

This parameter affects the

the random access procedure

the cell selection procedure

Random access

If there is a collision of channel requests on the random access

channel the one with the higher received level has a good chance

to be decoded and to get a response by the BTS

Hence MS with higher output power are preferred This imbalance

can be avoided by choosing a low maximum allowed transmit power

PARAMETERS SETTING

Cell Selection

To be selected by the cell selection procedure a cell has to fulfill the

C1 criterion

C1 gt 0 where

C1 = AV_RXLEV - RXLEV_ACCESS_MIN - Max(0

MS_TXPWR_MAX_CCH - P )

Choosing for example MS_TXPWR_MAX_CCH = Pmin where Pmin is

the output power level for the minimum power class 5 (29 dBm)

the C1 criterion reduces to AV_RXLEV gt RXLEV_ACCESS_MIN

for MSs of all power classes Hence the same idle mode cell border

is seen by each mobile

Choosing for example MS_TXPWR_MAX_CCH = Pmax where Pmax is

the output power level for the maximum power class 1 (43 dBm)

the C1 criterion reduces to

AV_RXLEV gt RXLEV_ACCESS_MIN + ( MS_TXPWR_MAX_CCH - P )

for MSs of all power classes Hence a larger cell radius is seen by a

mobile of higher output power than by a mobile of lower output

power On the other hand one can ensure by this mechanism that a

certain uplink received level is exceeded by each MS independent of

its power class

Object DB Name Range Step Size Unit

BTS MSTXPMAXCH 031 1 2 dB

MS_TXPWR_MAX_CCH - Maximum allowed MS transmit power on RACH

default 2

MS GSM900 MS GSM900 MS DCS1800

Phase 1 Phase 2

0 = 43 dBm 0 = 39 dBm 0 = 30 dBm

1 = 41 dBm 1 = 39 dBm 1 = 28 dBm

2 = 39 dBm 2 = 39 dBm 2 = 26 dBm

3 = 37 dBm 3 = 37 dBm 3 = 24 dBm

15 = 13dBm 19 = 5 dBm 15 = 0 dBm

16-31 = 13 dBm 20-31 = 5 dBm 16-31 = 0 dBm

POWER_OFFSET - Additional Parameter for Class 3

DCS1800 MS

The parameter POWER_OFFSET is only used by class 3

DCS1800 MS to calculate the C1-criterion described as

follows

C1 = AV_RXLEV - RXLEV_ACCESS_MIN -

Max(0MS_TXPWR_MAX_CCH + POWER_OFFSET- P)

Object DB Name Range Step Size Unit

BTS PWROFS 03 1 2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for Reselection of a Cell

from another Location Area

In idle mode the MS selects a new (neighbor) cell if the received level of the

neighbor cell exceeds the received level of the current cell in order to be

served by the cell with the expected best link quality However due to

fading effects the propagation conditions may change rapidly and

therefore a reselection may occur very frequently

If the cells involved in the reselection process belong to the same location

area frequent cell reselection does not have an effect on the network

performance

But if the involved cells belong to different location area the reselection of

a new cell triggers a location update procedure which causes signaling

load (eg on the SDCCH) and involves all network elements

To avoid unnecessary signaling load by forward and backward reselection due to fading

a hysteresis given by the parameter CELL_RESELECT_HYSTERESIS is introduced ie

a cell from another location area is selected only if the corresponding received level

exceeds the level of the current serving cell by the value of this parameter This is

expressed in terms of the C1 (phase 1) or C2 (phase 2) criterion

C1 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C1 (suitable neighbor cell)

or

C2 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C2 (suitable neighbor cell)

respectively

The adjustment of CELL_RESELECT_HYSTERESES should be a compromise between

reduction of unnecessary location updates (high value) and

selection of the cell with best reception quality (low value)

Object DB Name Range Step Size Unit

BTS CELLRESH 07 1

2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for

reselection of a cell from another location area

default 2

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter

Indication

CELL_RESELECT_PARAM_IND=1

The cell reselection parameters CELL_RESELECT_OFFSET

TEMPORARY_OFFSET and PENALTY_TIME used for the C2 criterion as well as

the parameter CELL_BAR_QUALIFY are broadcasted on the BCCH These

parameters are taken into account by phase 2 MS but are ignored by

phase 1 MS

CELL_RESELECT_PARAM_IND = 0

The cell reselection parameters and CELL_BAR_QUALIFY are not

broadcasted on the BCCH

A phase 2 MS then uses the value 0 for all these parameters ie C1 = C2

Object DB Name Range

BTS CRESPARI 01

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter Indication default 1

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

For penalty time = 31 the whole time

C2 = C1 - CELL_RESELECT_OFFSET

CELL_RESELECT_OFFSET TEMPORARY_OFFSET and

PENALTY_TIME are cell reselection parameters which

are broadcasted on the BCCH of the cell in the

system informations if CELL_RESLECT_PARAM_IND

(Cell Reselection Parameter Indication) is set to 1

A negative TEMPORARY_OFFSET reduces the

priority of a cell in the list of strongest neighbor

cells

A positive CELL_RESELECT_OFFSET increases the

priority of a cell in the list of strongest neighbor

cells

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells

When a mobile reaches the coverage area of a (neighbor) micro cell given

by the C1 criterion this cell becomes effectively excluded from reselection

during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell be-fore PENALTY_TIME is reached and hence the micro cell is not

selected

In contrast a slow moving mobile is assumed to be still within the coverage

area of the micro cell when PENALTY_TIME has expired

Applying the positive CELL_RESELECT_OFFSET this cell is selected with

preference

Triggers for Cell Reselection

Cell reselection is triggered by the following conditions

1 C1 lt 0 for the serving cell for a period of 5 s

2 MS detects a downlink signaling failure

3 Serving cell becomes barred

Phase 1 MS

C1 (serving cell) lt C1 (suitable neighbor cell) if the suitable neighbor cell is

in the same location area

C1 (serving cell) + CELL_RESELECT_HYSTERESIS lt C1 (suitable

neighbor cell) if the suitable neighbor cell is in another location area for a

period of 5 sec

Phase 2 MS

C2 (serving cell) lt C2 (suitable neighbor cell) if the suitable neighbor cell is in

the same location area

C2 (serving cell) + CELL_RESELECT_HYSTERESIS lt C2 (suitable neighbor

cell) if the suitable neighbor cell is in another location area for a period of 5

sec

A random access attempt is unsuccessful even after the maximum number

of repetitions

For phase 2 there is the additional trigger

A location update request has been rejected with cause rdquolocation area not

allowedrdquo

PARAMETERS SETTING

BA (BCCH) - BCCH Allocation broadcasted on BCCH

In each cell the absolute radio frequency carrier number

BCCH_ARFCN_NC(n) of each of its neighbor cell n has to be

known This information is broadcasted as the so-called BCCH

Allocation to all MS in the respective cell On the

corresponding frequencies the MS take measurement samples

of the received level used for cell selection reselection

Furthermore the BCCH of neighbor cells has to be decoded by

the MS (at least every 5 min) to know the current values of the

control parameters for the reselection algorithm

PARAMETERS SETTING

Object DB Name Range Step Size

Unit ADJC BCCHFREQ 01023 1

PARAMETERS SETTING

CELL_BAR_ACCESS - Cell Barred for Access

A mobile station cannot camp on a barred cell ie a barred cell is not

selected by the cell selectionreselection procedure

Mobile stations which camp on a cell while it becomes barred initialize the

reselection procedure to find a new (unbarred) cell ie traffic load is

distributed to neighbor cells

This means that eg neither a call nor a location update can start in a

barred cell

However a cell barred for access is not barred for incoming handovers To

barr a cell completely eg for maintenance reasons also incoming

handovers have to be avoided

To reduce overload in a certain cell more moderately without distributing

the overload to neighbor cells barring of access classes has to be used

Barring access for an access class does not trigger a cell reselection for

MSs of that class

Object DB Name Range

BTS CELLBARR FALSETRUE

RXLEV_ACCESS_MIN - Minimum Downlink Received Level for Cell to be

selected

The parameter RXLEV_ACCESS_MIN determines the cell border for a MS in idle

mode by means of the C1 or C2 criterion respectively

Choosing a high value reduces the risk of a handover immediately after call

setup

On the other hand the value has to be low enough to achieve a sufficient overlap

between adjacent cells (especially if they belong to different location areas)

It has to be observed that the overlap may be different for mobiles of different

power classes (refer to MS_TXPWR_MAX_CCH)

In any case RXLEV_ACCESS_MIN has to be above the MS receiver sensitivity level

(-100 dBm for DCS1800 -102 dBm for GSM handhelds -104 dBm for other GSM

MS)

Furthermore it has to harmonize with the

handover thresholds (RXLEV_MIN L_RXLEV_HO)

Object DB Name Range Step Size Unit

BTS RXLEVAMI 063 1

RXLEV

MS_TXPWR_MAX_CCH - Maximum allowed MS Transmit

Power on RACH

The transmit power level the MS uses for the access on the

Random Access Channel is given by the minimum of two

values

the maximum possible transmit power of the MS (given by

the power class P of the MS) the maximum allowed power

for access within the respective cell

(given by MS_TXP WR_MAX_CCH)

This parameter affects the

the random access procedure

the cell selection procedure

Random access

If there is a collision of channel requests on the random access

channel the one with the higher received level has a good chance

to be decoded and to get a response by the BTS

Hence MS with higher output power are preferred This imbalance

can be avoided by choosing a low maximum allowed transmit power

PARAMETERS SETTING

Cell Selection

To be selected by the cell selection procedure a cell has to fulfill the

C1 criterion

C1 gt 0 where

C1 = AV_RXLEV - RXLEV_ACCESS_MIN - Max(0

MS_TXPWR_MAX_CCH - P )

Choosing for example MS_TXPWR_MAX_CCH = Pmin where Pmin is

the output power level for the minimum power class 5 (29 dBm)

the C1 criterion reduces to AV_RXLEV gt RXLEV_ACCESS_MIN

for MSs of all power classes Hence the same idle mode cell border

is seen by each mobile

Choosing for example MS_TXPWR_MAX_CCH = Pmax where Pmax is

the output power level for the maximum power class 1 (43 dBm)

the C1 criterion reduces to

AV_RXLEV gt RXLEV_ACCESS_MIN + ( MS_TXPWR_MAX_CCH - P )

for MSs of all power classes Hence a larger cell radius is seen by a

mobile of higher output power than by a mobile of lower output

power On the other hand one can ensure by this mechanism that a

certain uplink received level is exceeded by each MS independent of

its power class

Object DB Name Range Step Size Unit

BTS MSTXPMAXCH 031 1 2 dB

MS_TXPWR_MAX_CCH - Maximum allowed MS transmit power on RACH

default 2

MS GSM900 MS GSM900 MS DCS1800

Phase 1 Phase 2

0 = 43 dBm 0 = 39 dBm 0 = 30 dBm

1 = 41 dBm 1 = 39 dBm 1 = 28 dBm

2 = 39 dBm 2 = 39 dBm 2 = 26 dBm

3 = 37 dBm 3 = 37 dBm 3 = 24 dBm

15 = 13dBm 19 = 5 dBm 15 = 0 dBm

16-31 = 13 dBm 20-31 = 5 dBm 16-31 = 0 dBm

POWER_OFFSET - Additional Parameter for Class 3

DCS1800 MS

The parameter POWER_OFFSET is only used by class 3

DCS1800 MS to calculate the C1-criterion described as

follows

C1 = AV_RXLEV - RXLEV_ACCESS_MIN -

Max(0MS_TXPWR_MAX_CCH + POWER_OFFSET- P)

Object DB Name Range Step Size Unit

BTS PWROFS 03 1 2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for Reselection of a Cell

from another Location Area

In idle mode the MS selects a new (neighbor) cell if the received level of the

neighbor cell exceeds the received level of the current cell in order to be

served by the cell with the expected best link quality However due to

fading effects the propagation conditions may change rapidly and

therefore a reselection may occur very frequently

If the cells involved in the reselection process belong to the same location

area frequent cell reselection does not have an effect on the network

performance

But if the involved cells belong to different location area the reselection of

a new cell triggers a location update procedure which causes signaling

load (eg on the SDCCH) and involves all network elements

To avoid unnecessary signaling load by forward and backward reselection due to fading

a hysteresis given by the parameter CELL_RESELECT_HYSTERESIS is introduced ie

a cell from another location area is selected only if the corresponding received level

exceeds the level of the current serving cell by the value of this parameter This is

expressed in terms of the C1 (phase 1) or C2 (phase 2) criterion

C1 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C1 (suitable neighbor cell)

or

C2 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C2 (suitable neighbor cell)

respectively

The adjustment of CELL_RESELECT_HYSTERESES should be a compromise between

reduction of unnecessary location updates (high value) and

selection of the cell with best reception quality (low value)

Object DB Name Range Step Size Unit

BTS CELLRESH 07 1

2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for

reselection of a cell from another location area

default 2

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter

Indication

CELL_RESELECT_PARAM_IND=1

The cell reselection parameters CELL_RESELECT_OFFSET

TEMPORARY_OFFSET and PENALTY_TIME used for the C2 criterion as well as

the parameter CELL_BAR_QUALIFY are broadcasted on the BCCH These

parameters are taken into account by phase 2 MS but are ignored by

phase 1 MS

CELL_RESELECT_PARAM_IND = 0

The cell reselection parameters and CELL_BAR_QUALIFY are not

broadcasted on the BCCH

A phase 2 MS then uses the value 0 for all these parameters ie C1 = C2

Object DB Name Range

BTS CRESPARI 01

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter Indication default 1

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

A negative TEMPORARY_OFFSET reduces the

priority of a cell in the list of strongest neighbor

cells

A positive CELL_RESELECT_OFFSET increases the

priority of a cell in the list of strongest neighbor

cells

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells

When a mobile reaches the coverage area of a (neighbor) micro cell given

by the C1 criterion this cell becomes effectively excluded from reselection

during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell be-fore PENALTY_TIME is reached and hence the micro cell is not

selected

In contrast a slow moving mobile is assumed to be still within the coverage

area of the micro cell when PENALTY_TIME has expired

Applying the positive CELL_RESELECT_OFFSET this cell is selected with

preference

Triggers for Cell Reselection

Cell reselection is triggered by the following conditions

1 C1 lt 0 for the serving cell for a period of 5 s

2 MS detects a downlink signaling failure

3 Serving cell becomes barred

Phase 1 MS

C1 (serving cell) lt C1 (suitable neighbor cell) if the suitable neighbor cell is

in the same location area

C1 (serving cell) + CELL_RESELECT_HYSTERESIS lt C1 (suitable

neighbor cell) if the suitable neighbor cell is in another location area for a

period of 5 sec

Phase 2 MS

C2 (serving cell) lt C2 (suitable neighbor cell) if the suitable neighbor cell is in

the same location area

C2 (serving cell) + CELL_RESELECT_HYSTERESIS lt C2 (suitable neighbor

cell) if the suitable neighbor cell is in another location area for a period of 5

sec

A random access attempt is unsuccessful even after the maximum number

of repetitions

For phase 2 there is the additional trigger

A location update request has been rejected with cause rdquolocation area not

allowedrdquo

PARAMETERS SETTING

BA (BCCH) - BCCH Allocation broadcasted on BCCH

In each cell the absolute radio frequency carrier number

BCCH_ARFCN_NC(n) of each of its neighbor cell n has to be

known This information is broadcasted as the so-called BCCH

Allocation to all MS in the respective cell On the

corresponding frequencies the MS take measurement samples

of the received level used for cell selection reselection

Furthermore the BCCH of neighbor cells has to be decoded by

the MS (at least every 5 min) to know the current values of the

control parameters for the reselection algorithm

PARAMETERS SETTING

Object DB Name Range Step Size

Unit ADJC BCCHFREQ 01023 1

PARAMETERS SETTING

CELL_BAR_ACCESS - Cell Barred for Access

A mobile station cannot camp on a barred cell ie a barred cell is not

selected by the cell selectionreselection procedure

Mobile stations which camp on a cell while it becomes barred initialize the

reselection procedure to find a new (unbarred) cell ie traffic load is

distributed to neighbor cells

This means that eg neither a call nor a location update can start in a

barred cell

However a cell barred for access is not barred for incoming handovers To

barr a cell completely eg for maintenance reasons also incoming

handovers have to be avoided

To reduce overload in a certain cell more moderately without distributing

the overload to neighbor cells barring of access classes has to be used

Barring access for an access class does not trigger a cell reselection for

MSs of that class

Object DB Name Range

BTS CELLBARR FALSETRUE

RXLEV_ACCESS_MIN - Minimum Downlink Received Level for Cell to be

selected

The parameter RXLEV_ACCESS_MIN determines the cell border for a MS in idle

mode by means of the C1 or C2 criterion respectively

Choosing a high value reduces the risk of a handover immediately after call

setup

On the other hand the value has to be low enough to achieve a sufficient overlap

between adjacent cells (especially if they belong to different location areas)

It has to be observed that the overlap may be different for mobiles of different

power classes (refer to MS_TXPWR_MAX_CCH)

In any case RXLEV_ACCESS_MIN has to be above the MS receiver sensitivity level

(-100 dBm for DCS1800 -102 dBm for GSM handhelds -104 dBm for other GSM

MS)

Furthermore it has to harmonize with the

handover thresholds (RXLEV_MIN L_RXLEV_HO)

Object DB Name Range Step Size Unit

BTS RXLEVAMI 063 1

RXLEV

MS_TXPWR_MAX_CCH - Maximum allowed MS Transmit

Power on RACH

The transmit power level the MS uses for the access on the

Random Access Channel is given by the minimum of two

values

the maximum possible transmit power of the MS (given by

the power class P of the MS) the maximum allowed power

for access within the respective cell

(given by MS_TXP WR_MAX_CCH)

This parameter affects the

the random access procedure

the cell selection procedure

Random access

If there is a collision of channel requests on the random access

channel the one with the higher received level has a good chance

to be decoded and to get a response by the BTS

Hence MS with higher output power are preferred This imbalance

can be avoided by choosing a low maximum allowed transmit power

PARAMETERS SETTING

Cell Selection

To be selected by the cell selection procedure a cell has to fulfill the

C1 criterion

C1 gt 0 where

C1 = AV_RXLEV - RXLEV_ACCESS_MIN - Max(0

MS_TXPWR_MAX_CCH - P )

Choosing for example MS_TXPWR_MAX_CCH = Pmin where Pmin is

the output power level for the minimum power class 5 (29 dBm)

the C1 criterion reduces to AV_RXLEV gt RXLEV_ACCESS_MIN

for MSs of all power classes Hence the same idle mode cell border

is seen by each mobile

Choosing for example MS_TXPWR_MAX_CCH = Pmax where Pmax is

the output power level for the maximum power class 1 (43 dBm)

the C1 criterion reduces to

AV_RXLEV gt RXLEV_ACCESS_MIN + ( MS_TXPWR_MAX_CCH - P )

for MSs of all power classes Hence a larger cell radius is seen by a

mobile of higher output power than by a mobile of lower output

power On the other hand one can ensure by this mechanism that a

certain uplink received level is exceeded by each MS independent of

its power class

Object DB Name Range Step Size Unit

BTS MSTXPMAXCH 031 1 2 dB

MS_TXPWR_MAX_CCH - Maximum allowed MS transmit power on RACH

default 2

MS GSM900 MS GSM900 MS DCS1800

Phase 1 Phase 2

0 = 43 dBm 0 = 39 dBm 0 = 30 dBm

1 = 41 dBm 1 = 39 dBm 1 = 28 dBm

2 = 39 dBm 2 = 39 dBm 2 = 26 dBm

3 = 37 dBm 3 = 37 dBm 3 = 24 dBm

15 = 13dBm 19 = 5 dBm 15 = 0 dBm

16-31 = 13 dBm 20-31 = 5 dBm 16-31 = 0 dBm

POWER_OFFSET - Additional Parameter for Class 3

DCS1800 MS

The parameter POWER_OFFSET is only used by class 3

DCS1800 MS to calculate the C1-criterion described as

follows

C1 = AV_RXLEV - RXLEV_ACCESS_MIN -

Max(0MS_TXPWR_MAX_CCH + POWER_OFFSET- P)

Object DB Name Range Step Size Unit

BTS PWROFS 03 1 2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for Reselection of a Cell

from another Location Area

In idle mode the MS selects a new (neighbor) cell if the received level of the

neighbor cell exceeds the received level of the current cell in order to be

served by the cell with the expected best link quality However due to

fading effects the propagation conditions may change rapidly and

therefore a reselection may occur very frequently

If the cells involved in the reselection process belong to the same location

area frequent cell reselection does not have an effect on the network

performance

But if the involved cells belong to different location area the reselection of

a new cell triggers a location update procedure which causes signaling

load (eg on the SDCCH) and involves all network elements

To avoid unnecessary signaling load by forward and backward reselection due to fading

a hysteresis given by the parameter CELL_RESELECT_HYSTERESIS is introduced ie

a cell from another location area is selected only if the corresponding received level

exceeds the level of the current serving cell by the value of this parameter This is

expressed in terms of the C1 (phase 1) or C2 (phase 2) criterion

C1 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C1 (suitable neighbor cell)

or

C2 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C2 (suitable neighbor cell)

respectively

The adjustment of CELL_RESELECT_HYSTERESES should be a compromise between

reduction of unnecessary location updates (high value) and

selection of the cell with best reception quality (low value)

Object DB Name Range Step Size Unit

BTS CELLRESH 07 1

2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for

reselection of a cell from another location area

default 2

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter

Indication

CELL_RESELECT_PARAM_IND=1

The cell reselection parameters CELL_RESELECT_OFFSET

TEMPORARY_OFFSET and PENALTY_TIME used for the C2 criterion as well as

the parameter CELL_BAR_QUALIFY are broadcasted on the BCCH These

parameters are taken into account by phase 2 MS but are ignored by

phase 1 MS

CELL_RESELECT_PARAM_IND = 0

The cell reselection parameters and CELL_BAR_QUALIFY are not

broadcasted on the BCCH

A phase 2 MS then uses the value 0 for all these parameters ie C1 = C2

Object DB Name Range

BTS CRESPARI 01

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter Indication default 1

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells

When a mobile reaches the coverage area of a (neighbor) micro cell given

by the C1 criterion this cell becomes effectively excluded from reselection

during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell be-fore PENALTY_TIME is reached and hence the micro cell is not

selected

In contrast a slow moving mobile is assumed to be still within the coverage

area of the micro cell when PENALTY_TIME has expired

Applying the positive CELL_RESELECT_OFFSET this cell is selected with

preference

Triggers for Cell Reselection

Cell reselection is triggered by the following conditions

1 C1 lt 0 for the serving cell for a period of 5 s

2 MS detects a downlink signaling failure

3 Serving cell becomes barred

Phase 1 MS

C1 (serving cell) lt C1 (suitable neighbor cell) if the suitable neighbor cell is

in the same location area

C1 (serving cell) + CELL_RESELECT_HYSTERESIS lt C1 (suitable

neighbor cell) if the suitable neighbor cell is in another location area for a

period of 5 sec

Phase 2 MS

C2 (serving cell) lt C2 (suitable neighbor cell) if the suitable neighbor cell is in

the same location area

C2 (serving cell) + CELL_RESELECT_HYSTERESIS lt C2 (suitable neighbor

cell) if the suitable neighbor cell is in another location area for a period of 5

sec

A random access attempt is unsuccessful even after the maximum number

of repetitions

For phase 2 there is the additional trigger

A location update request has been rejected with cause rdquolocation area not

allowedrdquo

PARAMETERS SETTING

BA (BCCH) - BCCH Allocation broadcasted on BCCH

In each cell the absolute radio frequency carrier number

BCCH_ARFCN_NC(n) of each of its neighbor cell n has to be

known This information is broadcasted as the so-called BCCH

Allocation to all MS in the respective cell On the

corresponding frequencies the MS take measurement samples

of the received level used for cell selection reselection

Furthermore the BCCH of neighbor cells has to be decoded by

the MS (at least every 5 min) to know the current values of the

control parameters for the reselection algorithm

PARAMETERS SETTING

Object DB Name Range Step Size

Unit ADJC BCCHFREQ 01023 1

PARAMETERS SETTING

CELL_BAR_ACCESS - Cell Barred for Access

A mobile station cannot camp on a barred cell ie a barred cell is not

selected by the cell selectionreselection procedure

Mobile stations which camp on a cell while it becomes barred initialize the

reselection procedure to find a new (unbarred) cell ie traffic load is

distributed to neighbor cells

This means that eg neither a call nor a location update can start in a

barred cell

However a cell barred for access is not barred for incoming handovers To

barr a cell completely eg for maintenance reasons also incoming

handovers have to be avoided

To reduce overload in a certain cell more moderately without distributing

the overload to neighbor cells barring of access classes has to be used

Barring access for an access class does not trigger a cell reselection for

MSs of that class

Object DB Name Range

BTS CELLBARR FALSETRUE

RXLEV_ACCESS_MIN - Minimum Downlink Received Level for Cell to be

selected

The parameter RXLEV_ACCESS_MIN determines the cell border for a MS in idle

mode by means of the C1 or C2 criterion respectively

Choosing a high value reduces the risk of a handover immediately after call

setup

On the other hand the value has to be low enough to achieve a sufficient overlap

between adjacent cells (especially if they belong to different location areas)

It has to be observed that the overlap may be different for mobiles of different

power classes (refer to MS_TXPWR_MAX_CCH)

In any case RXLEV_ACCESS_MIN has to be above the MS receiver sensitivity level

(-100 dBm for DCS1800 -102 dBm for GSM handhelds -104 dBm for other GSM

MS)

Furthermore it has to harmonize with the

handover thresholds (RXLEV_MIN L_RXLEV_HO)

Object DB Name Range Step Size Unit

BTS RXLEVAMI 063 1

RXLEV

MS_TXPWR_MAX_CCH - Maximum allowed MS Transmit

Power on RACH

The transmit power level the MS uses for the access on the

Random Access Channel is given by the minimum of two

values

the maximum possible transmit power of the MS (given by

the power class P of the MS) the maximum allowed power

for access within the respective cell

(given by MS_TXP WR_MAX_CCH)

This parameter affects the

the random access procedure

the cell selection procedure

Random access

If there is a collision of channel requests on the random access

channel the one with the higher received level has a good chance

to be decoded and to get a response by the BTS

Hence MS with higher output power are preferred This imbalance

can be avoided by choosing a low maximum allowed transmit power

PARAMETERS SETTING

Cell Selection

To be selected by the cell selection procedure a cell has to fulfill the

C1 criterion

C1 gt 0 where

C1 = AV_RXLEV - RXLEV_ACCESS_MIN - Max(0

MS_TXPWR_MAX_CCH - P )

Choosing for example MS_TXPWR_MAX_CCH = Pmin where Pmin is

the output power level for the minimum power class 5 (29 dBm)

the C1 criterion reduces to AV_RXLEV gt RXLEV_ACCESS_MIN

for MSs of all power classes Hence the same idle mode cell border

is seen by each mobile

Choosing for example MS_TXPWR_MAX_CCH = Pmax where Pmax is

the output power level for the maximum power class 1 (43 dBm)

the C1 criterion reduces to

AV_RXLEV gt RXLEV_ACCESS_MIN + ( MS_TXPWR_MAX_CCH - P )

for MSs of all power classes Hence a larger cell radius is seen by a

mobile of higher output power than by a mobile of lower output

power On the other hand one can ensure by this mechanism that a

certain uplink received level is exceeded by each MS independent of

its power class

Object DB Name Range Step Size Unit

BTS MSTXPMAXCH 031 1 2 dB

MS_TXPWR_MAX_CCH - Maximum allowed MS transmit power on RACH

default 2

MS GSM900 MS GSM900 MS DCS1800

Phase 1 Phase 2

0 = 43 dBm 0 = 39 dBm 0 = 30 dBm

1 = 41 dBm 1 = 39 dBm 1 = 28 dBm

2 = 39 dBm 2 = 39 dBm 2 = 26 dBm

3 = 37 dBm 3 = 37 dBm 3 = 24 dBm

15 = 13dBm 19 = 5 dBm 15 = 0 dBm

16-31 = 13 dBm 20-31 = 5 dBm 16-31 = 0 dBm

POWER_OFFSET - Additional Parameter for Class 3

DCS1800 MS

The parameter POWER_OFFSET is only used by class 3

DCS1800 MS to calculate the C1-criterion described as

follows

C1 = AV_RXLEV - RXLEV_ACCESS_MIN -

Max(0MS_TXPWR_MAX_CCH + POWER_OFFSET- P)

Object DB Name Range Step Size Unit

BTS PWROFS 03 1 2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for Reselection of a Cell

from another Location Area

In idle mode the MS selects a new (neighbor) cell if the received level of the

neighbor cell exceeds the received level of the current cell in order to be

served by the cell with the expected best link quality However due to

fading effects the propagation conditions may change rapidly and

therefore a reselection may occur very frequently

If the cells involved in the reselection process belong to the same location

area frequent cell reselection does not have an effect on the network

performance

But if the involved cells belong to different location area the reselection of

a new cell triggers a location update procedure which causes signaling

load (eg on the SDCCH) and involves all network elements

To avoid unnecessary signaling load by forward and backward reselection due to fading

a hysteresis given by the parameter CELL_RESELECT_HYSTERESIS is introduced ie

a cell from another location area is selected only if the corresponding received level

exceeds the level of the current serving cell by the value of this parameter This is

expressed in terms of the C1 (phase 1) or C2 (phase 2) criterion

C1 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C1 (suitable neighbor cell)

or

C2 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C2 (suitable neighbor cell)

respectively

The adjustment of CELL_RESELECT_HYSTERESES should be a compromise between

reduction of unnecessary location updates (high value) and

selection of the cell with best reception quality (low value)

Object DB Name Range Step Size Unit

BTS CELLRESH 07 1

2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for

reselection of a cell from another location area

default 2

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter

Indication

CELL_RESELECT_PARAM_IND=1

The cell reselection parameters CELL_RESELECT_OFFSET

TEMPORARY_OFFSET and PENALTY_TIME used for the C2 criterion as well as

the parameter CELL_BAR_QUALIFY are broadcasted on the BCCH These

parameters are taken into account by phase 2 MS but are ignored by

phase 1 MS

CELL_RESELECT_PARAM_IND = 0

The cell reselection parameters and CELL_BAR_QUALIFY are not

broadcasted on the BCCH

A phase 2 MS then uses the value 0 for all these parameters ie C1 = C2

Object DB Name Range

BTS CRESPARI 01

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter Indication default 1

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

Triggers for Cell Reselection

Cell reselection is triggered by the following conditions

1 C1 lt 0 for the serving cell for a period of 5 s

2 MS detects a downlink signaling failure

3 Serving cell becomes barred

Phase 1 MS

C1 (serving cell) lt C1 (suitable neighbor cell) if the suitable neighbor cell is

in the same location area

C1 (serving cell) + CELL_RESELECT_HYSTERESIS lt C1 (suitable

neighbor cell) if the suitable neighbor cell is in another location area for a

period of 5 sec

Phase 2 MS

C2 (serving cell) lt C2 (suitable neighbor cell) if the suitable neighbor cell is in

the same location area

C2 (serving cell) + CELL_RESELECT_HYSTERESIS lt C2 (suitable neighbor

cell) if the suitable neighbor cell is in another location area for a period of 5

sec

A random access attempt is unsuccessful even after the maximum number

of repetitions

For phase 2 there is the additional trigger

A location update request has been rejected with cause rdquolocation area not

allowedrdquo

PARAMETERS SETTING

BA (BCCH) - BCCH Allocation broadcasted on BCCH

In each cell the absolute radio frequency carrier number

BCCH_ARFCN_NC(n) of each of its neighbor cell n has to be

known This information is broadcasted as the so-called BCCH

Allocation to all MS in the respective cell On the

corresponding frequencies the MS take measurement samples

of the received level used for cell selection reselection

Furthermore the BCCH of neighbor cells has to be decoded by

the MS (at least every 5 min) to know the current values of the

control parameters for the reselection algorithm

PARAMETERS SETTING

Object DB Name Range Step Size

Unit ADJC BCCHFREQ 01023 1

PARAMETERS SETTING

CELL_BAR_ACCESS - Cell Barred for Access

A mobile station cannot camp on a barred cell ie a barred cell is not

selected by the cell selectionreselection procedure

Mobile stations which camp on a cell while it becomes barred initialize the

reselection procedure to find a new (unbarred) cell ie traffic load is

distributed to neighbor cells

This means that eg neither a call nor a location update can start in a

barred cell

However a cell barred for access is not barred for incoming handovers To

barr a cell completely eg for maintenance reasons also incoming

handovers have to be avoided

To reduce overload in a certain cell more moderately without distributing

the overload to neighbor cells barring of access classes has to be used

Barring access for an access class does not trigger a cell reselection for

MSs of that class

Object DB Name Range

BTS CELLBARR FALSETRUE

RXLEV_ACCESS_MIN - Minimum Downlink Received Level for Cell to be

selected

The parameter RXLEV_ACCESS_MIN determines the cell border for a MS in idle

mode by means of the C1 or C2 criterion respectively

Choosing a high value reduces the risk of a handover immediately after call

setup

On the other hand the value has to be low enough to achieve a sufficient overlap

between adjacent cells (especially if they belong to different location areas)

It has to be observed that the overlap may be different for mobiles of different

power classes (refer to MS_TXPWR_MAX_CCH)

In any case RXLEV_ACCESS_MIN has to be above the MS receiver sensitivity level

(-100 dBm for DCS1800 -102 dBm for GSM handhelds -104 dBm for other GSM

MS)

Furthermore it has to harmonize with the

handover thresholds (RXLEV_MIN L_RXLEV_HO)

Object DB Name Range Step Size Unit

BTS RXLEVAMI 063 1

RXLEV

MS_TXPWR_MAX_CCH - Maximum allowed MS Transmit

Power on RACH

The transmit power level the MS uses for the access on the

Random Access Channel is given by the minimum of two

values

the maximum possible transmit power of the MS (given by

the power class P of the MS) the maximum allowed power

for access within the respective cell

(given by MS_TXP WR_MAX_CCH)

This parameter affects the

the random access procedure

the cell selection procedure

Random access

If there is a collision of channel requests on the random access

channel the one with the higher received level has a good chance

to be decoded and to get a response by the BTS

Hence MS with higher output power are preferred This imbalance

can be avoided by choosing a low maximum allowed transmit power

PARAMETERS SETTING

Cell Selection

To be selected by the cell selection procedure a cell has to fulfill the

C1 criterion

C1 gt 0 where

C1 = AV_RXLEV - RXLEV_ACCESS_MIN - Max(0

MS_TXPWR_MAX_CCH - P )

Choosing for example MS_TXPWR_MAX_CCH = Pmin where Pmin is

the output power level for the minimum power class 5 (29 dBm)

the C1 criterion reduces to AV_RXLEV gt RXLEV_ACCESS_MIN

for MSs of all power classes Hence the same idle mode cell border

is seen by each mobile

Choosing for example MS_TXPWR_MAX_CCH = Pmax where Pmax is

the output power level for the maximum power class 1 (43 dBm)

the C1 criterion reduces to

AV_RXLEV gt RXLEV_ACCESS_MIN + ( MS_TXPWR_MAX_CCH - P )

for MSs of all power classes Hence a larger cell radius is seen by a

mobile of higher output power than by a mobile of lower output

power On the other hand one can ensure by this mechanism that a

certain uplink received level is exceeded by each MS independent of

its power class

Object DB Name Range Step Size Unit

BTS MSTXPMAXCH 031 1 2 dB

MS_TXPWR_MAX_CCH - Maximum allowed MS transmit power on RACH

default 2

MS GSM900 MS GSM900 MS DCS1800

Phase 1 Phase 2

0 = 43 dBm 0 = 39 dBm 0 = 30 dBm

1 = 41 dBm 1 = 39 dBm 1 = 28 dBm

2 = 39 dBm 2 = 39 dBm 2 = 26 dBm

3 = 37 dBm 3 = 37 dBm 3 = 24 dBm

15 = 13dBm 19 = 5 dBm 15 = 0 dBm

16-31 = 13 dBm 20-31 = 5 dBm 16-31 = 0 dBm

POWER_OFFSET - Additional Parameter for Class 3

DCS1800 MS

The parameter POWER_OFFSET is only used by class 3

DCS1800 MS to calculate the C1-criterion described as

follows

C1 = AV_RXLEV - RXLEV_ACCESS_MIN -

Max(0MS_TXPWR_MAX_CCH + POWER_OFFSET- P)

Object DB Name Range Step Size Unit

BTS PWROFS 03 1 2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for Reselection of a Cell

from another Location Area

In idle mode the MS selects a new (neighbor) cell if the received level of the

neighbor cell exceeds the received level of the current cell in order to be

served by the cell with the expected best link quality However due to

fading effects the propagation conditions may change rapidly and

therefore a reselection may occur very frequently

If the cells involved in the reselection process belong to the same location

area frequent cell reselection does not have an effect on the network

performance

But if the involved cells belong to different location area the reselection of

a new cell triggers a location update procedure which causes signaling

load (eg on the SDCCH) and involves all network elements

To avoid unnecessary signaling load by forward and backward reselection due to fading

a hysteresis given by the parameter CELL_RESELECT_HYSTERESIS is introduced ie

a cell from another location area is selected only if the corresponding received level

exceeds the level of the current serving cell by the value of this parameter This is

expressed in terms of the C1 (phase 1) or C2 (phase 2) criterion

C1 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C1 (suitable neighbor cell)

or

C2 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C2 (suitable neighbor cell)

respectively

The adjustment of CELL_RESELECT_HYSTERESES should be a compromise between

reduction of unnecessary location updates (high value) and

selection of the cell with best reception quality (low value)

Object DB Name Range Step Size Unit

BTS CELLRESH 07 1

2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for

reselection of a cell from another location area

default 2

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter

Indication

CELL_RESELECT_PARAM_IND=1

The cell reselection parameters CELL_RESELECT_OFFSET

TEMPORARY_OFFSET and PENALTY_TIME used for the C2 criterion as well as

the parameter CELL_BAR_QUALIFY are broadcasted on the BCCH These

parameters are taken into account by phase 2 MS but are ignored by

phase 1 MS

CELL_RESELECT_PARAM_IND = 0

The cell reselection parameters and CELL_BAR_QUALIFY are not

broadcasted on the BCCH

A phase 2 MS then uses the value 0 for all these parameters ie C1 = C2

Object DB Name Range

BTS CRESPARI 01

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter Indication default 1

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

Phase 2 MS

C2 (serving cell) lt C2 (suitable neighbor cell) if the suitable neighbor cell is in

the same location area

C2 (serving cell) + CELL_RESELECT_HYSTERESIS lt C2 (suitable neighbor

cell) if the suitable neighbor cell is in another location area for a period of 5

sec

A random access attempt is unsuccessful even after the maximum number

of repetitions

For phase 2 there is the additional trigger

A location update request has been rejected with cause rdquolocation area not

allowedrdquo

PARAMETERS SETTING

BA (BCCH) - BCCH Allocation broadcasted on BCCH

In each cell the absolute radio frequency carrier number

BCCH_ARFCN_NC(n) of each of its neighbor cell n has to be

known This information is broadcasted as the so-called BCCH

Allocation to all MS in the respective cell On the

corresponding frequencies the MS take measurement samples

of the received level used for cell selection reselection

Furthermore the BCCH of neighbor cells has to be decoded by

the MS (at least every 5 min) to know the current values of the

control parameters for the reselection algorithm

PARAMETERS SETTING

Object DB Name Range Step Size

Unit ADJC BCCHFREQ 01023 1

PARAMETERS SETTING

CELL_BAR_ACCESS - Cell Barred for Access

A mobile station cannot camp on a barred cell ie a barred cell is not

selected by the cell selectionreselection procedure

Mobile stations which camp on a cell while it becomes barred initialize the

reselection procedure to find a new (unbarred) cell ie traffic load is

distributed to neighbor cells

This means that eg neither a call nor a location update can start in a

barred cell

However a cell barred for access is not barred for incoming handovers To

barr a cell completely eg for maintenance reasons also incoming

handovers have to be avoided

To reduce overload in a certain cell more moderately without distributing

the overload to neighbor cells barring of access classes has to be used

Barring access for an access class does not trigger a cell reselection for

MSs of that class

Object DB Name Range

BTS CELLBARR FALSETRUE

RXLEV_ACCESS_MIN - Minimum Downlink Received Level for Cell to be

selected

The parameter RXLEV_ACCESS_MIN determines the cell border for a MS in idle

mode by means of the C1 or C2 criterion respectively

Choosing a high value reduces the risk of a handover immediately after call

setup

On the other hand the value has to be low enough to achieve a sufficient overlap

between adjacent cells (especially if they belong to different location areas)

It has to be observed that the overlap may be different for mobiles of different

power classes (refer to MS_TXPWR_MAX_CCH)

In any case RXLEV_ACCESS_MIN has to be above the MS receiver sensitivity level

(-100 dBm for DCS1800 -102 dBm for GSM handhelds -104 dBm for other GSM

MS)

Furthermore it has to harmonize with the

handover thresholds (RXLEV_MIN L_RXLEV_HO)

Object DB Name Range Step Size Unit

BTS RXLEVAMI 063 1

RXLEV

MS_TXPWR_MAX_CCH - Maximum allowed MS Transmit

Power on RACH

The transmit power level the MS uses for the access on the

Random Access Channel is given by the minimum of two

values

the maximum possible transmit power of the MS (given by

the power class P of the MS) the maximum allowed power

for access within the respective cell

(given by MS_TXP WR_MAX_CCH)

This parameter affects the

the random access procedure

the cell selection procedure

Random access

If there is a collision of channel requests on the random access

channel the one with the higher received level has a good chance

to be decoded and to get a response by the BTS

Hence MS with higher output power are preferred This imbalance

can be avoided by choosing a low maximum allowed transmit power

PARAMETERS SETTING

Cell Selection

To be selected by the cell selection procedure a cell has to fulfill the

C1 criterion

C1 gt 0 where

C1 = AV_RXLEV - RXLEV_ACCESS_MIN - Max(0

MS_TXPWR_MAX_CCH - P )

Choosing for example MS_TXPWR_MAX_CCH = Pmin where Pmin is

the output power level for the minimum power class 5 (29 dBm)

the C1 criterion reduces to AV_RXLEV gt RXLEV_ACCESS_MIN

for MSs of all power classes Hence the same idle mode cell border

is seen by each mobile

Choosing for example MS_TXPWR_MAX_CCH = Pmax where Pmax is

the output power level for the maximum power class 1 (43 dBm)

the C1 criterion reduces to

AV_RXLEV gt RXLEV_ACCESS_MIN + ( MS_TXPWR_MAX_CCH - P )

for MSs of all power classes Hence a larger cell radius is seen by a

mobile of higher output power than by a mobile of lower output

power On the other hand one can ensure by this mechanism that a

certain uplink received level is exceeded by each MS independent of

its power class

Object DB Name Range Step Size Unit

BTS MSTXPMAXCH 031 1 2 dB

MS_TXPWR_MAX_CCH - Maximum allowed MS transmit power on RACH

default 2

MS GSM900 MS GSM900 MS DCS1800

Phase 1 Phase 2

0 = 43 dBm 0 = 39 dBm 0 = 30 dBm

1 = 41 dBm 1 = 39 dBm 1 = 28 dBm

2 = 39 dBm 2 = 39 dBm 2 = 26 dBm

3 = 37 dBm 3 = 37 dBm 3 = 24 dBm

15 = 13dBm 19 = 5 dBm 15 = 0 dBm

16-31 = 13 dBm 20-31 = 5 dBm 16-31 = 0 dBm

POWER_OFFSET - Additional Parameter for Class 3

DCS1800 MS

The parameter POWER_OFFSET is only used by class 3

DCS1800 MS to calculate the C1-criterion described as

follows

C1 = AV_RXLEV - RXLEV_ACCESS_MIN -

Max(0MS_TXPWR_MAX_CCH + POWER_OFFSET- P)

Object DB Name Range Step Size Unit

BTS PWROFS 03 1 2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for Reselection of a Cell

from another Location Area

In idle mode the MS selects a new (neighbor) cell if the received level of the

neighbor cell exceeds the received level of the current cell in order to be

served by the cell with the expected best link quality However due to

fading effects the propagation conditions may change rapidly and

therefore a reselection may occur very frequently

If the cells involved in the reselection process belong to the same location

area frequent cell reselection does not have an effect on the network

performance

But if the involved cells belong to different location area the reselection of

a new cell triggers a location update procedure which causes signaling

load (eg on the SDCCH) and involves all network elements

To avoid unnecessary signaling load by forward and backward reselection due to fading

a hysteresis given by the parameter CELL_RESELECT_HYSTERESIS is introduced ie

a cell from another location area is selected only if the corresponding received level

exceeds the level of the current serving cell by the value of this parameter This is

expressed in terms of the C1 (phase 1) or C2 (phase 2) criterion

C1 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C1 (suitable neighbor cell)

or

C2 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C2 (suitable neighbor cell)

respectively

The adjustment of CELL_RESELECT_HYSTERESES should be a compromise between

reduction of unnecessary location updates (high value) and

selection of the cell with best reception quality (low value)

Object DB Name Range Step Size Unit

BTS CELLRESH 07 1

2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for

reselection of a cell from another location area

default 2

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter

Indication

CELL_RESELECT_PARAM_IND=1

The cell reselection parameters CELL_RESELECT_OFFSET

TEMPORARY_OFFSET and PENALTY_TIME used for the C2 criterion as well as

the parameter CELL_BAR_QUALIFY are broadcasted on the BCCH These

parameters are taken into account by phase 2 MS but are ignored by

phase 1 MS

CELL_RESELECT_PARAM_IND = 0

The cell reselection parameters and CELL_BAR_QUALIFY are not

broadcasted on the BCCH

A phase 2 MS then uses the value 0 for all these parameters ie C1 = C2

Object DB Name Range

BTS CRESPARI 01

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter Indication default 1

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

PARAMETERS SETTING

BA (BCCH) - BCCH Allocation broadcasted on BCCH

In each cell the absolute radio frequency carrier number

BCCH_ARFCN_NC(n) of each of its neighbor cell n has to be

known This information is broadcasted as the so-called BCCH

Allocation to all MS in the respective cell On the

corresponding frequencies the MS take measurement samples

of the received level used for cell selection reselection

Furthermore the BCCH of neighbor cells has to be decoded by

the MS (at least every 5 min) to know the current values of the

control parameters for the reselection algorithm

PARAMETERS SETTING

Object DB Name Range Step Size

Unit ADJC BCCHFREQ 01023 1

PARAMETERS SETTING

CELL_BAR_ACCESS - Cell Barred for Access

A mobile station cannot camp on a barred cell ie a barred cell is not

selected by the cell selectionreselection procedure

Mobile stations which camp on a cell while it becomes barred initialize the

reselection procedure to find a new (unbarred) cell ie traffic load is

distributed to neighbor cells

This means that eg neither a call nor a location update can start in a

barred cell

However a cell barred for access is not barred for incoming handovers To

barr a cell completely eg for maintenance reasons also incoming

handovers have to be avoided

To reduce overload in a certain cell more moderately without distributing

the overload to neighbor cells barring of access classes has to be used

Barring access for an access class does not trigger a cell reselection for

MSs of that class

Object DB Name Range

BTS CELLBARR FALSETRUE

RXLEV_ACCESS_MIN - Minimum Downlink Received Level for Cell to be

selected

The parameter RXLEV_ACCESS_MIN determines the cell border for a MS in idle

mode by means of the C1 or C2 criterion respectively

Choosing a high value reduces the risk of a handover immediately after call

setup

On the other hand the value has to be low enough to achieve a sufficient overlap

between adjacent cells (especially if they belong to different location areas)

It has to be observed that the overlap may be different for mobiles of different

power classes (refer to MS_TXPWR_MAX_CCH)

In any case RXLEV_ACCESS_MIN has to be above the MS receiver sensitivity level

(-100 dBm for DCS1800 -102 dBm for GSM handhelds -104 dBm for other GSM

MS)

Furthermore it has to harmonize with the

handover thresholds (RXLEV_MIN L_RXLEV_HO)

Object DB Name Range Step Size Unit

BTS RXLEVAMI 063 1

RXLEV

MS_TXPWR_MAX_CCH - Maximum allowed MS Transmit

Power on RACH

The transmit power level the MS uses for the access on the

Random Access Channel is given by the minimum of two

values

the maximum possible transmit power of the MS (given by

the power class P of the MS) the maximum allowed power

for access within the respective cell

(given by MS_TXP WR_MAX_CCH)

This parameter affects the

the random access procedure

the cell selection procedure

Random access

If there is a collision of channel requests on the random access

channel the one with the higher received level has a good chance

to be decoded and to get a response by the BTS

Hence MS with higher output power are preferred This imbalance

can be avoided by choosing a low maximum allowed transmit power

PARAMETERS SETTING

Cell Selection

To be selected by the cell selection procedure a cell has to fulfill the

C1 criterion

C1 gt 0 where

C1 = AV_RXLEV - RXLEV_ACCESS_MIN - Max(0

MS_TXPWR_MAX_CCH - P )

Choosing for example MS_TXPWR_MAX_CCH = Pmin where Pmin is

the output power level for the minimum power class 5 (29 dBm)

the C1 criterion reduces to AV_RXLEV gt RXLEV_ACCESS_MIN

for MSs of all power classes Hence the same idle mode cell border

is seen by each mobile

Choosing for example MS_TXPWR_MAX_CCH = Pmax where Pmax is

the output power level for the maximum power class 1 (43 dBm)

the C1 criterion reduces to

AV_RXLEV gt RXLEV_ACCESS_MIN + ( MS_TXPWR_MAX_CCH - P )

for MSs of all power classes Hence a larger cell radius is seen by a

mobile of higher output power than by a mobile of lower output

power On the other hand one can ensure by this mechanism that a

certain uplink received level is exceeded by each MS independent of

its power class

Object DB Name Range Step Size Unit

BTS MSTXPMAXCH 031 1 2 dB

MS_TXPWR_MAX_CCH - Maximum allowed MS transmit power on RACH

default 2

MS GSM900 MS GSM900 MS DCS1800

Phase 1 Phase 2

0 = 43 dBm 0 = 39 dBm 0 = 30 dBm

1 = 41 dBm 1 = 39 dBm 1 = 28 dBm

2 = 39 dBm 2 = 39 dBm 2 = 26 dBm

3 = 37 dBm 3 = 37 dBm 3 = 24 dBm

15 = 13dBm 19 = 5 dBm 15 = 0 dBm

16-31 = 13 dBm 20-31 = 5 dBm 16-31 = 0 dBm

POWER_OFFSET - Additional Parameter for Class 3

DCS1800 MS

The parameter POWER_OFFSET is only used by class 3

DCS1800 MS to calculate the C1-criterion described as

follows

C1 = AV_RXLEV - RXLEV_ACCESS_MIN -

Max(0MS_TXPWR_MAX_CCH + POWER_OFFSET- P)

Object DB Name Range Step Size Unit

BTS PWROFS 03 1 2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for Reselection of a Cell

from another Location Area

In idle mode the MS selects a new (neighbor) cell if the received level of the

neighbor cell exceeds the received level of the current cell in order to be

served by the cell with the expected best link quality However due to

fading effects the propagation conditions may change rapidly and

therefore a reselection may occur very frequently

If the cells involved in the reselection process belong to the same location

area frequent cell reselection does not have an effect on the network

performance

But if the involved cells belong to different location area the reselection of

a new cell triggers a location update procedure which causes signaling

load (eg on the SDCCH) and involves all network elements

To avoid unnecessary signaling load by forward and backward reselection due to fading

a hysteresis given by the parameter CELL_RESELECT_HYSTERESIS is introduced ie

a cell from another location area is selected only if the corresponding received level

exceeds the level of the current serving cell by the value of this parameter This is

expressed in terms of the C1 (phase 1) or C2 (phase 2) criterion

C1 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C1 (suitable neighbor cell)

or

C2 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C2 (suitable neighbor cell)

respectively

The adjustment of CELL_RESELECT_HYSTERESES should be a compromise between

reduction of unnecessary location updates (high value) and

selection of the cell with best reception quality (low value)

Object DB Name Range Step Size Unit

BTS CELLRESH 07 1

2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for

reselection of a cell from another location area

default 2

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter

Indication

CELL_RESELECT_PARAM_IND=1

The cell reselection parameters CELL_RESELECT_OFFSET

TEMPORARY_OFFSET and PENALTY_TIME used for the C2 criterion as well as

the parameter CELL_BAR_QUALIFY are broadcasted on the BCCH These

parameters are taken into account by phase 2 MS but are ignored by

phase 1 MS

CELL_RESELECT_PARAM_IND = 0

The cell reselection parameters and CELL_BAR_QUALIFY are not

broadcasted on the BCCH

A phase 2 MS then uses the value 0 for all these parameters ie C1 = C2

Object DB Name Range

BTS CRESPARI 01

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter Indication default 1

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

PARAMETERS SETTING

Object DB Name Range Step Size

Unit ADJC BCCHFREQ 01023 1

PARAMETERS SETTING

CELL_BAR_ACCESS - Cell Barred for Access

A mobile station cannot camp on a barred cell ie a barred cell is not

selected by the cell selectionreselection procedure

Mobile stations which camp on a cell while it becomes barred initialize the

reselection procedure to find a new (unbarred) cell ie traffic load is

distributed to neighbor cells

This means that eg neither a call nor a location update can start in a

barred cell

However a cell barred for access is not barred for incoming handovers To

barr a cell completely eg for maintenance reasons also incoming

handovers have to be avoided

To reduce overload in a certain cell more moderately without distributing

the overload to neighbor cells barring of access classes has to be used

Barring access for an access class does not trigger a cell reselection for

MSs of that class

Object DB Name Range

BTS CELLBARR FALSETRUE

RXLEV_ACCESS_MIN - Minimum Downlink Received Level for Cell to be

selected

The parameter RXLEV_ACCESS_MIN determines the cell border for a MS in idle

mode by means of the C1 or C2 criterion respectively

Choosing a high value reduces the risk of a handover immediately after call

setup

On the other hand the value has to be low enough to achieve a sufficient overlap

between adjacent cells (especially if they belong to different location areas)

It has to be observed that the overlap may be different for mobiles of different

power classes (refer to MS_TXPWR_MAX_CCH)

In any case RXLEV_ACCESS_MIN has to be above the MS receiver sensitivity level

(-100 dBm for DCS1800 -102 dBm for GSM handhelds -104 dBm for other GSM

MS)

Furthermore it has to harmonize with the

handover thresholds (RXLEV_MIN L_RXLEV_HO)

Object DB Name Range Step Size Unit

BTS RXLEVAMI 063 1

RXLEV

MS_TXPWR_MAX_CCH - Maximum allowed MS Transmit

Power on RACH

The transmit power level the MS uses for the access on the

Random Access Channel is given by the minimum of two

values

the maximum possible transmit power of the MS (given by

the power class P of the MS) the maximum allowed power

for access within the respective cell

(given by MS_TXP WR_MAX_CCH)

This parameter affects the

the random access procedure

the cell selection procedure

Random access

If there is a collision of channel requests on the random access

channel the one with the higher received level has a good chance

to be decoded and to get a response by the BTS

Hence MS with higher output power are preferred This imbalance

can be avoided by choosing a low maximum allowed transmit power

PARAMETERS SETTING

Cell Selection

To be selected by the cell selection procedure a cell has to fulfill the

C1 criterion

C1 gt 0 where

C1 = AV_RXLEV - RXLEV_ACCESS_MIN - Max(0

MS_TXPWR_MAX_CCH - P )

Choosing for example MS_TXPWR_MAX_CCH = Pmin where Pmin is

the output power level for the minimum power class 5 (29 dBm)

the C1 criterion reduces to AV_RXLEV gt RXLEV_ACCESS_MIN

for MSs of all power classes Hence the same idle mode cell border

is seen by each mobile

Choosing for example MS_TXPWR_MAX_CCH = Pmax where Pmax is

the output power level for the maximum power class 1 (43 dBm)

the C1 criterion reduces to

AV_RXLEV gt RXLEV_ACCESS_MIN + ( MS_TXPWR_MAX_CCH - P )

for MSs of all power classes Hence a larger cell radius is seen by a

mobile of higher output power than by a mobile of lower output

power On the other hand one can ensure by this mechanism that a

certain uplink received level is exceeded by each MS independent of

its power class

Object DB Name Range Step Size Unit

BTS MSTXPMAXCH 031 1 2 dB

MS_TXPWR_MAX_CCH - Maximum allowed MS transmit power on RACH

default 2

MS GSM900 MS GSM900 MS DCS1800

Phase 1 Phase 2

0 = 43 dBm 0 = 39 dBm 0 = 30 dBm

1 = 41 dBm 1 = 39 dBm 1 = 28 dBm

2 = 39 dBm 2 = 39 dBm 2 = 26 dBm

3 = 37 dBm 3 = 37 dBm 3 = 24 dBm

15 = 13dBm 19 = 5 dBm 15 = 0 dBm

16-31 = 13 dBm 20-31 = 5 dBm 16-31 = 0 dBm

POWER_OFFSET - Additional Parameter for Class 3

DCS1800 MS

The parameter POWER_OFFSET is only used by class 3

DCS1800 MS to calculate the C1-criterion described as

follows

C1 = AV_RXLEV - RXLEV_ACCESS_MIN -

Max(0MS_TXPWR_MAX_CCH + POWER_OFFSET- P)

Object DB Name Range Step Size Unit

BTS PWROFS 03 1 2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for Reselection of a Cell

from another Location Area

In idle mode the MS selects a new (neighbor) cell if the received level of the

neighbor cell exceeds the received level of the current cell in order to be

served by the cell with the expected best link quality However due to

fading effects the propagation conditions may change rapidly and

therefore a reselection may occur very frequently

If the cells involved in the reselection process belong to the same location

area frequent cell reselection does not have an effect on the network

performance

But if the involved cells belong to different location area the reselection of

a new cell triggers a location update procedure which causes signaling

load (eg on the SDCCH) and involves all network elements

To avoid unnecessary signaling load by forward and backward reselection due to fading

a hysteresis given by the parameter CELL_RESELECT_HYSTERESIS is introduced ie

a cell from another location area is selected only if the corresponding received level

exceeds the level of the current serving cell by the value of this parameter This is

expressed in terms of the C1 (phase 1) or C2 (phase 2) criterion

C1 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C1 (suitable neighbor cell)

or

C2 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C2 (suitable neighbor cell)

respectively

The adjustment of CELL_RESELECT_HYSTERESES should be a compromise between

reduction of unnecessary location updates (high value) and

selection of the cell with best reception quality (low value)

Object DB Name Range Step Size Unit

BTS CELLRESH 07 1

2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for

reselection of a cell from another location area

default 2

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter

Indication

CELL_RESELECT_PARAM_IND=1

The cell reselection parameters CELL_RESELECT_OFFSET

TEMPORARY_OFFSET and PENALTY_TIME used for the C2 criterion as well as

the parameter CELL_BAR_QUALIFY are broadcasted on the BCCH These

parameters are taken into account by phase 2 MS but are ignored by

phase 1 MS

CELL_RESELECT_PARAM_IND = 0

The cell reselection parameters and CELL_BAR_QUALIFY are not

broadcasted on the BCCH

A phase 2 MS then uses the value 0 for all these parameters ie C1 = C2

Object DB Name Range

BTS CRESPARI 01

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter Indication default 1

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

PARAMETERS SETTING

CELL_BAR_ACCESS - Cell Barred for Access

A mobile station cannot camp on a barred cell ie a barred cell is not

selected by the cell selectionreselection procedure

Mobile stations which camp on a cell while it becomes barred initialize the

reselection procedure to find a new (unbarred) cell ie traffic load is

distributed to neighbor cells

This means that eg neither a call nor a location update can start in a

barred cell

However a cell barred for access is not barred for incoming handovers To

barr a cell completely eg for maintenance reasons also incoming

handovers have to be avoided

To reduce overload in a certain cell more moderately without distributing

the overload to neighbor cells barring of access classes has to be used

Barring access for an access class does not trigger a cell reselection for

MSs of that class

Object DB Name Range

BTS CELLBARR FALSETRUE

RXLEV_ACCESS_MIN - Minimum Downlink Received Level for Cell to be

selected

The parameter RXLEV_ACCESS_MIN determines the cell border for a MS in idle

mode by means of the C1 or C2 criterion respectively

Choosing a high value reduces the risk of a handover immediately after call

setup

On the other hand the value has to be low enough to achieve a sufficient overlap

between adjacent cells (especially if they belong to different location areas)

It has to be observed that the overlap may be different for mobiles of different

power classes (refer to MS_TXPWR_MAX_CCH)

In any case RXLEV_ACCESS_MIN has to be above the MS receiver sensitivity level

(-100 dBm for DCS1800 -102 dBm for GSM handhelds -104 dBm for other GSM

MS)

Furthermore it has to harmonize with the

handover thresholds (RXLEV_MIN L_RXLEV_HO)

Object DB Name Range Step Size Unit

BTS RXLEVAMI 063 1

RXLEV

MS_TXPWR_MAX_CCH - Maximum allowed MS Transmit

Power on RACH

The transmit power level the MS uses for the access on the

Random Access Channel is given by the minimum of two

values

the maximum possible transmit power of the MS (given by

the power class P of the MS) the maximum allowed power

for access within the respective cell

(given by MS_TXP WR_MAX_CCH)

This parameter affects the

the random access procedure

the cell selection procedure

Random access

If there is a collision of channel requests on the random access

channel the one with the higher received level has a good chance

to be decoded and to get a response by the BTS

Hence MS with higher output power are preferred This imbalance

can be avoided by choosing a low maximum allowed transmit power

PARAMETERS SETTING

Cell Selection

To be selected by the cell selection procedure a cell has to fulfill the

C1 criterion

C1 gt 0 where

C1 = AV_RXLEV - RXLEV_ACCESS_MIN - Max(0

MS_TXPWR_MAX_CCH - P )

Choosing for example MS_TXPWR_MAX_CCH = Pmin where Pmin is

the output power level for the minimum power class 5 (29 dBm)

the C1 criterion reduces to AV_RXLEV gt RXLEV_ACCESS_MIN

for MSs of all power classes Hence the same idle mode cell border

is seen by each mobile

Choosing for example MS_TXPWR_MAX_CCH = Pmax where Pmax is

the output power level for the maximum power class 1 (43 dBm)

the C1 criterion reduces to

AV_RXLEV gt RXLEV_ACCESS_MIN + ( MS_TXPWR_MAX_CCH - P )

for MSs of all power classes Hence a larger cell radius is seen by a

mobile of higher output power than by a mobile of lower output

power On the other hand one can ensure by this mechanism that a

certain uplink received level is exceeded by each MS independent of

its power class

Object DB Name Range Step Size Unit

BTS MSTXPMAXCH 031 1 2 dB

MS_TXPWR_MAX_CCH - Maximum allowed MS transmit power on RACH

default 2

MS GSM900 MS GSM900 MS DCS1800

Phase 1 Phase 2

0 = 43 dBm 0 = 39 dBm 0 = 30 dBm

1 = 41 dBm 1 = 39 dBm 1 = 28 dBm

2 = 39 dBm 2 = 39 dBm 2 = 26 dBm

3 = 37 dBm 3 = 37 dBm 3 = 24 dBm

15 = 13dBm 19 = 5 dBm 15 = 0 dBm

16-31 = 13 dBm 20-31 = 5 dBm 16-31 = 0 dBm

POWER_OFFSET - Additional Parameter for Class 3

DCS1800 MS

The parameter POWER_OFFSET is only used by class 3

DCS1800 MS to calculate the C1-criterion described as

follows

C1 = AV_RXLEV - RXLEV_ACCESS_MIN -

Max(0MS_TXPWR_MAX_CCH + POWER_OFFSET- P)

Object DB Name Range Step Size Unit

BTS PWROFS 03 1 2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for Reselection of a Cell

from another Location Area

In idle mode the MS selects a new (neighbor) cell if the received level of the

neighbor cell exceeds the received level of the current cell in order to be

served by the cell with the expected best link quality However due to

fading effects the propagation conditions may change rapidly and

therefore a reselection may occur very frequently

If the cells involved in the reselection process belong to the same location

area frequent cell reselection does not have an effect on the network

performance

But if the involved cells belong to different location area the reselection of

a new cell triggers a location update procedure which causes signaling

load (eg on the SDCCH) and involves all network elements

To avoid unnecessary signaling load by forward and backward reselection due to fading

a hysteresis given by the parameter CELL_RESELECT_HYSTERESIS is introduced ie

a cell from another location area is selected only if the corresponding received level

exceeds the level of the current serving cell by the value of this parameter This is

expressed in terms of the C1 (phase 1) or C2 (phase 2) criterion

C1 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C1 (suitable neighbor cell)

or

C2 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C2 (suitable neighbor cell)

respectively

The adjustment of CELL_RESELECT_HYSTERESES should be a compromise between

reduction of unnecessary location updates (high value) and

selection of the cell with best reception quality (low value)

Object DB Name Range Step Size Unit

BTS CELLRESH 07 1

2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for

reselection of a cell from another location area

default 2

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter

Indication

CELL_RESELECT_PARAM_IND=1

The cell reselection parameters CELL_RESELECT_OFFSET

TEMPORARY_OFFSET and PENALTY_TIME used for the C2 criterion as well as

the parameter CELL_BAR_QUALIFY are broadcasted on the BCCH These

parameters are taken into account by phase 2 MS but are ignored by

phase 1 MS

CELL_RESELECT_PARAM_IND = 0

The cell reselection parameters and CELL_BAR_QUALIFY are not

broadcasted on the BCCH

A phase 2 MS then uses the value 0 for all these parameters ie C1 = C2

Object DB Name Range

BTS CRESPARI 01

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter Indication default 1

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

Object DB Name Range

BTS CELLBARR FALSETRUE

RXLEV_ACCESS_MIN - Minimum Downlink Received Level for Cell to be

selected

The parameter RXLEV_ACCESS_MIN determines the cell border for a MS in idle

mode by means of the C1 or C2 criterion respectively

Choosing a high value reduces the risk of a handover immediately after call

setup

On the other hand the value has to be low enough to achieve a sufficient overlap

between adjacent cells (especially if they belong to different location areas)

It has to be observed that the overlap may be different for mobiles of different

power classes (refer to MS_TXPWR_MAX_CCH)

In any case RXLEV_ACCESS_MIN has to be above the MS receiver sensitivity level

(-100 dBm for DCS1800 -102 dBm for GSM handhelds -104 dBm for other GSM

MS)

Furthermore it has to harmonize with the

handover thresholds (RXLEV_MIN L_RXLEV_HO)

Object DB Name Range Step Size Unit

BTS RXLEVAMI 063 1

RXLEV

MS_TXPWR_MAX_CCH - Maximum allowed MS Transmit

Power on RACH

The transmit power level the MS uses for the access on the

Random Access Channel is given by the minimum of two

values

the maximum possible transmit power of the MS (given by

the power class P of the MS) the maximum allowed power

for access within the respective cell

(given by MS_TXP WR_MAX_CCH)

This parameter affects the

the random access procedure

the cell selection procedure

Random access

If there is a collision of channel requests on the random access

channel the one with the higher received level has a good chance

to be decoded and to get a response by the BTS

Hence MS with higher output power are preferred This imbalance

can be avoided by choosing a low maximum allowed transmit power

PARAMETERS SETTING

Cell Selection

To be selected by the cell selection procedure a cell has to fulfill the

C1 criterion

C1 gt 0 where

C1 = AV_RXLEV - RXLEV_ACCESS_MIN - Max(0

MS_TXPWR_MAX_CCH - P )

Choosing for example MS_TXPWR_MAX_CCH = Pmin where Pmin is

the output power level for the minimum power class 5 (29 dBm)

the C1 criterion reduces to AV_RXLEV gt RXLEV_ACCESS_MIN

for MSs of all power classes Hence the same idle mode cell border

is seen by each mobile

Choosing for example MS_TXPWR_MAX_CCH = Pmax where Pmax is

the output power level for the maximum power class 1 (43 dBm)

the C1 criterion reduces to

AV_RXLEV gt RXLEV_ACCESS_MIN + ( MS_TXPWR_MAX_CCH - P )

for MSs of all power classes Hence a larger cell radius is seen by a

mobile of higher output power than by a mobile of lower output

power On the other hand one can ensure by this mechanism that a

certain uplink received level is exceeded by each MS independent of

its power class

Object DB Name Range Step Size Unit

BTS MSTXPMAXCH 031 1 2 dB

MS_TXPWR_MAX_CCH - Maximum allowed MS transmit power on RACH

default 2

MS GSM900 MS GSM900 MS DCS1800

Phase 1 Phase 2

0 = 43 dBm 0 = 39 dBm 0 = 30 dBm

1 = 41 dBm 1 = 39 dBm 1 = 28 dBm

2 = 39 dBm 2 = 39 dBm 2 = 26 dBm

3 = 37 dBm 3 = 37 dBm 3 = 24 dBm

15 = 13dBm 19 = 5 dBm 15 = 0 dBm

16-31 = 13 dBm 20-31 = 5 dBm 16-31 = 0 dBm

POWER_OFFSET - Additional Parameter for Class 3

DCS1800 MS

The parameter POWER_OFFSET is only used by class 3

DCS1800 MS to calculate the C1-criterion described as

follows

C1 = AV_RXLEV - RXLEV_ACCESS_MIN -

Max(0MS_TXPWR_MAX_CCH + POWER_OFFSET- P)

Object DB Name Range Step Size Unit

BTS PWROFS 03 1 2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for Reselection of a Cell

from another Location Area

In idle mode the MS selects a new (neighbor) cell if the received level of the

neighbor cell exceeds the received level of the current cell in order to be

served by the cell with the expected best link quality However due to

fading effects the propagation conditions may change rapidly and

therefore a reselection may occur very frequently

If the cells involved in the reselection process belong to the same location

area frequent cell reselection does not have an effect on the network

performance

But if the involved cells belong to different location area the reselection of

a new cell triggers a location update procedure which causes signaling

load (eg on the SDCCH) and involves all network elements

To avoid unnecessary signaling load by forward and backward reselection due to fading

a hysteresis given by the parameter CELL_RESELECT_HYSTERESIS is introduced ie

a cell from another location area is selected only if the corresponding received level

exceeds the level of the current serving cell by the value of this parameter This is

expressed in terms of the C1 (phase 1) or C2 (phase 2) criterion

C1 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C1 (suitable neighbor cell)

or

C2 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C2 (suitable neighbor cell)

respectively

The adjustment of CELL_RESELECT_HYSTERESES should be a compromise between

reduction of unnecessary location updates (high value) and

selection of the cell with best reception quality (low value)

Object DB Name Range Step Size Unit

BTS CELLRESH 07 1

2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for

reselection of a cell from another location area

default 2

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter

Indication

CELL_RESELECT_PARAM_IND=1

The cell reselection parameters CELL_RESELECT_OFFSET

TEMPORARY_OFFSET and PENALTY_TIME used for the C2 criterion as well as

the parameter CELL_BAR_QUALIFY are broadcasted on the BCCH These

parameters are taken into account by phase 2 MS but are ignored by

phase 1 MS

CELL_RESELECT_PARAM_IND = 0

The cell reselection parameters and CELL_BAR_QUALIFY are not

broadcasted on the BCCH

A phase 2 MS then uses the value 0 for all these parameters ie C1 = C2

Object DB Name Range

BTS CRESPARI 01

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter Indication default 1

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

RXLEV_ACCESS_MIN - Minimum Downlink Received Level for Cell to be

selected

The parameter RXLEV_ACCESS_MIN determines the cell border for a MS in idle

mode by means of the C1 or C2 criterion respectively

Choosing a high value reduces the risk of a handover immediately after call

setup

On the other hand the value has to be low enough to achieve a sufficient overlap

between adjacent cells (especially if they belong to different location areas)

It has to be observed that the overlap may be different for mobiles of different

power classes (refer to MS_TXPWR_MAX_CCH)

In any case RXLEV_ACCESS_MIN has to be above the MS receiver sensitivity level

(-100 dBm for DCS1800 -102 dBm for GSM handhelds -104 dBm for other GSM

MS)

Furthermore it has to harmonize with the

handover thresholds (RXLEV_MIN L_RXLEV_HO)

Object DB Name Range Step Size Unit

BTS RXLEVAMI 063 1

RXLEV

MS_TXPWR_MAX_CCH - Maximum allowed MS Transmit

Power on RACH

The transmit power level the MS uses for the access on the

Random Access Channel is given by the minimum of two

values

the maximum possible transmit power of the MS (given by

the power class P of the MS) the maximum allowed power

for access within the respective cell

(given by MS_TXP WR_MAX_CCH)

This parameter affects the

the random access procedure

the cell selection procedure

Random access

If there is a collision of channel requests on the random access

channel the one with the higher received level has a good chance

to be decoded and to get a response by the BTS

Hence MS with higher output power are preferred This imbalance

can be avoided by choosing a low maximum allowed transmit power

PARAMETERS SETTING

Cell Selection

To be selected by the cell selection procedure a cell has to fulfill the

C1 criterion

C1 gt 0 where

C1 = AV_RXLEV - RXLEV_ACCESS_MIN - Max(0

MS_TXPWR_MAX_CCH - P )

Choosing for example MS_TXPWR_MAX_CCH = Pmin where Pmin is

the output power level for the minimum power class 5 (29 dBm)

the C1 criterion reduces to AV_RXLEV gt RXLEV_ACCESS_MIN

for MSs of all power classes Hence the same idle mode cell border

is seen by each mobile

Choosing for example MS_TXPWR_MAX_CCH = Pmax where Pmax is

the output power level for the maximum power class 1 (43 dBm)

the C1 criterion reduces to

AV_RXLEV gt RXLEV_ACCESS_MIN + ( MS_TXPWR_MAX_CCH - P )

for MSs of all power classes Hence a larger cell radius is seen by a

mobile of higher output power than by a mobile of lower output

power On the other hand one can ensure by this mechanism that a

certain uplink received level is exceeded by each MS independent of

its power class

Object DB Name Range Step Size Unit

BTS MSTXPMAXCH 031 1 2 dB

MS_TXPWR_MAX_CCH - Maximum allowed MS transmit power on RACH

default 2

MS GSM900 MS GSM900 MS DCS1800

Phase 1 Phase 2

0 = 43 dBm 0 = 39 dBm 0 = 30 dBm

1 = 41 dBm 1 = 39 dBm 1 = 28 dBm

2 = 39 dBm 2 = 39 dBm 2 = 26 dBm

3 = 37 dBm 3 = 37 dBm 3 = 24 dBm

15 = 13dBm 19 = 5 dBm 15 = 0 dBm

16-31 = 13 dBm 20-31 = 5 dBm 16-31 = 0 dBm

POWER_OFFSET - Additional Parameter for Class 3

DCS1800 MS

The parameter POWER_OFFSET is only used by class 3

DCS1800 MS to calculate the C1-criterion described as

follows

C1 = AV_RXLEV - RXLEV_ACCESS_MIN -

Max(0MS_TXPWR_MAX_CCH + POWER_OFFSET- P)

Object DB Name Range Step Size Unit

BTS PWROFS 03 1 2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for Reselection of a Cell

from another Location Area

In idle mode the MS selects a new (neighbor) cell if the received level of the

neighbor cell exceeds the received level of the current cell in order to be

served by the cell with the expected best link quality However due to

fading effects the propagation conditions may change rapidly and

therefore a reselection may occur very frequently

If the cells involved in the reselection process belong to the same location

area frequent cell reselection does not have an effect on the network

performance

But if the involved cells belong to different location area the reselection of

a new cell triggers a location update procedure which causes signaling

load (eg on the SDCCH) and involves all network elements

To avoid unnecessary signaling load by forward and backward reselection due to fading

a hysteresis given by the parameter CELL_RESELECT_HYSTERESIS is introduced ie

a cell from another location area is selected only if the corresponding received level

exceeds the level of the current serving cell by the value of this parameter This is

expressed in terms of the C1 (phase 1) or C2 (phase 2) criterion

C1 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C1 (suitable neighbor cell)

or

C2 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C2 (suitable neighbor cell)

respectively

The adjustment of CELL_RESELECT_HYSTERESES should be a compromise between

reduction of unnecessary location updates (high value) and

selection of the cell with best reception quality (low value)

Object DB Name Range Step Size Unit

BTS CELLRESH 07 1

2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for

reselection of a cell from another location area

default 2

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter

Indication

CELL_RESELECT_PARAM_IND=1

The cell reselection parameters CELL_RESELECT_OFFSET

TEMPORARY_OFFSET and PENALTY_TIME used for the C2 criterion as well as

the parameter CELL_BAR_QUALIFY are broadcasted on the BCCH These

parameters are taken into account by phase 2 MS but are ignored by

phase 1 MS

CELL_RESELECT_PARAM_IND = 0

The cell reselection parameters and CELL_BAR_QUALIFY are not

broadcasted on the BCCH

A phase 2 MS then uses the value 0 for all these parameters ie C1 = C2

Object DB Name Range

BTS CRESPARI 01

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter Indication default 1

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

Furthermore it has to harmonize with the

handover thresholds (RXLEV_MIN L_RXLEV_HO)

Object DB Name Range Step Size Unit

BTS RXLEVAMI 063 1

RXLEV

MS_TXPWR_MAX_CCH - Maximum allowed MS Transmit

Power on RACH

The transmit power level the MS uses for the access on the

Random Access Channel is given by the minimum of two

values

the maximum possible transmit power of the MS (given by

the power class P of the MS) the maximum allowed power

for access within the respective cell

(given by MS_TXP WR_MAX_CCH)

This parameter affects the

the random access procedure

the cell selection procedure

Random access

If there is a collision of channel requests on the random access

channel the one with the higher received level has a good chance

to be decoded and to get a response by the BTS

Hence MS with higher output power are preferred This imbalance

can be avoided by choosing a low maximum allowed transmit power

PARAMETERS SETTING

Cell Selection

To be selected by the cell selection procedure a cell has to fulfill the

C1 criterion

C1 gt 0 where

C1 = AV_RXLEV - RXLEV_ACCESS_MIN - Max(0

MS_TXPWR_MAX_CCH - P )

Choosing for example MS_TXPWR_MAX_CCH = Pmin where Pmin is

the output power level for the minimum power class 5 (29 dBm)

the C1 criterion reduces to AV_RXLEV gt RXLEV_ACCESS_MIN

for MSs of all power classes Hence the same idle mode cell border

is seen by each mobile

Choosing for example MS_TXPWR_MAX_CCH = Pmax where Pmax is

the output power level for the maximum power class 1 (43 dBm)

the C1 criterion reduces to

AV_RXLEV gt RXLEV_ACCESS_MIN + ( MS_TXPWR_MAX_CCH - P )

for MSs of all power classes Hence a larger cell radius is seen by a

mobile of higher output power than by a mobile of lower output

power On the other hand one can ensure by this mechanism that a

certain uplink received level is exceeded by each MS independent of

its power class

Object DB Name Range Step Size Unit

BTS MSTXPMAXCH 031 1 2 dB

MS_TXPWR_MAX_CCH - Maximum allowed MS transmit power on RACH

default 2

MS GSM900 MS GSM900 MS DCS1800

Phase 1 Phase 2

0 = 43 dBm 0 = 39 dBm 0 = 30 dBm

1 = 41 dBm 1 = 39 dBm 1 = 28 dBm

2 = 39 dBm 2 = 39 dBm 2 = 26 dBm

3 = 37 dBm 3 = 37 dBm 3 = 24 dBm

15 = 13dBm 19 = 5 dBm 15 = 0 dBm

16-31 = 13 dBm 20-31 = 5 dBm 16-31 = 0 dBm

POWER_OFFSET - Additional Parameter for Class 3

DCS1800 MS

The parameter POWER_OFFSET is only used by class 3

DCS1800 MS to calculate the C1-criterion described as

follows

C1 = AV_RXLEV - RXLEV_ACCESS_MIN -

Max(0MS_TXPWR_MAX_CCH + POWER_OFFSET- P)

Object DB Name Range Step Size Unit

BTS PWROFS 03 1 2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for Reselection of a Cell

from another Location Area

In idle mode the MS selects a new (neighbor) cell if the received level of the

neighbor cell exceeds the received level of the current cell in order to be

served by the cell with the expected best link quality However due to

fading effects the propagation conditions may change rapidly and

therefore a reselection may occur very frequently

If the cells involved in the reselection process belong to the same location

area frequent cell reselection does not have an effect on the network

performance

But if the involved cells belong to different location area the reselection of

a new cell triggers a location update procedure which causes signaling

load (eg on the SDCCH) and involves all network elements

To avoid unnecessary signaling load by forward and backward reselection due to fading

a hysteresis given by the parameter CELL_RESELECT_HYSTERESIS is introduced ie

a cell from another location area is selected only if the corresponding received level

exceeds the level of the current serving cell by the value of this parameter This is

expressed in terms of the C1 (phase 1) or C2 (phase 2) criterion

C1 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C1 (suitable neighbor cell)

or

C2 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C2 (suitable neighbor cell)

respectively

The adjustment of CELL_RESELECT_HYSTERESES should be a compromise between

reduction of unnecessary location updates (high value) and

selection of the cell with best reception quality (low value)

Object DB Name Range Step Size Unit

BTS CELLRESH 07 1

2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for

reselection of a cell from another location area

default 2

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter

Indication

CELL_RESELECT_PARAM_IND=1

The cell reselection parameters CELL_RESELECT_OFFSET

TEMPORARY_OFFSET and PENALTY_TIME used for the C2 criterion as well as

the parameter CELL_BAR_QUALIFY are broadcasted on the BCCH These

parameters are taken into account by phase 2 MS but are ignored by

phase 1 MS

CELL_RESELECT_PARAM_IND = 0

The cell reselection parameters and CELL_BAR_QUALIFY are not

broadcasted on the BCCH

A phase 2 MS then uses the value 0 for all these parameters ie C1 = C2

Object DB Name Range

BTS CRESPARI 01

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter Indication default 1

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

MS_TXPWR_MAX_CCH - Maximum allowed MS Transmit

Power on RACH

The transmit power level the MS uses for the access on the

Random Access Channel is given by the minimum of two

values

the maximum possible transmit power of the MS (given by

the power class P of the MS) the maximum allowed power

for access within the respective cell

(given by MS_TXP WR_MAX_CCH)

This parameter affects the

the random access procedure

the cell selection procedure

Random access

If there is a collision of channel requests on the random access

channel the one with the higher received level has a good chance

to be decoded and to get a response by the BTS

Hence MS with higher output power are preferred This imbalance

can be avoided by choosing a low maximum allowed transmit power

PARAMETERS SETTING

Cell Selection

To be selected by the cell selection procedure a cell has to fulfill the

C1 criterion

C1 gt 0 where

C1 = AV_RXLEV - RXLEV_ACCESS_MIN - Max(0

MS_TXPWR_MAX_CCH - P )

Choosing for example MS_TXPWR_MAX_CCH = Pmin where Pmin is

the output power level for the minimum power class 5 (29 dBm)

the C1 criterion reduces to AV_RXLEV gt RXLEV_ACCESS_MIN

for MSs of all power classes Hence the same idle mode cell border

is seen by each mobile

Choosing for example MS_TXPWR_MAX_CCH = Pmax where Pmax is

the output power level for the maximum power class 1 (43 dBm)

the C1 criterion reduces to

AV_RXLEV gt RXLEV_ACCESS_MIN + ( MS_TXPWR_MAX_CCH - P )

for MSs of all power classes Hence a larger cell radius is seen by a

mobile of higher output power than by a mobile of lower output

power On the other hand one can ensure by this mechanism that a

certain uplink received level is exceeded by each MS independent of

its power class

Object DB Name Range Step Size Unit

BTS MSTXPMAXCH 031 1 2 dB

MS_TXPWR_MAX_CCH - Maximum allowed MS transmit power on RACH

default 2

MS GSM900 MS GSM900 MS DCS1800

Phase 1 Phase 2

0 = 43 dBm 0 = 39 dBm 0 = 30 dBm

1 = 41 dBm 1 = 39 dBm 1 = 28 dBm

2 = 39 dBm 2 = 39 dBm 2 = 26 dBm

3 = 37 dBm 3 = 37 dBm 3 = 24 dBm

15 = 13dBm 19 = 5 dBm 15 = 0 dBm

16-31 = 13 dBm 20-31 = 5 dBm 16-31 = 0 dBm

POWER_OFFSET - Additional Parameter for Class 3

DCS1800 MS

The parameter POWER_OFFSET is only used by class 3

DCS1800 MS to calculate the C1-criterion described as

follows

C1 = AV_RXLEV - RXLEV_ACCESS_MIN -

Max(0MS_TXPWR_MAX_CCH + POWER_OFFSET- P)

Object DB Name Range Step Size Unit

BTS PWROFS 03 1 2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for Reselection of a Cell

from another Location Area

In idle mode the MS selects a new (neighbor) cell if the received level of the

neighbor cell exceeds the received level of the current cell in order to be

served by the cell with the expected best link quality However due to

fading effects the propagation conditions may change rapidly and

therefore a reselection may occur very frequently

If the cells involved in the reselection process belong to the same location

area frequent cell reselection does not have an effect on the network

performance

But if the involved cells belong to different location area the reselection of

a new cell triggers a location update procedure which causes signaling

load (eg on the SDCCH) and involves all network elements

To avoid unnecessary signaling load by forward and backward reselection due to fading

a hysteresis given by the parameter CELL_RESELECT_HYSTERESIS is introduced ie

a cell from another location area is selected only if the corresponding received level

exceeds the level of the current serving cell by the value of this parameter This is

expressed in terms of the C1 (phase 1) or C2 (phase 2) criterion

C1 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C1 (suitable neighbor cell)

or

C2 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C2 (suitable neighbor cell)

respectively

The adjustment of CELL_RESELECT_HYSTERESES should be a compromise between

reduction of unnecessary location updates (high value) and

selection of the cell with best reception quality (low value)

Object DB Name Range Step Size Unit

BTS CELLRESH 07 1

2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for

reselection of a cell from another location area

default 2

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter

Indication

CELL_RESELECT_PARAM_IND=1

The cell reselection parameters CELL_RESELECT_OFFSET

TEMPORARY_OFFSET and PENALTY_TIME used for the C2 criterion as well as

the parameter CELL_BAR_QUALIFY are broadcasted on the BCCH These

parameters are taken into account by phase 2 MS but are ignored by

phase 1 MS

CELL_RESELECT_PARAM_IND = 0

The cell reselection parameters and CELL_BAR_QUALIFY are not

broadcasted on the BCCH

A phase 2 MS then uses the value 0 for all these parameters ie C1 = C2

Object DB Name Range

BTS CRESPARI 01

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter Indication default 1

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

This parameter affects the

the random access procedure

the cell selection procedure

Random access

If there is a collision of channel requests on the random access

channel the one with the higher received level has a good chance

to be decoded and to get a response by the BTS

Hence MS with higher output power are preferred This imbalance

can be avoided by choosing a low maximum allowed transmit power

PARAMETERS SETTING

Cell Selection

To be selected by the cell selection procedure a cell has to fulfill the

C1 criterion

C1 gt 0 where

C1 = AV_RXLEV - RXLEV_ACCESS_MIN - Max(0

MS_TXPWR_MAX_CCH - P )

Choosing for example MS_TXPWR_MAX_CCH = Pmin where Pmin is

the output power level for the minimum power class 5 (29 dBm)

the C1 criterion reduces to AV_RXLEV gt RXLEV_ACCESS_MIN

for MSs of all power classes Hence the same idle mode cell border

is seen by each mobile

Choosing for example MS_TXPWR_MAX_CCH = Pmax where Pmax is

the output power level for the maximum power class 1 (43 dBm)

the C1 criterion reduces to

AV_RXLEV gt RXLEV_ACCESS_MIN + ( MS_TXPWR_MAX_CCH - P )

for MSs of all power classes Hence a larger cell radius is seen by a

mobile of higher output power than by a mobile of lower output

power On the other hand one can ensure by this mechanism that a

certain uplink received level is exceeded by each MS independent of

its power class

Object DB Name Range Step Size Unit

BTS MSTXPMAXCH 031 1 2 dB

MS_TXPWR_MAX_CCH - Maximum allowed MS transmit power on RACH

default 2

MS GSM900 MS GSM900 MS DCS1800

Phase 1 Phase 2

0 = 43 dBm 0 = 39 dBm 0 = 30 dBm

1 = 41 dBm 1 = 39 dBm 1 = 28 dBm

2 = 39 dBm 2 = 39 dBm 2 = 26 dBm

3 = 37 dBm 3 = 37 dBm 3 = 24 dBm

15 = 13dBm 19 = 5 dBm 15 = 0 dBm

16-31 = 13 dBm 20-31 = 5 dBm 16-31 = 0 dBm

POWER_OFFSET - Additional Parameter for Class 3

DCS1800 MS

The parameter POWER_OFFSET is only used by class 3

DCS1800 MS to calculate the C1-criterion described as

follows

C1 = AV_RXLEV - RXLEV_ACCESS_MIN -

Max(0MS_TXPWR_MAX_CCH + POWER_OFFSET- P)

Object DB Name Range Step Size Unit

BTS PWROFS 03 1 2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for Reselection of a Cell

from another Location Area

In idle mode the MS selects a new (neighbor) cell if the received level of the

neighbor cell exceeds the received level of the current cell in order to be

served by the cell with the expected best link quality However due to

fading effects the propagation conditions may change rapidly and

therefore a reselection may occur very frequently

If the cells involved in the reselection process belong to the same location

area frequent cell reselection does not have an effect on the network

performance

But if the involved cells belong to different location area the reselection of

a new cell triggers a location update procedure which causes signaling

load (eg on the SDCCH) and involves all network elements

To avoid unnecessary signaling load by forward and backward reselection due to fading

a hysteresis given by the parameter CELL_RESELECT_HYSTERESIS is introduced ie

a cell from another location area is selected only if the corresponding received level

exceeds the level of the current serving cell by the value of this parameter This is

expressed in terms of the C1 (phase 1) or C2 (phase 2) criterion

C1 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C1 (suitable neighbor cell)

or

C2 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C2 (suitable neighbor cell)

respectively

The adjustment of CELL_RESELECT_HYSTERESES should be a compromise between

reduction of unnecessary location updates (high value) and

selection of the cell with best reception quality (low value)

Object DB Name Range Step Size Unit

BTS CELLRESH 07 1

2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for

reselection of a cell from another location area

default 2

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter

Indication

CELL_RESELECT_PARAM_IND=1

The cell reselection parameters CELL_RESELECT_OFFSET

TEMPORARY_OFFSET and PENALTY_TIME used for the C2 criterion as well as

the parameter CELL_BAR_QUALIFY are broadcasted on the BCCH These

parameters are taken into account by phase 2 MS but are ignored by

phase 1 MS

CELL_RESELECT_PARAM_IND = 0

The cell reselection parameters and CELL_BAR_QUALIFY are not

broadcasted on the BCCH

A phase 2 MS then uses the value 0 for all these parameters ie C1 = C2

Object DB Name Range

BTS CRESPARI 01

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter Indication default 1

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

PARAMETERS SETTING

Cell Selection

To be selected by the cell selection procedure a cell has to fulfill the

C1 criterion

C1 gt 0 where

C1 = AV_RXLEV - RXLEV_ACCESS_MIN - Max(0

MS_TXPWR_MAX_CCH - P )

Choosing for example MS_TXPWR_MAX_CCH = Pmin where Pmin is

the output power level for the minimum power class 5 (29 dBm)

the C1 criterion reduces to AV_RXLEV gt RXLEV_ACCESS_MIN

for MSs of all power classes Hence the same idle mode cell border

is seen by each mobile

Choosing for example MS_TXPWR_MAX_CCH = Pmax where Pmax is

the output power level for the maximum power class 1 (43 dBm)

the C1 criterion reduces to

AV_RXLEV gt RXLEV_ACCESS_MIN + ( MS_TXPWR_MAX_CCH - P )

for MSs of all power classes Hence a larger cell radius is seen by a

mobile of higher output power than by a mobile of lower output

power On the other hand one can ensure by this mechanism that a

certain uplink received level is exceeded by each MS independent of

its power class

Object DB Name Range Step Size Unit

BTS MSTXPMAXCH 031 1 2 dB

MS_TXPWR_MAX_CCH - Maximum allowed MS transmit power on RACH

default 2

MS GSM900 MS GSM900 MS DCS1800

Phase 1 Phase 2

0 = 43 dBm 0 = 39 dBm 0 = 30 dBm

1 = 41 dBm 1 = 39 dBm 1 = 28 dBm

2 = 39 dBm 2 = 39 dBm 2 = 26 dBm

3 = 37 dBm 3 = 37 dBm 3 = 24 dBm

15 = 13dBm 19 = 5 dBm 15 = 0 dBm

16-31 = 13 dBm 20-31 = 5 dBm 16-31 = 0 dBm

POWER_OFFSET - Additional Parameter for Class 3

DCS1800 MS

The parameter POWER_OFFSET is only used by class 3

DCS1800 MS to calculate the C1-criterion described as

follows

C1 = AV_RXLEV - RXLEV_ACCESS_MIN -

Max(0MS_TXPWR_MAX_CCH + POWER_OFFSET- P)

Object DB Name Range Step Size Unit

BTS PWROFS 03 1 2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for Reselection of a Cell

from another Location Area

In idle mode the MS selects a new (neighbor) cell if the received level of the

neighbor cell exceeds the received level of the current cell in order to be

served by the cell with the expected best link quality However due to

fading effects the propagation conditions may change rapidly and

therefore a reselection may occur very frequently

If the cells involved in the reselection process belong to the same location

area frequent cell reselection does not have an effect on the network

performance

But if the involved cells belong to different location area the reselection of

a new cell triggers a location update procedure which causes signaling

load (eg on the SDCCH) and involves all network elements

To avoid unnecessary signaling load by forward and backward reselection due to fading

a hysteresis given by the parameter CELL_RESELECT_HYSTERESIS is introduced ie

a cell from another location area is selected only if the corresponding received level

exceeds the level of the current serving cell by the value of this parameter This is

expressed in terms of the C1 (phase 1) or C2 (phase 2) criterion

C1 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C1 (suitable neighbor cell)

or

C2 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C2 (suitable neighbor cell)

respectively

The adjustment of CELL_RESELECT_HYSTERESES should be a compromise between

reduction of unnecessary location updates (high value) and

selection of the cell with best reception quality (low value)

Object DB Name Range Step Size Unit

BTS CELLRESH 07 1

2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for

reselection of a cell from another location area

default 2

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter

Indication

CELL_RESELECT_PARAM_IND=1

The cell reselection parameters CELL_RESELECT_OFFSET

TEMPORARY_OFFSET and PENALTY_TIME used for the C2 criterion as well as

the parameter CELL_BAR_QUALIFY are broadcasted on the BCCH These

parameters are taken into account by phase 2 MS but are ignored by

phase 1 MS

CELL_RESELECT_PARAM_IND = 0

The cell reselection parameters and CELL_BAR_QUALIFY are not

broadcasted on the BCCH

A phase 2 MS then uses the value 0 for all these parameters ie C1 = C2

Object DB Name Range

BTS CRESPARI 01

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter Indication default 1

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

Choosing for example MS_TXPWR_MAX_CCH = Pmax where Pmax is

the output power level for the maximum power class 1 (43 dBm)

the C1 criterion reduces to

AV_RXLEV gt RXLEV_ACCESS_MIN + ( MS_TXPWR_MAX_CCH - P )

for MSs of all power classes Hence a larger cell radius is seen by a

mobile of higher output power than by a mobile of lower output

power On the other hand one can ensure by this mechanism that a

certain uplink received level is exceeded by each MS independent of

its power class

Object DB Name Range Step Size Unit

BTS MSTXPMAXCH 031 1 2 dB

MS_TXPWR_MAX_CCH - Maximum allowed MS transmit power on RACH

default 2

MS GSM900 MS GSM900 MS DCS1800

Phase 1 Phase 2

0 = 43 dBm 0 = 39 dBm 0 = 30 dBm

1 = 41 dBm 1 = 39 dBm 1 = 28 dBm

2 = 39 dBm 2 = 39 dBm 2 = 26 dBm

3 = 37 dBm 3 = 37 dBm 3 = 24 dBm

15 = 13dBm 19 = 5 dBm 15 = 0 dBm

16-31 = 13 dBm 20-31 = 5 dBm 16-31 = 0 dBm

POWER_OFFSET - Additional Parameter for Class 3

DCS1800 MS

The parameter POWER_OFFSET is only used by class 3

DCS1800 MS to calculate the C1-criterion described as

follows

C1 = AV_RXLEV - RXLEV_ACCESS_MIN -

Max(0MS_TXPWR_MAX_CCH + POWER_OFFSET- P)

Object DB Name Range Step Size Unit

BTS PWROFS 03 1 2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for Reselection of a Cell

from another Location Area

In idle mode the MS selects a new (neighbor) cell if the received level of the

neighbor cell exceeds the received level of the current cell in order to be

served by the cell with the expected best link quality However due to

fading effects the propagation conditions may change rapidly and

therefore a reselection may occur very frequently

If the cells involved in the reselection process belong to the same location

area frequent cell reselection does not have an effect on the network

performance

But if the involved cells belong to different location area the reselection of

a new cell triggers a location update procedure which causes signaling

load (eg on the SDCCH) and involves all network elements

To avoid unnecessary signaling load by forward and backward reselection due to fading

a hysteresis given by the parameter CELL_RESELECT_HYSTERESIS is introduced ie

a cell from another location area is selected only if the corresponding received level

exceeds the level of the current serving cell by the value of this parameter This is

expressed in terms of the C1 (phase 1) or C2 (phase 2) criterion

C1 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C1 (suitable neighbor cell)

or

C2 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C2 (suitable neighbor cell)

respectively

The adjustment of CELL_RESELECT_HYSTERESES should be a compromise between

reduction of unnecessary location updates (high value) and

selection of the cell with best reception quality (low value)

Object DB Name Range Step Size Unit

BTS CELLRESH 07 1

2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for

reselection of a cell from another location area

default 2

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter

Indication

CELL_RESELECT_PARAM_IND=1

The cell reselection parameters CELL_RESELECT_OFFSET

TEMPORARY_OFFSET and PENALTY_TIME used for the C2 criterion as well as

the parameter CELL_BAR_QUALIFY are broadcasted on the BCCH These

parameters are taken into account by phase 2 MS but are ignored by

phase 1 MS

CELL_RESELECT_PARAM_IND = 0

The cell reselection parameters and CELL_BAR_QUALIFY are not

broadcasted on the BCCH

A phase 2 MS then uses the value 0 for all these parameters ie C1 = C2

Object DB Name Range

BTS CRESPARI 01

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter Indication default 1

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

MS_TXPWR_MAX_CCH - Maximum allowed MS transmit power on RACH

default 2

MS GSM900 MS GSM900 MS DCS1800

Phase 1 Phase 2

0 = 43 dBm 0 = 39 dBm 0 = 30 dBm

1 = 41 dBm 1 = 39 dBm 1 = 28 dBm

2 = 39 dBm 2 = 39 dBm 2 = 26 dBm

3 = 37 dBm 3 = 37 dBm 3 = 24 dBm

15 = 13dBm 19 = 5 dBm 15 = 0 dBm

16-31 = 13 dBm 20-31 = 5 dBm 16-31 = 0 dBm

POWER_OFFSET - Additional Parameter for Class 3

DCS1800 MS

The parameter POWER_OFFSET is only used by class 3

DCS1800 MS to calculate the C1-criterion described as

follows

C1 = AV_RXLEV - RXLEV_ACCESS_MIN -

Max(0MS_TXPWR_MAX_CCH + POWER_OFFSET- P)

Object DB Name Range Step Size Unit

BTS PWROFS 03 1 2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for Reselection of a Cell

from another Location Area

In idle mode the MS selects a new (neighbor) cell if the received level of the

neighbor cell exceeds the received level of the current cell in order to be

served by the cell with the expected best link quality However due to

fading effects the propagation conditions may change rapidly and

therefore a reselection may occur very frequently

If the cells involved in the reselection process belong to the same location

area frequent cell reselection does not have an effect on the network

performance

But if the involved cells belong to different location area the reselection of

a new cell triggers a location update procedure which causes signaling

load (eg on the SDCCH) and involves all network elements

To avoid unnecessary signaling load by forward and backward reselection due to fading

a hysteresis given by the parameter CELL_RESELECT_HYSTERESIS is introduced ie

a cell from another location area is selected only if the corresponding received level

exceeds the level of the current serving cell by the value of this parameter This is

expressed in terms of the C1 (phase 1) or C2 (phase 2) criterion

C1 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C1 (suitable neighbor cell)

or

C2 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C2 (suitable neighbor cell)

respectively

The adjustment of CELL_RESELECT_HYSTERESES should be a compromise between

reduction of unnecessary location updates (high value) and

selection of the cell with best reception quality (low value)

Object DB Name Range Step Size Unit

BTS CELLRESH 07 1

2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for

reselection of a cell from another location area

default 2

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter

Indication

CELL_RESELECT_PARAM_IND=1

The cell reselection parameters CELL_RESELECT_OFFSET

TEMPORARY_OFFSET and PENALTY_TIME used for the C2 criterion as well as

the parameter CELL_BAR_QUALIFY are broadcasted on the BCCH These

parameters are taken into account by phase 2 MS but are ignored by

phase 1 MS

CELL_RESELECT_PARAM_IND = 0

The cell reselection parameters and CELL_BAR_QUALIFY are not

broadcasted on the BCCH

A phase 2 MS then uses the value 0 for all these parameters ie C1 = C2

Object DB Name Range

BTS CRESPARI 01

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter Indication default 1

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

POWER_OFFSET - Additional Parameter for Class 3

DCS1800 MS

The parameter POWER_OFFSET is only used by class 3

DCS1800 MS to calculate the C1-criterion described as

follows

C1 = AV_RXLEV - RXLEV_ACCESS_MIN -

Max(0MS_TXPWR_MAX_CCH + POWER_OFFSET- P)

Object DB Name Range Step Size Unit

BTS PWROFS 03 1 2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for Reselection of a Cell

from another Location Area

In idle mode the MS selects a new (neighbor) cell if the received level of the

neighbor cell exceeds the received level of the current cell in order to be

served by the cell with the expected best link quality However due to

fading effects the propagation conditions may change rapidly and

therefore a reselection may occur very frequently

If the cells involved in the reselection process belong to the same location

area frequent cell reselection does not have an effect on the network

performance

But if the involved cells belong to different location area the reselection of

a new cell triggers a location update procedure which causes signaling

load (eg on the SDCCH) and involves all network elements

To avoid unnecessary signaling load by forward and backward reselection due to fading

a hysteresis given by the parameter CELL_RESELECT_HYSTERESIS is introduced ie

a cell from another location area is selected only if the corresponding received level

exceeds the level of the current serving cell by the value of this parameter This is

expressed in terms of the C1 (phase 1) or C2 (phase 2) criterion

C1 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C1 (suitable neighbor cell)

or

C2 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C2 (suitable neighbor cell)

respectively

The adjustment of CELL_RESELECT_HYSTERESES should be a compromise between

reduction of unnecessary location updates (high value) and

selection of the cell with best reception quality (low value)

Object DB Name Range Step Size Unit

BTS CELLRESH 07 1

2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for

reselection of a cell from another location area

default 2

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter

Indication

CELL_RESELECT_PARAM_IND=1

The cell reselection parameters CELL_RESELECT_OFFSET

TEMPORARY_OFFSET and PENALTY_TIME used for the C2 criterion as well as

the parameter CELL_BAR_QUALIFY are broadcasted on the BCCH These

parameters are taken into account by phase 2 MS but are ignored by

phase 1 MS

CELL_RESELECT_PARAM_IND = 0

The cell reselection parameters and CELL_BAR_QUALIFY are not

broadcasted on the BCCH

A phase 2 MS then uses the value 0 for all these parameters ie C1 = C2

Object DB Name Range

BTS CRESPARI 01

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter Indication default 1

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

CELL_RESELECT_HYSTERESIS - Hysteresis for Reselection of a Cell

from another Location Area

In idle mode the MS selects a new (neighbor) cell if the received level of the

neighbor cell exceeds the received level of the current cell in order to be

served by the cell with the expected best link quality However due to

fading effects the propagation conditions may change rapidly and

therefore a reselection may occur very frequently

If the cells involved in the reselection process belong to the same location

area frequent cell reselection does not have an effect on the network

performance

But if the involved cells belong to different location area the reselection of

a new cell triggers a location update procedure which causes signaling

load (eg on the SDCCH) and involves all network elements

To avoid unnecessary signaling load by forward and backward reselection due to fading

a hysteresis given by the parameter CELL_RESELECT_HYSTERESIS is introduced ie

a cell from another location area is selected only if the corresponding received level

exceeds the level of the current serving cell by the value of this parameter This is

expressed in terms of the C1 (phase 1) or C2 (phase 2) criterion

C1 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C1 (suitable neighbor cell)

or

C2 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C2 (suitable neighbor cell)

respectively

The adjustment of CELL_RESELECT_HYSTERESES should be a compromise between

reduction of unnecessary location updates (high value) and

selection of the cell with best reception quality (low value)

Object DB Name Range Step Size Unit

BTS CELLRESH 07 1

2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for

reselection of a cell from another location area

default 2

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter

Indication

CELL_RESELECT_PARAM_IND=1

The cell reselection parameters CELL_RESELECT_OFFSET

TEMPORARY_OFFSET and PENALTY_TIME used for the C2 criterion as well as

the parameter CELL_BAR_QUALIFY are broadcasted on the BCCH These

parameters are taken into account by phase 2 MS but are ignored by

phase 1 MS

CELL_RESELECT_PARAM_IND = 0

The cell reselection parameters and CELL_BAR_QUALIFY are not

broadcasted on the BCCH

A phase 2 MS then uses the value 0 for all these parameters ie C1 = C2

Object DB Name Range

BTS CRESPARI 01

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter Indication default 1

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

To avoid unnecessary signaling load by forward and backward reselection due to fading

a hysteresis given by the parameter CELL_RESELECT_HYSTERESIS is introduced ie

a cell from another location area is selected only if the corresponding received level

exceeds the level of the current serving cell by the value of this parameter This is

expressed in terms of the C1 (phase 1) or C2 (phase 2) criterion

C1 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C1 (suitable neighbor cell)

or

C2 (serving cell) + CELL_RESELECT_HYSTERESES(serving) lt C2 (suitable neighbor cell)

respectively

The adjustment of CELL_RESELECT_HYSTERESES should be a compromise between

reduction of unnecessary location updates (high value) and

selection of the cell with best reception quality (low value)

Object DB Name Range Step Size Unit

BTS CELLRESH 07 1

2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for

reselection of a cell from another location area

default 2

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter

Indication

CELL_RESELECT_PARAM_IND=1

The cell reselection parameters CELL_RESELECT_OFFSET

TEMPORARY_OFFSET and PENALTY_TIME used for the C2 criterion as well as

the parameter CELL_BAR_QUALIFY are broadcasted on the BCCH These

parameters are taken into account by phase 2 MS but are ignored by

phase 1 MS

CELL_RESELECT_PARAM_IND = 0

The cell reselection parameters and CELL_BAR_QUALIFY are not

broadcasted on the BCCH

A phase 2 MS then uses the value 0 for all these parameters ie C1 = C2

Object DB Name Range

BTS CRESPARI 01

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter Indication default 1

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

Object DB Name Range Step Size Unit

BTS CELLRESH 07 1

2 dB

CELL_RESELECT_HYSTERESIS - Hysteresis for

reselection of a cell from another location area

default 2

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter

Indication

CELL_RESELECT_PARAM_IND=1

The cell reselection parameters CELL_RESELECT_OFFSET

TEMPORARY_OFFSET and PENALTY_TIME used for the C2 criterion as well as

the parameter CELL_BAR_QUALIFY are broadcasted on the BCCH These

parameters are taken into account by phase 2 MS but are ignored by

phase 1 MS

CELL_RESELECT_PARAM_IND = 0

The cell reselection parameters and CELL_BAR_QUALIFY are not

broadcasted on the BCCH

A phase 2 MS then uses the value 0 for all these parameters ie C1 = C2

Object DB Name Range

BTS CRESPARI 01

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter Indication default 1

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter

Indication

CELL_RESELECT_PARAM_IND=1

The cell reselection parameters CELL_RESELECT_OFFSET

TEMPORARY_OFFSET and PENALTY_TIME used for the C2 criterion as well as

the parameter CELL_BAR_QUALIFY are broadcasted on the BCCH These

parameters are taken into account by phase 2 MS but are ignored by

phase 1 MS

CELL_RESELECT_PARAM_IND = 0

The cell reselection parameters and CELL_BAR_QUALIFY are not

broadcasted on the BCCH

A phase 2 MS then uses the value 0 for all these parameters ie C1 = C2

Object DB Name Range

BTS CRESPARI 01

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter Indication default 1

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

Object DB Name Range

BTS CRESPARI 01

CELL_RESELCT_PARAM_IND_ - Phase 2 Reselection Parameter Indication default 1

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

CELL_BAR_QUALIFY

Parameter is used to assign a priority to a cell selection process

A suitable cell of low priority is only selected if no suitable cell of

normal priority can be found

This parameter can be used eg in hierarchical cell structures

that the MS initially selects an umbrella cell

Object DB Name Range

BTS CBQ 01 1

default 0

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

PENALTY_TIME - Time to Apply a Negative Offset to C2 of a Neighbor Cell

PENALTY_TIME lt 31

A timer T is started in the MS for each cell in the list of the 6 strongest neighbor cells

as soon as it is placed on the list

T is reset to 0 if the cell is removed from the list During Penalty Time

(T lt PENALTY_TIME) a negative TEMPORARY_OFFSET is applied to the C2 of the

respective neighbor cell

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET

which is removed after Penalty Time (T gt PENALTY_TIME)

C2 = C1 + CELL_RESELECT_OFFSET

PENALTY_TIME = 31

C2 = C1 - CELL_RESELECT_OFFSET

For PENALTY_TIME = 31 the priority of a neighbor cell for reselection is permanently

reduced

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

Object Range Step Size

Unit

BTS 030 and 31 1 20

sec

PENALTY_TIME - Time to apply a negative offset to

C2 of a neighbor cell

default 5

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

TEMPORARY_OFFSET

Subtracting TEMPORARY_OFFSET from CELL_RESELECT_OFFSET

reduces the priority of a cell in the list of strongest neighbor

cells ie during run time of the timer the corresponding

neighbor cell is effectively barred for cell reselection

Object DB Name Range Step Size Unit

BTS TEMPOFF 07 1 10 dB

7 infinity

TEMPORARY_OFFSET

default 1

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

CELL_RESELECT_OFFSET

Adding CELL_RESELECT_OFFSET increases the priority of a cell in the list of

strongest neighbor cells when the timer has expired

This mechanism may be applied in hierarchical cell structures to keep fast

moving mobiles in the umbrella cells and slow moving mobiles in the micro

cells When a mobile reaches the coverage area of a (neighbor) micro cell

given by the C1 criterion this cell becomes effectively excluded from

reselection during the PENALTY_TIME

A fast moving mobile is assumed to have left the coverage area of the

micro cell before PENALTY_TIME is reached and hence the micro cell is not

selected In contrast a slow moving mobile is assumed to be still within the

coverage area of the micro cell when PENALTY_TIME has expired Applying

the positive CELL_RESELECT_OFFSET this cell is selected with preference

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

Object DB Name Range Step Size Unit

BTS CRESOFF 063 1 2 dB

CELL_RESELECT_OFFSET

default 1

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION

CELL SELECTION RESELECTION

K S MadanpuriD G M (GSM amp AN)

BRBRAITT Jabalpur

THE END

• CELL SELECTION RESELECTION