gsm tuning parameters

8/11/2019 GSM tuning parameters

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10/4/99 1Company Confodential

Cell Access Parameters

Cell Options Parameters

Cell Selection and Reselection Parameters Resource Allocation Parameters

Frequency Hopping Parameters

Power Control and Handover Parameters

GSM System SettableParameters


2/31


RACH Control Parameters

Tx-Integer

- The maximum permissible limits of T3120 between RACH retransmissions.

Values : 3 - 12 /14/16/20/25/32/50 RACH Slots

Max Retransmissions

- No of times mobile can re-send a RACH to get AGCH.

Values set could be 1,2,4,7

Call Re-establishment Allowed

-- On Radio Link Failure can a Mobile do Call Re-establishment

0 : allowed // 1 : not allowed



3/31


Access Control Class 000 - 015

- Informs which access class is barred access.

For each class ; 0 : not barred // 1 : access barred

Cell_Bar_Access

- Informs whether the cell is barred or not for access.

0 : not barred // 1 : barred

Emergency Calls

-- All MS allowed or only emergency class MS allowed to make emergency calls

0 : allowed to all MS's // 1 : allowed only to MS's of class 11- 15

RACH Control Parameters



4/31


Neighbor Cells Description

- ARFCN numbers of neighboring cells on which the mobile should perform

measurements.

Cell Reselection - BCCH Allocation List ( BA List )

"0" : ARFCN not used

"1" : ARFCN used

EXT-

IND

BA-

IND

124

1

1

20

119

118

117

116

11

008

007

006

005

004



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PLMN Permitted

- Informs the Mobile which NCCs on the BCCH it should monitor.

- Coded in a bit map of 8 bits

" 0 " - not permitted

" 1 " - permitted

( NCC : xyy

x : operator

y : country )



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Cell Identity

-- Informs the Mobile the Cell global identity of the cell

-- Only used for engineering purpose

-- Coded in 2 octets. May be used in hex

-- If CGI less than 16 bits, than remaining bits coded to " 0 "

Digit

C

Digit

D

Digit

A

Digit

B

Cell Id : ABCD hex



7/31


Location Area Identification

-- Informs the Location Area of the cell

-- Coded as : MCC + MNC + LAI

CCdigit2

1 1 1 1

NCdigit2

L(ti



8/31


DTX Indicator

- Informs whether mobiles should use Discontinuous Transmission or not.

Values : " 0 " - MS's may use DTX

" 1 " - MS's shall use DTX

" 2 " - MS's shall not use DTX

Power Control Indicator ( PWRC )

- Indicates whether Downlink Power Control is used or not

Values : 0 : not used // 1 : used

RADIO-LINK-TIMEOUT

- Radio Link Time-out Counter Value.

Values : 4 - 64

Cell Options

Cell Options Parameters


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RXLEV-ACCESS-MIN

- This informs the mobile the minimum signal level which it should receive

to access system.

Values : 0 - 63

MX-TXPWR-MAX-CCH

- The maximum power at which the mobile can send a RACH.

Values : 0 - 31

Cell-Reselect Hysterisis

- The difference in db between new selected BCCH and the current BCCH for

cell reselection if Location Areas differ.

Values : 0 - 14 db

Cell Selection Parameters

Cell Selection and Reselection Parameters


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Optio nal Cell Reselectio n Parameters

C2 Cell Reselection Parameters

Cell_Reselect Offset :

-- Positive or negative offset value which the MS applies to the C2 value

Range : 0 - 126 dB // in steps of 2 dB

Temporary_Offset :

-- Negative offset value which the MS applies to the C2 value for a particular

duration..

Range : 0 - 60 dB in steps of 10 dB // value of 7 indicates infinity

Penalty_Time :-- The duration for which the above mentioned offset is applied

Range : 20s - 620s in steps of 20s// Value of 31 indicates that

cell_reslect_offset is negative.



11/31


Cell_Bar_Qualify :

Used to assign normal or low priority to a cell for cell selection.. Used inconjunction with the cell_bar_qualify parameter

* 3rd and 4th conditions are same, because Phase 1 MS will not understand

the cell_bar_qualify parameter, so if access is "1" it will always consider thecell to be barred, where as a Ph 2 MS will look for the qualify also, and if set

to "1", then it will not consider the cell to be barred, but assign low priority and

will only select this cell if other normal priority suitable cells are not available.



12/31


Power Offset

Used only by DCS 1800 Class 3 MSs to add a power offset to the value of the

Access Power used for its random attempts. It is also used by the MS in its

calculation of C1 and C2 parameters.Range : 0 - 6 dB // in steps of 2 dB

Cell Selection and ReselectionParameters


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Attach - Detach allowed- Informs whether mobile should perform IMSI Attach/Detach or not.

0 : not allowed // 1 : allowed

Control Channel Description

CCCH - CONF

- Defines the Multiframe structure of CCCH blocks.

- Informs how many CCCH's and SDCCH's are available

Value BS_CC_CHANS BS_CCCH_SDCCH_COMB

000 1 No

001 1 Yes

010 2 No

100 3 No110 4 No

BS_CC_CHANS : No of PCHNS ( timeslots ) supporting CCCH

BS_CCCH_SDCCH_COMB : Whether SDCCH is combine with CCCH ( TN 0)

or is on a separate timeslot

Resource Allocation Parameters


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T3212 timeout value

- Informs the mobile the timeout value for Periodic Location Update.

Values 0 - 255 decihours.

( "0" indicates no periodic update will be used )

Control Channel Description

BS-PA-MFRMS

-- No of multiframes for transmission of paging messages to same paging group

Values : 0 - 9

BS - AG - BLKS - RES

- Informs the Mobile the number of blocks reserved for AGCH.

Values : 0 - 2 for combined

0 - 7 for non combined

Resource Allocation Parameters


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Channel type and TDMA offset- Informs the Mobile , the channel type and subchannel for CBCH

Values : 0 0 1 T T -- CBCH ( SDCCH/ 4 )

0 1 T T T -- CBCH ( SDCCH/ 8 )

T indicates the subchannel

Training Sequence Code

- It is the Base Station Color Code. BCC of BSIC

Values : 0 - 7

Timeslot Number ( TN )

-- Indicates the timeslot number for CBCH

Values : 0 - 7

( CBCH ) Channel Description

Hopping Channel ( H )

-- informs whether CBCH channel is hopping or single

Values : 0 - Single RF Channel

1 - RF hopping channel

CBCH Parameters


16/31


Cell Allocation Number- Informs the band number of the frequency channels used.

0 0 -- Band 0 ( current GSM band )

Cell Allocation ARFCN Number

- The ARFCN channels used in the cell for the purpose of hopping- ARFCN numbers are coded in bitmap of 124 bits

Cell Channel Description


"1" : ARFCN used

"Max 64 channels can be coded"

1241

12011911811711611

008007006005004



17/31


Mobile Allocation Index Offset ( MAIO )-- Informs the mobile where to start the hopping sequence

Values : 0 - 63

Hopping Sequence Number ( HSN )

-- Informs the mobile in what order the ARFCN's should be used for hopping

Values : 0 - 63

( HSN = 0 indicates cyclic hopping,

HSN = 1 - 63 , Frequency hopping algorithm is used )



18/31


Mobile Allocation Table

-- Informs the mobile the which RF channels set in the cell allocation areused in the mobile hopping sequence

Cell Allocation

Values : 0 = ARCN not used for hopping

1 = ARFCN used for hopping

Mobile Allocation

124123122121120119118117116115114113

016

1

015

1

014

1

013

0

012

1

011

1

010

0

009

1

008

1

007

1

006

0

005

1

004

0

003

1

002

0

001

1

010120011100900081007001



19/31


Derives the sequence of ARFCN's on which the mobile will hop

Algorithm

MAIO Frame No HSN

Mobile Allocation Table

ARFCN Number corresponding to Frame number

Frequency Hopping Algorithm


20/31


Neighbor Cells Description

- ARFCN numbers of neighboring cells on which the mobile should perform

measurements in the active mode.

Active Mode - Type 5 Neighbor List


"1" : ARFCN used

EXT-

IND

BA-

IND

1241

12011911811711611

008007006005004

Handover Parameters


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Measurement Results Averaging period ( Hreqave)

Measurement Results Averaging Type

Power Control Algorithm parameters

Handover Decision Algorithm Parameters

Handover Target Cell Algorithm Parameters

Handover Margin

Power Control and HandoverParameters


22/31


--- MS sends Downlink measurement report to BTS every 480ms.

--- BTS sends the report from MS and its own uplink measurement every 480ms to

the BSC.

The BSC Averages the Measurement received after a set period ( Hreqave )

--- The averaging could be following types :

Unweighted Average

Weighted Average

Modified Median

Hreqave : Averaging Period for Rxlev,Rxqual & Timing Advance

( In terms of SACCH Frames ( 480ms ). Range : ( 1, 31 )

Measurement Averaging


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Based on Measurements BSC will decide for Power Control or Handover

Uplink Power Control Increase Algorithm for Rxlev

RXLEV_UL : Rxlev reported by BTS on UplinkL_RXLEV_UL_P :Rxlev threshold on Uplink for power increase ( - 103 to - 73 dbm )

N1 : Number of Rxlev Measurement Averages to initiate process ( Range = 1 , 31 )

P1 : Proportion of Averages for comparison ( Range = 1, 31 )

" If , P1 out of N1 are lower than L_RXLEV_UL_P , then Increase Power"

RXLEV_UL : Rxlev reported by BTS on Uplink

U_RXLEV_UL_P: Rxlev threshold on Uplink for power decrease

N2 : Number of RXlev Measurement Averages to initiate process ( Range = 1 , 31 )


"If , P2 out of N2 are greater than U_RXLEV_UL_P , then Decrease Power"

Uplink Power Control Decrease Algorithm for Rxlev

Other Parameters : Pow_Incr_Step_Size= Range 2, 4 or 6 db

Pow_Red_Step_Size= Range 2, or 4 db

P_Con_Interval= Min Interval betn changes in Power level ( 0, 30s )

For Downlink Power Control on Rxlev the Parameters remain the same

Power Control Algorithm Parameters


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For Downlink Power Control on Rxqual the Parameters remain the same

Uplink Power Control Increase Algorithm for Rxqual

RXQUAL_UL : Rxqual reported by BTS on Uplink

L_RXQUAL_UL_P :Rxqual threshold on Uplink for power increase

N3 : Number of Rxqual Measurement Averages to initiate process( Range = 1 , 31 )


"If , P3 out of N3 are greater than L_RXQUAL_UL_P , then Increase Power"

RXQUAL_UL : Rxqual reported by BTS on Uplink

U_RXQUAL_UL_P: Rxqual threshold on Uplink for power decrease

N4 : Number of Rxqual Measurement Averages to initiate process ( Range = 1 , 31 )


"If , P4 out of N4 are lower than U_RXLEV_UL_P , then Decrease Power"

Uplink Power Control Decrease Algorithm for Rxqual

Other Parameters : Pow_Incr_Step_Size= Range 2, 4 or 6 db

Pow_Red_Step_Size= Range 2, or 4 db

P_Con_Interval= Min Interval betn changes in Power level ( 0, 30s )

Power Control Algorithm Parameters


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Thresholds :

If set too low, Uplink Interference to other users will be reduced

Less transition time from Power Control to Handover

(may result into drops on edges)

Talk time for Mobile Phones will increase if coverage is moderate

If set high, Uplink interference to other users will increase

Probability of call drops will reduce since handovers will increase

Talk time for Mobile Phones will reduce if coverage is moderate

N and P parameters

If set low, ( lowest value 480ms) Power control will be fast, poor quality mobiles will be misbehave

If set high,(highest value 14.88 sec) Power control will be slow, may result into proxy handovers

Effect of Settings


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RXLEV_XX : Rxlev reported by BTS [ XX = UL or DL ]

L_RXLEV_XX_H :Rxlev threshold for Handover ( - 103 to - 73 dbm ) [ XX = UL or DL ]N5 : Number of Rxlev Measurement Averages to initiate process ( Range = 1 , 31 )


On Rxlev

" If , P5 out of N5 are lower than L_RXLEV_XX_P , then Handover is required "

On Rxqual

RXQUAL_XX : Rxqual reported by BTS [ XX = UL or DL ]L_RXQUAL_XX_H :Rxqual threshold on Uplink for power increase

N6 : Number of Rxqual Measurement Averages to initiate process( Range = 1 , 31 )


" If , P6 out of N6 are greater than L_RXQUAL_XX_P , then Handover is required "

On Timing AdvanceMS_RANGE_MAX : Maximum permissible limits

N8 : Number of Rxlev Measurement Averages to initiate process ( Range = 1 , 31 )


"If , P8 out of N8 are greater than MS_RANGE_MAX , then Handover is required"

Handover Comparison Algorithm Parameters


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1. RXLEV_NCELL ( n ) > RXLEV_MIN ( n ) + Max ( 0, Pa )where : Pa = [ MS_TXPWR_MAX (n) - P ) ]

2. [ Min ( MS_TXPWR_MAX, P ) - RXLEV_DL - PWR_C_D ]

- [ Min ( MS_TXPWR_MAX (n), P ) - RXLEV_NCELL (n) ]

- HO_MARGIN (n) > 0

BSC will evaluate Equation 2 for each Neighbor cell ,

only if the cell satisfied Equation 1.

BSC shall compile list of preferred neighbor cells depending on Equation 2

The cell with maximum value of Eqn. 2 will be be first target cell and so on

where,

PWR_C_D : Max_DL_RFPOWER - Actual_DL_RFPOWER ( due to BS Pwr Cntl )

P : Maximum TXPWR capability of the Mobile

HO_MARGIN (n) : Hytserisis value to avoid repetitive handover ( 0 to 24 db )

Target Cell is always decided on the basis of Rxlev

*

* This parameter not reqd if DL Power control is not used

Handover Decision Algorithm Parameters


28/31


Criteria

Uplink Interference Downlink Interference

O & M

Resource Management

Uplink Interference Handover

Parameters for Decision

RXQUAL_UL & RXQUAL_DL

L_RXQUAL_UL_H & L_RXQUAL_DL_H( Rxqual Threshold for Handover )

RXLEV_UL & RXLEV_DL

RXLEV_UL_IH & RXLEV_DL_IH

( Rxlev thresholds for Interference Handover)

(Range : - 80dbm to -40dbm )

N7 = No of Rxlev Averaged Measurements

P7 = Proportion for Comparison

RXQUAL_UL > L_RXQUAL_UL_H

&

RXLEV_UL > RXLEV_UL_IH

Downlink Interference Handover

RXQUAL_DL > L_RXQUAL_DL_H

&

RXLEV_DL > RXLEV_DL_IH

Decision

IF ....

..... then,Intracell Handover

..... then,Intracell Handover

IF.....

P7 out of N7 for

P7 out of N7 for

Intra - Cell Handover Parameters


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PBGT(n) =[ Min ( MS_TXPWR_MAX, P ) - RXLEV_DL - PWR_C_D ]

- [ Min ( MS_TXPWR_MAX (n), P ) - RXLEV_NCELL (n) ]

If PBGT ( n ) > 0 & PBGT ( n ) > HO_MARGIN ( n )

......... then, Handover on the basis of Power Budget is initiated

Power Budget ( PBGT )

If PBGT is enabled , then every 480 ms the BSC shall evaluate the following

equation for each of the 16 possible neighbor cells.

Power Budget HandoverParameters


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Calculate the minimum and the maximum time

with reference to the parameter settings , a

handover command will come to the Mobile?

Quiz ??


31/31


Min value of Hrequave = 1

So Handover algorithm will start every 480ms

Min value of N = 1

So Handover algorithm will also end every 480ms

Minimum time for Handover Command = 480ms + Processing time

Max value of Hrequave = 31

So Handover algorithm will start every 14.88sec

Max value of N = 31

So Handover algorithm will end after another 14.88 sec

Maximum time for Handover Command = 29.76sec + Processing time

Solution

gsm tuning parameters

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