2gsm radio network tuning_handover (day 2)
TRANSCRIPT
GSM Radio Network Tuning
Babak Kardel
Mehrdad Sedaghat
March 2008
Introduction
• Network Mode
• Operation In Idle Mode
• Operation In Active Mode
• Radio Resource Administration
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DUAL BAND SPECIFIC PARAMETERS
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DUAL BAND SPECIFIC PARAMETERS
Dual Band Cell (DBC), YesDual Band Cell (DBC), Yes
� When the option dual band is activated, all the cells under the dualband BSC
broadcast sysinfo 2ter in idle mode.
Early Classmark Sending (ESI), YesEarly Classmark Sending (ESI), Yes
� By default, the ESI is set to yes, even when the option Dualband is not
activated
� All the dualband phones send the CM3 IE to the network
� In the dedicated mode and if the mobile is Dualband, the Early classmark
sending procedure will be triggered that tells the BSC to add the system
information 5ter containing the frequencies of the other band to be measured
for this call
Multi Band Reporting (MBR), 1Multi Band Reporting (MBR), 1
� The network tells the mobile to report 1 frequency of the other band if it can
find any.Then the mobile will complete the report with frequencies of the
same band. If still less than 6 neighbors, the mobile tries to report
frequencies of the other band.
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DUAL BAND SPECIFIC PARAMETERS
6.82 multiband cell reporting (MBR)
Q3 name: multiBandCellReporting
Modification: Online
Range: 0..3
MML default: 1
Description: With this parameter you define the number of adjacent cells
from the other frequency band that the MS will report in the RX level report.
Related command(s): EQM, EQO
Note: OPTIONAL (Dual Band GSM/DCS)
Multi Cell Reporting
• Multi_Cell_Rep : Number of neighbour cells the MS will report from each band
900
900 900
1800
1800
900 900
1800
900
1800 1800
1800
Measure 32
neighbours 6Report 6 best
measurements
Mobile can.....
3 3
1 5
1800 900
1800 900
Strongest
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•EarlySendingIndication : The parameter defines the requirements
for an MS in sending the Classmark 3 in call setup phase to the
network.
• Range : Yes (Early classmark sending accepted) / No (Early
classmark sending is forbidden)
• Recommended value : Yes in a Dual Band network
BTS Parameters - 2
DUAL BAND SPECIFIC PARAMETERS
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Q3 name: multiBandCell
Range: Y/N
MML default: Y for Dual Band cells
N for cells that do not belong to the frequency bands of the Dual
Band
Description: With this parameter you define whether adjacent cells with a BCCH allocated
from a different frequency band than the serving cell BCCH are taken into account in
handovers and in idle mode cell selection or reselection.
Related command(s): EQF, EQO
Note: OPTIONAL (Dual Band GSM/DCS)
adjacency on other band (DBC)
System Information MessagesSystem Information Messages
• Sys_Info Messages 2ter and 5ter tell the dual band MS about the adjacent cells allocated from the other
frequency band
• 2ter in idle mode• 5ter during a call
• Single band MS will ignore Sys_Info 2ter and 5ter
Idle mode
900Sys_Info_2
Sys_info_2bis
Sys_info_2ter
Sys_Info_2
Sys_info_2bis
1800 1800
1800
900
900 900
900
900 900
Single band MS Dual band MS
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Dual Band Protocol
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Dual Band Protocol
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Multi-layer Dual Band Network
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Call setup Strategy
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Call setup with 900 Band
Traffic handover to 1800 Band
2G Type RXP
Macro 900 -105 dBm
Macro 1800 -84 dBm
Micro outdoor -80 dBm
Micro Metro -105 dBm
Micro indoor -105 dBm
C1 ( 900) = Rxl-RXP = -70-(-105) = 35
C1 ( 1800) = Rxl-RXP = -70-(-84) = 14
C1 (Micro outdoor) = Rxl-RXP = -70-(-80) = 10
C1 (Pico) = Rxl-RXP = -70-(-105) = 35
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Handover
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Synchronized Handover
• If source and target cells are controlled by the same BCF, these are
synchronized to each other.
• Thus the MS does not need timing advance information from the network.
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Non Synchronized Handover
If original and target cells are controlled by different BCFs, the MS needs
timing advance information from the network. This is transferred by a socalled
physical info message.
To ensure a successful transmission, it can be repeated a certain number of
times. This is controlled by the parameter maxNumberOfRepetition
(NY1)(SEG)(5..35)(5).
Furthermore, there is a restricted time between the first handover access and the
last physical info message. This timer always is set to 320 ms, it is fixed in
GSM specifications. Usually any handover is a non synchronized
handover. The
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Handover Failure
If the signalling timer mentioned above expires or the radio link within
the target cell cannot be established, the MS returns to the old cell
HANDOVER PROCESS Causes
Timing Advance
Adjacent Cells
Downlink Quality
Uplink Quality AV_RXQUAL_UL_HO
AV_RXQUAL_DL_HO
Downlink Level
Uplink Level AV_RXLEV_UL_HO
AV_RXLEV_DL_HO
AV_RANGE_HO
AV_RXLEV_NCELL(n)
QUALITY&
INTERFERENCE
QUALITY&
INTERFERENCE
LEVELLEVEL
DISTANCEDISTANCE
PERIODICCHECKS
UMBRELLAUMBRELLA
POWER BUDGETPOWER BUDGET
IMPERATIVE HO
CHANNEL ADMINISTRATIONCHANNEL ADMINISTRATION
DIRECTED RETRYDIRECTED RETRY
THRESHOLD COMPARISON
RAPID FIELD DROPRAPID FIELD DROP
Others:
Intelligent Underlay Overlay
Traffic Reason
……….
MS SPEEDMS SPEED
MS Speed AV_MS_SPEED
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upper layer (macro)
same layer (serving
layer)
lower layer (micro)
HANDOVER PROCESSmultilayer networks
N (not in use)
Parameter
adjacentCellLayer(ACL)
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Handover Parameters
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Target Cell Selection
If handover shall be carried out, a suitable target cell must be found. The
standard selection process uses as criteria the traffic loads, priorities
and RX levels of the adjacent cells.
Standard Selection• First of all, the traffic load of all adjacent cells is verified. If it exceeds the
threshold defined by the parameter (the unit is %) btsLoadThreshold
(BLT)(SEG)(0..100)(70), the cell is overloaded.
• Next the cell priorities are considered. These are defined by the
parameter hoPriorityLevel (PRI)(ADJC)(0..7)(3)
• If a cell is overloaded, the priority is reduced by a certain value which is
defined by the parameter hoLoadFactor (OF)(ADJC)(0..7)(1).
• Now the cells are ranked according their corrected priority. If two cells
have the same priority, they are ranked according their RX level.
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Source Target PRI OF ACL SL AUCL
Macro 900 Macro 900 3 1 Same
- 95
dBm - 47dBm
Macro 900 Macro 1800 4 1 Lower
- 84
dBm - 80dBm
Macro 900 Micro outdoor 4 1 Lower
- 80
dBm - 75dBm
Macro 900
Micro
Metro&indoor 4 1 Same
- 95
dBm - 47dBm
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Handover Parameters
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Handover Parameters
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Source Target PRI OF ACL SL AUCL
Macro 900 Macro 900 3 1 Same - 95 dBm
-
47dBm
Macro 900 Macro 1800 4 1 Lower - 84 dBm
-
80dBm
Macro 900 Micro outdoor 4 1 Lower - 80 dBm
-
75dBm
Macro 900
Micro
Metro&indoor 4 1 Same - 95 dBm
-
47dBm
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Source Target PRI OF ACL SL AUCL
Macro 1800 Macro 900 3 1 Upper
- 95
dBm
-
47dBm
Macro 1800 Macro 1800 4 1 Same
- 84
dBm
-
47dBm
Macro 1800 Micro outdoor 4 1 Lower
- 75
dBm
-
75dBm
Macro 1800
Micro
Metro&indoor 4 1 Same
- 95
dBm
-
47dBm
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Handover Execution
After a target cell has been found, the BSC tries to move the MS to it. To
avoid repetitive handovers or handover attempts in case of a failure,
certain time limits can be set by the parameters minIntBetweenHOReq
(MIH)(HOC)(0..31)(5) and minIntBetweenUnsuccHOAttempt
(MIU)(HOC)(0..31)(3) (the unit is s).
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MIH : The first parameter sets the minimum time between two handovers
related to the same connection.
MIU : The second one indicates the time the MS has to wait after an
unsuccessful handover attempt, before it can try a handover again.
Further important time scales are controlled by the parameters
hoPeriodPBGT (HPP)(HOC)(0..63)(6) and hoPeriodUmbrella
(HPU)(HOC)(0..63)(6) (the unit is SACCH periods). These indicate the
time interval between consecutive estimations of the RX levels of the
adjacent cells for power budget and umbrella handover.
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handover period power budget (HPP)
GSM reference: No ref.
Q3 name: hoPeriodPBGT
Modification: Online
Range: 0..63
MML default: 6 (SACCH Periods)
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Handover Parameters
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Handover :
1- periodic Handover
1-1 : power budget Handover
1-2 : Umberla Handover
2- trigger Handover
2-1 : Interference
2-2 : Quality ( rxlevel adj > rxlev source + QMRG)
2-3 : Level (rxlev > SL , rxlevel adj > rxlev source + LMRG)
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Ranking
The condition has to be fulfilled by any kind of handover, except the
umbrella handover
(1a) AV_RXLEV_NCELL (n) > rxLevMinCell (n) (SL)
. The condition has to be fulfilled priodical After 6 SACCH (3S)
(1b) AV_RXLEV_NCELL (n) > hoLevelUmbrella (n) (AUCL)
The parameter hoLevelUmbrella (AUCL)(ADJC)(-110..-47)(-47) defines
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(2a) PBGT > hoMarginPGBT(n) PMRG
PBGT =(AV_RXLEV_DL_HO - AV_RXLEV_NCELL (n))
For handover due to RX level or RX quality also the handover margins
for the RX level and the RX quality are used. This leads to the modified
Condition
(2b) PBGT > hoMarginLevel/Qual(n) (PMRG , QMRG)
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rxLevMinCell (SL) (ADJC)(-110..-47)(-100) hoLevelUmbrella (AUCL) (ADJC)
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Handover due to Interference
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t1:
hoThresholdQualDL > 4
hoThresholdInterferenceDL > -85
N HO triggered (not triggering attempt counter)
AV_RXLEV_NCELL–AV_RXLEV_DL_HO < hoMarginQual (=0)
N No suitable target cell -> Intra HO not possible -> HO fail
(not triggering the failure counter)
t2:
hoThresholdQualDL > 4
hoThresholdInterferenceDL > -85
N HO triggered
AV_RXLEV_NCELL–AV_RXLEV_DL_HO > hoMarginQual (=0)
N HO successful
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enable HO margin lev qual (MRGS)
GSM reference: No ref.
Q3 name: enableHoMarginLevQual
Range: Y/N
MML default: Y
Description: With this parameter you define whether the handover margins
for
signal level and quality will be taken into account in the handover
decision algorithm.
Related command(s): EAM, EAO
Interference handover
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HO preference order interference DL (HDL)
GSM reference: No ref.
Q3 name: hoPreferenceOrderInterfDL
Range: INTER, INTRA
MML default: INTER
Description: With this parameter you define the order of preference between
intra-cell and inter-cell handovers when the cause of the handover
is downlink interference.
Related command(s): EEM, EEO
a network with frequency hopping. The preferred handover type is set by the parameter
hoPreferenceOrderInterDL/UL (HDL/HUL) (BSC) (INTER,INTRA) (INTER).
The intra cell handover must be enabled using the parameter
enableIntraHOInterDL/UL (EIH/EIC)(HOC)(Y/N)(Y).
Handover due to Interference
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Interference handover
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Interference handover
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Handover Parameters
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Handover Parameters
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Interference handover
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Interference handover
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Now only inter cell handover is possible, so that the handover fails,
if no suitable adjacent cell can be found.
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Interference handover
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Interference handover
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Handover Parameters
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Handover Parameters
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rxLevMinCell (SL) (ADJC)(-110..-47)(-100) hoLevelUmbrella (AUCL) (ADJC)
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Rxlev sourse < LDR OR LUR
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Handover Parameters
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threshold level uplink Rx level (LUR), Px (LUP), Nx(LUN)
Q3 name: hoThresholdsLevUL
Modification: Online
Range: Rx level: -110..-47 (dBm)
Px: 1..32
Nx: 1..32
MML default: Rx level: -95
Px: 1
Nx: 1
Description: The parameters compare the averaged values of signal strength
uplink measurements for triggering the handover process.
Px: Number of averages that have to be upper/lower than the
threshold.
Nx: Number of averages that have to be taken into account when
making a handover decision.
Related command(s): EHC, EHO, EHS
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Handover Parameters
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Handover Parameters
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Pure Power Budget Handover
This kind of handover is executed, if an adjacent cell offers a better power budget than the
serving cell, even if the averaged measurements for the serving cell do not exceed a threshold
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enable power budget handover (EPB)
Q3 name: enablePwrBudgetHandover
Range: Y/N
MML default: Y
Description: With this parameter you indicate whether the BTS power
budget
handover control is enabled.
Related command(s): EHC, EHG, EHO
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Handover Parameters
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handover period power budget (HPP)
Q3 name: hoPeriodPBGT
Range: 0..63
MML default: 6 (SACCH Periods)
Description: With this parameter you define the interval between power budget
handover threshold comparisons.
Related command(s): EHC, EHG, EHO
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This kind of handover is used for multi layer networks, especially for
such ones with macro and micro cells. Its purpose is to move the MS to
a suitable layer in dependence on its power class. Umbrella handover
must be enabled by setting the parameter enableUmbrellaHandover
(EUM)(HOC)(Y/N)(N) to Y. Than the RX levels of the adjacent cells are
checked periodically, according the value of the parameter hoPeriodUmbrella
Pure Umbrella Handover
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1. Than the RX levels of the adjacent cells are
checked periodically, according the value of the parameter HPU(6SACCH)
2. RXLEV ADJ > AUCL
3. Better target selection
4. Algoritm pri,of,rlev adj
5. Rxlev adj > rxlev serv + LMRG
Condition of Umberella Handover
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After the ranking of the adjacent cells, further conditions must be
checked. First the average signal level AV_RXLEV_NCELL is
considered, which must follow the condition
(1a) AV_RXLEV_NCELL (n) > rxLevMinCell (n) (SL)
(1b) AV_RXLEV_NCELL (n) > hoLevelUmbrella (n) (AUCL)
The parameter hoLevelUmbrella (AUCL)(ADJC)(-110..-47)(-47) defines
the minimum signal level to be allowed for an umbrella adjacent cell.
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Handover Parameters
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Handover Parameters
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Handover Parameters
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� All Types: 33 dbm
Handover Parameters
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� All Types: 30 dbm
Handover Parameters
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General Parameters
� All Types: 80
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All Types: 0
General Parameters
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� All Types: 15 dbm
General Parameters
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� All types: 1
General Parameters
Power Control
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• In the dedicated mode, both the BTS and the MS transmit with a power
as low as possible for the following reasons.
• On the uplink, the power consumption of each MS is decreased and
thus a longer service time for the rechargeable battery is achieved.
• Both on the uplink and downlink interference is reduced, so that the
network capacity and the spectral efficiency are improved.
This power control is carried out independently for uplink and downlink,
and also independently for each call.
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Power Control Motivation
Power Control Parameters
Power Control Parameters
Power Control Parameters
Power Control Parameters
Power Control Parameters
Power Control Parameters
Power Control Parameters
Power Control Parameters
Power Control Parameters
Power Control Parameters
Power Control Parameters
Power Control Parameters
Power Control Parameters
Power Control Parameters
Power Control Parameters
Power Control Parameters
Power Control Parameters
Power Control Parameters
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