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3G -2G interworking integration meeting- VMS
Time :22-Oct-2009
Location: Hanoi
Handover and reselection control
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Handover Control
• Handover Types• Intra-Frequency Handover • Inter-Frequency &Inter-System Handover • Optional: GSM ISHO
Cell Reselction
Cell Reselction
• Reselection from WCDMA to GSM
• Reselection from GSM to WCDMA
Agenda
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Handover Types• Intra-Frequency Handovers
• Softer Handover
• Handover between sectors of the same Node B (handled by BTS)• No extra transmissions across Iub interface• Maximum Ratio Combining (MRC) is occurring in both the UL and DL
• Soft Handover • MS simultaneously connected to multiple cells (from different Node Bs)• Extra transmission across Iub, more channel cards are needed (compared to non-SHO)• Mobile Evaluated Handover (MEHO)• DL/UE: MRC & UL/RNC: Frame selection combining
• Hard Handover • Arises when inter-RNC SHO is not possible (Iur not supported or Iur congestion)• Decision procedure is the same as SHO (MEHO and RNC controlled)• Causes temporary disconnection of the (RT) user
• Inter-Frequency Handover • Can be intra-BS, intra-RNC, inter-RNC
• Network Evaluated Handover (NEHO)• Decision algorithm located in RNC
• Inter-RAT Handover • Handovers between WCDMA and GSM (NEHO) or GAN (WLAN)
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HC Parameter Database Structure
• RNC = Radio Network Controller level parameters
• WBTS = Node B level parameters
• WCELL = Cell level parameters
• FMCx = Frequency Measurement Control parameters (S=intra-frequency set; I=inter-frequency; G=inter-RAT)
• ADJx = Adjacent Cell parameters (S=intra-frequency set; I=inter-frequency; G=inter-RAT; D=Detected Set)
• HOPx = Handover Path parameters (S=intra- frequency set; I=inter-frequency; G=inter-RAT)
S:Intra-Frequency
S:Intra-Frequency
I:Inter-Frequency
I:Inter-Frequency
G:Inter-System
G:Inter-System
WCELL
ADJG
ADJI
ADJS
WBTS
RNC
FMCS
FMCI
FMCG
100
100
100
HOPS 100
HOPI 100
HOPG 100
32
48
32
ADJD
32
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Handover Control Parameters
• Handover are controlled mainly by four groups of parameters
• ADJx Adjacency definition, specific offset, HOPx set selection
• FMCx Handover related measurement report triggering and decision
• HOPx Intra-frequency hard handover, cell re-selection
• WCEL FMCx set selection, Cell re-selection hysteresis
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ADJS, HOPS & FMCSHO ParameterCategories
Intra-Frequency
Inter-Frequency
Inter-System
Handover Control Parameter sRNC parametersWCEL parameters
HOPS parametersFMCS parameters
ADJS paramete rsHOPI parametersFMCI parameters
ADJI param etersHOPG parametersFMCG parameters
ADJG param eters
100HOPS parametersCell Re-sele ction HCS PriorityCell Re-selection HCS ThresholdCell Re-selection Minimum QualityCell Re-sele ction Minimum RX LevelCell Re-sele ction Penalty TimeCell Re-selection Quality Offset 1Cell Re-selection Quality Offset 2
Cell Re-sele ction Temporary Offset 1Cell Re-sele ction Temporary Offset 2CPICH Ec/No Averaging WindowEnable Inter-RNC Soft Handover Enable RRC Connection ReleaseHHO Margin for Average Ec/NoHHO Margin for Peak Ec/NoRelease Margin for Average Ec/NoRelease Margin for Peak Ec/No
Define Target CellSelection
1100
FMCS paramete rs Active Set Weighting Coefficient Addition Reporting Interval Addition Time Addition WindowCPICH Ec/No Filter CoefficientCPICH Ec/No HHO CancellationCPICH Ec/No HHO Cancellation TimeCPICH Ec/No HHO ThresholdCPICH Ec/No HHO Time HysteresisCPICH RSCP HHO CancellationCPICH RSCP HHO Cancellation TimeCPICH RSCP HHO Filter CoefficientCPICH RSCP HHO ThresholdCPICH RSCP HHO Time HysteresisDrop TimeDrop WindowMaximu m Active Set SizeReplacement Reporting Interval
Replacement TimeReplacement Window
Define AdjacentCellMeasurementControl
1
InGSM:
Define HO TriggerHoThresholdsLevDL Rx (LDR):-92 dBm Px (LDP): 3 Nx(LDN): 4
Define Target CellSelectionRx Lev Min Cell: -95dBm
Define AdjCell
31ADJS parame tersCell Identifier CPICH Ec/No OffsetDisable Effect on Reporting RangeLocation Area CodeMaximum UE TX Power on RACHMobile Country CodeMobile Network CodeMobile Network Code LenPrimary CPICH power NRT HOPS Identifier Primary Scrambling Co deRNC Identifier Routing Area CodeRT HOPS Identifier Tx Divers ity Indicator
Define AdjCell
1
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Soft Handover • HC supports the following measurement reporting events and features:
• Event 1A: A primary CPICH enters the reporting range (Ncell addition)
• Event 1B: A primary CPICH leaves the reporting range (Ncell deletion)
• Event 1C: A non-active CPICH becomes better than an active primary CPICH (Ncellreplacement)
• Cell individual offsets for modifying measurement reporting behaviour
• Mechanism for forbidding a neighboring cell to affect the reporting range
• Handover decision performed by RNC based on measurements and availableresources
• Admission Control can reject the branch addition in case the maximum load isachieved in DL (threshold + offset), valid both for RT and NRT bitrates.
• Hard blocking may prevent branch addition
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1A: A Primary CPICH Enters the Reporting Range
Strongest CPICH in AS
time
Ec /I o
P CPICH 3
P CPICH 1
P CPICH 2
1
2
AdditionWind ow
AdditionTime
AdditionReportingInterval
RNC
MeasurementReport
Add tothe AS?
no
ActiveSetWeightingCoefficient
3
4
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Strongest CPICH in AS
Time
Ec /I o
P CPICH 3
P CPICH 1
P CPICH 2
1
2
3
DropWindow
DropTime
MeasurementReport
1B: A Primary CPICH leaves the Reporting Range
Removethe
reportedcell from
the AS
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time
weakest CPICH3 in AS
Ec /I o
P CPICH 3
P CPICH 1
P CPICH 2P CPICH 4
AS has 3 cells
ReplacementReportingInterval
3
1
2
ReplacementWindow
ReplacementTime
Measuremen tReport
RNC
ASupdate?
no
1C: A non-active CPICH becomes better than an activeprimary CPICH
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Handover Control
• Handover Types
• Intra-Frequency Handover
• Inter-Frequency & Inter-System Handover • Measurement triggering• Inter-Frequency & Inter-System Measurements• Compressed-Mode• Inter-Frequency HO decision• Inter-System HO decision• Forced AMR voice call handover to GSM
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IFHO/ISHO Process Overview
HO Triggering Thresholds set in RNCHO Triggering Thresholds set in RNC
Event Triggered Coverage/Capacitybased HO fulfilled in RNC
Event Triggered Coverage/Capacitybased HO fulfilled in RNC
RNC commands selected UE(s) to startIF/IS measurements
RNC commands selected UE(s) to startIF/IS measurements
Measurements are done inCompressed Mode (CM)
Measurements are done inCompressed Mode (CM)
UE reports GSM cells withstrongest RSSI signals to RNC
UE reports GSM cells withstrongest RSSI signals to RNC
RNC makes HO decision andcommands UE to target cell
RNC makes HO decision andcommands UE to target cell
RSSI measurements and BSICverification for GSM cellsRSSI measurements and BSIC
verification for GSM cells
Different decision methods for IF HOOnly one decision method for IS HO
5 Coverage/Capacity HO Reasons
About 25 HO parameters
Reporting cells are active set cells(max 3) + max 6 IFHO, max 6 ISHO nei
Max 32 neighbours could be measured
(31 Intra-Freq neighbours)48 Inter-Freq neighbours32 Inter-System neighbours can be measu
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IFHO/ISHO measurements- difference
• IF measurements
• IS measurements
• BSIC verification required in case neighbour list includes multiple GSMneighbours using the same RF carrier
WCDMA
IS-HOMeasurement
Trigger Target Cell found
RSSI meas. BSIC verification
IS-HODecision
WCDMA
IF-HOMeasurement
Trigger Target Cell found
IF -measurements
IF-HODecision
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Handover Control
• Handover Types
• Intra-Frequency Handover
• Inter-Frequency & Inter-System Handover:• Measurement triggering• Inter-Frequency & Inter-System Measurements• Compressed-Mode• Inter-Frequency HO decision
• Inter-System HO decision• Inter-System HO cancellation• Forced AMR voice call handover to GSM• 3G-2G Cell Reselection
• Optional: GSM ISHO
• Overview on selected further functionality
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IF/IS Handover Measurement Triggering Reasons
4. DL DPCH approaches itsmaximum allowed powerFMCI: IFHOcauseTxPwrDL
FMCG: GSMcauseTxPwrDL
5. Quality deterioration reportfrom UL outer loop PCFMCI: IFHOcauseUplinkQuality FMCG: GSMcauseUplinkQuality
3. UE Tx powerapproaches itsmaximum allowedpower, event 6A/6DFMCI: IFHOcauseTxPwrULFMCG:GSMcauseTxPwrUL
2 . Low measured absoluteCPICH RSCP, events 1E/1FFMCI: IFHOcauseCPICHrscp ,FMCG: GSMcauseCPICHrscp
1. Low measured absoluteCPICH Ec/No, event 1E/1F FMCI: IFHOcauseCPICHEcNoFMCG: GSMcauseCPICHEcNo
Measurement
Trigger
6 . Others- Load and Service based HO- IMSI based HO- Emergency ISHO
Frequency Measuring Control for Inter-Frequency = FMCIFrequency Measuring Control for Inter-System (GSM) = FMCG
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Handover Control
• Handover Types
• Intra-Frequency Handover:
• Inter-Frequency & Inter-System Handover:• Measurement triggering• Inter-Frequency & Inter-System Measurements• Compressed-Mode• Inter-Frequency HO decision
• Inter-System HO decision• Forced AMR voice call handover to GSM
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Decision Algorithm
UE Tx Power (Event 6A\6B)• Threshold:InterFreqUETxPwrThrXX • L3 filter: InterFreqUETxPwrFilterCoeff * • Hysteresis margin (time totrigger): InterFreqUETxPwrTimeHyst * • Data rate threshold HHOMAxAllowedBitrateUL *
UL Quality• Timer:ULQualDetRepThreshold• Data rate threshold
HHOMAxAllowedBitrateUL
DL DPCH power• Threshold:
InterFreqDLTxPwrThrXX• Data rate threshold HHOMAxAllowedBitrateDL
(XX=AMR,NrtPS,RtPS)
CPICH RSCP (Event 1F)• Thresholds:HHoRscpThreshold
HHoRscpCancel• L3 filter: HHoRscpFilterCoefficient*• Time to trigger:HHoRscpTimeHysteresis*HHoRscpCancelTime *
CPICH Ec/Io (Event 1F)• Thresholds:HHoEcNoThreshold
HHoEcNoCancel • L3 filter:EcNoFilterCoefficient * • Time to trigger:HHoEcNoTimeHysteresis * HHoEcNoCancelTime *
AdjiPlossMargin
AdjiMinEcNo AdjiMinRSCP AdjiTxPwrDPCH
AdjiEcNoMargin
InterFreqMaxMeasPeriod *InterFreqMeasRepInterval *
InterFreqNcellSearchPeriod *InterFreqMinHoInterval *InterFreqMinMeasInterval *InterFreqMeasAveWindow *
Handover Triggering
Handover Execution
IF HO meas control parameters
(* = parameters already optimised)
IFHO Parameters
(in purple = parameters under study)
more optional trigger in RAN04:
IMSI based IFHO
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Decision Algorithm
UE Tx Power (Event 6A)• Threshold:GsmUETxPwrThrXX• L3 filter: GsmUETxPwrFilterCoeff • Hysteresis margin: GsmUETxPwrTimeHyst• Data rate threshold
HHOMAxAllowedBitrateUL
UL Quality• Timer:ULQualDetRepThreshold• Data rate threshold HHOMAxAllowedBitrateUL
DL DPCH power• Threshold:
GsmDLTxPwrThrXX• Data rate threshold
HHOMAxAllowedBitrateDL
(XX=AMR,CS,NrtPS,RtPS)
CPICH RSCP (Event1F)
• Thresholds:HHoRscpThresholdHHoRscpCancelL3 filter:
HHoRscpFilterCoefficient• Timers:HHoRscpTimeHysteresisHHoRscpCancelTime
CPICH Ec/Io (Event 1F)• Thresholds:HHoEcNoThresholdHHoEcNoCancel• L3 filter:Done already for SHO
• Timers:HHoEcNoTimeHysteresisHHoEcNoCancelTime
AdjgTxPwrMaxTCHAdjgRxLevMinHO (n)GsmMeasAveWindow
GsmMeasRepIntervalGsmNcellSearchPeriodGsmMinMeasIntervalGsmMaxMeasPeriod
Handover Triggering
Handover Execution2G-to-3G back prevention
GsmMinHoInterval
GSM measurement reporting
ISHO parameters
2 more optional triggers in RAN04:
IMSI based ISHO Emergency ISHO (EMISHO)
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Handover Control
• Handover Types
• Intra-Frequency Handover
• SRNS Relocation
• Inter-Frequency & Inter-System Handover:• Measurement triggering• Inter-Frequency & Inter-System Measurements• Compressed-Mode• Inter-Frequency HO decision• Inter-System HO decision• Forced AMR voice call handover to GSM
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How many UEs in Compressed Mode ?
PtxTarget/ PrxTarget
DL/ULpower
Load
PtxOffset/ PrxOffset
New UEs can be switched to CMwhen:
Pxx_Total < Pxx_Target &# of UEs in CM <MaxNumbUECMcoverHO
One new UE in CM can beallowedif the limit is not reached
No new UE can be in CMhere
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Handover Control
• Handover Types
• Intra-Frequency Handover:
• SRNS Relocation
• Inter-Frequency & Inter-System Handover • Measurement triggering• Inter-Frequency & Inter-System Measurements• Compressed-Mode• Inter-Frequency HO decision• Inter-System HO decision• Inter-System HO cancellation• Forced AMR voice call handover to GSM• 3G-2G Cell Reselection
• Optional: GSM ISHO
• Overview on selected further functionality
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Quality Criterion in case trigger was DL DPCH Power or CPICH Ec/No:AVE_RSCP_NCELL (n) > AdjiMinRSCP(n) + max(0, AdjiTxPwrDPCH(n)
- P_MAX)
Signal level from new cell > required Signal level in new cell + adjustment due toallowed power
AVE_EcNo_NCELL (n) > AVE_CPICH_EcNo + AdjiEcNoMargin(n)EcNo on new cell better than EcNo in old cell + margin
• Pathloss Criterion in case trigger wasUE Tx Power, CPICH RSCPor UL DPCH Quality :
AVE_EcNo_NCELL (n) > AdjiMinEcNo(n) EcNo on new cell better than required EcNo in new cell (default –14 dB)
CPICH_POWER - AVE_CPICH_RSCP >CPICH_POWER_NCELL (n) - AVE_RSCP_NCELL (n) +
AdjiPlossMargin(n) PathLoss in old cell > PathLoss in new cell + Margin (default 2 dB)
RNC uses RRC:Physical channel reconfiguration to execute HO (continued)
IFHO Decision criteria
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The meaning of the parameters is:• AVE_RSCP_NCELL (n) and AVE_EcNo_NCELL (n) are the averaged CPICH Ec/No and RSCP
values of the best (according to CPICH Ec/No) neighbor cell (n).• AVE_CPICH_EcNo is the averaged CPICH Ec/No of the best active set cell.• P_MAX is the maximum UE power capability.• HOPI: AdjiMinRSCP(n) Range: -115..-25 dBm, step 1 dBm, Default value: -100 dBm
Determines the minimum required CPICH RSCP (dBm) level in the best inter-frequencyneighbor cell (n).
• ADJI: AdjiTxPwrDPCH Range: -50..33 dBm, step 1 dBm Indicates the maximum
transmission power level that an UE may use on the DPCH in the neighbor cell. It is usedin the IF handover decision algorithm• HOPI: AdjiEcNoMargin(n) Range: -24..24 dB, step 0.5 dB Default value: 1 dB determines
the margin (dB) by which the CPICH Ec/No of the best neighbor cell (n) must exceed theCPICH Ec/No of the best active set cell before the inter-frequency handover is possible
• HOPI: AdjiMinEcNo(n ) Range: -24..0 dB, step 0.5 dB Default value: -13 dB determines theminimum required CPICH Ec/No (dB) in the inter-frequency best neighbor cell (n) before
the IFHO is possible• HOPI: AdjiPlossMargin(n ) Range: -50..100 dB, step 1 dB Default value: 2 dB determinesthe margin (dB) by which the propagation loss of the best active set cell must exceed thepropagation loss of the best neighbor cell (n) before the inter-frequency Handover ispossible
IFHO Parameters
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Handover Control
• Handover Types
• Intra-Frequency Handover:
• SRNS Relocation
• Inter-Frequency & Inter-System Handover:• Measurement triggering• Inter-Frequency & Inter-System Measurements• Compressed-Mode• Inter-Frequency HO decision• Inter-System HO decision• Forced AMR voice call handover to GSM
ISHO Decision
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The following conditions have to be satisfied, before an inter-system Handovercan be conducted. The best neighboring cell must fulfil following criterion(„best“ according to Ec/No):
AVE_RXLEV_NCell(n)> AdjgRxLevMinHO(n) + max(0, AdjgTxPwrMaxTCH(n) -P_max )where
• AVE_RXLEV _Ncell(n) is the averaged GSM carrier RSSI value of theGSM neighbor cell(n), averaging done directly from dBm values (nolinear averaging); FMCG: GSMMeasAveWindow / 6, 1…32 measreport.
• AdjgRxLevMinHO(n) determines the minimum Required RSSI (dBm)level of the neighbor cell(n).
• AdjgTxPwrMaxTCH(n) indicated the maximum Tx power level (dBm) anUE may use in GSM neighbor cell(n).
• P_MAX is the maximum UE power capability.
• If several GSM cells fulfil the equation above, cells are ranked based on HOPG: AdjgPriorityCoverage/0 , range 0…7
• A cell is ranked higher than another cell if it has a higher priority leveleven though its signal strength condition was worse
• Inter-system HO could be forbidden during the first measurements reports from
ISHO Decision
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WCDMA-TO-GSM Handover message flow
WCDMA GPRS i ll M fl
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WCDMA to GPRS intersystem-cell Massage flow
Handover 3G -> 2G
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• FMCG• GSMcauseCPICHEcNo = 1 ( enable)• GSMcauseCPICHrscp =1 (enable)
• FMCS• HHoRscpThreshold = -105(The parameter HHoRscpThreshold determines the absolute CPICH RSCP threshold which is used by
the UE to trigger the reporting event 1F. When the measured CPICH RSCP of all active set cells hasbecome worse than or equal to the threshold in question, the RNC starts inter-frequency or inter-RAT (GSM) measurements in compressed mode for the purpose of hard handover.)
• HHoRscpCancel = -102• HHoEcNoThreshold = -12• HHoEcNoCance l = -9• HHoEcNoCancelTime = 640 ms• HHoRscpCancelTime = 640 ms
• HOPG• AdjgRxLevMinHO = 95
This parameter determines the minimum required GSM RSSI level which the averaged RSSI value of the GSM neighbour cell must exceed before the coverage (or quality) reason handover to GSM is possible.
Handover 3G -> 2G
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Handover 3G > 2G
CMmasterSwitch RNC
Scope Configurable
Yes
Nokia Range
0 (false), 1 (true)
WCEL Yes 0 to 255WCEL Yes
WCEL Yes
WCEL Yes
MaxNumbUECMcoverHO
PrxTarget
PrxOffset
PtxTarget
PtxOffset WCEL Yes
Default/T-Mobile UK
1
0 to 30 dB
0 to 6 dB
-10 to 50 dBm
0 to 6 dB
164 dB
1 dB
40 dBm
1 dB
CMmasterSwitch RNC
Scope Configurable
Yes
Nokia Range
0 (false), 1 (true)
WCEL Yes 0 to 255WCEL Yes
WCEL Yes
WCEL Yes
MaxNumbUECMcoverHO
PrxTarget
PrxOffset
PtxTarget
PtxOffset WCEL Yes
Default/T-Mobile UK
1
0 to 30 dB
0 to 6 dB
-10 to 50 dBm
0 to 6 dB
164 dB
1 dB
40 dBm
1 dB
GSM t WCDMA h d M g fl
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GSM-to-WCDMA handover Message flow
GPRS-to-WCDMA inter-system change message flow
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GPRS to WCDMA inter system change message flow
ISHO 2G 3G P
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ISHO 2G -> 3G ParametersParameter Specification name Nokia parameter Range Default value
min traffic load for speech call LOAD_THRESHOLD_FOR_SC_ IS_HO
utranHoThScTpdc (LTSC) 0-100% 80%
minimum CPICH Ec/Io level MIN_ECNO_THRESHOLD minEcnoThreshold(MET)
-24…0.5 dB -15 dB
min interval between unsucc ISHOattempt
MIN_INTERVAL_BETWEEN_UNSUCC_ISHO_ATTEMPT
minIntUnsuccIsHo (UMIU) 0…255 s 3 s
threshold for multi-RAT MS Qsearch_C qSearchC (QSRC) 0…15 15 (never) rec. 7(always)
Specification name Parameter explanation Value range Note
FDD_REP_QUANT Indicates the reporting quantity for UTRANFDD cells
0=RSCP,1=EC/NO
Not tunable,Fixed value 1
3G_SEARCH_PRIO Indicates if 3G cells may be searched whenBSIC decoding is required
0 = no,1 = yes
Not tunable,Fixed value 1
FDD_MULTIRAT_REPORTING The number of cells from the accesstechnology/mode FDD that shall be included
in the measurement report
0…3 Not tunable,Fixed value 2
Qsearch_C_Initial Indicates the Qsearch value to be used inconnected mode before Qsearch_C isreceived
0 = use Qsearch_I,1 = ∞ (always)
Not tunable,Fixed value 0
C h a n g e a b l e
H i d d e n
Handover 2G -> 3G
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• EN_3G_HO : YES
• A_ECNO_HO :8 ( number of SACH multiframe taken ECNO average)• THR_ECNO_HO : Always 3G whatever ECNO• FDD_MULTIRAT_REPORTING :2 • EN_2G_3G_HO_NO_SERVICE_HO : Enable• THR_CELL_LOAD_3G_REG :0 • THR_CELL_LOAD_3G_REJECT : 0
H d C t l
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Handover Control
• Handover Types
•Intra-Frequency Handover:
• SRNS Relocation
• Inter-Frequency & Inter-System Handover:• Measurement triggering• Inter-Frequency & Inter-System Measurements
• Compressed-Mode• Inter-Frequency HO decision• Inter-System HO decision• Forced AMR voice call handover to GSM• Load Based from GSM to WCDMA
Forced Handover for AMR Voice Call
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Forced Handover for AMR Voice Call
• Feature can be used to push3G AMR calls to 2G
• Extreme parameter settingfor ISHO trigger cause“UE Tx power” (event 6A)
WCDMA
GSM
AMR voice call setup in 3G
forced handoverto GSM
[..]UE RNC
RRC: RadioBearerSetup
RRC: RadioBearerSetupComplete
RRC: MeasurementControl
RRC: MeasurementReport (event 6A)
FMCG:GSMcauseTxPwrUL
FMCG:GsmUETxPwrThrAMR
ISHO measurements& HO to GSM
UE immediatelyanswers
with MeasurementReporth“ means Handover, not Directed-Retry !
Forced Handover for AMR Voice Call
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Forced Handover for AMR Voice Call
• FMCG: GSMcauseTxPwrUL• Range and step: 0 (False), 1 (True)
• Indicates whether a handover to GSM caused by high UE TX power level is enabled. Thehandover is enabled when the value of the parameter is "Used“
• To enable feature, setting must be 1 (True)
• FMCG: GsmUETxPwrThrAMR • Range and step: -60..0 dB
• This parameter determines the UE TX power threshold for a CS voice connection. If thehandover to GSM caused by high UE TX power level is enabled, the RNC starts inter-RAT(GSM) measurements when the UE TX power reaches this threshold. The UE TX power threshold is relative to the maximum TX power level an UE can use on the DPCH in the cell (or the maximum RF output power capability of the UE, whichever is lower
• To enable feature, setting must be –60 dB
Handover Control
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Handover Control
• Handover Types
• Intra-Frequency Handover:
• Inter-Frequency & Inter-System Handover:• Measurement triggering• Inter-Frequency & Inter-System Measurements
• Compressed-Mode• Inter-Frequency HO decision• Inter-System HO decision• Forced AMR voice call handover to GSM• Load Base handover from GSM to WCDMA
Load based Handover GSM > WCDMA
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Load based Handover GSM -> WCDMA
100%
80%
0%
Load reasonHandoversfor speech
Load of GSM cell
Packet Data to WCDMAregardless of GSM load
Packet Data to WCDMAregardless of GSM load
Speech to WCDMAonly with high GSM load
Speech to WCDMAonly with high GSM load
Higher bit ratesfor data users
Higher bit ratesfor data users
Morecapacity for
speech
Morecapacity for
speech
Packet BCCH parameters can be usedto push GPRS mobiles to WCDMA
Packet BCCH parameters can be usedto push GPRS mobiles to WCDMA
Load and Coverage Reason Handover
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GSMGSM
GSMGSM
Load and Coverage Reason Handover
GSMGSM
GSM highloaded
WCDMA lowloaded
GSMGSM GSMGSM
WCDMAWCDMA WCDMAWCDMA
Load reasonHandover for speech
and for HSCSD
Load reasonHandover for speechand for HSCSD
WCDMAWCDMA GSMGSM
Load reasonHandover
Coverage reasonHandover
WCDMA can be usedto relieve GSM overload
GSM can be used to extendWCDMA coverage area
WCDMA can be used
to relieve GSM overloadGSM can be used to extend
WCDMA coverage area
Mobile moving
Load based Handover Process: GSM-> WCDMA
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Load based Handover Process: GSM > WCDMA
Handover Triggering Thresholds set in BSCHa ndover Triggering Thresholds set in BSC
Inter-RAT measurements starts in case The RXLEV of the serving cell is above or
below the given threshold Qsearch_C
Inter-RAT measurements starts in case The RXLEV of the serving cell is above or
below the given threshold Qsearch_C
Handover Decision is done in case of Load of the serving cell > Load_Thresholdand CPICH Ec/No> min Ec/No Threshold
Handover Decision is done in case of Load of the serving cell > Load_Thresholdand CPICH Ec/No> min Ec/No Threshold
MS selects the target UTRAN cell basedon measurement results
MS selects the target UTRAN cell basedon measurement results
Handover command is send to MSCHandover command is send to MSC
In the S10.5 MS is measuring the UTRAN cellscontinuously if they are defined as a neighbor ,
The number of GSM neighbor reported could be 3depending on the set value of parameterFDD_MULTIRAT_REPORT (0,1,2=def,3).
The load is measured in the celllevel by comparing the occupied
TCHs to the available TCHs (20 sinterval used)
Load Threshold for Speech Calls or
Transparent Data inter-RATHandover:utranHoThScTpdc (Min TrafficLoad TDHO), default = 80%minEcnoThreshold (Min CPICHEC/NO Threshold), default –15
Parameters are sent from the BSC tothe mobilein the Measurement Informationmessage
Reselection Control in Idle Mode
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• Reselection from WCDMA to GSM• Reselection from GSM to WCDMA
Reselection Control in Idle Mode
Cell Reselection: Measurement Rules
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S intrasearchS intersearchSsearch RAT m
No need tomeasure
neighbour cells
Intra-frequency
Sx=Squal (in FDD mode)
Intra-frequencyInter-frequency
serving cell
Example: NSNQ qualmin = -18 dB,S intrasearch = 10dB,S intersearch = 8dB,S search_RAT = 4dB
When to performmeasurements
Intra-frequency
Inter-freqencyInter-RAT
Cell Reselection: Measurement Rules
-8 dB-10 dB-14 dBEC/N0 =
SinterSearch :0...20; def.: 8 dB
SintraSearch :0...20; def.: 10 dB
Ssearch_RAT :0...20; def.: 4 dB
QqualMin :-24...0; def.: -18 dB
Squal =CPICH Ec/No
-qQualMin
Cell Reselection 3G -> 2G
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Cell Reselection 3G 2G
First ranking of all the cells based onCPICH RSCP (WCDMA) and RSSI (GSM)
Rs = CPICH RSCP + Qhyst1Rn= Rxlev(n) - Qoffset1
Fi rst ranking of all the cells based onCPICH RSCP (WCDMA) and RSSI (GSM)
Rs = CPICH RSCP + Qhyst1Rn= Rxlev(n) - Qoffset1
Rn (GSM) > Rs (WCDMA)And
Rxlev (GSM) > QrxlevMin
Rn (GSM) > Rs (WCDMA)And
Rxlev (GSM) > QrxlevMin
YesNo
Cell re-selectionto GSMCell re-selectionto GSM
Neighbour WCDMA or GSMcell calculation with offset
parameter
Serving WCDMA cellcalculation, with
hysteresis parameter
UE starts GSM measurements if CPICH Ec/No < qQualMin + sSearchRAT
UE starts GSM measurements if CPICH Ec/No < qQualMin + sSearchRAT
SintraSearch
SinterSearch
SsearchRAT
CPICH EcNo
qQualMin
Second ranking only for WCDMAcells based on CPICH Ec/No
Rs = CPICH Ec/No + Qhyst2Rn=CPICH_Ec/No(n)-Qoffset2
Second ranking only for WCDMAcells based on CPICH Ec/No
Rs = CPICH Ec/No + Qhyst2Rn=CPICH_Ec/No(n)-Qoffset2 Cell re-selection to
WCDMA cell of highestR value
Cell re-selection toWCDMA cell of highest
R value
Cell Reselection 3G -> 2G
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• UE ranks the serving cell and the measured neighboring cells to find out if reselection should be made
• All the measured suitable cells (S-criteria) are included in the ranking.
• Criteria for a suitable cell (S-criteria) is defined as• WCDMA intra-frequency neighbor cell:
• CPICH Ec/No > AdjsQqualmin and CPICH RSCP > AdjsQrexlevmin
• WCDMA inter-frequency cell:
• CPICH Ec/No > AdjiQqualmin and CPICH RSCP > AdjiQrexlevmin• GSM cell:
• Rxlev > Qrxlevmin
• Ranking is done using Criteria R, and the UE reselects to the cell with highest R-criteria. R-criteria is defined as:
• For serving cell: Rs = Qmeas,s + Qhysts
• For neighboring cell Rn = Qmeas,n – Qoffsetts,n
• Qmeas is CPICH Ec/No for WCDMA cell and RxLev for GSM cell
Cell Reselection 3G -> 2G
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• There is no timer defined how long the GSM should be fulfilling the re-selectioncriteria
• However there is running average of 4 GSM measurements which providessome protection against ping – pong (time vice –based on DRX cycle length andas sliding window average)
• In case additional protection is needed it can be arranged by using the Qhyst1 parameter (for WCDMA serving cell RSCP) or AdjgQoffset1 (for GSM neighbor
ing cell RxLev)
First ranking of all the cells based onCPICH RSCP (WCDMA) and RSSI (GSM)
Rs = CPICH RSCP + Qhyst1Rn= Rxlev(n) - Qoffset1
Fi rst ranking of all the cells based onCPICH RSCP (WCDMA) and RSSI (GSM)
Rs = CPICH RSCP + Qhyst1Rn= Rxlev(n) - Qoffset1
How to avoid ping pong ?
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p g p g
• When phone is camped on 3G, GSM measurements can start when CPICH Ec/Io of serving cell is below Ssearch_RAT + QqualMin .
• When phone is camped on GSM, cell reselection to 3G is possible if CPICH Ec/Io of thecandidate is above FDD_Qmin .
• Therefore, to avoid ping pongs between 3G and GSM the following condition should bemet:
FDD_Qmin >=QqualMin+Ssearch_RAT
QqualMin=-18 dB
Ssearch_RAT=4 dB
CPICH Ec/Io
FDD_Qmin >=-12 dB
QqualMin +Ssearch_RAT
tCamping on 3G Camping on GSM Camping on 3G
Reselection Control in Idle Mode
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• Cell Reselection from WCDMA to 2G in Idle mode• Cell Reselection from GSM to WCDMA in Idle mode
Cell Reselection 2G -> 3G
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C e l l R e s e l e c t i o n L i s t
GSM MS starts WCDMA measurements if :RLA_C< F(Qsearch_I) for 0<Qsearch_I<=7
orRLA_C> F(Qsearch_I) for 7<Qsearch_I<=15
If, for suitable UMTS cell& for a period of 5 s:
CPICH RSCP > RLA_C + FDD_Qoffset
CPICH Ec/No ≥ FDD_Qmin
no priorities
betweenWCDMAneighbors
Measurement Updates:•
RLC_C value of the serving cell• + least 6 strongest non serving GSM c
at least every 5 s
check
andWCDMA cellreselection
B C C H : FDD _Qmin, FDD _Qof f set
Fdd_Qoffset:select allways(value is-infinity)
FDD_Qmin= -12dB
Cell Re-selection Parameters
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• Qsearch_I and Qsearch_P define the threshold for non-GPRS/GPRS (respectively) capableUEs to measure 3G neighbour cells when a running average of the received downlink
signal level (RLA_C) of the serving cell is below (0-7) or above (8-15) the threshold
Value
0 1 … 6 7 8 9 10 … 14 15
dBm -98 -94 … -74 Always
-78 -74 -70 … -54 Never
• FDD_Qoffset and FDD_GPRS_Offset the non-GPRS/GPRS (respectively) capable UEsadd this offset to the RLA_C of the GSM cells. After that the UE compares themeasured RSCP values of 3G cells with signal levels of the GSM cells
Value 0 1 2 3 … 8 … 14 15
dBm -always -28 -24 -20 … 0 … 24 28
Always selectirrespective of
RSCP value
Reselect in caseRSCP > GSM RXLev
(RLA_C) +28dB
If RLA_C < -94 UE
starts 3Gmeasurements
UE alwaysmeasures 3G cells
If RLA_C > -70 UE
starts 3Gmeasurements
Cell Re-selection Parameters
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• FDD_Qmin , defines minimum Ec/No threshold that a 3G cell must exceed, in order the UEmakes a cell reselection from 2G to 3G. This is the new mapping table
• FDD_REP_QUANT defines the reporting quantity for UTRAN cell (1=Ec/No or 0=RSCP, default
1). This parameter is non-configurable• 3G_Search_PRIO parameter allows to extend the BSIC reporting interval from 10 s to 13s by
checking the BSICs from non-serving BCCH carriers and also make WCDMA measurements asoften as possible. Range is 0=no, 1=yes, default value .This parameter is hidden and it can notbe tuned
• Defined in the SI2quater and PSI3quater if PBCCH is allocated
ParameterParameter
Name forSys Info (SI)Name for
Sys Info (SI)
Qsearch_IQsearch_I
2quater2quaterQsearch_PQsearch_P Qsearch_PQsearch_P
2quater2quater 3quater3quaterFDD_QMinFDD_QMin
2ter2ter
FDD_(GPRS)Qoffset
FDD_(GPRS)Qoffset
2quater2quater
FDD_REP_QUANT
FDD_REP_QUANT
2ter2ter
3G_search_PRIO
3G_search_PRIO
2(3)quarter(PBCCH)
2 (3)quarter(PBCCH)
Fdd_Qmin mapping Aif parameter 0 1 2 3 4 5 6 7Fdd_Qmin (old) [dB] -20 -19 -18 -17 -16 -15 -14 -13Fdd_Qmin (new) [dB] -20 -6 -18 -8 -16 -10 -14 -12
Cell Reselection 2G -> 3G
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Recommended parameters1. En_2G_TO_3G_Cell_Reselection: “ Enable with 3G
search activated”
2. FDD_Qmin=-123. FDD_Qoffset=-24
4. FDD_GPRS_Qoffset=-24
5. FDD_Qmin_Offset:0
6. FDD_RSCPmin=-102
7. Qsearch
– Qsearch_c: “Always search for 3G neighbour cells” – Qsearch_I :“Always search for 3G neighbour
cells” – Q_Search_p “Always search for 3G neighbour
cells”
– Qsearch_P_PTM “Always search for 3G neighbour cells”
8. EN_CPICP_2G_3G_RELECTION: RSCP & ECNO
9. EN_FAST_3G_ReLECTION: Fast 3G cell reselection isused
10. EN_2G_TO_3GTDD_CELL_RESELECTION: Disable
TRIAL STRATEGY
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Trial Strategy for preventing any negative effects of 3G trials on 2G performance:
1. Cell selection/Reselection from 2G to 3G only done manually. Automaticselection/reselection is disable at 2G site
2. In idle mode after 3G network selected UE is camped only to 3G network if quality of 3G is very good( CPICH RSCP=105 or CPICH EcNo>=-7 by setQQualMin=-14 and SSearchRat=8
3. In 3G dedicated mode UE will handover to 2G if CPICH EcNo of 3G site below-8 dB.
4. Two ways Ho 2G 3G are enable for PS service
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