RU10-2G_3G_interworking

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1 © Nokia Siemens Networks Presentation / Author / DateI insert classification level

3G -2G interworking integration meeting- VMS

Time :22-Oct-2009

Location: Hanoi

Handover and reselection control



2 © Nokia Siemens Networks Presentation / Author / DateSoc Classification level

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




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)




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



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



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




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




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




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




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




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




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




Handover Control

• Handover Types


• 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




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




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




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




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)




Handover Control

• Handover Types


• 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




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




Handover Control

• Handover Types


• 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




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




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




Handover Control

• Handover Types


• 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




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




WCDMA-TO-GSM Handover message flow

WCDMA GPRS i ll M fl




WCDMA to GPRS intersystem-cell Massage flow

Handover 3G -> 2G




• 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




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




GSM-to-WCDMA handover Message flow

GPRS-to-WCDMA inter-system change message flow




GPRS to WCDMA inter system change message flow

ISHO 2G 3G P




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


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)


C h a n g e a b l e

H i d d e n

Handover 2G -> 3G




• 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




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





• 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 !






• 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




Handover Control

• Handover Types


• 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




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




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




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




• Reselection from WCDMA to GSM• Reselection from GSM to WCDMA


Cell Reselection: Measurement Rules




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




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)


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





• 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





• 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)


Fi rst ranking of all the cells based onCPICH RSCP (WCDMA) and RSSI (GSM)


How to avoid ping pong ?




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





• Cell Reselection from WCDMA to 2G in Idle mode• Cell Reselection from GSM to WCDMA in Idle mode





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




• 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




• 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





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




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

RU10-2G_3G_interworking

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