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Call Drop Analysis Guide

1. Relationship of different counters

CS call drop counter

VS.RAB.NormRel.AMR Normal call terminate times

VS.RAB.AbnormRel.AMR Call drop times

For call drop, below counter describe the reasons:

Main counter Sub counter

VS.RAB.AbnormRel.CS.RF

VS.RAB.AbnormRel.CS.RF.SRBReset

VS.RAB.AbnormRel.CS.RF.ULSync

VS.RAB.AbnormRel.CS.RF.UuNoReply

Other reason

VS.RAB.AbnormRel.CS.OM

VS.RAB.AbnormRel.CS.Preempt

VS.RAB.AbnormRel.CS.UTRANgen

VS.RAB.AbnormRel.CS.IuAAL2

VS.RAB.AbnormRel.CS.OLC

PS call drop counter

VS.RAB.AbnormRel.PSR99 PS R99 drop times

VS.RAB.NormRel.PSR99 Normal call terminate times

VS.RAB.AbnormRel.PS PS drop times(including R99 and HSDPA)

VS.RAB.NormRel.PS Normal call terminate times

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Main counter Sub-counter

VS.RAB.AbnormRel.PS.RF

VS.RAB.AbnormRel.PS.RF.SRBReset

VS.RAB.AbnormRel.PS.RF.ULSync

VS.RAB.AbnormRel.PS.RF.UuNoReply

VS.RAB.AbnormRel.PS.RF.TRBReset

Other reason

VS.RAB.AbnormRel.PS.GTPULoss

VS.RAB.AbnormRel.PS.OM

VS.RAB.AbnormRel.PS.Preempt

VS.RAB.AbnormRel.PS.OLC

2. Common Reason

Call drop for abnormal reasons

Failure reason Common reason

VS.RAB.AbnormRel.CS.OM Caused by some risk operation

VS.RAB.AbnormRel.CS.Preempt Check whether congestion

VS.RAB.AbnormRel.CS.UTRANgen Check alarms

VS.RAB.AbnormRel.CS.IuAAL2 Check IUCS transmission configuration and

alarm.

VS.RAB.AbnormRel.CS.OLC Check RTWP / congestions

VS.RAB.AbnormRel.PS.GTPULoss Check IUPS transmission alarms

For RF reasons:

VS.RAB.AbnormRel.CS.RF.SRBRes

et

Check missing neighbors, alarms, coverage

VS.RAB.AbnormRel.CS.RF.ULSync UL limited, check RTWP, check UE TX power

VS.RAB.AbnormRel.CS.RF.UuNoRe

ply

Check missing neighbor, coverage

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Optimization SOP for RF reason call drops

1. check alarms

2. Using Nastar to check missing neighbors/ pilot pollution

3. Using the Naster to check the coverage of the cells.

How to solve the call drops if the cell located in weak coverage area/network edge?

1. Identify whether RF tuning is required or not (if some area a lot sites around but still

coverage not good then RF tuning is required)

2. Modify the handover threshold/cell reselection parameters, let UE come to 2G quickly

when 3G coverage become bad.

3. If UL limited, change the CPICH power or down tilt.

MML reference for Call drop optimization:

MOD UCELLSELRESEL: CellId=13041, QualMeas=CPICH_ECNO,

QrxlevminExtSup=FALSE, IdleSintrasearch=7, SsearchRat=4,

NonhcsInd=NOT_CONFIGURED;

UE will do intra-cell reselection when 3G EcIo is below -4dB, will do inter-RAT cell

reselection when 3G EcIo is below -10dB.

ADD UCELLINTERRATHOCOV: CellId=13041,

InterRatReportMode=PERIODICAL_REPORTING, InterRATCSThd2DEcN0=-10,

InterRATCSThd2FEcN0=-8, InterRATCSThd2DRSCP=-95, InterRATCSThd2FRSCP=-92;

UE will start compress mode when 3G EcIo is below -10 or RSCP is below -92.

MOD UPCPICHPWR: CellId=13451, MaxPCPICHPower=370, MinPCPICHPower=320;

MOD UCELL: CellId=13451, PCPICHPower=340;

Change the Cell CPICH power from 36dBm to 34dBm.

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