This document provides techniques to improve IRAT KPI (Inter-RAT handover Key Performance Indicator) in a Huawei WCDMA network. It discusses two main ways: 1) basic 2G cell information and neighbor definition optimization and 2) parameter optimization. Specific steps discussed include optimizing 2G cell information sharing with 3G, checking 2G GPRS/EDGE KPI, optimizing the 2G neighbor definition, analyzing failure counters and alarms for problem 3G cells, and adjusting parameters like the 2G signal threshold, penalty time, RelocIuRelCmdTmr, and T309 timers. The goal is to ensure good 2G signal quality when 3G performs inter-RAT handovers to 2G

1. How to resolve IRAT KPI issue in Huawei-WCDMA Network
IRAT KPIinWCDMA networkisveryseriousproblem.
we can do some parameteroptimization&remove discrepancytoimprove IRATKPI,here i wanttoshare few suchtechniquesto
Improve IRATKPI.
To optimize IRATHHOKPI,basic there are 2 ways,one isthe basic 2G cell informationandneighbordefinitionoptimization,and
the otheris parameteroptimization.Inthe following,Iwill introduce this2waysdetailed.
1. Basic information optimization.
a. In RNCCFGMML, the external 2GCell informationoptimization.
In the live 2G network,periodicisisoptimized,maybe the 2GBCCH&BASIC&LACetc.will changed,andnotshare with3G
correlative guy.Sothisworkshouldbe done periodic.The 2Gcell informationformatrequirementshare with3Gas below:
these all failure packinthiscounterVS.IRAT.HOfailoutCS.cfgunsupp.
b. 2G GPRS&EDGE KPIcheck
As youknow,if 3G UE wantto handoverto2G, firstlythe core networkwill helpgetthe 2G resource forthis3G UE, if thistime,
the 2G cell alreadycongested,sothe 3G UE will notable tohandovertothis2G. From 3G counter,
we can get the failure counterasbelow:IRATHO.FailOutPSUTRAN.PhyChFail/IRATHO.FailOutPSUTRAN.Other.Thiscountermeans
the 2G signal istoo lowor the 2G networkisnot available.Soatthistime,we needcheckthe 2G GPRS&EDGE KPI toconfirmed,
the 2G counterrequirementasbelow
If from the above 2G KPI,the 2G PS alreadycongested,the 2Gside needdothe optimizationorexpansion,duringthistime,we
can temporarilyclose this2Gcell’sPSIRAT HHO functionasbelow commandtoavoidthe 3G handovertothis2G cell.
MOD UEXT2GCELL: GSMCellIndex=0,RatCellType=GSM;
Afterthis2G cell’sPSisnormal,we can use belowcommand toenable the PSIRATHHO function.
MOD UEXT2GCELL: GSMCellIndex=0,RatCellType=EDGE;
c. 2G Neighbordefinitionoptimization.
Neighboroptimizationisaperiodicwork,in3G side,we needevery2weekstocheckthe neighbordefinitioniscorrectorno t, the
neighborisdefinedornot.Andisthere any 2G neighbormissingornot.
2. 3G TOPN worst cells optimization
To improve the IRATHHO, we alsoneedconsiderthe 3G networkproblem, atthe conditionof the good3G situation,the
improvementof IRATHHO ispossible.Whenwe foundoutthe cellsfacingCS&PSissue,we needfollow the belowsetpto
analyze.
a. Alarmis there or not.
b. Get the CS&PS dropreasoncounterfrom M2000, fromthe counterwe can know whatis the reason.Base on thatwe can do
furtheranalyze.The counterisas belowshown.
Cell CSInterRATHO Out Failure Analysis-
IRATHO.failrelocprepOutCS--check2Gcapacity
IRATHO.failoutCS.cfgunsupp--check2Gconfiguration(LAC,RAC,NCC,BCC,BCCH)
IRATHO.failOutCS.phychfail---checkcongestionalarm&coverage issue in2G that time we chekc 2G GPRS/Edge KPI.
Cell PSInterRATHO Failure Analysis

2. c. Checkthe NodeBpacketlose rate.
d. Checkthe site RTWPis normal or not
e. Do the DT aroundthe issue site,checkwhetherthere are overshooting,coverage gap,swap,notpropertiltorazimuth,
buildingblock,antennainstallationproblem, neighbormissingornotand etc
3. After the basic information optimization, if the IRAT issue still there, we need do some parameter optimization.
a. 3G IRAT HHO Switchaudit.
In 3G RNCside,we have 3 IRAT HHO switchto control thisfunction,sowe needmake sure thisparameterissetcorrectly.As
below:
SET UCORRMALGOSWITCH: HoSwitch=HO_INTER_RAT_CS_OUT_SWITCH-1&HO_INTER_RAT_PS_OUT_SWITCH-1;
SET UHOCOMM: CoexistMeasThdChoice=COEXIST_MEAS_THD_CHOICE_INTERRAT;
SET UINTERRATHOCOV:
InterRATCSThd2DEcN0=-13,InterRATCSThd2FEcN0=-11,InterRATR99PsThd2DEcN0=-13,InterRATHThd2DEcN0=-13,
InterRATR99PsThd2FEcN0=-11,InterRATHThd2FEcN0=-11,InterRATCSThd2DRSCP=-102,InterRATCSThd2FRSCP=-99,
InterRATR99PsThd2DRSCP=-107,InterRATHThd2DRSCP=-107,InterRATR99PsThd2FRSCP=-104,InterRATHThd2FRSCP=-104;
b. If the above “a” isno issue,sowe can dothe furtherparameteroptimization.
As default,in3Gside,we considerwhenthe 2G signal ismore than -95dbm, and the 3G signal meetthe IRATHHO condition,the
IRAT HHO will happen,asyouknow,whenthe 3G signal isbad,2G will alsonotverygood,and -95dbm for2G is nota good signal,
so we can increase the 2G signal threshold andInter-RATHOPhysical Channel Failure PenaltyTimertomake sure when3G wanto
to handoverto2G, the 2G signal isgood.As blowcommand:
MOD UCELLINTERRATHOCOV:
CellId=0,TargetRatCsThd=26,TargetRatR99PsThd=26, TargetRatHThd=26, PenaltyTimeForPhyChFail=60;
As experience,thiscommandwillincreasePSIRATHHO KPIaround 0.7%.
For improvingmore the IRATKPI,fromRNCside,there are 2 parameteralsocan be changed.
RelocIuRelCmdTmr:A timertoRNCwaitfor the Iu release commandmessage inrelocationprocedure.Protocoldefaultvalueis
45s. Can be changedto 60s.
T309: T309 is startedafterthe UE is re selectedtoa cell belongingtoanotherradioaccesssysteminconnectedmode,orthe CELL
CHANGE ORDER FROMUTRAN message isreceived.Itisstoppedafterthe UE is successfullyconnectedinthe newcell.The UE
will continue the connectiontoUTRAN uponexpiry.Protocol defaultvalueis5s.Can be changedto 8s.
So we can modifythis2 parameteras below:
SET USTATETIMER: RelocIuRelCmdTmr=60000;
SET UCONNMODETIMER: T309=8;