UMTS KPI Optimization Analysis Guide V1.1 UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.I LEGAL INFORMATION By accepting this certain document of ZTE CORPORATIN you agree to the following terms. If you do not agree to the following terms, please notice that you are not allowed to use this document. Copyright2009ZTECORPORATION.Anyrightsnotexpresslygrantedhereinarereserved.This documentcontainsproprietaryinformationofZTECORPORATION.Anyreproduction,transfer, distribution, use or disclosure of this document or any portion of this document, in any form by any means, without the prior written consent of ZTE CORPORATION is prohibited. andareregisteredtrademarksofZTECORPORATION.ZTEscompanyname,logo andproductnamesreferencedhereinareeithertrademarksorregisteredtrademarksofZTE CORPORATION. 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All rights reserved.II Revision History Product VersionDocument VersionSerial NumberReason for Revision V1.0First published V1.1Content modification Author DateDocument Version Prepared by Reviewed byApproved by 2007-12-28V1.0 Qin Jianhan Wang Zhenhai, and Jin Zhengtuan Jin Zhengtuan 2010-07-12V1.1 Wang Cun Wang Zhenhai, and Jin Zhengtuan Jin Zhengtuan UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.III Key Words: KPI(keyperformanceindicator),indicatordefinition,formula,KPImonitoring flow, KPI optimization, KPI classification Abstract: Thisguidemainlydescribestheformulae,KPIclassification,KPImonitoring methods and flows, and KPI optimization methods. Abbreviations AbbreviationFull name ATMAsynchronous Transfer Mode CDRCall Drop Rate CEChannel Element CNCore Network CPICHCommon Pilot Channel CQIChannel Quality Indicator CQTCall Quality Test DTDrive Test E-DCH Enhanced uplink Dedicated Channel HSDPA High Speed Downlink Packet Access HS-DSCH High Speed Downlink Shared Channel HS-SCCH High Speed Shared Control Channel HSUPAHigh Speed Uplink Packet Access ICMPInternet Control Message Protocol IPInternet Protocols IPoAInternet Protocols Over ATM KPIKey Performance Index LANLocal Area Network MACMedia Access Control MBMS Multimedia Broadcast and Multicast ServiceNodeBNode B OMCOperation & maintenance Centre UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.IV AbbreviationFull name PDPPacket data protocol PIPerformance Index PPPPoint to Point Protocol PSPacket-Switched domain QoSQuality of Service RABRadio Access Bearer RFRadio Frequency RNCRadio Network Controller RRCRadio Resource Control RRURadio Remote Unit RSCPReceived Signal Code Power RTWPReceived Total Wideband Power SAALSignaling ATM Adaptation Layer SCCPSignaling Connection Control Part SNRSignal to Noise Ratio TBTransport Block TCPTransfer Control Protocol UDPUser Datagram Protocol UEUser Equipment VIPVery Important People VPVideo Phone WANWide Area Network UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.V About This Document Summary ChapterDescription 1OverviewBrief introduction to KPI optimization 2KPI Monitoring ProcessKPI monitoring process 3KPI Analysis MethodsCommon KPI analysis methods, basic KPI analysis skills, and general process for KPI optimization analysis 4KPI Optimization AnalysisKPI Optimization Analysis on CS call drops, PS call drops, accessibility indicators, mobility indicators, and resource indicators UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.VI TABLE OF CONTENTS 1Overview ......................................................................................................... 1 2KPI Monitoring Process ................................................................................. 2 2.1KPI Monitoring Process .................................................................................... 2 2.2Routine KPI Monitoring Process ....................................................................... 3 2.3KPI Monitoring Process During Parameter Modification .................................... 5 2.4KPI Monitoring During RNC or NodeB Version Upgrade ................................... 6 2.5KPI Monitoring During Cutover ......................................................................... 7 3KPI Analysis Methods .................................................................................... 7 3.1KPI Analysis Methods ....................................................................................... 7 3.1.1TOP N Worst Cells Method ............................................................................... 8 3.2Basic KPI Analysis Skills ................................................................................ 11 3.2.1KPI Monitoring Tools ...................................................................................... 12 3.2.2KPI Analysis Tools .......................................................................................... 12 3.3General Process of KPI Optimization Analysis ................................................ 14 4KPI Optimization Analysis ........................................................................... 18 4.1CS Call Drop Optimization .............................................................................. 18 4.1.1Definition of Call Drop ..................................................................................... 18 4.1.2CS Call Drop Analysis Flowchart .................................................................... 19 4.2PS Call Drop Optimization .............................................................................. 21 4.2.1Optimization Flowchart ................................................................................... 21 4.3Optimization of Accessibility Indicators ........................................................... 23 4.3.1Definition of Access Failure ............................................................................ 23 4.3.2Analysis on RRC Connection Failures ............................................................ 24 4.3.3Analysis on RAB/RB Setup Failures ............................................................... 30 4.4Optimization of Mobility Indicators .................................................................. 36 4.4.1Optimization of Soft Handovers ...................................................................... 36 4.4.2Optimization of Hard Handovers ..................................................................... 42 4.4.3Optimization of Inter-RAT Handovers ............................................................. 47 4.5Optimization of Resource Indicators ............................................................... 51 4.5.1Resource Indicator Optimization Flowchart ..................................................... 52 4.5.2Code Resource Optimization .......................................................................... 54 4.5.3Monitoring CE Resource ................................................................................. 54 4.5.4Optimization of Power Control ........................................................................ 55 4.5.5Speeding up Rate Downgrade ........................................................................ 55 4.5.6Monitoring and Optimizing Uplink Capacity ..................................................... 56 4.5.7Optimization of Uplink Capacity at the Whole Network Level .......................... 56 4.5.8Optimization of Uplink Capacity for a Single Cell ............................................ 56 UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.VII FIGURES Figure 1-1Joint KPI analysis ................................................................................................. 2 Figure 2-1Routine KPI monitoring process............................................................................ 3 Figure 2-2KPI monitoring process during parameter modification ......................................... 5 Figure 2-3KPI monitoring workflow during RNC or NodeB version upgrade .......................... 6 Figure 3-1RF configuration at HIC site ................................................................................ 10 Figure 3-2Antenna energy distribution at HIC site ............................................................... 10 Figure 3-3KPI optimization analysis process ....................................................................... 17 Figure 4-1CS call drop analysis flowchart ........................................................................... 19 Figure 4-2PS call drop optimization flowchart ..................................................................... 21 Figure 4-3Analysis flowchart of RRC connection setup failures .......................................... 26 Figure 4-4Analysis flowchart of RAB setup failures ............................................................. 31 Figure 4-5Soft handover optimization flowchart .................................................................. 37 Figure 4-6Hard handover optimization flowchart ................................................................. 44 Figure 4-7Inter-RAT handover optimization flowchart ......................................................... 49 Figure 4-8Resource indicator optimization flowchart ........................................................... 52 TABLES Table 3-1List of CS TOP N Worst Cells ................................................................................ 9 Table 3-2Indicators Related with CS Call Drop ................................................................... 11 Table 4-1Parameters That 2G Shall Provide to 3G ............................................................. 47 Table 4-2Parameters That 3G Shall Provide to 2G ............................................................. 47 Table 4-3Resource KPIs and Alarm Thresholds ................................................................. 51 Table 4-4Adjusting Code Resource Allocation .................................................................... 54 Table 4-5Example of Parameter Modification for Rate Downgrade ..................................... 55 Table 4-6Example of Power Control Parameter Modification .............................................. 56 Table 4-7Example of Power Control Parameter Modification for Heavy-Traffic Cell ............ 57 UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.1 1Overview The radio network KPIs directly reflect the network quality, and KPI monitoring is animportantmeanstolocatethefaults.KPImonitoringandoptimizationare mostlyperformedduringthenetworkoperationandmaintenancestage. Abnormal events are supposed to be detected as early as possible and handled with proper solutions so that sound voice and data services can be ensured for the subscribers. Atthebeginningofthenetworkconstruction,theoptimizationteamshouldput moreemphasisontheRFadjustmentratherthantheoptimizationofKPIs exceptforCScalldroprate,thePScalldroprate,andtheRTWPindicator. Duringthenetworkoperationandmaintenancestage,KPIoptimization(also called parameter optimization) plays the main role, that is, the optimization team shouldoptimizeacertainindicatorthroughintegratedparameteradjustmentto meet the customers requirements. KPIdatacomesfromNetNumenT31,thenetworkmanagementsysteminthe operationandmaintenancecenter(OMC).BasedontheanalysisonKPIs,the currentstatesofthoseindicatorsarelearnedandtheyareimportantreference forassessingthenetworkperformance.TheKPIsincludethenetworkservice retaining capacity, accessibility, mobility, system capacity, and so on. According to the current values of these indicators, for example, some site has congestion, somesitehasacalldroprateof10%,orsomeRNChasacertainworstcell proportion,busycellproportion, cellcoderesourceavailability,accesssuccess rate, call delay and handover success rate, the optimization team should judge and locate the area, scope and severity of the fault.KPIsaredividedintoserviceKPIsandnetworkKPIsbythestatisticsources. Service KPIs are collected through field drive tests (DTs) while network KPIs are collectedfromtheunifiednetworkmanagementsystem.Thisarticlemainly discussestheanalysisonnetworkKPIs.Usually,thefinalsolutionismade basedonthejointanalysisontheOMCKPIdata,alarms,subscribers complaints, and DT results. UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.2 Figure 1-1Joint KPI analysis 2KPI Monitoring Process The purpose of KPI monitoring is to find out abnormal events that affect services as well as subscribers perception and solve the problems as early aspossible. For instance, if the call drop rate at a certain site goes over 50%, we need to find the problem and work out the solution in the earliest time. As it is very urgent and important to locate KPI problems, we need a whole set ofscientificKPImonitoringmechanismandproblemshootingprocess,aswell asappropriatemonitoringtoolandanalysistooltohelpusfindthecalldrops causedbytransmissionproblems,resourcecongestion,cellsservice interruption,seriousinterference,hardwarefaultwithNodeB,wrong configuration of RNC parameters in time.WeclassifyKPImonitoringintofourcategories:routineKPImonitoring,KPI monitoring during the process of parameter modification, KPI monitoring during theRNCorNodeBversionupgrade,andKPImonitoringduringtheprocessof cutover.RoutineKPImonitoringshouldbeperformedeverydayandbe recorded in a KPI daily report, which should involve the worst CS cell, the worst PScell,thecellwiththelowestRRCconnectionrate,thecellwiththemost serious resource limit, and so on. 2.1KPI Monitoring Process KPI monitoring falls into four categories: routine KPI monitoring, KPI monitoring during the process of parameter modification, KPI monitoring during the version upgradeofRNCorNodeB,andKPImonitoringduringtheprocessofcutover. Eachtypeofmonitoringhasitsownmonitoringitemsandoutputform.For instance, the output of the routine KPI monitoring should be a daily report, while UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.3 theoutputofotherKPImonitoringtypesshouldbeaKPIcomparisonreport. DifferenttypesofKPImonitoringshouldhavedifferenttimegranularities according to the requirement of problem location. RoutineKPImonitoringshouldbedonepersistentlyandberecordedinadaily report,whichshouldincludeacollectionofthecellsworstindifferentaspects, and be sent to relevant person by email. 2.2Routine KPI Monitoring Process Figure 2-1Routine KPI monitoring process UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.4 Parameter problem Hand to the planning personnel Classification of the worst cells Problem handling team classifies, collects and locates the worst cells Hand to the network optimization personnel Hand to R&D dept. or customer service dept. Send email in fixed format to relevant personnel Coverage problem Equipment/version problem Screen out the worst cells with KPI tool EMS exports the one-day granularity of the whole network cell Output KPI daily report in Excel UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.5 2.3KPI Monitoring Process During Parameter Modification Figure 2-2KPI monitoring process during parameter modification Old parameter configurationConfigure data according to the worksheetNetwork KPI monitoring (15-minute granularity)Whether the KPIs at the RNC level are normal.Keep on monitoring (15-minute granularity)Output a report in Word (hourly granularity KPIs before and after the parameter modification)EndYesNotify the person in charge by mail or phoneRollback or not?Locate the worst cells, and check if they are caused by the parameter modification.NoYesNo UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.6 2.4KPI Monitoring During RNC or NodeB Version Upgrade Figure 2-3KPI monitoring workflow during RNC or NodeB version upgrade Yes No No End Locate the worst cells. Determine whether they are related with the version update. Yes Network KPI monitoring 15 minutes time granularity Execute the worksheet to upgrade version Output formal Word report(Compare the hourly granularity KPIs before and after the parameter modification, and output the result every hour.) Whether the RNC-level KPI is normal Keep on monitoring(15 minutes granularity) Send mail to or call the person in charge Rollback or not Current version UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.7 2.5KPI Monitoring During Cutover Forthenetworkonwhichtheequipmentneedstobereplaced(forinstance, HongKong CSL network, for which we replaced Nokias equipment with ZTEs), afterthenetworkoptimizationiscompleted,thesubscribersontheexisting networkshouldbecutovertoournetworkgradually.Duringthecutover,there willbesubscribersregisteringonournetworkconstantly,whichwillcauseload increaseonthenetwork.Inthiscase,weshouldwatchKPIchangesclosely. Themonitoringprocess,items,methodandreportarethesameasthose describedinsection2.4,KPIMonitoringDuringRNCorNodeBVersion Upgrade. Please read it for reference. 3KPI Analysis Methods 3.1KPI Analysis Methods Differentnetworkproblemsrequiredifferentperformanceanalysismethods. Choose one or more appropriate methods after learning the running state of the existingnetworkandtheproblemswithit.Commonanalysismethodsareas follows: TOPNworstcellsmethod:Basedonthetrafficstatisticsindicatorswecare about (such as the call drop rate, connection rate, and soft handoff failure rate), choose N worst cells whose average indicator values in the peak hours or of the wholedayarethelowestasthetargetoffaultanalysisandoptimization.Or prioritize objects of optimization against these indicator values. Timetendencychartmethod:Tendencychartofindicatorchangeiscommonly used in the traffic analysis. The analysis engineer can work out an hourly, daily orweeklytendencychartofoneormoreindicatorsofthewholenetwork,a cluster, or a single cell, and find out the change rule of traffic statistics indicators. Regional location method: The change of network performance indicators often occursinsomeregions.Theindicatorsintheseregionsmaybeworsenedby trafficincrease,trafficmodechange,radioenvironmentchange,faultswitha smallnumberofstations,oruplink/downlinkinterference,whichwilltherefore affecttheperformanceindicatorsofthewholenetwork.Bycomparingthe networkperformanceindicatorsbeforeandafterthechange,wecanmarkout the station or the sector with the greatest indicator change on an electronic map, and take these problem regions as the analysis focus. UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.8 Comparison method: A single traffic statistics indicator may be affected by many factors. While some factors change, others may not. Choose a proper object for comparison to confirm the existence of problems, and then analyze the causes of the problems. When examining an indicator, do not care whether the absolute indicatorvalueishighorlowonly,paymoreattentiontowhetherthevalueis high or low compared to other indicators instead. 3.1.1TOP N Worst Cells Method DuringthewholeprocessofKPIoptimizationanalysis,TOPNworstcells analysismethodisthemosteffectiveone,whichcanbeusedthroughoutthe whole optimization phase. By focusing on the TOP N worst cells, you can solve themajorproblemswiththenetwork.Abnormalcalldropeventsmayhappen every day, and these events may represent problems of a kind. After solving the problemswithTOPNcells,youcansolvetheproblemsofthesamekind. Therefore,focusingonTOPNcellsisoneofthemosteffectivewaystosolve problems. TOP N worst cells analysis method is applicable to the optimization analysis of alltheindicators.ChooseTOPNworstcellsaccordingtoacertainthreshold, whichvariesdependingondifferentindicators.Nstandsforthenumberofthe worst cells. When the worst cells are too many to be worked on, the number of theworstcellscanbedecreasedsothatyoucanfocusonthem.TOPNcells analysis method includes the following steps: Step 1: Screen out TOP N cells according to the condition of the indicators you care about. Step2:Conductahealthcheck for TOPNcells.Checkwhetherthereareany problemswithtransmissionorboards,andcheckwhethertheworstcellsare causedbyexternalabruptincidents,suchasterribleweather,gatherings,or holiday (because during gatherings and holidays the traffic is usually heavy). Step3:Checktheradioparametersconfigurationofthesecells,theradiusof these cells and their neighboring cells, and compare them with the normal cells. Step4:Exporttheindicatorrelevantmostcloselywiththeindicatorsyoucare about and analyze it to find the problem indirectly. Forinstance,oneday,CScalldroprateofawholenetworkwashigh.We analyzed the problem by the TOP N cells analysis method.Step 1: Screen out TOP N cells according to the condition of the indicators you care about. UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.9 We used the CNO KPI analysis function to screen out TOP N cells (other tools can be also used), and selected 10 cells with the highest CS call drop rate. Table 3-1List of CS TOP N Worst Cells IndexCellRNS subnet IDCell ID Call drop rate, CS AMR Number of call drop, voice 1 ZBL1U-AI-1 (201)1291141.58%553 2 ZBL1U-AI-3 (201)1291339.55%545 3 HKE1U-5H-1 (203)3046115.56%370 4 HKE1U-5H-3 (203)3046315.81%360 5 LAK1U-9M-3 (202)110633.39%282 6 HIC1U-9R-1 RNC101(101)108912.26%216 7 LAK1U-9M-1 (202)110612.49%215 8 EBP1U-9R-3 RNC101(101)128232.30%205 9 SRS1U-5H-1 RNC102-CSL(102) 120913.92%169 10 HRM1U-6R-1 RNC102-CSL(102) 206713.41%167 Step2:CheckthetransmissionandhardwareoftheTOPNcellsandcheck whether they are caused by external abrupt incidents, such as terrible whether, gatherings, or holidays when traffic is usually heavy. Andthen,weconductedahealthcheckforeachcellandpaidattentionto routinealarmsandBPCboardproblems.Wefoundtherewerebroken associations in some HKE sites.Step3:Checktheradioparametersconfigurationofthesecells,theradiusof these cells and their neighboring cells, and compare them with the normal cells. (1)Problem with the cellradius: Afterthe check, we found the cell radius of the LAKsitewas2.5km.BecausetheLAKsitewassituatedbytheseaandthe antenna was placed very high, the radius of 2.5 km was far from enough. So we changedthecellradiusto10km,andtheproblemofhighcalldropratewas thus solved. UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.10 (2)Problemwithconfiguration:HICsiteisanindoorPOIsite.TheRRURxTx port and the RRU Rx port were configured reversely, which is the cause of high calldroprate.AftermodifyingHIC,wefoundthatsignalsofthesecondRRU were received by the Rx port. So we changed the configuration of the RxTx port and the Rx port, the problem of high call drop rate was thus solved. Figure 3-1RF configuration at HIC site Figure 3-2Antenna energy distribution at HIC site Step4:Exporttheindicatorrelevantmostcloselywiththeindicatorsyoucare about and analyze it to find the problem indirectly. UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.11 Table 3-2Indicators Related with CS Call Drop IndexCell RAB release number for Iu connection release request by UTRAN for CS domain in cell, radio connection with UE lost RAB release number for Iu connection release request by UTRAN for CS domain in cell, failure in the radio Interface procedure RAB release number for Iu connection release request by UTRAN for CS domain in cell, release due to overload control RAB release number for Iu connection release request by UTRAN for CS domain in cell, unspecified failure Average cell freq RTWP (dbm) 1 ZBL1U-AI-1 48243029-104.177 2 ZBL1U-AI-3 47340033-104.125 3 HKE1U-5H-1 3461608-105.908 4 HKE1U-5H-3 33018013 -106.0777 5 LAK1U-9M-3 69196018 -103.1906 6 HIC1U-9R-1 100100016 -101.5404 7 LAK1U-9M-1 64131020 -103.1934 8 EBP1U-9R-3 9890017-101.413 9 SRS1U-5H-1 8759022 -104.3528 10 HRM1U-6R-1 42111013 -102.7697 3.2Basic KPI Analysis Skills Be able to use the KPI statistics tool and the analysis tool Usetoolstolearnabouttherunningstateofthewholenetworkquickly,and screen out TOP N worst cells quickly. Usedifferentanalysistoolstofindproblemsfromdifferentaspectsandlocate the problem quickly. Understand the signaling process and basic principle UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.12 Intheprocessofabnormitylocation,keepaclearaiminmind,andbeableto applytheprocessandbasicprincipletochecktheotherrelevantindicators rapidly to facilitate the analysis. Befamiliarwiththeprocessandbasicprincipleandbeabletomakelogical association between abnormal KPI problems and network problems (such as the coverageproblemandtheinterferenceproblem).Beabletodeterminethe problem nature according to the abnormal KPI, and then choose the appropriate tool to analyze the problem in depth. Performance analysis requires engineers to understand basic signaling process, befamiliarwiththeprotocolstacksofstandardinterfaces,andknowrelevant algorithmstorealizetheproductfunctions.Engineersshouldatleasthavea conceptaboutthevariousalgorithms.Iftheanalysisofacommercialnetwork involves some algorithms, engineers should study these algorithms in depth. 3.2.1KPI Monitoring Tools NetworkmanagementtoolNetNumenT31:countKPIoriginaldata, alarmdata,radioparameterconfigurationincells,andparameter configuration on the earth. KPIdailyreportgeneratingtool:classifykeyindicatorsaccordingtoa certain condition, and screen out the worst cells. 3.2.2KPI Analysis Tools CNOTool:CNOtoolhastheKPIanalysisfunction.Sousingit,you canscreenouttheworstcellsaccordingtovariousconditions,and point out the corresponding counter of an indicator.SignalTrace: Trace the signaling (RNL signaling and RNL signaling) of RNCinterfaces,whichincludestheIuinterface,theIurinterface,the Iub interface and the Uu interface (the signaling flow between RNC and UEatRRClayer).AndRNLsignalingtraceisacommonwayfor locatingtheKPIproblem.BeingabletotracetheRNCsignalingisa basicrequirementfortheon-siteKPIoptimizationengineersandthe networkoptimizationandmaintenanceengineers.Thissignaling tracing tool is very powerful, which can trace signaling according to the UEcellandIMSIintheKPIanalysis.AccordingtotheUEcell,itcan tracethesignalingofmultiplesubscribers,whileaccordingtoIMSI,it cantracethesignalingofonlyonesubscriber.However,iftheRRC connectionisnotestablishedyet,signalingcannotbetraced.Thatis UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.13 becauseonlywhenRRCconnectionhasbeenestablished,canthe RNC obtain the subscribers IMSI from the CN.RNCASSLog:ASSlogisusuallyappliedwhenthereisabnormity and RNC signaling is out of trace. In this case, use ASS log to analyze the signaling before and after the abnormity occurs. Abnormity can be queriedaccordingtoIMSIorcellID.ASSlogcanbealsousedto collect various abnormities.NodeB LMT: NodeB local operation and maintenance tool. Apart from alltheoperationfunctionsoftheOMCB,thistoolcancollectmore detailedinformationaboutcellsandUE.NodeBlocalmaintenance terminals include: EOMS, EFMS, DMS, and PMS. NodeBAbnormityProbe:Onthesiteof WCDMAcommercialoffice, NodeB abnormity probe is an effective tool to monitor the running state oftheNodeB.EverymoduleofNodeBcanrecordtheabnormal informationautomatically,whichmakesiteasytolocateproblems. Howeverthismethodrequiresprofessionalknowledge,suchas knowledge about the function and interface of each module or board. If theon-siteengineerscannotmakethesimpleanalysis,theycanjust obtaintheabnormityprobeandsendittotheR&Dengineersatthe rear side. The abnormities reported on the NodeB will be stored at the OMCBserveraccordingtodifferentRNCs.ToconductNodeB abnormity probe analysis, you need to download abnormity probe files from different OMCB servers and then use the abnormity probe tool to make a comprehensive analysis.CTS Tool: CTS is a tool developed by the CN department, which can tracesignalingindepthaccordingtoIMSI,andtracesignalingacross RNCs.SothisisparticularlysuitabletotraceVIPsubscribers.Inthis case,CTSiseasiertousethanSignalTrace,whichcanonlytrace signaling of RNCs one by one. CTS can trace the interactive signaling betweennetworkelements(NEs)withintheCN,aswellasthe signaling of the Iu interface and the Uu interface. This kind of signaling tracing is what we called in-depth tracing. The work principle of CTS is tosetupanIMSItaskontheCTSserverandsendittotheCNfront side,whichwillthensendthistasktoeachCNmoduleviathe interfacesdedicatedtotheCNmodulesandtheRNC,andtheneach module, after receiving the signaling related to the IMSI task, will send thesignalingbacktotheCTSserverviatheCNfrontside.The interfaces mentioned above are private interfaces, so this tool can only supportourownCNandRNC.CTSsignalingcanbecheckedand UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.14 analyzed with an offline tool, but the offline tool does not work very well because of the lack of continuous optimization and perfection.UElog:DTtestisalsoanimportantauxiliarywayinanalyzingKPI indicators. There are many problems that cannot be located by tracing signaling at the network side, and can only be located by the use of UE log.Thecommonlyuseddrivetestsoftwareincludes:QXDM/APEX (QCAT),CNT/CANandTEMS.CNT/CANandTEMSareoftenused for network optimization. For the useof CNT/CAN, please refer to the corresponding help file and the instruction document publicly released by the Network Optimization Tool Department. QXDM and the analysis toolAPEX(QCAT)providedbyQualcommisverypowerful,which havecontributedalotforthestabilityandmaturityofoursystemfor many years.3.3General Process of KPI Optimization Analysis Basic analyzing ideas: KPI optimization is a process to find and solve problems. KPI optimization during the operation and maintenance stage is mainly to pick out the performance data that needs special attention from the OMC, classify these performance data, and thencomparethevalueofthesedatawiththatrequiredbytheoperator.Ifthe valueofanindicatorislowerthantheoperatorsrequirement,analyzethis indicatorandfindoutthefactorthataffecttheindicator,andthenproposea solution to the operator. If the values are higher than the operators requirement, theres no need to pay special attention to them. KPI analysis is a process from the whole to the part.Step 1: Check the key indicators from the view of the whole network. If there is not any problem, just ignore them. Otherwise, try to locate the RNC NE that has the problem.Step2:AnalyzetheindicatorsofthecorrespondingRNCtofindouttheRNC whose indicators have the problem. Step 3: Analyze the indicators of the cell under the problem RNC to find out the worstcellsorTOPNcells.IftheindicatorsofallthecellsundertheRNCare tendtobelow,itisacommonproblemprobablycausedbyparameter configuration.Andthen checkwhethertheradioparameterconfigurationinthe cells under this RNC is the same as that in the cells under the normal RNCs. UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.15 Step 4: Make a comprehensive analysis on the KPIs, alarms, DT testdata, and customer complains of the worst cells to find out a solution. Analysis method: After learning the KPI analysis ideas, we must know some common KPI analysis methodstoruleoutcausesofproblemsfromtheobviousonestothehidden ones. Forexample,wefoundthattheTCPcodewordswerestrictlylimitedateight sitesnearapark,andthecalldropraterosesuddenly.Howtosolvethis problem? Method one: First, we checked whether the alarms, transmission, and boards of thesesiteswerenormal.Aftertheyareprovedallnormal,wesentsome engineers to the site to do test. And meanwhile, we traced the RNC signaling at theOMC.Itturnedoutthatthetestresultwasnormal,andtheindicatorsof thesesitesofthatdaydidnothaveanyproblemandcodewordswerenot limited. And later we knew from the news that there was a big gathering of about one million people at the park at that moment. Until then we came to know that thecongestionwascausedbytoomanyusersusingthenetworkatthesame time. Methodtwo:First,becausetheeightsiteswentworseallofasudden,itwas unlikelythattheproblemliedinthehardware.Thenwecheckedwhetherthe radio parameters had been modified the day before. The result is no worksheet had been issued to modify those parameters, and no alarm was found at those sites.Therefore,weexcludedthepossibilityofhardwareproblem.Thenwe checked the traffic trend graph of the last few days (over seven days) and found thatthehighcalldropratemightbecausedbyhightraffic.Thegraphshowed thattrafficofeachsiterosesuddenlyonthedaybefore.Thuswecametothe conclusionthatthiswasanabnormalabruptevent,whichmayhavebeen caused by a gathering. And later we were told that there was a big gathering at the park. So we were assured the code words limitation and high call drop rate at the eight sites were caused by too many subscribers using the network at the same time. Bycomparingthetwomethodsabove,wecanfindthatalthoughthefirstone (sending engineers to the site, without the consideration of abnormal events) is commonlyused,itisinefficientandcostsmoreresource.Thesecondmethod (analyzingtheproblembythemeansofexclusionandassociation)ismore efficient.Fromthiscase,wewouldliketoemphasizethatKPIanalysisisa processofproblemexclusion.Usingthecomprehensivemethods(likeMethod One) at the first brush may be making a detour. UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.16 Exclusionmethod:CheckthealarmsontheOMCtolearnaboutthe stateoftheRNC,NodeB,BPCboard,andthetransmission.Ifthere areobviousbrokenlinkintransmissionorhardwareproblem,the cause of the problem is easy to locate. Incident association: If the problem is with a great number of sites, take abruptincidentsintoaccount,suchaslarge-scalegathering,terrible weatherofincorrectoperation.Theseincidentswillputinfluenceof different levels and ranges on the network indicators. Comparison of radio parameters: If some site goes wrong in a sudden, checkwhethertheradioparameterconfigurationofthissiteis consistent with that of other normal sites. If not, change it as that of the normalsites,becausetheindicatordecreasemaybecausedbyan incorrect modification of radio parameters. Relevantindicatorsassociation:Ifacertainindicatorisinpoor condition,checkitsrelevantindicatorsandfindthecommonproblem from these relevant indicators. Comprehensiveproblemlocation:Whentheabovereasonsare excluded, use DT data, KPI data, RNC signaling analysis data to locate the problem with indicators comprehensively. UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.17 Figure 3-3KPI optimization analysis processStartPickoutperformanceindexesRNCindexabnormal?Equipmentalarmsexist?DealwithequipmentalarmsRNCindexrecovers?Commonproblemwiththeworstcells?Transmission,software/hardwareversion,wirelessparameterconfigurationCN/RNCTransmissionHardware SoftwareInterferenceWirelessparametersTimerangeAbruptandself-curableabnormality?AnalyzeandrecordcausesSuggestionaboutimprovementCommonproblemsanalysisProblemresolved?SuccessfulcallCalldropSofthandover2/3GalternateoperationPSrate DealwiththerelevantproblemIndexesnormal?EndClimatechange,holidays,assembly,transmissioninterruption,powerfault,andsoonYNYYNYNAbnormalindexesanalysisinonecellYNNNYNYShowTOPNabnormalcellsandtheirlocationsIftheproblemisprovedtobeequipmentbugorsystemproblemafterseveralattempts,feeditbacktoR&Ddept. UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.18 4KPI Optimization AnalysisThischaptermainlydemonstrateshowtoanalyzetheindicatorproblemsfrom theaspectofOMCdata,andprovidesflowchartsforKPIoptimization.The detailed analyzing method and cases of every special subject can be checked in the optimization guides of all the subjects.4.1CS Call Drop OptimizationThe CS call drop rate is the most important indicator in KPI optimization. 4.1.1Definition of Call Drop After checking the signaling on the Uu interface at the UE side, the engineer can judgethesituationacalldropiftheUuinterfacemessagesatisfiesoneofthe following three conditions during the calling process (in connection). RNC Release is not received, but the UE condition changes from CELL_DCH to IDLE. RRC Release is received and the released cause value is Not Normal. One of the following three messages CC Disconnect, CC Release Complete, andCCReleaseisreceived,andthereleasedcausevalueisNotNormal Clearing or Not Normal, Unspecified. In a board sense, the call dropincludes the calldrop rates ofCN and UTRAN. The call drop of UTRAN includes the following two aspects:Afterthesuccessfulserviceestablishment,RNCsendstheRABRelease Request to CN.After the successful service establishment, RNC sends the IU Release Request to CN. Later, RNC receives the IU Release Command from CN. NotethatRANcalldropstatistics,whichisdefinedfromtheaspectoflu interface signaling, means the launching times ofRAB Release Request and lu ReleaseRequestofRNC.AndtheDTcalldropstatisticsisdefinedfromthe aspectsoftheUuinterfacemessage,non-accessstratummessageandcause value.RANcalldropstatisticsandDTcalldropstatisticsarenotexactlythe same. UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.19 4.1.2CS Call Drop Analysis Flowchart Figure 4-1CS call drop analysis flowchart UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.20

ExtractperformancedataCSTOPNcellfilteringAnalyzeasinglecell1.CheckNEalarms2.Associateemergencies3.Compareparameterconfigurations4.Associateindicators5.LocatethefaultcomprehensivelyExistornot?HandlealarmsSolvedornot?YesYesEndNoNoExistornot?HandleemergenciesSolvedornot?YesNoNoExistornotCorrectwrongparameterconfigurationsSolvedornotYesNoNoListrelatedindicatorcountersCall-drop-relatedcountersRTWPHandoversuccessrateTrafficvolumeResourcelimitindicatorsCheck&analysisofinterferenceOptimizationanalysisofhandoverfailuresOptimizationanalysisofresourcelimitCall-drop-relatedcountersC301230362C301230363C301230365C301230315C301230316C301230318C301230319C301230322C301230323Solvedornot?YesYesNoDriveTest+RNCsignalingtraceYes UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.21 4.2PS Call Drop Optimization 4.2.1Optimization Flowchart Figure 4-2PS call drop optimization flowchart UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.22

ExtractperformancedataPSTOPNcellfilteringAnalyzeasinglecell1.CheckNEalarms2.Associateemergencies3.Compareparameterconfigurations4.Associateindicators5.LocatethefaultcomprehensivelyExistornotHandlealarmsSolvedornotYesYesEndNoNoExistornotHandleemergenciesSolvedornotYesNoNoExistornotCorrectwrongparameterconfigurationsSolvedornotYesNoNoListrelatedindicatorcountersCall-drop-relatedcountersRTWPHandoversuccessrateTrafficvolumeResourcelimitindicatorsCheck&analysisofinterferenceOptimizationanalysisofhandoverfailuresOptimizationanalysisofresourcelimitCall-drop-relatedcountersC301230372C301230373C301230375C301230330C301230332C301230333C301230334C301230337C301230338Solvedornot?YesYesNoDriveTest+RNCsignalingtraceYes UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.23 4.3Optimization of Accessibility Indicators AccessibilityperformanceincludesthesuccessrateofRRCconnectionsetup and the success rate of CS/PS RAB assignment. These two kinds of KPIs play importantrolesinthenetworkoptimizationanddirectlyinfluencethesuccess rate of CS/PS service establishment. In this document, this kind of problems are found from the aspect of OMC data, and solved through parameter optimization.4.3.1Definition of Access Failure For the mobile originated call in the CS domain, the access failure event means thattheUEsendsRRCREQUEST,andIEestablishcauseisOriginating Conversational Call, but alerting of the direct transfer message is not received.The relevant events are defined as follows in the access failure stage.RRCconnectionsetupfailure:Afterconsideringtheresendingtimesandthe waitingtime,theUEsendsRRCCONNECTIONREQUEST,anddoesnot receivetheresponsefromRNCorRRCCONNECTIONREJECTdeliveredby RNC. Initial direct transfer and security mode establishment failure: After sending RRC CONNECTION SETUP COMPLETE, the UE does not send NAS SETUP.RAB assignment failure: After receiving CALL PROCEEDING, the UE does not receive RBSETUP delivered by RNC. Or the UE replieswithRB SETUPFAIL afterreceivingRBSETUP.OrtheUEreceivesDISCONNECTwiththecause value not being Normal Release after receiving RB SETUP. At this time, the UE has not reported RB SETUP CMP.Failure after RAB assignment: After the UE sends RB SETUP COMPLETE, the originatingUEreceivesDISCONNECT/RELEASEfromCN.OrtheUEwaits CONNECT or ALERTING overtime, and launches the Call Clearing process; Or the UE becomes IDLE before receiving Alerting, and starts to receive the system message.For the mobile terminated in the CS domain, the access failure event means that theterminatingUEreceivesthepagingofpagingtype1,anddoesnotsend RRCCONNECTIONREQUESTwiththecausevaluebeingTerminating ConversationalCall.OrtheUEdoesnotsendthealertingofdirecttransfer message to CN after sending RRC CONNECTION REQUEST.The relevant events are defined as follows in the access failure stage. UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.24 RRCconnectionsetupfailure:AftersendingRRCCONNECTIONREQUEST, theUEdoesnotreceivetheresponsefromRNCorRRCCONNECTION REJECT delivered by RNC.Initial direct transfer and security mode establishment failure: After sending RRC CONNECTION SETUP COMPLETE, the UE does not receive the SETUP direct transfer message. Or the UE sends RELEASE COMPLETE. Or the UE receives DISCONNECT from CN.RAB assignment failure: The UE does not receive RB SETUP delivered by RNC aftersendingCALLCONFIRM.OrtheUEreplieswithRBSETUPFAILafter receivingRBSETUP.OrtheUEreceivesDISCONNECTwiththecausevalue notbeingNormalReleaseafterreceivingRBSETUP.Atthistime,the UEhas not reported RB SETUP CMP. Failure after RAB assignment: After the UE sends RB SETUP COMPLETE, the terminating UE receives DISCONNECT/RELEASE from CN. 4.3.2Analysis on RRC Connection Failures TheproblemofRRCconnectionsetup failurecanbeanalyzedthroughtheUE signaling flow and RNC single-user tracing. The RRC connection setup includes the following steps:The UE sends RRC Connection Request through the RACH channel.RNC sends RRC Connection Setup through the FACH channel.TheUEsendsRRCConnectionSetupCompletethroughthededicateduplink channel after the downlink dedicated channel is established and synchronized.RRC connection setup failures are always caused by following issues: Uplink RACH problem Problem about downlink FACH power allocation proportion Parameter reselection problem of the cell Low downlink dedicated initial transmitting power Uplink initial power control problem Congestion UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.25 Equipment malfunctions Amongtheseissues,theproblemsofuplinkRACH,downlinkFACHpower allocationproportion,parameterreselectionofthecellandequipment malfunctions appear more frequently. UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.26 4.3.2.1Analysis Flowchart of RRC Connection Setup Failures Figure 4-3Analysis flowchart of RRC connection setup failures UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.27

ExtractperformancedataTOPNcellfilteringAnalyzeasinglecell1.CheckNEalarms2.Associateemergencies3.Compareparameterconfigurations4.Associateindicators5.LocatethefaultcomprehensivelyExistornotHandlealarmsSolvedornotYesYesEndNoNoExistornotHandleemergenciesSolvedornotYesNoNoExistornotCorrectwrongparameterconfigurationsSolvedornotYesNoNoListrelatedindicatorcountersCountersrelatedtoRRCsetupfailuresRTWPResourcelimitindicatorsCheck&analysisofinterferenceOptimizationanalysisofresourcelimitCountersrelatedtoRRCsetupfailuresC301480485C301480486C301480487C301480489C301480490C301480491C301481288C301481289C301481337C301481338C301481339C301481407C301481408SolvedornotYesYesNoDriveTest+RNCsignalingtraceYes UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.28 4.3.2.2UE sends RRC Connection Request, but RNC does not receive it If the Ec/Io of downlink CPICH is relatively low, it is the problem of coverage. If the Ec/Io of downlink CPICH is not very low (for example, the value is larger than -14 dB). Usually, it is the problem of RACH, and the following issues may cause the problem:The power of Preamble does not rise to a required value, and the rising times of Preamble should be increased.TheoutputpowerofUEislowerthantherequiredvalue,whichis causedbypoorUEperformance.Inthiscase,theUEshouldbe changed.TheNodeBequipmenthasastandingwaveandtheengineershould check whether NodeB has any SWR alarm.Theradiusofthecellissetimproperly.Iftheradiusparameterofthe cell is set too small, the NodeB can not synchronize the UE beyond the range of the radius, and the access fails. This problem often happens intheplaceswithlargecoverage,suchastheruralareasandthe suburbs. 4.3.2.3RNC delivers RRC Connection Reject after receiving RRC Setup Request. When RRC ConnectionReject appears, the engineer should check the specific reject cause value. Usually, there are two kinds of causes: The CPU load of RNC control plane board is too heavy and more boards should be added. DCH and FACH admission is rejected. However, this situation does not always happen. 4.3.2.4UE does not receive RRC Connection Setup delivered by RNC This problem may be caused by the following reasons: Poor coverage Improper parameters of cell selection and reselection Checking method: The engineer should check the Ec/Io of CPICH. If the value is lowerthan-12dB(Ec/Iois-12dBbydefault),andthereisnocellofbetter UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.29 quality in the monitor set, the cause of this problem is poor coverage. If there is better cell in the monitor set, cell reselection may cause this problem. Poorcoveragecanbeimprovedbycoverageenhancement,suchasadding somesitestocovertheplaceswithoutsignalcoverageandadjustingthe engineering parameters. If the coverage can not be improved, the engineer can enhancetheFACHpoweraccordingtothePCPICHEc/Iocoverageofthe current network. For example, if all the pilot Ec/Io values are larger than -12 dB inthecoveragearea,thepowerproportionofthecommonchannelshouldbe configured on the basis of the situation that the Ec/Io value is larger than -12 dB. And so, the success rate of the idle UE assessment can be ensured. As for the access problem caused by cell selection and reselection, the engineer canspeedupthecellselectionandreselectionbyadjustingthecellselection andreselectionparameters,andtheproblemofRRCconnectionsetupfailure caused by improper cell selection and reselection parameters can be solved. Note: The RRC Connection Setup message is borne by FACH. RRC Connection Request sent by the UE is received by UTRAN at the preamble of PRACH, and then it is sent from the RACHchannelbasedonthecurrentpreamblepower.Andthetransmitpowerof preamble can rise all the time until the response is received (There is a limitation for the maximumnumberofpreambleretransmissions).Therefore,intheareaswithpoor coverage, the RACH coverage and FACH coverage may become unbalanced, and as a result, UTRAN can receive RRC Connection Request sent by the UE but the UE can not receive RRC Connection Setup sent by RNC. 4.3.2.5UEreceivesRRCConnectionSetupanddoesnotsendRRCSetup Complete Ifthedownlinksignalqualityisnormal,thisproblemmaybecausedbythe abnormal condition of the cell phone. Anotherreasonofthisproblemmaybethedownlinksynchronizationfailure causedbythelowinitialpowerofdownlinkdedicatedchannel.Youcansolve this problem by adjusting the service downlink Eb/No. 4.3.2.6RNC does not receive RRC Setup Complete sent by UE BecausetheuplinkinitialpowercontrolmayincreasetheUEtransmitpower, this kind of problem seldom appears. If it appears, the engineer can increase the UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.30 ConstantValueofthededicatedchannelproperlytoraisetheuplinkDPCCH initial transmission power of the UE.Atthe same time, thisproblemisalso relevantwiththeuplinkSIRinitialtarget valueconfigurationbecausethisvaluemayaffecttheuplinkinitial synchronization at the initial stage of link setup.If the value of the parameter is set too large, there will be too much uplink inference brought by the initial setup of the link. If the value is set too small, the uplink synchronization will take longer time,andtheinitialsynchronizationmayevenfail.ThisparameterisanRNC-levelparameter,whichhasagreatinfluenceonnetworkperformance. Therefore, the engineer should be cautious while adjusting this parameter. Note: RRCConnectionSetupCompleteissentthroughuplinkDPCH,andtheUE calculatestheinitialpowerofuplinkDPCCHaccordingtothereceived IEDPCCH_Power_offset and the measured CPICH_RSCP value. DPCCH_Initial_power = DPCCH_Power_offset - CPICH_RSCP DPCCH_Power_offset=PrimaryCPICHDLTXPower+ULInterference+Constant Value. The Constant Value can be configured in the OMC. If this value is set too small, the UE may not have enough power to send RRC Connection Setup Complete. 4.3.3Analysis on RAB/RB Setup Failures WhenRABorRBsetupfails,RNCwillsendRABAssignmentFailintheRAB AssignmentResponsesignaling.Theengineercanfindoutthespecificfailure reasonfromthefailurecausevaluecarriedinrelevantcells.Thereasonsfor common RAB/RB setup failures include: RNCdirectlyrejectingRABSetupRequestbecauseofwrongparameter configuration Admission reject RAB setup failure because the UE fails to respond to RB Setup RequestRAB setup failure because the Uu interface fails to set up RB UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.31 4.3.3.1Analysis Flowchart of RAB Setup Failures Figure 4-4Analysis flowchart of RAB setup failures UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.32

ExtractperformancedataTOPNcellfilteringAnalyzeasinglecell1.CheckNEalarms2.Associateemergencies3.Compareparameterconfigurations4.Associateindicators5.LocatethefaultcomprehensivelyExistornotHandlealarmsSolvedornotYesYesEndNoNoExistornotHandleemergenciesSolvedornotYesNoNoExistornotCorrectwrongparameterconfigurationsSolvedornotYesNoNoListrelatedindicatorcountersCountersrelatedtoRABsetupfailuresRTWPResourcelimitindicatorsCheck&analysisofinterferenceOptimizationanalysisofresourcelimitCountersrelatedtoRABsetupfailuresCSdomain PSdomainC301230290 C301230302C301230291 C301230303C301230292 C301230304C301230293 C301230305C301230294 C301230306C301230295 C301230307C301230296 C301230308C301230297 C301230309C301230298 C301230310C301230299 C301230311C301230300 C301230312C301230301 C301230313SolvedornotYesYesNoDriveTest+RNCsignalingtraceYes UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.33 4.3.3.2RNC Directly RejectingRAB Setup Request Because Of Wrong Parameter Configuration The case that RNC responds with RAB Setup Failure directly is seldom caused by invalid parameter configuration in the business network. Usually, this case is caused by special operations of the special users.The main scenario is that the subscription information of the users PS service is beyond the capability of the UE, which leads to the direct refusal from RNC. For example,aspecialuserssubscriptionratesofuplinkanddownlinkare384K, butthemaximumuplinkrateoftheUEisonly64K.Themaximumuplinkand downlinkratesoftheQoSmessageusedforactivatingPDPsetbytheAT command or mobile terminal software used by the user are 384 K, so the RNC willfindthemaximumuplinkrateisbeyondtheUEscapability,directlyreply withRABSetupFailureandwillnotlaunchtheRBsetupprocess,whenit receives RAB Assignment Request.AftertheRABsetupfailsbecausetheparameterconfigurationisbeyondthe UEscapability,SGSNwillnegotiateagaintolaunchthenewRABassignment untiltheUEhasthecapabilitytosupporttheassignment,andtheRAB assignment is finished. For the users, the PDP activation is still successful, and the actual maximum rate is the maximum rate the UE can support.However, if the minimum guaranteed bit rate required by the QoS setting in the UEsPDPactivationrequestisbeyondtheUEscapability,thoughthenetwork negotiatesalowerratetoaccepttheUEsPDPactivationrequest,theUEwill launch the request of deactivating PDP when it finds that the rate negotiated by thenetworkinPDPactivationacceptrequestislowerthantheminimum guaranteed bit rate, and finally the PDP activation can not be completed.4.3.3.3Admission Reject Forthenon-HSDPAuser,ifthereareinsufficientsystemresources(including power, channel code, lub transmission resource and CE), the call establishment failurewillbecausedbytheadmissionreject.Atthistime,itisnecessaryto checkthenetworkload,coderesource,lubtransmissionresourceandCE resource occupation to make sure the congestion is caused by the limitation of a certainkindofresource.Whatismore,theengineershouldplanthe corresponding expansion method.IfthecelldoesnotsupporttheHSDPAservice,theR99useradmissionis judgedaccordingtothefixedR99admissionthreshold.Ifthecellsupportsthe HSDPAservice,andtheHSDPAandR99dynamicpowerisallocated,the UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.34 uplinkadmissionofnon-HSDPAisjudgedbasedonRTWPortheequivalent user number. If the uplink load is too heavy, the non-HSDPA user admission will also fail.If the bandwidth configuration on the lub interface is insufficient, the lub interface will reject the R99 data service activation because of limited bandwidth.TheadmissioncontroloftheNodeBCreditresourceissimilartothepower admissioncontrol.WhethertheremainingCreditcansupportthecurrently requestedserviceornotcanbejudgedaccordingtothespectrumspreading factor of the new access user. According to the condition of the RAB Downsizing Switch, RNC will deal with the issue in the corresponding way.FortheHSDPAuser,inthedynamicpowerallocationmode,besidesthe mentioned system resources such as the power, channel code, lub transmission resourceandCE,theadmissionrejectshouldtakeintoconsiderationwhether thenumberofHuserssupportedbyNodeBandthenumberofHusers supported by the cell are over the regulated threshold or not into consideration.FortheHSDPAuser,whenthebandwidthconfigurationonlubinterfaceis insufficient,theadmissionrejectwillnothappen,buttheratewillbereduced. What is more, the AAL2PATHs of HSDPA and R99 are configured respectively, andtheHSDPAAAL2PATHmustbeconfiguredtotheHSDPA_RTor HSDPA_NRT type. If the HSDPA AAL2PATH is configured to RT or NRT of R99 AAL2PATHtype,theRABassignmentfailurewillnothappen,butRNCwill establish the HSDPA service as R99 384 Kbps. For the downlink power admission, Besides whether the R99 service load is over the non-HSDPA service threshold, DCHserviceshouldtakeintoconsiderationwhethernon-HSDPApowerand HSDPA GBP (the minimum power needed for the guaranteed bit rate) are over the general power threshold of the cell.FortheHSDPAservice,itisnecessarytocheckwhetherthethroughputrate provided by the cell is over the sum of all the users GBR thresholds, or whether theGBPsofthestreamserviceandthebackgroundserviceareoverthe HSDPA power of the cell. At the same time, whether the non-HSDPA power and theHSDPAGBP(theminimumpowerneededfortheguaranteedbitrate)are overtheoverallpowerthresholdofthecellshouldbealsotakeninto consideration. For the lub admission, UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.35 FortheDCHservice,theadmissionismadeaccordingtothemultiplicationof the peak rate and the service activation factor.For HSDPA service, the admission is made according to the GBR.Ifthelubexceedsthecongestionthreshold,theDCCCratereductionwillbe triggered. And if the RLC_AM retransmission rate is over a certain threshold, the Iub Overbooking switch can be opened to trigger the TF which limits R99 or to reduce the rate of HSDPA service by a certain factor.4.3.3.4RAB Setup Failure Because the UE Fails to Respond to RB Setup The UE fails to respond to RB setup mainly because of the users operation. Take the following cases as examples:Whentheuseralreadyhashadthedownlink12Kdataservice,hereceivesRB Setup Request of the VP service (either the originated call in the VP domain or the terminatedcallintheVPdomain).BecausetheUEdoesnotsupporttheVPand high-speed PS servicein the downlinkat the same time,it directly replieswithRB Setup Failure, and the cause value is unsupported configuration.Comparedwiththe WCDMAsubscriberoriginatingtheVPservice,theterminating subscriber resides in the GSM network, and so it does not support the VP service. AfterRNCreceivesRABAssignmentRequest,thecorenetworkwilldeliverthe Disconnectcommandrightaftercallproceeding,andthecausevalueisBearer capabilitynotauthorized.Atthistime,theUEhasjustreceivedtheRBSETUP command and has no enough time to finish the RB setup. So the UE will reply with RB Setup Failure after it receives the Disconnect command, and the RNC will reply withRABSetupFailure,withthecausevaluebeingfailureinradiointerface procedure. 4.3.3.5RAB Setup Failure Because the Uu Interface Fails to Set Up RB RNCsendstheRadioBearerSetupcommandtotheUEbutfailstoreceive RadioBearerSetupCompete.Thiskindofsituation(RBsetupfailure)often appearsinthecellswithweaksignals.Therearetwocausesofweaksignals: one is that the UE does not reside in the best server to launch the access, and the other is poor coverage.IftheUEdoesnotresideinthebestservertolaunchtheaccess,itwillhopeto enterthebestserverthroughactivesetupdateintheRBsetupprocess(Atthe same time, the fast signal change will drastically weaken the signals in the cell), but theactivesetupdatecanonlybeprocessedaftertheRBsetupiscompleted, because the procedures can not be processed alternately (Neither the network nor theterminalsupportsit).Therefore,RBcanonlybesetupinthecellwithweak UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.36 signals, and the setup is easy to fail. As for this situation, the starting threshold and speed of co-frequency cell reselection should be increased to make the UE reside in the best server and launch the access as soon as possible.RB setup failure may be caused by the poor downlink/uplink coverage. If the failure iscausedbydownlinkcoverage,theUEcannotreceivetheRadioBearerSetup command,whichmaybecausedbytheuplinkinterference,andthiscanbefixed through checking RTWP. The poor downlink coverage is partly caused by the bad UEdemodulationperformance,andothercausesshouldbesolvedbyRF optimization.4.4Optimization of Mobility Indicators Mobilityindicatorsmainlyfallintothreecategoriessofthandovers,hard handovers and inter-RAT handovers. The handover problems usually happen in the following cases. The best server changes too fast or there is no best server due to pilot pollution. Thehandoverisnotpromptortherearepingponghandoversduetoimproper parameter configuration. Adjusttheengineeringparametersforantennasinareaswithseverepilot pollution.Andadjustthehandoverparameters,suchasthevaluesof1A,1B, CIO,TTT(timetotrigger),Hysteresisandsoon,tosolvetheproblemthatthe handoverisnotpromptortherearepingponghandovers.Thissectiontriesto solvethiskindofproblemsthroughOMCdataanalysisandparameter optimization. 4.4.1Optimization of Soft Handovers Missedneighboringcellconfiguration,pilotpollution,impropersofthandover parameterconfiguration,andequipmentmalfunctionsarethemajorcausesof soft handover failures. To confirm the problems, the field DTs are required. UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.37 4.4.1.1Soft Handover Optimization Flowchart Figure 4-5Soft handover optimization flowchart UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.38

ExtractperformancedataTOPNcellfilteringAnalyzeasinglecell1.CheckNEalarms2.Associateemergencies3.Compareparameterconfigurations4.Associateindicators5.LocatethefaultcomprehensivelyExistornotHandlealarmsSolvedornotYesYesEndNoNoExistornotHandleemergenciesSolvedornotYesNoNoExistornotCorrectwrongparameterconfigurationsSolvedornotYesNoNoListrelatedindicatorcountersRTWPResourcelimitindicatorsCheck&analysisofinterferenceOptimizationanalysisofresourcelimitCountersrelatedtointra-frequencyhandoverfailuresC301391101 C301390593C301391102 C301390594C301391103 C301390595C301390586 C301390596C301390587 C301390597C301390588 C301390598C301390589 C301390599C301390590 C301390600C301390591 C301390601C301390592 C301390602SolvedornotYesYesNoDriveTest+RNCsignalingtraceYesCountersrelatedtosofthandoverfailures3005530056300573005830059300603006130062Cellhand-in/hand-outindicators UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.39 4.4.1.2Checking Missed Neighboring Cell Configuration Generallyspeaking,mostofthecalldropsatthebeginningoftheoptimization are caused by missed neighboring cell configuration. The following methods are oftenusedto judgewhether thecalldropsarecausedbymissedconfiguration of co-frequency neighboring cells. ObservetheactivesetEc/IoinformationrecordedbytheUEandtheBestServer Ec/Io information recorded by the Scanner before the call drop. If the former record is very bad but the latter record is very good, then check whether theBest Server scramblingcoderecordedbytheScannerappearsinthelatestlistofthe neighboringcellsunderintra-frequencymeasurementcontrol.Ifitdoesnot,then the call drop is caused by missed neighboring cell configuration. If the UE re-accesses immediately after the call drop and the cell scrambling codes duringtheUEreaccessandthoseduringthecalldroparedifferent,thenthecall dropmayalsobecausedbymissedneighboringcellconfiguration.Youcan confirmitthroughmeasurementcontrol(lookbackwardsfromthemessageofthe calldropeventforthelatestintra-frequencymeasurementcontrolmessageand check the neighboring cell list of this message). Some UE may report the Detected Set information. If the corresponding scrambling codeappearsintheDetectedSetinformationbeforethecalldrop,thenthecall drop is caused by missed neighboring cell configuration. 4.4.1.3Checking Pilot Pollution Definitionofpilotpollution:Excessivestrongpilotsignalsexistatacertain point,butnoneofthemisstrongenoughtobethebestserver.Toformpilot pollution, the following points in this definition should be satisfied. Strong pilot signal: The absolute pilot signal strength is used to judge whether the pilot signal is a strong one. The pilot signalstrength can be evaluated through the pilotRSCP.IfthepilotRSCPexceedsathreshold,itisconsideredastrongpilot signal. The formula is: Absolute RSCPTh RSCP CPICH__ Excessive:Thenumberofpilotsignalsisusedtojudgewhetherthereare excessivepilotsignalsatacertainpoint.Ifthenumberexceedsathreshold,itis regarded that excessive pilot signals exist at this point. The formula is: NTh Number CPICH _None of them is strong enough to be the best server: The relative strength of a pilotsignalisakeyfactorinjudgingwhetherthepilotsignalisstrongenough. Based on the above definition and formulae, if the difference between the strength UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.40 of thestrongest pilot signalandthat of the) 1 ( NTh strongestpilot signal at this pointislessthanathreshold,itisregardedthatthereisnopilotsignalstrong enough to be the best server at this point. The formula is: lative RSCP th Th bestTh RSCP CPICH RSCP CPICHNRe _ ) 1 () _ _ ( According to the above description, it is regarded that pilot pollution exists if the following conditions are both satisfied. Thenumberofpilotsignalsthatmeetthecondition Absolute RSCPTh RSCP CPICH__ is more thanNTh. lative RSCP th Th bestTh RSCP CPICH RSCP CPICHNRe _ ) 1 () _ _ ( For example, during the network optimization, suppose: dBm ThAbsolute RSCP95_ ,3 NTh , anddB Thlative RSCP5Re _ , if the following conditions are both satisfied, then it is regarded that pilot pollution exists. Thenumberofthepilotsignalsthatmeetthecondition dBm RSCP CPICH 95 _ is more than 3. dB RSCP CPICH RSCP CPICHth best5 ) _ _ (4 4.4.1.4Adjusting Soft Handover Algorithm Parameters Youcansolvethe following kindsofproblemsbyadjustinghandoveralgorithm parameters: 1.The handover is not prompt. From the perspective of the CS service signaling flow, the symptom of this problem isthattheUEcannotreceiveActiveSetUpdate(physicalchannelreallocationin thecaseoftheintra-frequencyhardhandover)becauseaftertheUEreportsthe measurement report, the source cell has a fast reductioninEc/Io. When theRNC sendsActiveSetUpdate,theUEhasclosedthetransmitterduetothelossof downlinksynchronization.ViewedfromtheUEside,itcannotreceiveActiveSet Update.InthePSservices,iftheUEcannotreceiveActiveSetUpdateorTRB resets before the handover, the handover will also fail. Fromtheperspectiveofsignals,thefollowingphenomenamayaccompanythis problem. UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.41 Corner effect: Ec/Io of the source cell decreases drastically, and Ec/Io of the target cell increases sharply (very high when it appears). Fast fading: Ec/Io of the source cell decreases quickly for a while and then increases, and Ec/Io of the target cell increases for a short while. 2.Pingpong handovers. The following phenomena may accompany this problem. Thebestserverchangesquickly:Twoormorecellstaketurnstobethebest server. But as the best server, none of the cells can last long though they has good RSCPs and Ec/Ios. Thereisnobestserver:Therearemultiplecells.TheirRSCPsarenormaland similar to each other. But Ec/Io of every cell is very bad. Fromtheperspectiveofthesignalingflow,Event1Aisreportedimmediately after one cell is deleted. Because the UE cannot receive Active Set Update from the RNC, the handover fails. 4.4.1.5Equipment Malfunctions Firstcheckthealarmconsoletoseewhetherthereareabnormalalarms,and analyzethemessagetracesatthesametime.Findoutinwhichstepthesoft handoverfails.Checkthefailuremessage,andcontactthelocalproduct maintaining engineer to confirm whether the equipment has malfunctions. 4.4.1.6Solutions Corresponding adjustments should be taken for the confirmed problems. Handover failures caused by pilot pollution: Adjust the engineering parameters of a certainantenna to set thisantennaas the best server in thisinterferedlocation.If thepowerofoneofitssectorsisreduced,thenIoofthepilotpollutionareawill decrease;evenifthepowersofotherpilotsarenotadjusted,Ec/Iowillalso increase.TherebytheEc/Iodifferenceswithotherscramblingcodesintheactive setwillbecomelargerandpilotpollutionwillbeeliminated.Throughalotof research,ZTEhasprovedthatthereductioninthepilottransmitpowerwillnot change cell capacity greatly. If condition allows, new base stations can be added to cover this area. Equipment malfunctions: Consult the customer service engineers, and ask them to help check whether there are alarms and whether the transport layer is abnormal. If therearealarms,coordinatewiththecustomerserviceengineersandthe engineering personnel to solve the problems. UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.42 Call drops because the handovers are not prompt: Adjust the antenna to expand the handover zone. ConfiguretheEvent1Ahandoverparameterstomakethehandover easier to happen. IncreaseCIOtomakethehandoverhappenearlierinthetargetcell. ThesumofCIOandtheactuallymeasuredvalueisusedforjudging theUEevents,includingtheUEintra-frequencyhandover.CIOhelps shift the cell border in the handover algorithm. If CIO is configured with a larger value, the handover will be easier to happen and there will be moreUEinthesoft-handoverstatus,butmoreresourceswillbe occupied.IfCIOisconfiguredwithasmallervalue,thesofthandover willbemoredifficulttohappenandthereceivingqualitymaybe impaired.ACIOofabout5dBisquitegoodforeliminatingthefast fadingandthecornereffect,butthisconfigurationhassomeside effects, such as the increase of handover proportion. Calldropscausedbypingponghandovers:Adjusttheantennatoformabest server in its coverage zone or set the Event 1B handover parameters (increase the thresholdofEvent1B,theEvent1BhysteresisorthetimetotriggerEvent1B)to increase the difficulty in deleting the active set. 4.4.2Optimization of Hard Handovers 4.4.2.1Classification of Hard handovers Hard handovers mainly fall into two classifications: Intra-frequencyhard handovers:The intra-frequencyhard handoveris triggered onlywhentheintra-frequencysoft/softerhandovercannotbeperformed,anditis applicable to the following circumstances. Inter-RNCintra-frequencycellhandoverswhenthereisnoIur interface. Insufficient Iur interface resources though there is the Iur interface. HandoverscontrolledbythethresholdofthePSservicerateinthe handover cell. Theintra-frequencysoft/softerhandoverscannotbeperformed(intra-frequency hard handover should be triggered) in the following scenarios. UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.43 Whentheintra-frequencyhandoverhappens,theUEisusingthe transmitdiversityintheactivesetcellbutthetargetcelldoesnot support the transmit diversity. The intra-frequency measurement report does not contain OFF and TM of the target cell. Whentheintra-frequencyhandoverhappensbetweenRNCs,theIur interface is unavailable. TheUE performs the multiuser detection in the active set cell, but the target cell does not support the multiuser detection. Thetargetcellandtheoriginalcellbelongtodifferentclassifications (ThecellsofR99,R5+R99,andR6+R5+R99belongtothesame classificationwhilethecellsofR5andR6+R5belongtoanother classification). Inter-frequency hard handovers: The inter-frequency hard handover means a UE connectionishandedoverfromacellofaUTRANfrequencytoacellofanother frequency. Many factors, including the radio quality, the load, and the speed of the moving UE, may trigger inter-frequency hard handovers. For example, the radio quality triggers the inter-frequency hard handover in the following way: WhenthequalityoftheUEradiofrequencybecomeslower,theinter-frequencymeasurementwillbetriggered,andaccordingtothe measurementresult,theUEconnectionwillbehandedovertoabetter frequency. UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.44 4.4.2.2Hard Handover Optimization Flowchart Figure 4-6Hard handover optimization flowchart UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.45

ExtractperformancedataTOPNcellfilteringAnalyzeasinglecell1.CheckNEalarms2.Associateemergencies3.Compareparameterconfigurations4.Associateindicators5.LocatethefaultcomprehensivelyExistornotHandlealarmsSolvedornotYesYesEndNoExistornotHandleemergenciesSolvedornotYesNoExistornotCorrectwrongparameterconfigurationsSolvedornotYesNoNoListrelatedindicatorcountersRTWPResourcelimitindicatorsCheck&analysisofinterferenceOptimizationanalysisofresourcelimitCountersrelatedtointer-frequencyhandoverfailuresC301110489C301110516C301110499C301110517C301110500C301110518C301110501C301110519C301110502C301110520C301110503C301110521C301110504C301110522C301110505C301110523SolvedornotYesYesNoDriveTest+RNCsignalingtraceYesCountersrelatedtohardhandoverfailures3004130042300433004430045300463004730048Cellhand-in/hand-outindicatorsNoNo UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.46 4.4.2.3Hard Handover Optimization Methods Theoptimizationflowforthehardhandoverissimilartothatofthesoft handover. The major differences are in the parameter optimization. To optimize intra-frequencyhardhandovers,youcanproperlyreducetheEvent1D hysteresisandthetimetotriggerEvent1Daccordingtotherealradio environment to ensure timely handovers. Inter-frequencycoverageisoftenappliedtosomespecialscenariossuchas indoor coverage and tested through CQT. The method of judging whether there ismissedconfigurationoftheinter-frequencyneighboringcellisalmostthe same as that of the co-frequency neighboring cell: when a call drop occurs, the UE fails to measure or report the inter-frequency neighboring cell; after the call drop, the UE resides in the inter-frequency neighboring cell again. The common hard handover problems are: 1.The handover is not prompt. The common symptoms are frequent call drops in the hard handovers when the UE moves. Solutions: Increase the threshold of activating the compressing mode. The compressing mode is usually activated before the inter-frequency handover or the inter-RAT handover, anditisusedtomeasurethequalityoftheinter-frequencyorinter-RATcell.You can set a threshold of the CPICH RSCP or Ec/Io to activate the compressing mode. And the RSCP is widely used. Requirementsonsettingthethresholdofactivatingthecompressing mode:Beforethecellqualitybecomeslowenoughtocauseacall drop,thesignalofthetargetcellshouldbemeasuredandreported, and the handover should be performed. Requirementonsettingthethresholdofdeactivatingthecompression mode:Frequentactivation/deactivationofthecompressionmode should be avoided. Increase CIOs of the inter-frequency cell pair. Reduce the threshold of triggering the target frequency handover under the inter-frequency coverage. 2.There are pingpong handovers. Solution:Increasethehardhandoverhysteresisandthetimetotriggerthe event. UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.47 4.4.3Optimization of Inter-RAT Handovers 4.4.3.1Configuring Basic Inter-RAT Parameters Mostoftheinter-RAThandoverfailuresarecausedbyincompleteparameter configuration. The following parameters need special attention. CompleteRNCparameterconfigurationfortheGSMneighboringcell:The2G systemshallprovidethe3Gsystemwiththecorrectradioparametersbasedon negotiation MCC, MNC, LAC, ID (CI), NCC, BCC, frequency band indicator (900 or 1800), and BCCH. Table 4-1Parameters That 2G Shall Provide to 3G MCCMNCLAC ID CI NCCBCC Frequency band indicator BCCH 460220219300900102 Complete GSM BSC parameter configuration for the WCDMA neighboring cell: The 3G system shall provide the 2G system with the correct radio parameters based on negotiationMCC,MNC,LAC,RNCID,cellID(C_ID),downlinkfrequency, scrambling code, and RAC. Table 4-2Parameters That 3G Shall Provide to 2G MCCMNCLAC RNC ID Cell ID C_ID Downlink frequency Scrambling code RAC 4603201851107875120 Accordingtothecurrentstrategyofone-wayinter-RAThandovers,ifthe parameterconfigurationiscomplete,oneprobablecauseoftheinter-RAT handoverfailureisthatthehandoverisnotprompt.Thecommonparameter adjustmentistoincreaseCIO,thethresholdtoactivate/deactivatethe compressing mode, and the threshold to trigger the WCDMA-to-GSM handover at the same time. Call drops during the inter-RAT handovers between WCDMA and GSM may be caused by: Inconsistent data configuration at the GSM side and the WCDMA side afterGSMmodifiestheconfigurationdatabutdoesnotinform WCDMA. Missedconfigurationof neighboringcells,whichcanbesolvedbythe correct configuration of neighboring cells. UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.48 Too fast signal changes. Pingpong reselection. FaultswiththeUE,forexample,theUEfailstorespondtothe handover or report the inter-RAT measurement report. Changes of the best server during the physical channel reallocation. WrongLACconfiguration,whichcanbelocatedthroughdata configuration check. UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.49 4.4.3.2Inter-RAT Handover Optimization Flowchart Figure 4-7Inter-RAT handover optimization flowchart UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.50

ExtractperformancedataTOPNcellfilteringAnalyzeasinglecell1.CheckNEalarms2.Associateemergencies3.Compareparameterconfigurations4.Associateindicators5.LocatethefaultcomprehensivelyExistornotHandlealarmsSolvedornotYesYesEndNoNoExistornotHandleemergenciesSolvedornotYesNoNoExistornotCorrectwrongparameterconfigurationsSolvedornotYesNoNoListrelatedindicatorcountersRTWPResourcelimitindicatorsCheck&analysisofinterferenceOptimizationanalysisofresourcelimitCountersrelatedtointer-RAThandoverfailuresC301130667C301130681C301130668C301130682C301130669C301130690C301130670C301130691C301130671C301130692C301130672C301130693C301130673C301130694C301130674C301130696C301130675C301130697C301130677C301130698C301130678C301130699C301130679C301130700C301130680SolvedornotYesYesNoDriveTest+RNCsignalingtraceYesCountersrelatedtointer-RAThandoverfailuresCellhand-in/hand-outindicators300493005030051300523005330054 UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.51 4.5Optimization of Resource Indicators Theresourceindicatorsdirectlyreflectthesystemcapacity.Increasing subscriberswillconsumemoresystemresourcesandsomeresourcesmaybe limited; for example, the code resource may be limited, the TCP access request mayberejected,andtheCEresourceusageratemayexceedthethreshold. Limitedsystemresourceshaveanegativeinfluenceonthewhole-network indicatorsandthesubscribersperception;forexample,calldropsmay frequentlyhappenandmoreTCPaccessrequestsmayberejectedduringthe voice services. Table 4-3Resource KPIs and Alarm Thresholds Resource typeKPI No. and name Alarm threshold TCP C301320150 Number of rejected services, DCH downlink TCP limit 50 PI30167 Average non-HSDPA TCP40% PI30092 Maximum Cell TCP (%)100% PI30093 Average Cell TCP70% UL Traffic PI30029 Handover Blocking Rate0.5% KPI RTWP (in busy hour)-98 dBm Code C301320153 Number of rejected services, DCH no code 50 PI30205 Average Cell HSUPA Users12 PI30172 Cell Average HSDPA Users16 CE PI301830006 Maximum use Ratio of Uplink NodeB CE 60% PI301830010 Maximum use Ratio of Downlink NodeB CE 60% UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.52 4.5.1Resource Indicator Optimization Flowchart Figure 4-8Resource indicator optimization flowchart UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.53

ExtractperformancedataTOPNcellfilteringAnalyzeasinglecell1.CheckNEalarms2.Associateemergencies3.Compareparameterconfigurations4.Associateindicators5.LocatethefaultcomprehensivelyExistornotHandlealarmsSolvedornotYesEndNoNoExistornotHandleemergenciesSolvedornotYesNoNoExistornotCorrectwrongparameterconfigurationsSolvedornotYesNoNoListrelatedindicatorcountersCoderesourceindicatorsCEresourceindicatorsTCPadmissionrejectcounterC301320150SolvedornotYesYesNoDriveTest+RNCsignalingtraceYesCounterrelatedtoTCPlimitCellTXpowerindicators300903009130092300933016630167301683016930170301713016330164301653007530223302243045030451YesYes UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.54 4.5.2Code Resource Optimization ThestatisticsofNumberofrejectedservicesandDCHnocode,theaverage coderesourceusagerateandthenumberoftheHSDPAsubscriberscanbe used to judge whether the code resource in a cell is limited. If the code resource is limited, you can adjust the code resource allocation to alleviate the situation. Basedonthesystemalgorithm,whenFormula1issatisfied,youcanaddan HS-PDSCH; when Formula 2 is satisfied, then an HS-PDSCH is deleted. Formula1:OcuRateNoHspdsch+OcuRateHspdsch+DpchCodeHy+32 512 OcuRateHspdschHSPDSCHmeansthenumberofthecodesofSF=512 blocked by the HS-PDSCH, OcuRateNoHspdsch means the number of codes of SF=512blockedbyotherchannels,DpchCodeHymeansthenumberofcodes of SF=512 reserved for the DPCH, and CodeUptHyA is the threshold to decide whether to delete the HSPDSCH. Therefore,toensuretheaccessoftheR99subscribers,youcanmakesome adjustment according to Table 4-4 when the code resource is limited, though the HSDPA rate may decrease. Table 4-4Adjusting Code Resource Allocation Abbreviation Parameter name Range and step Current value Update value Remark DpchCodeHyDPCH Code Hysteresis 0..5121628 To decrease the number of rejected services for DCH no codeCodeUptHyA Code Update Hysteresis A 0..5121628 To decrease the number of rejected services for DCH no code 4.5.3Monitoring CE Resource The CE resource is mainly monitored through the maximum UE uplink/downlink usagerate.Ifthereisanyproblem,youcansolveitbycontrollingtheloador adding more boards. UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.55 4.5.4Optimization of Power Control 4.5.4.1Monitoring and Optimizing Downlink Power Control Limited TCP in busy hours will not only increase access failures and call drops inthelocalcellbutalsoincreasesofthandoverfailuresandcalldropsinthe neighboring cells. Number of rejected services and DCH downlink TCP limit are intuitiveKPIstojudgewhetherTCPislimited.Althoughlimiteduplinkcapacity and massive UE moves in the rush hours may also cause call drops, the limited TCP is absolutely a key factor. BasedonthesystemalgorithmMinHsdpaPower(MinHspaPwrRto)+ NoHsPower>NodeB,ifthesafetythresholdisused(MinHsdpaPowermeans the power reserved for HSPA), then it will activate the downlink rate downgrade algorithmflowforthecongestion(lowerthedownlinkDCHrate).Althoughthe rate downgrade can ensure access of some subscribers, it is an irregular action and will degrade the performance. 4.5.5Speeding up Rate Downgrade Considering that the cells with heavy load reject more access requests, you can speeduptheratedowngradeduringtheresourcecongestiontoreleasethe resourcesassoonaspossibleandavoidcalldropscausedbyaccessfailures (thismethodisonlyapplicabletothecellswithmanyPSserviceusersbutnot thosewithonlyCSserviceusers).Table4-5isanexampleoftheparameter modification for the rate downgrade. Table 4-5Example of Parameter Modification for Rate Downgrade AbbreviationParameter name Range and step Current value Update value Remark UlDnMaxStgMaximum Number of Degraded Uplink Load Steps Every Time [1, 8]12Downgrade from 384 Kbps to 16 Kbps DlDnMaxStgMaximum Number of Degraded Downlink Load Steps Every Time [1, 8]13Downgrade from 384 Kbps to 8 Kbps UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.56 4.5.6Monitoring and Optimizing Uplink Capacity HandoverBlockingRateandRTWPcanreflecttheuplinkcapacityofthecell. BecauseinterferencemayalsoincreaseRTWP,thisfactorshouldbe distinguishedduringtheRTWPmonitoring.Anothereffectiveindicatoristhe voice service erl. If a cell has over 20 erls in busy hours, you should pay special attention to it. 4.5.7Optimization of Uplink Capacity at the Whole Network Level Case:Theuplinkcapacitywaslimitedinalargenumberofsitesafterthe cutover, and the symptoms are a sharp rise of RTWP and a high call drop rate during the rush hours. AfterthefollowingparametersweremodifiedasshowninTable4-6,the problem was solved. Table 4-6Example of Power Control Parameter Modification Abbreviation Parameter name Range Current value Update value ULINITSIR Uplink Initial SIR target (dB) UL 3.4 K/13.6 K signaling, UL 12.2 K AMR 4-53.5 ULMAXSIR Maximum Uplink SIR target (dB) UL 3.4 K/13.6 K signaling, UL 12.2 K AMR 1510 UlSirTargDnStep Uplink SIR Target Down Step Size (dB) UL 3.4 K/13.6 K signaling, UL 12.2 K AMR 0.10.2 4.5.8Optimization of Uplink Capacity for a Single Cell AlotofoptimizationmeasurescanbetakentobringdowntherisingRTWP. However,withincreasingsubscribers,thecapacitymaystillbelimitedinsome area while further modification of SirTarget will obviously degrade the call quality ofthewholenetworkandunderminethesubscribersperception.Inthiscase, youcanadjustthepowercontrolparametersforasinglesitethathasheavy traffic in the following way: add one set of DivPc parameters and use this set of parameters only for this site. Case: Table 4-7 shows an example of the power control parameter modification. After this modification, the call drop rate in the site with heavy traffic decreased to one quarter of the original one. UMTS KPI Optimization Analysis GuideInternal Use Only ZTE Confidential Proprietary 2015 ZTE CORPORATION. All rights reserved.57 Table 4-7Example of Power Control Parameter Modification for Heavy-Traffic Cell SRVTYPEULINITSIRULMAXSIRULMINSIR 03.5->1.510.0->3.52.0->1.0 1044.0->2.015.0->5.00.5->0 283.5->1.510.0->3.50.5->0 506.0->2.015.0->5.02.0->0 546.0->2.015.0->5.02.0->0