WCDMA无线网络规划与优化_m

WCDMARadioNetworkPlanningandOptimization,sppe12083,Contents,WCDMAFundamentals(includinglinkbudgetfundamentals)RadioResourceUtilizationCoverageandCapacityissuesCelldeploymentWCDMARadioNetworkPlanning(includingWCDMA-GSMCo-planningissues)Co-existingTDDtocoordinatetheusageoftheavailablehardwareresoucesandtomanagethecodetree.,BasicRRMfunctions*PowerControl*HandoverControl*CongestionControl*ResourceManagement,RADIORESOURCEUTILIZATION-powercontrol(1),UMTSPowerControl(PC)summary,RADIORESOURCEUTILIZATION-powercontrol(2),Uplink/Downlinkinner-andouter-looppowercontrol,RADIORESOURCEUTILIZATION-handovercontrol,Soft-Handover:ExampleofSoftHandoverAlgorithm,Event1A:AP-CPICHentersthereportingrange,Event1B:AP-CPICHleavesthereportingrange,Event1C:Anon-activePCPICHbecomesbetterthananactiveoneEvent1D:changeofbestcell.ReportingeventistriggeredwhenanyP-CPICHinthereportingrangebecomesbetterthanthecurrentbetoneplusanoptionalhysteresisvalue.Event1E:AP-CPICHbecomesbetterthananabsolutethresholdplusanoptionalhysteresisvalue.Event1F:AP-CPICHbecomesworsethananabsolutethresholdminusanoptionalhysteresisvalue.,RADIORESOURCEUTILIZATION-PCandSHOconclusion,BondingofSHOandPC(basedonthefactthatSHOgainisdependentonthePCefficiency)SHOgaindependsonthetypeofchannelandthedegreeofPCimperfection.ItisusuallyhigherwithimperfectPC.SHOdiversitycanreducethePCheadroom,thusimprovingthecoverage.ThetransmitandreceivepowerdifferencesasaresultofSHOmeasurementerrorsandSHOwindowscanaffectthePCerrorrateinuplink,reducingtheuplinkSHOgains.Inuplink,SHOgainistranslatedintoadecreaseintheouter-loopPCsEb/Notarget.,RADIORESOURCEUTILIZATION-congestioncontrol,Airinterfaceloaddefinition(loadcontrolprinciples)UplinkWidebandpower-baseduplinkloadingwhereThroughput-baseduplinkloadingDownlinkWidebandpower-baseddownlinkloadingThroughput-baseddownlinkloadingor,RADIORESOURCEUTILIZATION-congestioncontrol(contd),Congestioncontrol-keeptheairinterfaceloadunderpredefinedthresholdsAdmissioncontrol-handlingallthenewtrafficLoadcontrol-managingthesituationwhensystemloadhasexceededthethresholdPacketscheduling-handlingallthenon-real-timetraffic,RADIORESOURCEUTILIZATION-congestioncontrol(contd),PacketschedulingTimedivisionschedulingCodedivisionscheduling,RADIORESOURCEUTILIZATION-CodePlanning,CodeplanningCodeallocationisunderthecontrolofRNC.Codetreemaybecome“fragmented”andcodereshufflingisneeded(arrangedbyRNC).,CodeallocationScramblingandspreadingcodeallocationforuplink(byUTRAN)ScramblingandspreadingcodeallocationfordownlinkDownlinkchannelisationcodeallocation(byUTRAN)Downlinkscramblingcodeplanning512scramblingcodessubdividedinto64groupseachofeightcodes,RRMoptimization-SHOoptimization(1),AdditionwindowoptimizationDeterminestherelativedifferenceofthecellsattheMSendthataretobeincludedintheactivesetOptimizedsothatonlytherelevantcellsareintheactiveset,RRMoptimization-SHOoptimization(2),DropwindowoptimizationSlightlylargerthantheadditionwindow,FrequentanddelayedHos(cellsping-pongintheactiveset),RRMoptimization-SHOoptimization(3),ReplacementwindowoptimizationDeterminestherelativethresholdforMStotriggerthereportingEvent1C.Toohigh:slowbranchreplacementandthusnon-optimalactivesetToolow:ping-pongeffectwithunnecessarySHOs,RRMoptimization-SHOoptimization(4),Maximumactivesetsizeoptimization,RADIORESOURCEUTILIZATION-SHOoptimizationconclusion,SHOoverheadtargetlevelshouldbe30%40%.AdditionwindowCapacityestimationEstimationoftheamountofbasestationhardwareandsites,radionetworkcontrollers,equipmentatdifferentinterfacesandcorenetworkelementsKnowledgeofservicedistribution,trafficdensity,trafficgrowthestimatesandQoSrequirementsareessential,WCDMARadioNetworkPlanning-Dimensioning(2),Coverageanalysis:forthesingle-cellcase*:wherewhereisthereceivedlevelatthecelledge,isthepropagationconstant,istheaveragesignalstrengththresholdandisthestandarddeviationofthefieldstrengthandistheerrorfunction.foratypicalmacro-cellularenvironmentusingOkumura-Hatamodel,thefollowingformulargivesanexampleforanurbanmacro-cellwithbasestationantennaheightof25m,mobilestationantennaheightof1.5mandcarrierfrequencyof1950MHz:whereisthemaximumcellrangeandisthemaxpathloss.,*“MicrowaveMobileCommunications”,Jakes,W.C,JohnWileythenthereceivedinterferenceattheMSintheadjacentchannelisAssumingspeechservice(processinggainofGp=25dB)withanEb/NorequirementattheMsof5dBandanallowednoiseriseinthemacrocellof6dB,themaximumallowedpropagationlossLptokeeptheuplinkconnectionworkingisifwefurtherconsideraDLTxEb/Norequirementof8dB,thetransmitpowerwouldneedtobe,ThissimpleexampleshowsthatclearlyinthesecasestheDListheweakerlink,i.e.beforecomingtooclosetoamicroBS,theconnectionofamacroBSwillbedroppedduetoinsufficientDLpoweranditcannotblockthemicroBS.,WCDMARadioNetworkPlanning-Optimizationaspects(1),GuidelinesforRadioNetworkPlanningtoavoidACIinmulti-operatorenvironmentBasestationandantennalocationsCo-locateBSsDeploytheantennasinapositionashighaspossibleBasestationconfigurationOptimumantennabeam-width“desensitisation”-increasingthenoisefigureInter-frequencyhandoversInter-systemhandoversGuardbands,WCDMARadioNetworkPlanning-Optimizationaspects(2),SitelocationsandconfigurationsAntennainstallations(cablelosses)OptimumantennatiltingangleandcorrectantennaselectionOptimumsectorisationregardingtonumberofusersandSHOoverhead.*Usageofmastheadamplifier(MHA)*UsedinuplinkdirectiontocompensateforthecablelossesImproveduplinkcoverageprobabilityMayhavenegativeeffectondownlinkperformanceincaseofdownlink-limitedscenario,*“TheimpactofthebasestationsectorisationonWCDMARadioNetworkPerformance”,A.Wacker,J.Laiho-Steffens,K.Sipila,K.Heiska,VTC99Amsterdam.*“TheimpactoftheRadioNetworkPlanningandSiteConfigurationontheWCDMANetworkCapacityandQualityofService”,J.Laiho-Steffens,A.Wacker,P.Aikio,VTC2000,ExamplesofmaximumpathlosseswithexistingGSMandWCDMAsystem,WCDMA-GSMCo-PlanningIssues,WCDMA-GSMCo-PlanningIssues-interferenceissues,InterferencebetweenthetwosystemisthemainissueRadiofrequencyissueSecondharmonicsofGSM900couldprobablyfallintoWCDMAuplinkbandThird-orderinter-modulationproductsofPCS1800couldbeproblematic,Second-orderharmonicdistortionfromGSM900fallingintoWCDMAband,WCDMA-GSMCo-PlanningIssues-interferenceissues,InterferencemechanismsfromGSMsystemtoWCDMAsystemAdjacentChannelInterference(ACI):dependsonTx/Rxfilterandspatialandspectraldistancebetweentheownandadjacentcarrier,thecelltypeandthepowerlevelsused.WidebandNoise(WB):fromallout-of-bandemissioncomponents.Cross-modulation(XMD):dependsonnon-linearityoftheMSreceiver,theduplexisolationandthetransmittingmobilepower.Inter-ModulationDistortion(IMD):causedbynon-linearitiesofRFcomponentsoftransmitterorreceiver.,XMDisproportionaltothesquareoftransmittingpowerandverysensitivetotheTxpoweroftheMS!,Typicallyinmicro-cellsandcouldbereducedbyguardband.,Third-orderIMDwithmixtureofproductsoftheGSMcarrierfrequenciesf1andf2:2f1-f2or2f2-f1,WCDMA-GSMCo-PlanningIssues,HandoverGSMWCDMAforcapacityextensionorserviceoptimization,HandoverWCDMA-GSMforcoverageextension,Antennasharingandco-locatedsitescouldbepreferable.,Co-existingTDD&FDDmodes-UTRATDDmode,SomekeyparametersfortheUTRAFDDandTDDmodes,Ratherlowspreadingfactorsmakesitinadequatetoreuseallthetimeslotsinallthecells.Thatis,networkmustcontrolwhichslotsanddirectionsareusedinwhichcells.,Notasfastastofollowfastfadingpattern!,Co-existingTDD&FDDmodes-ExampleofTDDRLBuplink/downlink,GreaterEb/NodifferencebetweenwithorwithoutRxD!,SmallerMaxpathlossthanthatofFDDscenarioTDDcellshavesmallerradius!,Co-existingTDD&FDDmodes-TDD/TDDinterference,InterferencescenariosTDD-TDDInterferencescenarios/solutionsMStoMSinterference-whenMS1istransmittingwhileMS2isreceiving,especiallyatcellborders.Cannotbeavoidedbynetworkplanning,butmaybenefitfromDCAandradioresourcemanagementPowercontrolBStoBSinterference-whenBS1istransmittingwhileBS2isreceivingdependsheavilyonBSlocations.CouldbeavoidedbyprovidingsufficientcouplinglossbetweenbasestationsBSsbetterbesynchronizedandofsameasymmetry.,Co-existingTDD&FDDmodes-TDD/FDDinterference,TDD-FDDInterferencescenario