GSM无线部分试题和答案(eric)

分析题：1.ThereisaroamingcustomerfromHongKong,everytimehecomestomainland,hismobilewillcamponUnicom’snetworkfirst.ButhecanswitchthenetworktoCMCCmanuallyafterthemobile’sautomaticPLMNselection.Pleaseanalysethepossiblereason,andgiveoutatleast2solutions.(Pleasealsogiveoutthebackgroundsupporttheoryforyourreasons)可能原因1，机场移动信号覆盖较差低于-85dBm，但联通信号高于－85dBm；或者移动和联通电平都低于－85dBm，但是移动信号比联通还弱；可能原因2，机场移动和联通的信号都很强，但是由于用户原来在香港关机时使用的BCCH落在联通频点内方案1，把机场降落跑道的覆盖增强，把BCCH移动可用的最高端频点方案2，让用户把移动加入其优先选网列表中2.Inyouropinion,whatisapossibleexplanationforthedropratebeingsometimeshigheratnight?Howtoimproveit?Reason:1.lowerDL/ULwirelesssignalstrength2.worsespeechqualitybecauselowC/Iinlowsignalstrength.3.moreemergencyhandoverinindoorarearesultinmorehandoverlost4.badfrequencyplanningandneighborrelationplanning,suchaslessneighborrelationandSolution:1.improvesignalstrengthbyaddindoorsite,orrepeater,oraddnewmacrositeandsoon.2.ImproveC/Ibychangepowerandpowercontrolparameter.3.carefulcheckneighborrelationbycollectingnighthourdata,addnecessaryneighborrelation4.finetuningfrequency,reducefrequencyinterference5.reducenotneededhandover.6.IncreaseACCMIN3.WhenBTSoccur“Rxdiversitylost”alarm,whatarethemainreasonandhowtoimproveit?Reason:1.Antennafeederwrongconnected.2.RBSlinewrongconnected.3.DU/TRUhardwareproblem.4.驻波比问题Solution:1.Drivetesttoconfirmwhichcellshavewrongcoverageproblemtolocatedtheproblemcell.Ifithavewrongcoverage,ChecktheantennadirectionCheckallthejumpersandfeedersfromBTStoantennaandCheckallthelinesandconnectorsinBTS2.Ifnowrongcoverageproblem,plscheckTRUproblemorantennaRXproblem.4.PleasecompletethefollowingsignalingprocedureA.SubsequentHOfromMSCBtoMSCB’,MSCAisanchorMSCEndofthecallRELEASEMAP-SEND-END-SIGNALresponseBSSVLR-BMSC-B’VLR-B’BasicHOMSC-AMSC-BMAP-PREPARE-SUB-HOrequestMAP-PREPARE-HOrequestMAP-ALLOCATE-HO-NorequestMAP-SEND-HO-REPORTrequestMAP-PREPARE-HOresponseIAMMAP-SEND-HO-REPORTresponseACMMAP-PREPARE-SUB-HOresponseA-HO-COMMANDA-HO-DETECTMAP-PROCESS-ACCESS-SIGNALLINGrequestA-HO-COMPLETEMAP-SEND-END-SIGNALrequestANSWERRELEASEMAP-SEND-END-SIGNALresponseAMAPISUPA-HO-REQUIREDSubsequentHOB.MTBasicCallprocedure:MSCBSCBTSMSChannelRequest(RACH)4ChannelRequired5ChannelActivation6ChannelActivationAck7Immediate_AssigmentCommand8Immediate_Assigment(AGCH)9SABMPagingResponse(SDCCH)10PagingResponse(SDCCH)11PagingResponse12UA(SDCCH)13AuthenticationRequest14AuthenticationRequest(SDCCH)15AuthenticationReponse(SDCCH)16AutheicationReponse17CipheringModeCommand18CipheringModeCommand19CipheringModeCommand(SDCCH)20CipheringModeComplete(SDCCH)21CipheringModeComplete22TMSIReallocationCommand23TMSIReallocationCommand(SDCCH)24TMSIReallocationComplete(SDCCH)25TMSIReallocationComplete26Setup(SDCCH)28Setup27CallComfirm30CallComfirm(SDCCH)29AssignmentRequest31ChannelActivation32ChannelActivationAck33AssignmentCommand(SDCCH)34SABM(FACCH)35EstablishIndication36UA(FACCH)37AssignmentComplete(FACCH)38AssignmentComplete39RFChannelRelease40RFChannelReleaseAck41Alerting43Alerting(SDCCH)42Connect(SDCCH)44ConnectAck(FACCH)47ConnectAck46MeasurementReport(SACCH)48MeasurementReport49Disconnect(FACCH)50Disconnect51Connect45Release52Release(FACCH)53ReleaseComplete(FACCH)54ReleaseComplete55ClearCommand56ChannelRelease(FACCH)57DeactivateSACCH58DISC(FACCH)59UA(SACCH)60ReleaseIndication61RFChannelRelease62RFChannelReleaseAck63ClearComplete64SCCPRelease65SCCPReleaseAck66Paging1PagingCommand2PagingRequest3EstablishIndication