LTE初始接入流程及参数

LTERandomAccessProcedureIndex2RandomAccessProcedure13TypicalLTEProcedures

Auth/Identity(Option)AttachProcedure(PoweronAttachComplete)

InitialContextSetup

RRCConnectionEstablishment

RandomAccess

CellcampOnUEeNBMMEMasterInformationBlockPoweronSystemInformationRandomAccessPreambleRandomAccessResponseRRCConnectionRequestRRCConnectionSetupRRCConnectionSetupComplete(AttachRequest)InitialUEMessageRequest(AttachRequest)RRCConnectionReconfigurationRRCConnectionReconfigurationCompleteAuthenticationRequestAuthenticationResponseSecurityModeCommandSecurityModeCompleteIdentityRequestIdentityResponseS1AP:InitialContextSetupRequest(AttachAccept)UECapabilityEnquiryUECapabilityInformationSecurityModeCommandRRCConnectionReconfiguration(AttachAccept)SecurityModeCompleteRRCConnectionReconfigurationCompleteULNASTransfer(AttachComplete)S1AP:InitialContextSetupResponseULNASTransport(AttachComplete)S1AP:UECapabilityInfoIndicationS1AP:DLNASTransport(AuthenticationRequest)S1AP:ULNASTransport(AuthenticationResponse)S1AP:DLNASTransport(IdentityRequest)S1AP:ULNASTransport(IdentityResponse)SRB0SRB1eNbS1AP:UEIdentityMMES1AP:UEIdentityeNbS1AP:UEIdentityMMES1AP:UEIdentityeNbS1AP:UEIdentityeNbS1AP:UEIdentityMMES1AP:UEIdentitySRB2andDRBDLNASTransport(SecurityModeCommand)ULNASTransport(SecurityModeComplete)MOCProcedure

InitialContextSetup

RRCConnectionEstablishment

RandomAccessUEeNBMMERandomAccessPreambleRandomAccessResponseRRCConnectionRequestRRCConnectionSetupRRCConnectionSetupComplete(ServiceRequest)InitialUEMessageRequest(ServiceRequest)

Auth/Identity(Option)S1APInitialContextSetupRequestUECapabilityEnquiryUECapabilityInformationSecurityModeCommandRRCConnectionReconfigurationSecurityModeCompleteRRCConnectionReconfigurationCompleteS1APInitialContextSetupResponseSRB0SRB1SRB2andDRB

DedicatedE-RABSetupControlS1APE-RABSetupRequestS1APE-RABSetupResponseRRCConnectionReconfigurationRRCConnectionReconfigurationCompleteDedicatedRB1……Option

DedicatedE-RABSetupControlS1APE-RABSetupRequestS1APE-RABSetupResponseRRCConnectionReconfigurationRRCConnectionReconfigurationCompleteDedicatedRB4ULInfoTransfer(BearerResourceAllocationRequest)ULNASTransport(BearerRARequest)IntraFrequencyHandover-intraeNBUEeNBMMES1-APINITIALUEMESSAGERRCConnectionReconfigurationMeasurementConfigurationRRCConnectionReconfigurationCompleteDefaultE-RABestablishmentandsecurityactivationMeasurementReportHODecisionRRCConnectionReconfigurationRandomAccessPreambleRandomAccessResponseRRCConnectionReconfigurationCompleteMeasurementConfiguration,MobilityControlInformation(RAPreambleIndex)RadioResourceConfigurationDedicated,

Securityinformation,UERelatedInformation(C-RNTI)ReleaseUEassociatedresourcesinthesourcecellRrcIntraEnbHo

T304

SwitchDLtoTargetcellStartreceivingULinTargetcellStartRRCintegrityprotectionwithnewkeyStartRRCandUPULdecipheringwithnewkeysStartRRCandUPDLcipheringwithnewkeysStarttransmittingDLintargetcellStartRRCintegrityprotectionwithnewkeyStartRRCandUPULcipheringwithnewkeysC-RNTI5eventsand2formsforrandomaccessprocedureInitialaccessfromRRC_IDLEAfterhandover,inthetargetcellULdataarrivalduringRRC_CONNECTEDDLdataarrivalduringRRC_CONNECTEDRRCConnectionRe-establishmentRandomAccessprocedureContentionbased(4steps)(5events)Non-contentionbased(3steps)(handoverandDLdataarrival)ContentionbasedorNon-contentionbasedduetoWhetherUEcanlistenPDCCH,andacquireradioresourcefromeNBforuplinktransformCONTENTIONBASEDRANDOMACCESSPROCEDURE:4stepsUEeNBMessage1:RandomAccessPreambleMessage2:RandomAccessResponseMessage3:ScheduledTransmission(UseHARQ)Message4:ContentionResolution(UseHARQ)PRACH:RA-RNTI（5bits）Preamblesequenceselect[0,numberOfRAPreambles]PDCCH,PDSCH:RA-RNTI,TemporaryC-RNTI,TA,ULGrantraResponseWindowSize

3thsubframePUSCH:TemporaryC-RNTI,UEidentifier(S-TMSI/Randomnumber)maxHARQmsg3TxpreambleTransMaxPDCCH,PDSCH:TemporaryC-RNTI,UEidentifier(S-TMSI/RN)maximumNumberOfDLTransmisionsRACHMessage4macContentionResolutionTimerPromoteTemporaryC-RNTItoaC-RNTIRadioResourceandparametersinSIB26RBs，1subframeRBG0,4RBsHybrid-AutomaticRepeatRequest(H-ARQ)Hybrid-AutomaticRepeatRequest(H-ARQ)reducesthedelayandincreasestheefficiencyofretransmissiondataSub-framenumberofRACHmessages1-3inTDDTDDFrameStructure(onlyconfig1,2aresupported)

Sub-framenumbersofRACHmessagesinTDDUEeNBMessage1Message2Message37ms7msRandomAccessPreamblemessageRAP选择Zadoff-Chu序列的原因

具有很好的检测性能，包括较高的检测概率与较低的误检概率

正交序列的数量足够多，保证足够低的用户冲突碰撞概率

能够检测到TA信息，要求序列在一定带宽内具有良好的相关性具有较低的峰均比特性Zadoff-Chu序列介绍目前RandomAccessPreamble只支持格式0与格式4.对于格式0，共有838个根ZC序列,每个根Zadoff-Chu序列的长度Nzc为839;对于格式4,共有138个根ZC序列,每个根Zadoff-Chu序列的长度Nzc,为139一个根Zadoff-Chu序列通过循环移位,可获得多个正交的序列.循环移位大小Ncs决定了一个根ZC序列能产生多少个正交的序列,不同根Zadoff-Chu序列通过循环移位得到的序列并不一定正交一个LTE小区最多64个RandomAccessPreamble序列，来源于一个根Zadoff-Chu的循环移位或者多个根Zadoff-Chu序列的循环移位循环移位Ncs的设置小区半径越大，信号时延扩展越大，需要较大的循环移位Ncs，每个根ZC产生的正交序列会较少；而RACH负荷较高的小区需要较小的循环移位Ncs来产生较多正交的序列，小区半径受限PreambleformattransmissionwindowdurationMaximumcellradius01subframe14.53km12subframe77.34km23subframe29.53km34subframe100.16km4upPts1.4kmZadoff-Chu长度循环移位大小Ncs取值ZC序列经过循环移位获得正交序列数ZC根序列数量8391364.518392632.32839521648398310783910488RandomAccessFailure（FromUEView）UEMessage2:RandomAccessResponseraResponseWindowSizeexpiredMessage1:RandomAccessPreambleeNBUEMessage2:RandomAccessResponseMessage3:ScheduledTransmissionMessage4:ContentionResolutionmacContentionResolutionTimerexpiredMessage1:RandomAccessPreambleeNB??maxHARQmsg3TxPreambleTransMaxMessage1:RandomAccessPreambleMessage2:RandomAccessResponse?…..PL+preambleInitialReceivedTargetPower+PreambleTransmitPowerStepSize

…..Message3:ScheduledTransmissionMessage4:ContentionResolution?P0-Preamble+deltaPreambleMSG3+3dBPL+preambleInitialReceivedTargetPowerContentionResolutionfailsMaxHARQmsgTxReachedRandomAccessResponsefailsPreambleTransMaxReachedFailureToSetupTheRRCConnection（FromeNBView）Message3：RRCConnectionRequestUEMessage2:RandomAccessResponseMessage1:RandomAccessPreambleeNBRRCConnectionRejectWaitTimeeNBfailuretosetuptheRRCConnectionTheUEbacksoffforacertainperiodoftimeselectedrandomlyintherange[0,rABackoff],thenrestartstheprocedureRRCProcedureDefenceTimerExpiredIftheeNBdoesnotreceiveRRCCONNECTIONSETUPCOMPLETEbeforethetimerexpiry,theRRCconnectionisconsideredasfailedMessage3：RRCConnectionRequestUEMessage2:RandomAccessResponseMessage1:RandomAccessPreambleeNBRRCConnectionSetupRRCProcedureDefenceTimerExpiredRRCConnectionSetupCompleteMessage3PowerMPUSCH(I):

isthebandwidthoftheMsg3transmissioninsubframeiexpressedinnumberofresourceblocksP0_PUSCH(2)=P0_UE_PUSCH(2)+P0_NORMINAL_PUSCH(2)P0_NORMINAL_PUSCH(2)=P0_PREAMBLE+ΔPREAMBLE_Msg3=P0_PREAMBLE+3

α(2)=1ΔTF(i)=0f(0)=

(Npreamble-1)*ΔRAMP_UP+(TPCinMsg2)

=4dBConfiguredbytPCRACHMsg3

Msg1andMsg3POWERMessage1Power

P0_PREAMBLE=SINRTarget+IN+MARGIN(configuredbypreambleInitialReceivedTargetPower)

CONTENTIONBASEDRANDOMACCESSPROCEDURE:3stepsUEeNBMessage0(PDCCHOrder):RAPreambleAssignmentMessage1:RandomAccessPreambleMessage2:RandomAccessResponsesourceeNB(handover)orPDCCH(dataarrival)RAPreambleindex<>0PRACH:RA-RNTIPDCCH,PDSCH:RA-RNTI,TA,

ULgrant[64-numberOfRAPreambles,numberOfRAPreambles]receptionOfMsg1TimerPdcchOrderTransMaxRandomAccessFailureAfteracertainnumberofattempts(configuredbyparameterpreambleTransMax),

theMAClayerdeclarestheRandomAccessprocedureasfailedpreambleTransMaxParametersParameterObjectRange&UnitClass/CategoryDefaultValuecontentionFreeRACHenabledENBEquipment/Enb/LteCell/CellRachConfBooleanTrue/FalseB--Cell/FixedTRUEnumberOfRAPreamblesENBEquipment/Enb/LteCell/CellRachConfInteger[56..64]step=4B--Cell/Fixed56raResponseWindowSizeENBEquipment/Enb/LteCell/CellRachConfEnumerate{sf2(0),sf3(1),sf4(2),sf5(3),sf6(4),sf7(5),sf8(6),sf10(7)}B--Cell/FixedSf8preambleTransMaxENBEquipment/Enb/LteCell/CellRachConfEnumerate{n3(0),n4(1),n5(2),n6(3),n7(4),n8(5),n10(6),n20(7),n50(8),n100(9),n200(10)}C--Immediate-propagation/Fixedn3(0)macContentionResolutionTimerENBEquipment/Enb/LteCell/CellRachConfEnumerate{sf8(0