释放流程及异常原因分析V2.ppt

释放流程及异常释放原因分析 2016 05张恒 概述 主要内容说明 本次主要讨论的内容 LTE业务释放类型及相应信令流程的详解 相关的counter触发定义 以及异常问题分析 通过对这些内容的梳理和讨论 能够了解LTE释放的理论知识 并且在日常KPI和Log分析方面 提供帮助 释放流程及异常释放原因分析 主要内容 业务承载类型及业务建立过程业务释放类型及相应流程 原因E RABreleaseUEcontextreleaseRRCconnectionrelease异常释放的触发情景详解UEinitiateddropeNBinitiateddrop异常释放relatedCounterTriggersNetwork FieldKPI及Drops分析Summary 业务承载类型 LTE业务承载类型 LTE的业务承载类型分为默认承载 专用承载两种 默认承载 UE开机时获得承载 一定是MME发起的业务 优先级特别低 NonGBR 专用承载 一定是由PGW触发建立的 一个UE可以有不同的专用承载 GTPvariant EPSbearerterminationinPGW SRB与默认 专用承载关系 业务承载类型 无线承载分类 SRB SignallingRadioBearers SRBs 的定义是 仅用于传输RRC和NAS消息的RB RadioBearer DRB DataRadioBearer 用于传输业务数据的无线承载 与S1 U承载共同组成E RAB 分为UM AM两种 业务承载类型 UEcontext及E RAB E RAB UE至SGW之间的承载 E RAB是指用户平面的承载 由S1 U承载和DRB DataRadioBearer 数据无线承载 串联而成 进入LTE系统的业务数据主要通过E RAB进行传输 因此对于LTE 业务管理主要是在E RAB层次上进行的 一个UE可以有多个E RAB 目前最多支持8个EPS承载 个AMDRB 3个UMDRB 在应用上 E RAB常出现于性能指标的统计中 例如 E RAB建立成功率 E RAB建立成功指eNodeB成功为UE分配了通信通道的无线资源和用户面的无线承载 所以这个指标反映了eNodeB或小区接纳业务的能力 可以用来考虑系统负荷情况 业务承载类型 UEcontext及E RAB UEcontext IncludingE RABcontext securitycontext roamingrestriction UES1signallingconnectionID s etc intheeNB 在源eNB的UE上下文中还包含了与漫游和接入限制有关的信息 InitialUEcontext只能由MME发起 一个UE只有一个UEcontext 一个eNBUEcontext是eNB内和一个处于激活状态的UE相关联的一个信息块 这块信息是为了维持E UTRAN提供给这个激活态UE的服务所必须的信息 eNBUEcontext是在UE迁移到激活状态之后开始建立的 或者 eNBUEcontext是在切换目标eNB完成切换资源分配 切换准备阶段 之后开始建立的 RRCconnection层三信令连接 UE保持非IDLE的必须连接 一个UE只有一个RRCconnection 一旦连接释放 UE所有业务释放 并进入RRC IDLE态 LTE完整业务流程 默认承载建立信令流程 Attach Steps RandomAccessInitialNASmsgNASsecurityS1initsetupRRCsec UEcapSRB2 DRBsetupNASreply LTE完整业务流程 RA及RRC连接建立流程 SRB0 RRCconnectionrequest RRCconnectionsetup 消息中包含SRB1建立的相关信息 SRB1 RRCconnectionsetupcomplete LTE完整业务流程 专用承载建立流程 DedicatedBearerEstablishment E RAB建立 释放流程及异常释放原因分析 主要内容 业务承载类型及业务建立过程业务释放类型及相应流程 原因E RABreleaseUEcontextreleaseRRCconnectionreleaseAbnormalrelease的触发情景详解UEinitiateddropeNBinitiateddrop异常释放relatedCounterTriggersNetwork FieldKPI及Drops分析Summary 业务释放类型 release 根据业务承载类型 业务释放过程也分为三类 E RABreleaseThepurposeoftheE RABReleaseprocedureistoenablethereleaseofalreadyestablishedE RABsforagivenUE E RAB释放后 UE仍然可以处于ECM CONNECTED状态 UEcontextreleaseIftheeNBwantstoremoveallremainingE RABs e g foruserinactivity theUEContextReleaseRequestprocedureshallbeusedinstead 当UE回到ECM IDLE状态时 MME向eNodeB发UECONTEXTRELEASE消息 收到这条消息后 eNodeB删除eNBUEcontext MME继续保留MMEUEcontext 业务释放类型 release 根据业务承载类型 业务释放过程也分为两类 RRCconnectionreleaseThepurposeofthisprocedureistoreleasetheRRCconnection whichincludesthereleaseoftheestablishedradiobearersaswellasallradioresources RRC连接释放后 UE进入RRC IDLE状态 E RABrelease 释放类型 E RABrelease 根据3GPP定义 3GPPTS36 413 E RABrelease过程分为两大类 ENodeBInitiatedMMEInitiatedE RAB管理的相关信息都embed在context管理信令中 MMEInitiated ENodeBInitiated 释放流程信令详解 E RABrelease MMEInitiated E RABreleasecommand消息内容 shallcontaintheinformationrequiredbytheeNBtoreleaseatleastoneE RABintheE RABToBeReleasedListIE IfaNAS PDUIEiscontainedinthemessage theeNBshallpassittotheUE E RABToBeReleasedListIE theUEAggregateMaximumBitRateIE E RABreleaseresponse消息内容 AlistofE RABswhicharereleasedsuccessfullyshallbeincludedintheE RABReleaseListIE AlistofE RABswhichfailedtobereleased ifany shallbeincludedintheE RABFailedtoReleaseListIE 释放流程信令详解 E RABrelease MMEInitiated eNB收到E RABRELEASECOMMAND后 eNB将会释放被请求的ERABs 对于每一个要释放的E RAB eNB会释放其相应的DRB和空口资源 TheeNBshallpassthevaluecontainedintheE RABIDIEreceivedfortheE RABtotheradiointerfaceprotocolforeachDataRadioBearertobereleased TheeNBshallreleaseallocatedresourcesonS1fortheE RABsrequestedtobereleased Networktriggered fromDeleteBearer 释放流程信令详解 E RABrelease eNBInitiated E RABRELEASEINDICATION消息内容 TheE RABRELEASEINDICATIONmessageshallcontainatleastoneE RABreleasedattheeNB intheE RABReleasedListIE UponreceptionoftheE RABRELEASEINDICATIONmessagetheMMEshallnormallyinitiatetheappropriatereleaseprocedureonthecorenetworksidefortheE RABsidentifiedintheE RABRELEASEINDICATIONmessage InteractionwithUEContextReleaseRequestprocedure IftheeNBwantstoremoveallremainingE RABs e g foruserinactivity theUEContextReleaseRequestprocedureshallbeusedinstead 释放流程及异常释放原因分析 主要内容 业务承载类型及业务建立过程业务释放类型及相应流程 原因E RABreleaseUEcontextreleaseRRCconnectionreleaseAbnormalrelease的触发情景详解UEinitiateddropeNBinitiateddrop异常释放relatedCounterTriggersNetwork FieldKPI及Drops分析Summary UEcontextrelease 释放类型 UEcontextrelease 根据3GPP定义 3GPPTS36 413 UEcontext过程同样分为两大类 ENodeBInitiatedMMEInitiatedThisprocedureisusedtoreleasethelogicalS1 APsignallingconnection overS1 MME andallS1bearers inS1 U foraUE TheprocedurewillmovetheUEfromECM CONNECTEDtoECM IDLEinboththeUEandMME andallUErelatedcontextinformationisdeletedintheeNodeB UEcontextrelease 释放的触发条件 UEContextReleaseRequest 该信令 使基站可以根据E UTRAN的需要 向MME请求UE associatedS1链接的释放 ENodeB发起的Contextrelease情况 Normalrelease UserInactivity CSFallbacktriggered UENotAvailableforPSService Inter RATRedirection TimeCriticalHandover HandoverCancelled Detach Abnormalrelease RadioConnectionWithUELost CSGSubscriptionExpiry Redirectiontowards1xRTT UnspecifiedFailure O MIntervention RepeatedRRCsignallingIntegrityCheckFailure etc ENodeBInitiated UEcontextrelease 释放的触发条件 UEContextReleaseCommand MMEInitiated 该信令 使MME在多种情形下 可以控制UE associated链接的释放 MME发起的Contextrelease情况 Normalrelease e g completionofatransactionbetweentheUEandtheEPC orcompletionofsuccessfulhandover orcompletionofhandovercancellation orreleaseoftheoldUE associatedlogicalS1 connectionwhentwoUE associatedlogicalS1 connectionstowardthesameUEisdetectedaftertheUEhasinitiatedtheestablishmentofanewUE associatedlogicalS1 connection ortheUEisnolongerallowedtoaccesstheCSGcell i e theUEbecomesanon memberofthecurrentlyusedCSGcell Abnormalrelease LoadBalancingTAURequired authenticationfailure detach notallowedCSG celetc UEcontextrelease 正常释放原因信令实例 eNBinitiated MMEinitiated MMEinitiated eNBinitiated eNBinitiated UEcontextrelease 异常释放原因信令实例 MMEinitiated eNBinitiated MMEinitiated MMEinitiated MMEinitiated 释放流程信令详解 UEcontextrelease ENodeBInitiated TheUECONTEXTRELEASEREQUESTmessageshallindicatetheappropriatecausevalue e g UserInactivity RadioConnectionWithUELost CSGSubscriptionExpiry CSFallbacktriggered Redirectiontowards1xRTT Inter RATRedirection UENotAvailableforPSService fortherequestedUE associatedlogicalS1 connectionrelease InteractionswithUEContextReleaseprocedure TheUEContextReleaseprocedureshouldbeinitiateduponreceptionofaUECONTEXTRELEASEREQUESTmessage 释放流程信令详解 UEcontextrelease ENodeBInitiated Transitionduetoinavtivity UEconsumeslessbatterypowerinidlemode LessactiveUeswhichnetworkhastohandle Fastgoingtoinactivityhasdrawbackoflongerconnectionsetuptime moretransitionsidletoconnected 释放流程信令详解 UEcontextrelease ENodeBInitiated 释放流程信令详解 UEcontextrelease MMEInitiated TheUECONTEXTRELEASECOMMANDmessageshallcontaintheUES1APIDpairIEifavailable otherwisethemessageshallcontaintheMMEUES1APIDIE TheMMEprovidesthecauseIEsetto LoadBalancingTAURequired intheUECONTEXTRELEASECOMMANDmessagesenttotheeNBforallloadbalancingandoffloadcasesintheMME MMEUES1APisreleasedwhentheS1connectionisreleased nexttimeanewvalueisassigned eNBUES1APisreleased 释放流程信令详解 UEcontextrelease MMEInitiated UponreceptionoftheUECONTEXTRELEASECOMMANDmessage theeNBshallreleaseallrelatedsignallinganduserdatatransportresourcesandreplywiththeUECONTEXTRELEASECOMPLETEmessage IncaseofeNBsupportingL GWfunctionforLIPAoperation theeNBshallalsoreleasethenodeinternaltunnelresources 释放流程信令详解 UEcontextrelease MMEInitiated 释放流程信令详解 UEcontextrelease MMEInitiated 释放流程及异常释放原因分析 主要内容 业务承载类型及业务建立过程业务释放类型及相应流程 原因E RABreleaseUEcontextreleaseRRCconnectionreleaseAbnormalrelease的触发情景详解UEinitiateddropeNBinitiateddrop异常释放relatedCounterTriggersNetwork FieldKPI及Drops分析Summary RRCconnectionrelease 释放类型 根据3GPP定义 3GPPTS36 331 E UTRANinitiatestheRRCconnectionreleaseproceduretoaUEinRRC CONNECTED RRCconnectionreleaseThepurposeofthisprocedureistoreleasetheRRCconnection whichincludesthereleaseoftheestablishedradiobearersaswellasallradioresources RRCconnectionreleaserequestedbyupperlayersThepurposeofthisprocedureistoreleasetheRRCconnection AccesstothecurrentPCellmaybebarredasaresultofthisprocedure RRCconnectionrelease 释放原因 ThereleaseoftheRRCconnectionisinitiatedbyE UTRAN Theproceduremaybeusedtore directtheUEtoanotherfrequencyorRAT InexceptionalcasestheUEmayaborttheRRCconnection i e movetoRRC IDLEwithoutnotifyingE UTRAN 释放流程及异常释放原因分析 主要内容 业务承载类型及业务建立过程业务释放类型及相应流程 原因E RABreleaseUEcontextreleaseRRCconnectionreleaseAbnormalrelease的触发情景详解UEinitiateddropeNBinitiateddrop异常释放relatedCounterTriggersNetwork FieldKPI及Drops分析Summary Calldrop WhoInitiatesDrops UE MMEoreNB UEcan initiateadrop bystartingRRCConnectionRe establishmentNote besidesRLFalsoothercausescantriggerRRCConnRe EstablishmenteNBcaninitiateabnormalS1 RRCreleaseduetoRadionetworklayerproblem TAtimer RLF PDCCHOrderfailure Transportnetworklayerproblem GTP Uerror Trelocexpiry PathSwitchproblem OtherabnormalcauseMMEcaninitiateabnormalS1 RRCreleaseduetoRadionetworklayerproblemOtherabnormalcause UEinitiateddrop RLF WhenUEisinRRC CONNECTEDandRRCsecurityisactive itcantriggerRRCConnectionRe establishmentuponT310expiryuponreachingthemaximumnumberofULRLCretransmissionsuponhandoverfailure T304expiry uponnon HOrelatedrandomaccessproblemIfsuccessful RRCConnRe EstablishmentreconfiguresSRB1toresumedatatransferofRRCmsgsre activatesRRCsecuritywithoutchangingalgorithmsNOTE DRBshouldbere configuredafterSRB1NOTE ifUEisinRRC CONNECTEDwhileRRCsecurityisnotactive UEgoestoRRC IDLE performscellreselectionandTAU UEinitiateddrop RLFduetoT310ExpiryatUE UEinitiateddrop RLFduetoMaximumULRLCRe TxReached fromRRCConnectionReconfiguration drb ToAddModListdrb ToAddModListvalue1drb Identity 1rlc Configamul AM RLCt PollRetransmit ms40pollPDU p32pollByte kB25maxRetxThreshold t8 UEinitiateddrop RLFduetoHOFailure fromRRCConnectionReconfiguration mobilityControlInfotargetPhysCellId 33t304 ms1000newUE IdentityBin 14EB 5355 UEinitiateddrop RLFDuetoNon HORandomAccessFailure Non HOrandomaccess meansPDCCHorder triggeredRARandomAccessSchedulingRequest 释放流程及异常释放原因分析 主要内容 业务承载类型及业务建立过程业务释放类型及相应流程 原因E RABreleaseUEcontextreleaseRRCconnectionreleaseAbnormalrelease的触发情景详解UEinitiateddropeNBinitiateddrop异常释放relatedCounterTriggersNetwork FieldKPI及Drops分析Summary eNBinitiateddrop RLF eNBcandropthecallduetofollowingtriggerseNB detectedradiolinkproblemsPUSCHRLFCQIRLFAck NackRLFPDCCHOrderfailureSRSRLFTAtimerexpiryMaximumRLCretransmissionsexceededGTP Ufailure eNBinitiateddrop RadioLinkProblemDetectionateNB eNBradiolinkproblemdetectionmechanismsareNSN internallyspecifiedMultiplemethods called linkmonitors aredefinedtodetectaradiolinkproblemintheeNB Whenonelinkmonitordetectsaproblem itisreallyaradiolinkproblemevenifotherlinkmonitorshavenotyetindicatedanything Eachlinkmonitorhasitsinternalcriteriatodecidewhenradiolinkproblemisflaggedandde flagged radiolinkrecovers IftheRLPpersistslongerthanT RLF RRC S1releaseistriggeredT RLF t310 t311 eNB internaltimer Linkmonitors UplinkPUSCHDTXdetectionforscheduleduplinkdataCQIDTXdetectionforperiodicCQIreportsinPUCCHandPUSCHUplinkAck NackDTXdetectionfortransmitteddownlinkdataPDCCHOrderRLFSRSDTXdetection TD LTE eNBinitiateddrop 1 PUSCHRLF RlsCause PuschRlf ON WhenUEisscheduledforPUSCHtransmission eNBexpectstoreceiveULtransmissiononthescheduledPRBsIfsignalfromUEcannotbedetectedatall PUSCHDTXisdeclaredNOTE ThecasewhereULTBSisreceivedbutitfailsCRCcheckisnotDTX it saNACK DTXPUSCHindicationisprovidedbytheULphysicallayer TheresultisreceivedbyLTEMACinreliableULtransmissionFlagparameter Bothcounter basedandtimer basedRLFdetectionissupportedTimer basedPUSCHRLFdetection If DTX isreceivedonthePUSCHforaconfigurableperiodoftime rlpDetMaxTimeUl PUSCHRLFissetonCounter basedPUSCHRLFdetection If DTX isreceivedonthePUSCHforaconsecutivenumberoftimes rlpDetMaxNoUl PUSCHRLFissetonTherecoveryoftheradiolinkisindicatedwhenforaconfigurablenumberofcontiguousULresourceassignmentsdataisdetectedonPUSCH ACKorNACKreceived DefinedbyparameterrlpDetEndNoUl eNBinitiateddrop 1 PUSCHRLF RlsCause PuschRlf Counter basedRLFDetectionExample T RLF T310 T311 32 vendor fileparametersinthisexample eNBinitiateddrop 2 PeriodicCQIRLF RlsCause CqiRlf ON TheeNBsupportsCQIDTXdetectionforperiodicCQIreportsonPUCCHandPUSCH IfMAClayerreceivesnCqiDtxconsecutivereportsfromULPHY theMACdeclaresCqiRLF ONIftheMAChassetCqiRLF ONforaspecificUEandnCqiRecconsecutiveCQIreportsareagaindetectedsuccessfullyforthatUE theMACsetsCqiRLF OFFTheparametersnCqiDtxandnCqiRecareinthevendor specificparameterfileForbothPUSCHandPUCCHtheperiodicCQIisencodedusingaReedMullerblockcodeandcomesalongwithoutanyCRC Hence theULPHYindicatesaDTXdetectionforperiodicCQIreportsonPUCCHorPUSCHwheneverareportisconfiguredbutnoreliabletransmissionfromtheUEcouldbedetected SotheoutputofthedetectorshallbeeitherthedetectedCQIreportoraDTXindication NOTE CQI RLFdetectiondoesnotapplytoaperiodicCQIreportonPUSCH eNBinitiateddrop 2 PeriodicCQIRLF RlsCause CqiRlf Example 61 vendor fileparametersinthisexample T RLF T310 T311 eNBinitiateddrop 3 Ack NackRLF RlsCause AckNackRlf ON AfterDLscheduleddata eNBexpectsHARQACKorNACKonPUCCHorPUSCHatknownULTTITimer basedACK NACKRLFdetection IfACK NACK DTX isreceivedforaconfigurableperiodoftime rlpDetMaxTimeDl ACK NACKRLFissetonCounter basedACK NACKRLFdetection IfACK NACK DTX isreceivedforaconsecutivenumberoftimes rlpDetMaxNoDl ACK NACKRLFissetonTherecoveryoftheRLFisindicatedwhenforaconfigurablenumberofcontiguousACK NACKopportunitiesACKorNACKisdetectedonPUSCHorPUCCH noDTX DefinedbyparameterrlpDetEndNoDl eNBinitiateddrop 4 PDCCHOrderRLF IfthereDLdataineNBbufferandUEisout of sync UEmustbebroughtbacktoin sync timealigned withaRAprocedurebeforeDLdatacanbesentSignalingofdedicatedRApreambleviaPDCCH so calledPDCCHorder isdoneusingDCIformat1AIncasethatPDCCHorderfailsforaUE i e notransmissionofassigneddedicatedpreambledetectedbyeNodeB ornomsg3transmission thePDCCHordershallberepeatednoRepPdcchOrdertimes R Dconfigurableparameter range0 3 default1 againusingtheselectedpreambleandconsideringDRXstatusoftheUEaccordingly FinalfailureofthePDCCHorderprocessshallbeindicatedasradiolinkproblemtohigherlayerswithcause PDCCHorderfailure IfinactivitytimerfortheUEhasexpiredthenthereisnoT RLFtimerinvolved S1andRRCreleasedimmediately eNBinitiateddrop 5 SRSRLF TheeNBsupportsSRSDTXdetectionforradiolinkproblemdetectionIfMAClayerreceivesnSrsDtxconsecutivereportsfromULPHY theMACdeclaresSRSRLFIftheMAChassetSRSRLFforaspecificUEandnSrsRecconsecutiveSRStransmissionsaresuccesfullydetectedtheUE theMACsetsSRSRLFOFFHencetheSRSRLFhassimilarmechanismasCQIDTXRLFTheparametersnSrsDtxandnSrsRecareoperator configurableP7defaultvaluesfromRL15SCF 81 eNBinitiateddrop WhenisDrop RRC S1release TriggeredbyeNB 3GPPdoesnotspecifyeNBradiolinkfailures butNSNeNBmimicsthebehaviouroftheUERLFspecifiedin3GPP Whenaradiolinkproblemisdetected aneNB internaltimer T RLF isstarted ThetimerT RLFisstoppedwhenincaseofradiolinkfailurerecovery ForagivenUE T RLFisstartedwhenanyofthePUSCHRLF CQIRLF SRSRLForAckNackRLFissettoONstateForagivenUE T RLFisstoppedonlyifallRLFsareOFFWhenthetimerT RLFexpires theUEisreleasedfromtheeNBusingeNBinitiatedS1release RRCconnectionrelease calldropT RLF T310 T311 eNBinitiateddrop RLFTriggeringbyeNB Signalling OnlyL2AckneededforsuccessfulRRCConnRelease IfL2AcknotreceivedaftertimertL2AckRrcRelexpires def 800ms RRCisreleasedanyway NOTE NoRLCAckneededforRRCConnectionRelease NoreTxforRRCConnectionRelease eNBinitiateddrop In SyncandOut Of SyncStates Overview RRCconnectedsubstates ULin syncandULout of sync UplinkRASRordownlinkPDCCHordertobringUEbackin sync eNBinitiateddrop TATimerExpiryatUE AsUEdetectsOut of SyncstatususingaTimingAlignmentTimer thetimershallbestartedorrestartedwheneveraninitialTAoraTAupdatecommandisreceived see 3GPP 36 321 section5 2 Ifthetimerexpires theUEdetectsout of syncstatus 3GPPTS36 321 WhentimeAlignmentTimerexpiresatUE UEMAClayershall flushallHARQbuffers notifyRRClayertoreleasePUCCH SRS clearanyconfigureddownlinkassignmentsanduplinkgrants3GPPTS36 331 UponreceivingaPUCCH SRSreleaserequestfromMAClayer theUERRCshall releaseperiodicCQIreportingconfig ieitstopsCQIreportingonPUCCHreleaseSchedulingRequestConfig eNBinitiateddrop In Sync Out Of SyncHandlinginRL30 ParameterLNCEL applyOutOfSyncStatedefineshoweNBhandlesTAexpiryextendedDrxOnly onlyUEsbeingconfiguredwithextendedsettingsforthelongDRXcyclearenotdroppedifTAtimerexpires default allDrx allUEsbeingconfiguredforDRXprovidedthatappliedDRXprofileallowsarenotdroppedifTAtimerexpiresallUEs allUEsindependentlyofDRXconfigurationprovidedthatbearercombinationallowsarekeptRRCConnectedevenifTAtimerexpires IfDRXisnotusedatall thensetting allUEs shouldbeusedtopreventeNBdropsduetoTAtimerexpiry eNBinitiateddrop In SyncNormalCase ProceduredescribeshowanUEgetsbackintoULsynchronizationfromastateinwhichthetimealignmenthasbeenlosteNBdetectsthatthetimealignmentoftheUEisULout of sync e g expirationoftimealignmenttimer UEalsodetectsout of sync sametrigger andreleasesresourcesonPUCCHforCQIreportingandschedulingrequestIfeNBdetectsDLdata eitherdatatrafficorRRCsignalling eNBsendsaPDCCHorderforRAproceduretoUE DCI1Awithspecificcodepoint preferablynon contentionbasedRAdependingonpreambleavailability UEstartsarandomaccessprocedureeNBrecognizeswhenrandomaccessoftheUEwassuccessfulandUEULtimealignmentisback in sync IfUEdetectsULdata eitherdatatrafficorRRCsignalling UEstartsarandomaccessprocedure contention based eNBrecognizeswhenrandomaccessoftheUEwassuccessfulandUEULtimealignmentisback in sync eNBtriggerstheRRCprocedureRRCConnectionReconfigurationtoconfigure again thePUCCHresourcesforCQIreportingandschedulingrequestSameresourceusedforsimplificationbutcouldbeoptimizedoptionallyNote theRRCmessageRRCConnectionReconfigurationCompleteisalreadysentusingtheconfiguredPUCCHresourcesforschedulingrequest eNBinitiateddrop In SyncFailureCase ProceduredescribeshoweNBdetectsthatanUEhasbeenlost triggeredbydownlinktrafficeNBdetectsthatthetimealignmentoftheUEis out of sync e g expirationoftimealignmenttimer UEdetectsalsothatthetimealignmentisout of syncandreleasesitsPUCCHresourcesforCQIreportingandschedulingrequestand orUEdetectsaradiolinkfailureandmovestoRRC IDLEIfeNBdetectsDLdata eitherdatatrafficorRRCsignalling eNBsendsaPDCCHorderD