LTE典型信令过程.ppt

,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,LTE,典型信令过程,1,Software Architecture,2,3,类,NAS,信令流程,1.,会话管理相关,2.,位置管理相关,3.,鉴权管理相关,3,4,UE,eNB,MME,SGW,PGW,RRC:RRC Connection setup complete,NAS:Attach Request,NAS:PDN connectivity request,S1AP:Initial UE message,Authentication and NAS security procedure,HSS,S6a:Update Location request,S6a:Update Location answer,S11:Create bearer request,S5:Create bearer request,S5:Create bearer response,S11:Create bearer response,S1AP:Initial Context setup request,NAS:Attach accept,NAS:Activate Default EPS bearer request,NAS:Attach Request,NAS:PDN connectivity request,RRC:RRCConnectionReconfiguration,NAS:Attach accept,NAS:Activate Default EPS bearer request,RRC:RRCConReconfigComplete,S1AP:Initial Context setup response,RRC:UL information Transfer,NAS:Attach complete,NAS:Activate Default EPS bearer accept,S1AP:Uplink NAS Transport,NAS:Attach complete,NAS:Activate Default EPS bearer accept,5,UE initiated Detach Procedure,UE,eNB,MME,SGW,PGW,HSS,RRC:RRC Connection setup complete,NAS:Detach request,S1AP:Initial UE message,NAS:Detach request,Authentication and NAS security,S11:Delete session request,S5:Delete session request,S5:Delete session response,S11:Delete session response,S1AP:Downlink NAS transport,NAS:Detach accept,RRC:DLInformation transfer,NAS:Detach accept,Radio and S1 Release,S6a:TDelay purge timer expires,S6a:Purge UE request,S6a:Purge UE answer,6,UE Triggered Service Request Procedure,Initial UE Message,7,Network Triggered Service Request,8,TAU procedure,9,Inter MME-TAU-message flow,10,Handover,11,Handover Air Interface,TYPES OF HANDOVER,X2 Based Handover,:without SGW change and with SGW change,S1 Based Handover,:with eNB,MME and SGW change,12,X2 Handover,X2 is the interface between two eNBs and X2-AP is the protocols,used for communication over it.,The handover is directly performed between two eNodeBs.,Handover takes place when the eNB detects that UE can no longer,be served by it because of the power constraints.,The MME is only informed at the end of the handover procedure,once the handover is successful,The release of resources at the source side is directly triggered from,the target eNB.,13,RRC:Connection Reconfiguration Request,RRC:Connection Reconfiguration Complete,UE,S-eNB,T-eNB,MME,SGW,RRC:Measurement Control,X2AP:Handover Request,S11:Modify bearer request,S11:Modify bearer response,X2AP:SN Status Transfer,Sync,UL Allocation+TA for UE,UL Allocation,RRC:Measurement Report,Handover,Decision,X2AP:Handover Response,UE Detach from,old cell and sync,to new cell,S1AP:Path Switch Request,S1AP:Path Switch Response,X2AP:UE Context Release,End Marker,Switch,DL Path,Data Forwarding,Data Forwarding,End Marker,Flush,DL Buffer,14,S1 Handover,This type of handover takes place when there is no X2 connectivity,between source eNB and target eNB.,Both eNBs are served by different MMEs.SGWs can also be,different.,Source eNB is served by source MME and source SGW while target,eNB is served by target MME and target SGW.,Source and target MMEs can communicate over S10 interface.,All the handover decisions are taking place on S1 interface,its,called as S1 based handover.,15,UE,T-eNB,S-MME,T-MME,T-SGW,S10:Forward Relocation,Request,S11:Create Session Request,S11:Create Session Response,S1AP:eNB Status Transfer,S1AP:Handover Required,S1AP:Handover Request,UE Detach from old cell,and sync to new cell,S11:Modify Bearer Request,S1AP:UE Context Release Command,S-eNB,S-SGW,PGW,Handover Decision,S1AP:Handover Request Ack,S10:Forward Relocation,Response,S1AP:Handover Command,RRC:Connection Reconfiguration,RRC:Connection Reconfiguration Complete,S1AP:Handover Notify,S11:Modify Bearer Response,S5:Modify Bearer,Request,S1AP:UE Context Release Complete,S11:Delete Session Request,S11:Delete Session Response,S1AP:MME Status Transfer,S10:Forward SRNS,Context Notification,S10:Forward SRNS,Context Ack,S10:Forward Relocation,Complete,S10:Forward Relocation,Complete Ack,S5:Modify Bearer,Response,16,开始,17,Before the UE can do anything,a Radio Resource Control connection must be established.The RRC is a logical connection between the UE and E-UTRAN.There are two different RRC states:,RRC IDLE,RRC CONNECTED,18,RRC IDLE,This state indicates that there is no signaling radio bearer is established i.e.no RRC connection is established.,The UE is considered RRC_IDLE once it obtains the center frequency,reads the timing information,syncs to the eNodeB,and is ready to receive system broadcast information.,UE monitors a paging channel to detect incoming calls.,UE can performs neighboring cell measurements and measurement reporting.,19,RRC CONNECTED,This state indicates that there is signaling radio bearer established i.e.RRC connection is established.,Transfer of unicast data to/from an UE.,The UE Monitors control channels associated with the shared data channel to determine if data is scheduled for it.,The UE Provides channel quality and feedback information.,The UE Perform neighboring cell measurements and measurement reporting.,20,Radio Resource Control(RRC)protocol states,RRC_IDLE,state,vs.,RRC_CONNECTED,state,:,UE,does not have context,in eNB and only Signalling Radio Bearer 0(SRB0)is available for signalling between eNB and UE.,UE,has context,in eNB and communications between the UE and the network occurs on Signalling Radio Bearer 1(SRB1)and Signalling Radio Bearer 2(SRB2),UE generally has an id unique in the,tracking area,(,S-TMSI,=40 bits long);,UE generally has an id unique in the,eNB area,(,C-RNTI,=40 bits long,),UE may perform,cell selection/reselection,without involvement from eNB,;,UE can perform,handove,r(inter-eNB,intra-eNB,inter-RAT),under eNB control,;,UE can,request connection,establishment or re-establishment;eNB processes these requests,UE and eNBcan,transmit and/or receive data,to/from each other;,UE listens for,pages,at specific times(,DRX,configured by,MME);on request from the MME,eNB sends pages to the UE during UEs DRX up wake time,At PDCP/RLC/MAC level:,UE monitors L1/L2,control signalling channel to see if any transmission over the shared data channel has been allocated to the UE,UE reports channel quality,and feedback information to eNB,DRX/DTX period,can be,configured,according to UE activity level for UE power saving and efficient resource utilization.This is under control of eNB(RRC).,DRX=Discontinuous Reception;DTX=Discontinuous Transmission,21,Control plane:Radio-interface Related,PHY,MAC,RLC,PDCP,NAS,RRC,PHY,MAC,RLC,PDCP,RRC,NAS,UE,eNB,MME,L1,L2,IP,SCTP,S1-AP,L1,L2,IP,SCTP,S1-AP,eNB,MME,S1-MME,L1,L2,IP,SCTP,X2-AP,L1,L2,IP,SCTP,X2-AP,eNB,eNB,X2-C,Non-Access Stratum(NAS),:The key control interface between MME and UE,Radio Resource Control(RRC),:The main control interface between eNB and UE,Packet Data Convergence Protocol(PDCP),:Duplicate detection,ROHC,Radio Link Control(RLC),:Segmentation/re-assmebly,ARQ,acknowledge mode(AM)/un-acknowledged mode(UAM),etc,Medium Access Control(MAC),:Access the channel,Physical Layer(PHY),:Radio layer,eg modulation etc.,S1-AP,:S1-Application Protocol,X2-AP,:X2-Application Protocol,SCTP,:Stream Control Transmission Protocol,22,状态转换图,23,RRC,连接建立过程,24,UE,eNB,1.RRC,连接建立准备阶段,RRC,RRC,RRC,RRC,RRC,RRC,2.CCCH:RRC,连接请求,3.CCCH:RRC,连接建立,4.DCCH:RRC,连接建立完成,RRC,连接建立过程示意图,25,1.,准备阶段,(1)UE,用默认的物理信道参数来配置物理信道,(2)UE,为调度配置默认的半静态调度参数,(3)UE,配置默认的,MAC,主配置参数,(4)UE,配置,CCCH,参数,(5)UE,设置上行对齐定时器参数,2.,发,RRC,连接请求阶段,(1)UE,通过接入过程接入,E-UTRAN,获得在,UL_SCH,信道上传数据的许可,(2),设置,UE,标识,(ue-Identity):S-TMSI,或在,02,40,-1,之间任选一个数,(3),根据高层提供的,RRC,建立原因填写原因,(establishmentCause,信元,),(4),通过,PUSCH/UL_SCH/CCCH,向,E-UTRAN,发,RRC,连接请求消息,消息中携带,UE,标识和建立原因,3.,接收响应阶段,E-UTRAN,通过,PDSCH/DL_SCH/CCCH,想,UE,发,RRC,连接建立消息。,UE,收到,RRC,连接建立消息后，根据消息中的信元进行以下操作：,（,1,）根据,radioResourceConfigDedicated,信元进行无线资源配置过程,（,2,）填写,RRC,连接建立完成消息,4.,设置完成阶段,UE,通过,PUCH/UL_SCH/DCCH,向,E-UTRAN,发,RRC,连接建立完成消息,进入,RRC,连接状态,结束本次,RRC,连接建立过程,26,An example of a possible connection flow,UE,eNB,MME,Power ON,measurements,cell selection,BCCH/BCH:,MasterInformationBlock,BCCH/BCH:,SystemInformation,(,SIB-1),BCCH/BCH:,SystemInformation,(,SIB-2),RACH:preamble_id,PDCCH:UL grant,CCH:SRB0:,RRCConnectionRequest,(S-TMSI),CCH:SRB0:,RRCConnectionSetup,(S-TMSI,C-RNTI),DCCH:SRB1:,RRCConnectionSetupComplete,(C-RNTI,NAS_info),S1:INITIAL UE MESSAGE,S1:INITIAL CONTEXT,SETUP REQUEST(UE cap),DCCH:SRB1:,Security Mode Command,DCCH:SRB1:,Security Mode Complete,DCCH:SRB1:,RRCReconfigurationRequest,DCCH:SRB1:,RRCReconfigurationComplete,27,Random Access Procedure Contention Based(Initial Access Example),The four steps of the RACH procedures are:,1)(MSG.1)Random Access Preamble on RACH in uplink:,6 bits to carry:a 5 bit random ID,and 1 bit to indicate information on size of message 3 limited by radio conditions.,2)(MSG.2)Random Access Response in downlink:,semi-synchronous(within a flexible window)with message 1;,No HARQ;,Sent on DL-SCH,and intended for one or multiple UEs,3)(MSG.3)RRC Connection Request in uplink:,Uses HARQ;,RLC TM:no segmentation;,If the size of the message allows it,the,initial NAS message(or something allowing to build the initial NAS message in eNB)can be included;,Conveys UE identity,at least NAS UE identifier(initial access),or C-RNTI(other cases),4)(MSG.4)RRC Contention Resolution on DL-SCH:,Not synchronous with message 3.,HARQ is applied;,UE identity,as provided in message 3 is echoed in,RRC Contention Resolution message,HARQ feedback is transmitted only by the UE which detects its own UE identity,28,RRC,连接释放过程,由,E-UTRAN,发起,要求一个处于,RRC,连接状态的,UE,释放,RRC,连接,包括释放已建立的无线承载,(RB),和所有无线资源,RRC,连接重配置过程,E-UTRAN,通过向,UE,发,RRC,连接重配置消息,发起,RRC,连接重配置过程。当要求建立，修改，释放,RB,，或进行切换，或建立，修改，释放测量时，使用,RRC,连接重配置过程来修改,RRC,连接。,RRC,连接重配置消息中包括测量配置，移动控制，无线资源配置（包括,RB,，,MAC,主配置和物理信道配置）等消息以及所有相关的专用,NAS,信息和安全配置信息。,RRC,连接重配置消息以及,RRC,连接重配置完成消息使用,SRB1,且承载在,DCCH,逻辑信道上,29,E-UTRAN,附着,30,UE,eNB,MME,SGW,PGW,1.RRC:RRC Connection setup complete,NAS:Attach Request,NAS:PDN connectivity request,2.S1AP:Initial UE message,3.Authentication and NAS security procedure,HSS,4.S6a:Update Location request,5.S6a:Update Location answer,6.S11:Create bearer request,7.S5:Create bearer request,8.S5:Create bearer response,9.S11:Create bearer response,10.S1AP:Initial Context setup request,NAS:Attach accept,NAS:Activate Default EPS bearer request,NAS:Attach Request,NAS:PDN connectivity request,11.RRC:RRCConnectionReconfiguration,NAS:Attach accept,NAS:Activate Default EPS bearer request,12.RRC:RRCConReconfigComplete,13.S1AP:Initial Context setup response,14.RRC:UL information Transfer,NAS:Attach complete,NAS:Activate Default EPS bearer accept,15.S1AP:Uplink NAS Transport,NAS:Attach complete,NAS:Activate Default EPS bearer accept,31,UE,附着到,E-UTRAN,中时，要建立一个默认的,EPS,承载，该承载使,UE,获得一个“总是在线”的,IP,连接,1.UE,发起附着过程，向,eNodeB,发一个,RR,消息（,RRC,连接配置完成消息），消息中携带高层的附着请求消息。包括以下参数：,UE,的,IMSI,，旧的,GUTI,以及附加,GUTI,：旧,GUTI,可以由,P-TMSI,和,RAI(routing area identity),导出。如果,UE,没有一个有效的,GUTI,或,P-TMSI,，则必须提供,IMSI,；如果,IMSI,也没有，则必须提供,ME,的设备标识（,IMEI,）,上一次访问的,TAI,：如果,UE,中保存有上一次访问的,TAI,，则应该把该参数提供给,MME,UE,核心网能力：描述,UE,的能力，包括支持的,NAS,和,AS,安全算法,UE,专用,DRX,参数：在接入过程中,MAC,为,UE,分配的,DRX,参数,PDN,类型：表示请求的,IP,地址类型（,IPv4,IPv6,IPv4/IPv6),协议配置选项,PCO,：用于在,UE,和,P-GW,之间传输参数，比如,UE,希望的地址分配方式,加密选项传输标志位,附着类型：可以设为“切换”，“附着”，“紧急附着”,KSI,ASME,，,NAS,序列号，,NAS-MAC,此外，还携带两个,RRC,参数：被选网络，旧,GUMMI,2.eNodeB,根据收到附着请求消息中的,RRC,参数进行配置,并向,MME,转发附着请求消息,(,通过,S1AP,消息,:,初始,UE,消息,),32,3.,身份,ID,请求和响应,NAS,鉴权和安全功能激活,ME,标识校验请求和确认,4.MME,向,HSS,发一个更新位置请求消息,告诉,HSS,目前在该,MME,中,UE(,由,IMSI,标识,),正在发起附着,5.HSS,通过更新位置确认消息向,MME,提供该,UE,的签约数据,(,包括一个或多个,PDN,签约上下文,),。,MME,正式确认,UE,驻留在某个,TA,中，并为该,UE,生成上下文,6.MME,向,S-GW,发生成默认承载请求消息,要求,S-GW,为该,UE,生成一个默认承载,7.S-GW,在其,EPS,承载列表中建立一个新的条目,并向,P-GW,发送生成默认承载请求消息,要求,P-GW,为该,UE,生成一个默认承载,8.P-GW,在其,EPS,承载列表中建立一个新的条目,开始在外部,PDN,网络和,S-GW,之间转发用户面,PDU,并生成一个新的计费,ID,开始计费。,P-GW,向,S-GW,发送默认承载建立响应消息，其中包含给,UE,分配的,PDN,地址,9.S-GW,向,MME,发默认承载建立响应消息,通知,MME,默认承载已经建立,33,10.MME,通知,eNodeB(,通过,S1AP,的初始上下问建立请求消息,)UE,的附着请求已经被接受,并要求建立一个初始上下文,11.eNodeB,通知,UE,附着请求已经被接受,(,通过,RRC,连接重配置消息,),12.UE,进行,RRC,连接重配置,完成后,向,eNodeB,回复一个,RRC,连接重配置完成消息,13.eNodeB,向,MME,回复一个初始上下文建立响应消息,14.UE,通过,RRC,的上行信息传输消息向,eNodeB,发一个,NAS,消息,:,附着完成消息,这标志着,UE,侧和附着相关的操作及设置已经完成,15.eNodeB,通过,S1AP,的上行,NAS,传输消息向,MME,转发,UE,的附着完成消息。本步后,一旦,UE,获得,PDN,地址,UE,就想,eNodeB,发上行分组数据,这些分组数据可以通过隧道传到,S-GW,和,P-GW,更新承载请求及响应在,MME S-GW P-GW,之间完成后,EPS,承载的,E-UTRAN,部分和,EPC,部分就连起来了,这时候下行分组数据也开始传送了,34,会话管理过程,UE,和网络都能发起服务请求过程,.UE,发起的主呼,UE,被叫以及网络发起,ECM,空闲态,UE,的去附着都属于服务请求,35,UE Triggered Service Request Procedure,Initial UE Message,36,UE,触发的服务请求过程,(1)UE,向,MME,发送服务请求消息,(,为,NAS,消息,封装在给,eNodeB,的,RRC,消息中,如上行信息传输消息或,RRC,连接建立完成消息,),(2)eNodeB,向,MME,转发该,NAS,消息,(,封装在,S1AP,的初始,UE,消息中,初试,UE,消息携带了服务小区的,TAI,和,ECGI),如果,MME,不能处理服务请求,则会拒绝服务请求,(3)NAS,鉴权,(4)MME,通过,S1AP,向,eNodeB,发初始上下文建立请求消息,包含上行到,S-GW,的隧道端口号和地址,要求激活的所有,EPS,的,S1,承载和无线承载,.,(5)eNodeB,发起无线承载建立过程,(6)UE,的上行链路数据通过,eNode,转发给,S-GW,(7)eNodeB,通过,S1AP,向,MME,发初始上下文建立完成消息,其中携带下行到,eNodeB,的,S1-U,隧道端口号和地址,(8)MME,向,S-GW,发更新承载请求消息,告之下行的,S1-U TEID,和基站地址,以建立下行,S1,承载,.MME,从这一步开始能给,UE,传下行数据,(9),如果,RAT,类型改变,S-GW,还要向,P-GW,发更新承载请求消息,(10),如果配置了,PCC,P-GW,要和,PCRF,交互获得不同的,RAT,的,PCC,规则,如果没有配置动态,PCC,P-GW,可以使用本地,QoS,策略,(11)P-GW,向,S-GW,回复更新承载响应消息,(12)S-GW,向,MME,回复更新承载响应消息,37,Network Triggered Service Request,38,网络触发的服务请求,当,MME,需要给在,ECM,空闲态的,UE,发消息,如进行,MME/HSS,发起的去附着过程,或有下行数据到达,要求,S-GW,生成或修改专用承载,在,MME,会发起网络触发的服务请求过程,(1),当,S-GW,收到一个给,UE,的下行分组数据包,但,S-GW,的,UE,上下文中又没有下行用户面的,TEID,表示当前没有和,UE,建立用户面连接,则,S-GW,缓存下行分组数据包,并查询目前服务,UE,的是哪个,MME(SGSN),(2a)S-GW,向,MME(SGSN),发下行数据到达通知消息,请求用户面连接,(2b)MME(SGSN),向,S-GW,发下行数据到达通知确认消息,(3),如果,UE,注册到,MME,则,MME,向,UE,注册,TA,的所有,eNodeB,发寻呼消息,(4),如果,eNodeB,收到,MME,的寻呼消息,则开始寻呼,UE,(5),一旦收到,E-UTRAN,的寻呼消息,UE,发起”,UE,触发的服务请求过程”,(6),如果,ISR,是激活的,当,E-UTRAN,收到寻呼响应,S-GW,向,MME,发停止寻呼消息,39,切换过程,40,RRC,连接状态的,UE,在,E-UTRAN,中进行移动的一般原则如下,在,E-UTRAN,中,网络控制,UE,的移动,网络决定,UE,该进入哪个小区,哪个频点或哪个,RAT,。根据无线条件或负载情况等，网络会触发切换过程。,在给,UE,发送切换消息之前，源,eNodeB,为切换准备一个或多个目标,eNodeB,。目标,eNodeB,生成用于进行切换的消息，消息中包括目标小区的接如层详细配置信息，源,eNodeB,把该消息透穿给,UE,。等合适的时候，源,eNodeB,发起,DRB,的转发。接到切换消息后，,UE,在第一个可用的,RACH,时刻就开始尝试接入到目标小区，也就是说，切换是异步的。因此，如果目标小区为这个随机接入分配了一个专用前缀（,Preamble),，应该确保其在,UE,的第一个可能的,RACH,时刻就可用。一旦完成切换，,UE,给目标,eNodeB,发一个切换完成确认消息。源,eNodeB,中会保留,UE,的上下文一段时间，以防,UE,切换失败返回。检测到切换失败后，,UE,尝试在源小区或另一个也做好准备的小区使用,RRC,连接重建立过程，重新发起,RRC,连接。,41,RRC:Connection Reconfiguration Request,RRC:Connection Reconfiguration Complete,UE,S-eNB,T-eNB,MME,SGW,RRC:Measurement Control,X2AP:Handover Request,S11:Modify bearer request,S11:Modify bearer response,X2AP:SN Status Transfer,Sync,UL Allocation+TA for UE,UL Allocation,RRC:Measurement Report,Handover,Decision,X2AP:Handover Response,UE Detach from,old cell and sync,to new cell,S1AP:Path Switch Request,S1AP:Path Switch Response,X2AP:UE Context Release,End Marker,Switch,DL Path,Data Forwarding,Data Forwarding,End Marker,Flush,DL Buffer,42,Source eNB keeps asking UE for the power measurements in a RRC measurement control message.,UE responds with the measurements in RRC Measurement Report.The details of these messages can be found RRC protocol specification.,Based on the measurement report source eNB takes the decision to handover or not.If the source eNB realizes that other eNB can serve better,then it shall