1、 目的介绍GSM正常的呼叫流程(空中接口、A-bis接口和A接口)介绍部分常见的异常中断的流程 内容GSM网络协议介绍GSM逻辑信道介绍无线链路建立流程(Radio and Link Establishment Procedure)TCH正常分配流程(Normal Assignment Procedure)主叫流程(Originating Call)被叫流程(Terminating Call)位置更新流程(Location Updating)切换流程(Handover Procedure)呼叫释放流程(Call Release Procedure)信道释放流程(Channel Release
2、Procedure)目的和内容GSMGSM协议协议层数层数无线网络优化主要关心第三层的无线网络优化主要关心第三层的信令信令无线网络优化主要关心无线网络优化主要关心DTAPDTAP、RSLRSL的信令的信令无线网络优化主要关心无线网络优化主要关心DTAPDTAP、BSSMAPBSSMAP和部分和部分SCCPSCCP的信令的信令DTAPRSLOMLGSM网络协议 Layer 3介绍RR:无线资源管理(Radio Resource Management)由MS、BTS和BSC控制 功能举例Paging管理(Paging Management)加密管理(Ciphered Mode Management
3、)频点分配(Frequency Redefinition)信道分配(Dedicated Channel Assignment)切换(Handover Management)测量和功率控制(Measures and Power Control)MM:移动性管理(Mobility Management)由MS和MSC/VLR控制 功能举例鉴权和身份识别(Authentication/Identification Procedures)位置更新(Location Updating)IMSI Attach/DetachGSM网络协议网络协议pCC:呼叫控制(Call Control)由MS和MSC控制
4、功能举例 呼叫处理和路由(Call processing and routing)双音多频(DTMF Facilities)短消息服务(Short Message Service)附加服务(Supplementary Service)GSM网络协议网络协议呼叫流程中常用的逻辑信道PCH寻呼信道(Paging Channel)RACH随机接入信道(Random Access Channel)AGCH接入认可信道(Access Grant Channel)SDCCH独立专用控制信道(Stand-alone Dedicated Control Channel)SACCH慢联系控制信道(Slow As
5、sociated Channel)TCH话务信道(Traffic Channel)FACCH快联系控制信道(Fast Associated Control Channel)GSM呼叫流程中常用的逻辑信道呼叫流程中常用的逻辑信道PCHRACHAGCHSDCCH+SACCHTCH/FACCH+SACCH 定义 手机与网络间建立一个无线链路,用于信令传送 包括以下四个步骤 Paging过程(Paging Procedure)(仅用于被叫流程中)随机接入过程(Random Access Procedure)立即分配过程(Immediate Assignment Procedure)SCCP联接建立过程
6、(SCCP Connection Establishment Procedure)当手机需要与网络发生联系时,必须要当手机需要与网络发生联系时,必须要先建立无线链路和先建立无线链路和A A接口的信令连接接口的信令连接无线链路建立流程无线链路建立流程MSBTSBSCMSCChannel RequestChannel RequiredChannel Activation(SD)Channel Act Ack(SD)Immediate AssignmentCommandUI Imm Assignment/Imm Ass ExtST9103ET9103ST3126ET3126ST3101SABM L3
7、 InfoEstablish IndicationL3 InfoSCCP Con Rqrd L3SCCP Conn ConfirmET3101ST9105ET9105UA L3 Info(RACH)()(Est Cause,Rnd Nbr)(Est Cause,Rnd Nbr,TA)RACH_TA_FilteringRACH_TA_Filtering(TA,BS/MS_TxPwr-Max,Chann)TimerTimer;S-StartS-Start;E-EndE-EndEntityEntity信令消息信令消息空中接口空中接口AbisAbis接口接口A A接口接口(Rnd Nbr,TDMA F
8、rame Nbr,Chan,TA)(AGCH)同时对两个同时对两个MSMS分配分配SDCCHSDCCH(SDCCH)BSCBSC开始对开始对MSMS发出的上行发出的上行DTAPDTAP消息排消息排队(如队(如CM Serv AbortCM Serv Abort消息)。如果消息)。如果收到收到MSMS发出的发出的Classmark ChangeClassmark Change消消息,息,BSCBSC会在会在SCCPSCCP连接完成后发连接完成后发Classmark UpdateClassmark Update消息给交换机消息给交换机如如CM Serv ReqCM Serv Req,Pag Res
9、Pag Res,Loc Update ReqLoc Update Req等等Set Asynchronous Set Asynchronous Balance ModeBalance Mode。在任。在任何新信道登陆时均会何新信道登陆时均会有有SABMSABM过程过程Unnumbered AckUnnumbered Ack无线链路建立流程无线链路建立流程无线链路建立流程无线链路建立流程AbisAbis信令tChannel Required无线链路建立流程无线链路建立流程AbisChannel Activation无线链路建立流程无线链路建立流程AbisImmediately Assignmen
10、t无线链路建立流程无线链路建立流程异常情况异常情况对不同的呼叫类型有不同的等待时间:对不同的呼叫类型有不同的等待时间:WI_EC/CR/OC/OP.(OPWI_EC/CR/OC/OP.(OP主要指主要指LU,LU,被叫没有相应等待时间被叫没有相应等待时间)SDCCH拥塞如果BSC在收到Channel Required时,相应小区没有空闲的SDCCH,BSC将会如果小区参数En_Imm_Ass_Rej=“True”,则发Immediately Assignment Reject否则忽略Channel Required消息 T9103超时BSC发RF Channel Release消息到BTS B
11、SC收到Channel Activation NAck消息BSC内部释放BTS的相应无线信道(没有任何消息在Abis接口上传送)T3101超时Layer 3无法建立 BSC发RF Channel Release到BTS T9105超时BSC通过呼叫释放过程(Call Release Procedure)释放原先建立的SDCCH连接在A接口,BSC向MSC发SCCP释放请求 在RF部分,BSC向手机和BTS发信道释放消息 仅在仅在BSCBSC内部资源表中释放,在内部资源表中释放,在AbisAbis上没有信令传送上没有信令传送当信道激活不成功当信道激活不成功时触发的时触发的BTS RF Chan
12、Rel不包含不包含Phys Cont Req过程过程 BSC收到Establish Indication消息,但消息中不含Layer 3 InformationBSC向手机和BTS发信道释放消息 Abis上的其它异常中断消息的处理BSC收到Error Indication Cause为:“T200 Expiry”:监视SABM和UA过程“Unsolicited DM Response”(发生在Disconnect过程中)“Sequence Error”释放:A接口上,BSC发Clear Request“Radio Interface Failure”到交换机BSC向手机和BTS发信道释放消息B
13、SC收到Connection Failure indication(Cause:Radio Link Failure)在A接口上,BSC发Clear Request“Radio Interface Failure”到交换机 BSC向BTS发RF Channel Release消息BSC收到Release Indication当收到手机发出的DISC消息A接口上,BSC发Clear Request“Radio Interface Failure”到交换机BSC向手机和BTS发信道释放消息无线链路建立流程无线链路建立流程异常情况异常情况MSBTSBSCMSCAuthentication ReqCi
14、phering Mode CmdAuthentication ReqAuthentication ReqAuthentication RespAuthentication RespAuthentication RespEncryption CommandCiphering Mode CmdCiphering Mode CmpCiphering Mode CmpCiphering Mode CmpTMSI Realloc CmdTMSI Realloc CmdTMSI Realloc CmdTMSI Realloc CmpTMSI Realloc CmpTMSI Realloc CmpAuthe
15、nticationCipheringTMSI ReallocST3260ET3260*Authentication Reject*IdentificationIdentification RequestST3270ET3270Identification RequestIdentification RequestIdentification ResponseIdentification RespIdentification ResponseST3250ET3250(RAND)(SRES)RANDRAND与与KiKi经过经过A3A3算法算法得到得到SRESSRES;经过;经过A8A8算算法得到法
16、得到KcKc比较比较SRESSRES(IMSI)选择加密算法选择加密算法(Permitted Alg,Kc)准备解密接收准备解密接收(Alg,Kc)(Alg(A5算法)算法)开始加开始加密发射密发射和解密和解密接收接收如正确解密接收,则下条如正确解密接收,则下条消息加密发射消息加密发射已加密的消息已加密的消息(TMSI)VLRVLR从从HLRHLR处得处得到到RAND/SRRAND/SRES/KcES/Kc鉴权、身份识别、加密、鉴权、身份识别、加密、TMSI重重新分配过程新分配过程鉴权、身份识别、加密、鉴权、身份识别、加密、TMSI重重新分配过程新分配过程A口信令口信令Authenticati
17、on Request鉴权、身份识别、加密、鉴权、身份识别、加密、TMSI重重新分配过程新分配过程A口信令口信令Authentication Response鉴权、身份识别、加密、鉴权、身份识别、加密、TMSI重重新分配过程新分配过程A口信令口信令Identification Response 鉴权过程中的异常情况鉴权失败 如果鉴权过程中使用TMSI,网络将启动身份识别过程。如果手机送上来的IMSI与VLR中TMSI所对应的IMSI不一致,则重新进行鉴权 如果鉴权过程中已经使用IMSI,则网络发Authentication Reject消息。这个SIM将被认为是无权的T3260超时 第一次超时,
18、网络将重发鉴权请求;第二次超时,网络将释放该MM连接 身份识别过程中的异常情况T3270超时 第一次超时,网络将重发身份识别请求;第二次超时,网络将释放该MM连接 TMSI重新分配过程中的异常情况T3250超时 第一次超时,网络将重发TMSI重新分配请求;第二次超时,网络将释放该MM连接鉴权、身份识别、加密、鉴权、身份识别、加密、TMSI重重新分配过程新分配过程异常情况异常情况 定义 分配TCH的过程 特殊情况 排队(Queuing)直接重试(Directed Retry)TCH分配过程分配过程MSBTSBSCMSCChannel Activation TCHSABM(FACCH)Channe
19、l Activation Ack.Assignment CommandAssignment CommandAssignment RequestPhysical Context RequestPhysical Context ConfirmEstablish IndicationUAAssignment CompleteAssignment CompleteAssignment CmpRF Channel Release(SD)RF Channel Release Ack.STrr1ETrr1ST9108ET9108ST9103ET9103ST3107ET3107(Chn Type,Priori
20、ty,CIC,DL DTX,Queuing Flag)(TA,MS/BS_TxPwr)(SDCCH)(TA,MS/BS_TxPwr)(MA,TS,HSN,MAIO,MS_TxPwr)占用占用TCHTCH时,如需传送信令,则通过时,如需传送信令,则通过Stealing FlagStealing Flag将将TCHTCH转换成转换成FACCHFACCH一般情况下,在一般情况下,在RFRF信道释放前都有信道释放前都有Physical Context ReqPhysical Context Req过程过程TCH分配过程分配过程TCH分配过程分配过程A口口Assignment RequestEFRQue
21、uingTCH分配过程分配过程AbisAbis信令TCH分配过程分配过程AbistPhysical Context ComfirmTCH分配过程分配过程AbisSystem Information Type 5BA ListTCH分配过程分配过程AbistSystem Information Type 6LAC/CITCH分配过程分配过程AbistAssignment CommandFrequency Encoding(Bitmap 0)TCH分配过程分配过程AbistFrequency Encodingp频段分配pFrequency Encoding(主要有三种方式)Fixed Bitmap
22、 Bitmap 0 只能表现1124频点TCH分配过程分配过程AbisRecursive Dichotomy Algorithm 递归二分法Variable BitmapMSBTSBSCMSCSABM(FACCH)Channel ActivationHO CMDAssignment RequestPhysical Con ReqChan.Act.Ack.HO DetectionUAPhys.InfoAssignment CmpST11ST3103Queuing IndicationET11At this time,a TCH become freeTCH拥塞和排队Assignment Requ
23、estST11Queuing IndicationET11A Handover alarm is raised.A target BTS is selectedHO CMDHO AccessST9103ET9103TTSTTEstablish IndicationTTHO CMPTHO CMPST3124ET3124ET3103直接重试如果如果Queuing Ind=TrueQueuing Ind=True或或Queuing_Anyway=TrueQueuing_Anyway=True。(当。(当Queuing _AnywayQueuing _Anyway时时T11_ForcedT11_For
24、ced取代取代T11T11TCH分配过程分配过程排队和直接重试排队和直接重试 TCH拥塞情况 不允许排队或队列已满 在A接口BSC发Assignment Failure No Radio Resource Available 呼叫进入队列,但T11时间内没有TCH空出 在A接口BSC发Clear Request No Radio Resource Available 呼叫被优先级更高的呼叫挤出队列 在A接口BSC发Assignment Failure No Radio Resource Available”T9108超时:BTS对physical context request没有响应 之后的
25、Channel Activation消息中将不带TA和手机及BTS的发射功率信息 T9103超时:Channel Activation没有回应 A接口上BSC发Assignment Failure Radio Interface Failure BSC向BTS发RF Channel Release消息TCH分配过程分配过程异常情况异常情况 BSC收到Channel Activation Negative Acknowledge消息 Channel Activation Negative Acknowledge有以下几种原因:Channel Already Activated(CAA):BSC向
26、手机和BTS发信道释放消息(通道已经激活通道已经激活)Radio Resource Not Available(RRNA)-Protocol error (PE):BSC内部释放(无线电资源不可用无线电资源不可用)Requested transcoding rate not supported(RTRNS):BSC内部释放(要求代码转换速度不受支持的要求代码转换速度不受支持的)Encryption algorithm not implemented(EANI):BSC内部释放(加密加密算法没有实现算法没有实现)O&M Intervention(OI):BSC内部释放 在A接口上发Assignm
27、ent Failure消息 对于收到Chnav Neg Ack原因为EANI的情况,Assignment Failure的cause为Ciphering Algorithm not supported 其它情况,Assignment Failure的cause为Radio Interface FailureTCH分配过程分配过程异常情况异常情况在原来的信道上(如SDCCH信道)收到Assignment Failure消息 手机收到Assignment Command后,在新信道上发SABM消息,BTS收到后向手机发UA消息。但可能由于空中接口原因,手机没有收到UA消息。手机尝试N200次均未成
28、功。手机将会回到原来的信道。并发Assignment Failure消息BSC收到该消息后在A接口发Assignment Failure Reversion to Old ChannelBSC向BTS发RF Channel Release消息,释放新信道Assignment Command的内容有误手机发现Assignment Command消息中内容有误,手机发Assignment Failure消息到BSCBSC收到该消息后在A接口发Assignment Failure Reversion to Old ChannelBSC向BTS发RF Channel Release消息,释放新信道T3
29、107超时BSC在A接口发Assignment Failure“Radio Interface Message Failure”,并开始T9110计时BSC向BTS发RF Channel Release消息,释放新老信道MSC向BSC发Clear Command消息(呼叫释放),并停止T9110一般情况下,交换机收到该消一般情况下,交换机收到该消息后发息后发DISCDISC(temp failtemp fail)TCH分配过程分配过程异常情况异常情况 直接重试中的异常情况没有Candidate cell BSC在A接口发Assignment Failure“No Radio Resource
30、Available”Channel Activation过程中T9103超时 BSC在A接口发Assignment Failure“Radio Interface Failure”BSC向BTS发RF Channel Release消息BSC收到Channel Activation Negative Acknowledge消息 Channel Activation Negative Acknowledge有以下几种原因:Channel Already Activated(CAA):BSC向手机和BTS发信道释放消息Radio Resource Not Available(RRNA)-Proto
31、col error (PE):BSC内部释放Requested transcoding rate not supported(RTRNS):BSC内部释放Encryption algorithm not implemented(EANI):BSC内部释放O&M Intervention(OI):BSC内部释放 在A接口上发Assignment Failure消息对于收到Chnav Neg Ack原因为EANI的情况,Assignment Failure的cause为Ciphering Algorithm not supported其它情况,Assignment Failure的cause为Ra
32、dio Interface FailureTCH分配过程分配过程异常情况异常情况T3103超时:没有收到HO Failure或HO Complete消息 BSC在A接口发Assignment Failure“Radio Interface message Failure”BSC向手机和BTS发信道释放消息,释放新老信道收到手机发来的HO Failure消息 BSC在A接口发Assignment Failure“Reversion to Old Channel”消息 BSC向BTS发RF Channel Release消息,释放新信道 Abis上的其它异常中断消息的处理BSC收到Connecti
33、on Failure Indicaiton消息 Cause为:“Radio Interface Failure”:无线链路超时引起的释放释放:A接口上,BSC发Clear Request“Radio Interface Failure”到交换机BSC向BTS发RF Channel Release消息BSC收到Error Report消息BSC收到Error Indication消息BSC收到Release Indication消息 A中继信道拥塞或不可用情况TCH分配过程分配过程异常情况异常情况主叫过程(非OACSU情况)MSBTSBSCMSCCall ProceedingESTIN(CM_S
34、erv_Req)RR Connection EstablishmentRR Connection EstablishmentRR Connection EstablishmentAuthentication ProcedureAuthentication ProcedureAuthentication ProcedureCiphering ProcedureCiphering ProcedureCiphering ProcedureTMSI Realloc ProcedureTMSI Realloc ProcedureTMSI Realloc ProcedureSETUPSETUPSETUPC
35、all ProceedingCall ProceedingAssignment ProcedureAssignment ProcedureAssignment ProcedureAlertingAlertingAlertingConnectConnectConnectConnect Ack.Connect Ack.Connect Ack.SpeechCM_Serv_ReqOff Air Call SetupOff Air Call Setup(called party nbr)先建立先建立TCHTCH,再,再接通接通B B侧信道。侧信道。AlertingAlerting在在TCHTCH上发送上
36、发送(CM Serv Type,Mobile ID,Classmark2,Priority,),)SDCCHTCH主叫过程 A口tA口信令两次两次Classmark Update。前一次由于前一次由于Early Classmark Sending引起;引起;后者由于后者由于BSC下发下发Classmark Enquiry引起引起主叫过程 A口tCM Service Request主叫:主叫:MOC est/pkt mode con estab短信:短信:Short message service附加服务:附加服务:Suppl service activationCLASSMARKtCLASSM
37、ARKp包含以下信息MS Revision Level 手机的修正版本MS Ciphering Capability 手机支持的加密算法MS Frequency Capability 手机支持的频段MS RF Power Capability in Each Band 手机在各频段支持的发射功率主叫过程 A口tCLASSMARK主叫过程 A口tSetup主叫过程 A口被叫号码被叫号码MSBTSBSCMSCCall ProceedingESTIN(CM_Serv_Req)RR Connection EstablishmentRR Connection EstablishmentRR Connec
38、tion EstablishmentAuthentication ProcedureAuthentication ProcedureAuthentication ProcedureCiphering ProcedureCiphering ProcedureCiphering ProcedureTMSI Realloc ProcedureTMSI Realloc ProcedureTMSI Realloc ProcedureSETUPSETUPSETUPCall ProceedingCall ProceedingAssignment ProcedureAssignment ProcedureAs
39、signment ProcedureAlertingAlertingAlertingConnectConnectConnectConnect Ack.Connect Ack.Connect Ack.SpeechCM_Serv_ReqSDCCHTCH先接通先接通B B侧信道侧信道,再建立,再建立TCH TCH。AlertingAlerting在在SDCCHSDCCH上发送上发送主叫过程(OACSU情况)MSBTSBSCMSCCall ConfirmedESTIN(Paging Resp)RR Connection EstablishmentRR Connection EstablishmentR
40、R Connection EstablishmentAuthentication ProcedureAuthentication ProcedureAuthentication ProcedureCiphering ProcedureCiphering ProcedureCiphering ProcedureTMSI Realloc ProcedureTMSI Realloc ProcedureTMSI Realloc ProcedureSETUPSETUPSETUPCall ConfirmedCall ConfirmedAssignment ProcedureAssignment Proce
41、dureAssignment ProcedureAlertingAlertingAlertingConnectConnectConnectConnect Ack.Connect Ack.Connect Ack.SpeechPaging ResponsePagingPaging CommandPaging RequestST3113ET3113Paging GroupPaging Group的个数(的个数(N N):由):由BS_AG_BLKS_RESBS_AG_BLKS_RES和和BS_PA_MFRMSBS_PA_MFRMS决定决定;MS;MS的的Paging Group=(IMSI mod
42、1000)mod Paging Group=(IMSI mod 1000)mod N;MSN;MS只监听自己对应的只监听自己对应的Paging GroupPaging Group的的Paging ReqPaging Req消息消息(MS ID(TMSI/IMSI),),Cell ID(LAC/LAC+CI)(MS ID(TMSI/IMSI),),Paging Group)(MS ID(TMSI/IMSI)(最多可同时发(最多可同时发4个个TMSI)(Mobile ID,Classmark2,Priority,),)(calling party nbr)被叫过程tA口信令被叫过程 A口tPagi
43、ng被叫过程 A口IMSI号码,号码,BSC用来计算用来计算Paging GroupTMSI号码,空中接口号码,空中接口Paging时用,比较经济时用,比较经济LAC PagingtA口信令被叫过程 A口tSetup被叫过程 A口主叫号码主叫号码 T3113超时 如果T3113超时,Paging Response消息没有收到,网络会重发Paging消息,并重新开始T3113计时。重试的次数在交换机中定义。Paging失败MSBTSBSCMSCClear CMDESTIN(Loc Up Req)RR Connection EstablishmentRR Connection Establishm
44、entRR Connection EstablishmentAuthentication ProcedureAuthentication ProcedureAuthentication ProcedureCiphering ProcedureCiphering ProcedureCiphering ProcedureTMSI Realloc ProcedureTMSI Realloc ProcedureTMSI Realloc ProcedureLoc Up AcceptChannel ReleaseDeactivate SACCHDISCRelease IndicationUARF Ch R
45、eleaseLoc Up ReqLoc Up AcceptLoc Up AcceptChannel ReleaseRF Ch Release AckClear CMPST3210ET3210(LU Type,MS ID,LAI,Classmark1,),)位置更新过程tA口信令位置更新过程 A口注:在这段信令中,手机Location Update Request中所带的TMSI不能被VLR识别(一般在跨MSC位置更新时),所以MSC发Identification Request,要求手机上发IMSI号码。得到IMSI号码后,MSC到老的VLR中要到鉴权信息,并对手机进行鉴权。全部完成后MSC到
46、老的VLR中做Cancel Location,结束所有过程。tLocation Update Request位置更新过程 A口位置更新后没有后续的(位置更新后没有后续的(Follow-on)呼叫过程)呼叫过程手机原来的手机原来的LAC手机的手机的TMSItLocation Update Accept位置更新过程 A口新的新的LAC重新分配的重新分配的TMSI切换分为小区内切换(IntraCell Internal Handover):切换原因(按优先级排序)Cause 15&16 干扰切换(High level interference on UL or DL).Cause 10&11:同心圆
47、内圆电平过低而向外园切换(Too low level,inner zone(inner to outer zone HO,concentric cell)(UL&DL))Cause 13:同心圆外圆电平较高时向内圆切换(Too high level on the UL and DL,outer zone(outer to inner zone HO,concentric cell))BSC内部小区间切换(Intercell Internal Handover)切换原因(按优先级排序)Cause 7:微小区BadSACCH切换(Several consecutive Bad SACCH fram
48、es received(rescue microcell HO))Cause 17&18:微小区高门限切换(Too low level in a microcell compared to a high threshold(UL&DL))Cause 2&4:质量切换(Too Low Quality(UL&DL))Cause 3&5:电平切换(Too Low Level(UL&DL))Cause 6:太长距离且换(Too long MS-BS distance)Cause 22:扩站小区外小区太短距离切换(Too short MS-BS distance)Cause20:强制直接重试(Force
49、d Direct Retry)Cause25:GPRS重定向(GPRS Redirection)切换过程 Cause 21:Preferred Band切换(High level in neighbor cell in the preferred band)Cause 14:宏小区到微小区切换(High level in a neighbor microcell for macrocell to microcell HO.)Cause 12:PBGT切换(Power Budget(Better Cell HO))Cause 23:话务切换(Traffic HO)Cause 24:综合捕捉切换(
50、General Capture HO)p同步切换Intra Cell切换部分Internal Inter Cell切换p异步切换切换过程切换过程MSBTSBSCMSCMeasurement RepMeasurement ResIntra cell切换Phys Context ReqOCOCPhys Context ConfOC:Old ChannelNC:New ChannelNCNCChannel Activation AckChannel Activation Assignment CommandAssignment CommandOCSABMEstablish IndicationUAO