课程说明
1. 课程介绍
GSM通信流程包括两方面的内容：呼叫基本流程，信令基本流程。其中，呼叫流程主要包含：移动主叫流程，移动被叫流程，汇接呼叫流程。信令基本流程主要包含：鉴权流程，位置登记流程，呼叫重建流程，BSC内部切换流程，BSC间切换流程，MSC间切换流程，移动始发短消息流程，移动终结短消息流程，定向重试流程。
这些流程从系统的角度描述了移动用户经常发生的行为，描述了GSM的几个组成部分在呼叫流程、信令流程中的相互关系，对移动性特征做重点说明。
2. 课程目标
本课程的重点是介绍GSM系统的协同工作过程，涉及内容包含：呼叫、位置更新、切换、短消息。对流程的介绍突出了移动特征，具体的信令细节本课程不做描述，可以参考ETSI的GSM规范获得更加详细的内容。 通过学习本课程，可以基本掌握： 移动用户做位置登记的信令过程； 移动用户做主叫的信令过程； 移动用户做被叫的信令过程； MSC做汇接呼叫的信令过程； BSC内切换信令过程； BSC间切换的信令过程； MSC间切换的信令过程； 呼叫重建的信令过程；
对这些信令流程学习之后，对GSM系统的原理会有更加深刻的了解，对每个功能实体（MS，BTS，BSC，MSC，VLR，HLR，SC）的功能有更加深刻的体会。
3. 相关资料
ETSI关于GSM的规范，主要是：0408，0808。
位置更新流程
MSChan Request (RACH)BTSBSCMSCChan RequiredChan ActChan Act ACKImm Ass Cmd (Imm Ass)Imm Ass (AGCH)SABM (Loc Update Req)UA(Loc Update Req)Est Ind (Loc Update Req)CR (Loc Update Req)CCBSSMAP (Clear Cmd)Chan ReleaseDISCData Req (Chan Release)Deact SACCHRelease IndRF Chan ReleaseRF Chan Release ACKBSSMAP (Clear Cmp)Location Update Accept
手机关机流程
MSChan RequestBTSBSCMSCChan RequiredChan ActChan Act ACKImm Ass Cmd(Imm Ass)Est Ind (IMSI Detach Ind)DR (Chan Rel)Deact SACCHRelease IndRF Chan RelRF Chan Rel ACKImm AssSABM(IMSI Detach Ind)UA(IMSI Detach Ind)Chan RelDISCUACR(IMSI Detach Ind)CREF手机主叫流程
MSChan Request (RACH)BTSBSCMSCChan RequiredChan ActChan Act ACKImm Ass Cmd (Imm Ass)Imm AssSABM (CM Ser Req)UA (CM Ser Req)Est Ind (CM Ser Req)CR (CM Ser Req)CCCM Ser AcceptSet UpCall ProceedingAss RequestPhysical Context ReqPhysical Context ConfChan ActChan Act ACKAssignment CommandSABMUAAssignment CompleteAssignment CmpDeact SACCHRF Chan ReleaseRelease IndRF Chan Release ACKAlertingConnectConnect ACKDisconnectReleaseRelease CompleteChan ReleaseDISCDR (Chan Release)Deact SACCHRelease IndRF Chan ReleaseRF Chan Release ACKClear CmdClear CompleteRLSDRLCEst Ind
手机被叫流程
MSBTSBSCPagingPaging CmdMSCPaging ReqChan RequestChan RequiredChan ActChan Act AckImm Ass Cmd (Imm Ass)Imm AssignmentSABM(Pag Resp)UAEst Ind (Pag Resp)CR (Pag Resp)CCSetupCall ConfirmAssignment ReqPhysical Context ReqPhysical Context ConfChan ActChan Act AckAssignment CommandSABMUAAssignment CompleteAssignment CompleteAlertingConnectConnect AckEst IndDisconnectReleaseRelease CompleteChannel ReleaseDISCDR(Channel Release)Deact SACCHRelease IndRF Chan ReleaseRF Chan Release AckClear CommandClear CompleteRLSDRLC
切换---小区内切换 MSMeas RepMeas ResPhy Context ReqPhy Contest ConfChan ActChan Act ACKAssign CommandSABMUAEst IndAssign CompleteDeact SACCHRF Chan ReleaseRF Chan Rel ACKBTSBSCMSCHo Perform
切换---同一BSC下小区间切换
MSMeas RepBTS1BTS2Meas ResultChan ActChan Act ACKHO CMDHO AccessPhysical InformationSABMUAHO CompleteEst IndData Ind(HO Comp)RF Chan RelRF Chan Rel ACKData Req ( HO CMD)HO DetectBSCMSCHO Perform
切换---同一MSC下BSC间切换
MSMeas ResMeas RepHo RqdCR(Ho Req)CCHo Req ACKChan ActChan Act AckHo AccessHo DetectHo DetectEst IndClear CmdDeact SACCHRF Chan RelRF Chan Rel ACKClear CmpHo CompletePhy InfoSABMUABTS1BSC1MSCBSC2BTS2MS'Ho CmdHo Cmd
点对点短消息流程(带加密过程)--- 空闲态发短消息
MSChan RequestBTSBSCMSCChan RequiredChan ActivationChan Act ACKImm AssSABM(CM Ser Req)UA(CM Ser Req)Imm Ass Cmd(Imm Ass)Est Ind (CM Ser Req)Authentication ReqAuthentication RespCR (CM Ser Req)CC (Authen Req)Cipher Mode CmdCipher Mode CmpSABM(SAPI=3)UAEncryption CmdCipher Mode CmdCipher Mode CmpEst Ind (SAPI=3)CP_DATA(RP_DATA)CP_ACKCP_DATA(RP_ACK)CP_ACKChan ReleaseClear CmdClear CmpTo SCRP_DATAFrom SCRP_ACKDISC(SAPI=0)Deact SACCHRelease IndRF Chan ReleaseRF Chan Release ACK
点对点短消息流程(带加密过程)--- 空闲态收短消息
MSBTSPaging CmdChan RequiredChan ActChan Act ACKImm AssSABM(Paging Resp)Imm Ass Cmd(Imm Ass)Est Ind(Paging Resp)Authentication ReqAuthentication CompleteCipher Mode CmdCipher Mode CmpEst Req(SAPI=3)Est Conf(SAPI=3)CP_DATA(RP_DATA)CP_ACKCP_DATA(RP_ACK)CP_ACKChan ReleaseDISCDeact SACCHRelease IndRF Chan ReleaseRF Chan Release ACKClear CmdClear CompEncryption CmdCipher Mode CmdCipher Mode CmpCP_DATA(RP_DATA)CC(Paging Resp)CR (Authentication Req)BSCPagingMSCPaging RequestChan RequestSABM(SAPI=3)UA(SAPI=3)
点对点短消息流程(带加密过程)---通话时发短消息
FACCHSACCH
MSBTSBSCMSCActive CallCM Ser ReqCM Ser AcceptSABM(sapi=3)Est Ind(sapi=3)UA(sapi=3)CP_DATA(RP_DATA)To SCCP_ACKCP_DATA(RP_ACK)From SCCP_ACKActive Call点对点短消息流程(带加密过程)---通话时收短消息
SACCH
MSBTSBSCMSCActive CallCP_DATA(RP_DATA)From SCEst Req(sapi=3)SABM(sapi=3)UA(sapi=3)Est Conf(sapi=3)CP_DATA(RP_DATA)CP_ACKCP_DATA(RP_ACK)To SCCP_ACKActive Call
