eSRVCC信令流程.docx

23.216 V10.6.0SRVCC from E-UTRAN to GERAN without DTM supportDepicted in figure?-1 is a call flow for SRVCC from E-UTRAN to GERAN without DTM support. The flow requires that eNB can determine that the target is GERAN without DTM support or that the UE is without DTM support.Figure -1: SRVCC from E-UTRAN to GERAN without DTM support1.UE sends measurement reports to E-UTRAN.2.Based on UE measurement reports the source EUTRAN decides to trigger an SRVCC handover to GERAN.3.Source EUTRAN sends Handover Required (Target ID, generic Source to Target Transparent Container, SRVCC HO Indication) message to the source MME. The EUTRAN places the old BSS to new BSS information IE for the CS domain in the generic Source to Target Transparent Container. The SRVCC HO indication indicates to the MME that target is only CS capable, hence this is a SRVCC handover operation only towards the CS domain. The message includes an indication that the UE is not available for the PS service in the target cell.4.Based on the QCI associated with the voice bearer (QCI 1) and the SRVCC HO indication, the source MME splits the voice bearer from the non voice bearers and initiates the PS-CS handover procedure for the voice bearer only towards MSC Server.5.The MME sends a SRVCC PS to CS Request (IMSI, Target ID, STN-SR, CMSISDN, generic Source to Target Transparent Container, MM Context, Emergency Indication) message to the MSC Server. The Emergency Indication and the equipment identifier are is included if the ongoing session is emergency session. Authenticated IMSI and CMSISDN shall also be included, if available. The MME received STN-SR and CMSISDN from the HSS as part of the subscription profile downloaded during the EUTRAN attach procedure. The MM Context contains security related information. CS security key is derived by the MME from the EUTRAN/EPS domain key as defined in TS?33.401?[22]. The CS Security key is sent in the MM Context.6.The MSC Server interworks the PS-CS handover request with