8.10 Inter SGSN Routeing Area Update

23.2463GPPArchitecture and functional descriptionMultimedia Broadcast/Multicast Service (MBMS)Release 17TS

This procedure describes the handling of MBMS bearer services when an MBMS UE performs a Routeing Area Update and the serving SGSN changes. It is based on the Inter SGSN Routeing Area Update procedure specified in TS 23.060 [15]. The procedure is performed regardless whether MBMS sessions are ongoing or not. The handling of any PDP contexts established by the UE is not changed compared to the procedure without MBMS. The procedure described below does not show all details of the Routeing Area update procedure. Only for the MBMS specific additions the steps are described.

Figure 14: Inter SGSN Routeing Area Update

2) An SGSN supporting MBMS indicates its MBMS support in the SGSN Context Request message. If the SGSN indicates that it supports MBMS, the old SGSN includes the transfer of the MBMS UE Context(s) in the SGSN Context Response message.

7) For the MBMS UE context(s) received in step 2) the new SGSN sends Update MBMS UE Context Request (Serving network identity, MS Time Zone, CGI/SAI, RAT Type, Additional MBMS Trace Info) to the GGSNs concerned. The GGSNs update their MBMS UE Context fields and return Update MBMS UE Context Response.

8) The GGSN sends Update MBMS UE Context Request (RAI) to the BM-SC. The inclusion of CGI/SAI shall be according rules detailed in clause 15.1.1a in TS 23.060 [15]. The BM-SC updates its MBMS UE Context fields and return Update MBMS UE Context Response.

9) If the GGSN receives new or updated Additional MBMS Trace Info from the new SGSN, the GGSN sends an Activate Trace (Additional MBMS Trace Info) message to the BM-SC.

14) In case the new SGSN indicated no MBMS support in step 2) the old SGSN deactivates all MBMS UE context(s) of the UE in SGSN, GGSN and BM-SC by initiating deactivation procedure(s) as described in clause "8.7 MBMS Multicast Service Deactivation".

15) If the old SGSN does not have any more MBMS UE Contexts for the MBMS bearer service(s) and the "list of downstream nodes" in the corresponding MBMS Bearer Context is empty, the SGSN initiates the MBMS De-Registration Procedure. See clause "8.6 MBMS De-Registration Procedure".

16) In case the new SGSN indicated MBMS support in step 2), the new SGSN verifies for each MBMS UE Context received whether it has a corresponding MBMS Bearer Context. For each MBMS Bearer Context that the SGSN does not already have, the SGSN creates an MBMS Bearer Context (in "Standby" state) and initiates the MBMS Registration Procedure towards the GGSN. See clause "8.4 MBMS Registration Procedure".

17) An SGSN without MBMS support does not indicate MBMS feature support in the Routing Area Update Accept message. On the other hand if the SGSN supports MBMS, the Routing Area Update Accept indicates to the UE that the network supports MBMS.