An VAL group communication takes place, and the DL VAL data is delivered over eMBMS bearer, which is associated to the VAL group X.
The VAL UE performs handover to 5GS.
Location information indicating the RAT change from the VAL UE is provided to the NRM server. VAL UE`s location information is provided via the location management client, triggered by RAT change, to the location management server, where the latter provides the location information to the NRM server.
Also, location information handling can be based on notifications provided from the network to the NRM server related to 5GS supporting EPS interworking, as specified in TS 23.501
, TS 23.502
, and TS 23.503
. For that, the NRM server can subscribe to receive notifications of specific events from the network. For instance, the NRM server can subscribe to PCF related notifications (via N5 or Rx) for specific events, e.g., access network information notification and change of access type. Also, when SCEF+NEF is deployed, the NRM server can subscribe to SCEF+NEF related notifications for specific events, e.g., core network (CN) type change.
The NRM server analyses the RAT change and decides how to deliver the DL VAL data. If the NRM server decides to serve the client via 5G MBS session, it may send an MBS session announcement indicating information among others the session mode to serve the NRM client and the corresponding MBS session ID. This step is optional as the session announcement related information could be sent in advance (implementation specific).
The VAL UE acts according to the MBS session mode provided to receive the DL media.
In case of multicast MBS sessions, the VAL UE performs a UE session join towards the 5GC indicating the MBS session ID to join. It may as well send a UE session join acknowledgement to the NRM server.
In case of broadcast MBS sessions, the VAL UE starts monitoring the broadcast MBS session.
The NRM server may inform the VAL server to stop sending DL VAL data via the eMBMS bearer by sending the user plane delivery mode message, e.g., when the last UE moves out of the MBMS service area.
The NRM client sends an MBS listening status report to the server indicating its ability to receive media over the indicated MBS session.
The NRM server sends a MapVALGroupToSessionStream over the MBS session providing the required stream information to receive the media related to the group communication.
The NRM client processes the received information related to the DL VAL data over the MBS session.
The NRM server may inform the VAL server to start sending DL VAL data via the 5G MBS session by sending the user plane delivery mode message, e.g., the first UE(s) enters the MBS service area or joins the multicast MBS session.
The VAL group communication takes place over 5GS, and the DL VAL data is delivered over the broadcast or multicast MBS session.