The AF sends Nnef_MBSGroupMsgDelivery_Create Request to the NEF. The Request message contains the Group Message Payload, MBS service area, Group Message Delivery Start Time, Stop Time and External Group Identifier.
The NEF checks authorization of the AF. If geographical area information or civic address information was provided by the AF as MBS service area, the NEF translates the MBS service area to Cell ID list or TAI list. The NEF may further check the MBS capability within the MBS service area.
The NEF transforms the group message payload into a file, and determines the meta data information of the file (e.g. File URL, etc.). The NEF assigns a Group Message Correlation ID that identifies this group message delivery request.
If Application Service Provisioning specified in TS 26.502
has not been performed, step 4 to step 8 are executed. Otherwise, they can be skipped.
The NEF performs Application Service Provisioning by invoking Nmbsf_MBSUserService_Create
towards the MBSF using Object Distribution Method as specified in TS 26.502
The MBSF performs Distribution Session Provisioning as specified in TS 26.502
. The MBSF invokes Nmbstf_MBSDistributionSession_Create
on the MBSTF, passing the parameters of the MBS Distribution Session received in step 4 to the MBSTF.
The MB-SMF initiates the MBS Session Start for Broadcast procedure as specified in step 2 to step 9 in clause 7.3.1
If the MBSF performs the service announcement, it initiates the MBS User Service Announcement as specified in TS 26.502
. The application may receive the appropriate information through the MBS-6 API from the MBS Client (see TS 26.502
). The NEF may receive the service announcement information via Nmbsf_MBSUserDataIngestSession_StatusNotify
callback service operation (see TS 26.502
The NEF sends Nnef_MBSGroupMsgDelivery_Create
Response (Group Message Correlation ID, Acceptance Status, Cause) to the AF. The Acceptance Status indicates whether the group message delivery request is accepted or not. If not, the Cause is included indicating the appropriate failure reason. If the AF performs the service announcement, the NEF includes in the Group Message Response the service announcement information which contains information such as Session Description parameters (e.g. TMGI) and the object meta data as specified in TS 26.502
. The NEF may further include the area where MBS is not supported within the MBS service area in the Nnef_MBSGroupMsgDelivery_Create
response to the AF.
If the AF knows the UEs that are located in the area where MBS is not supported, AF may use unicast to send the group message to those UEs.
If the AF needs to perform the Service Announcement, the AF sends the application service announcement to the UE as specified in TS 26.502
The NEF performs the User Data Ingestion towards the MBSTF as specified in TS 26.502
. The NEF may push the file to the MBSTF or let MBSTF pull the file from the NEF.
The MBSTF performs packetization and optionally FEC encoding as specified in TS 26.502
The MBSTF delivers the packets to the MB-UPF to NG-RAN, and NG-RAN broadcast to the UE as specified in step 13 to step 15 in clause 7.3.1
Based on the service announcement information received in step 8 or step 10, when the UE receives the packets, the MBS client performs FEC decoding to restore the file and gets the group message from the file, as specified in TS 26.502
. The MBS Client can expose the file towards the application in the UE using the MBS-7 API (see TS 26.502
The MBSTF notifies the MBSF of User Data distribution status, and the MBSF then notifies the MBSF of the User Data ingestion status as specific in TS 26.502
The NEF sends Nnef_MBSGroupMsgDelivery_StatusNotify
to the AF, containing Group Message Correlation ID, Delivery Status. The Delivery Status indicates whether delivery of Group Message Payload is successful or not. The delivery status information is received by the NEF via Nmbsf_MBSUserDataIngestSession_StatusNotify
service operation (see TS 26.502