Figure 4.6.1-1 below depicts an architecture for downlink 5G Media Streaming via eMBMS that combines the functions and reference points of the 5GMS System with those of the MBMS System.
This arrangement allows 5GMS-based downlink media streaming to be deployed as an MBMS-aware Application on top of eMBMS as defined in TS 23.246, TS 26.346, TS 26.347 and TS 26.348.
In this case:
The 5GMSd AF configures the delivery of 5GMSd content to an MBMS Client in the UE by creating a Service as defined in clause 5.3 of TS 26.348. In order to additionally deliver this content over an MBMS User Service, the 5GMSd AF invokes xMB-C control plane procedures on the BM SC as specified in clauses 5.3 and 5.4 of TS 26.348 and, as a result, content is ingested by the BM-SC from the 5GMSd AS using the xMB-U File Distribution procedures specified in clause 5.5.2 of TS 26.348 to allow xMB-C Session types Application and Files.
The 5GMSd Client acts as eMBMS-Aware Application (as defined in TS 26.347) for the MBMS Client. Thus, the MBMS Client is controlled by the 5GMSd Client via the Media Streaming Service API specified in clause 6.3 of TS 26.347 or via the File Delivery Application Service API specified in clause 6.2 of TS 26.347. (This interaction is labelled MBMS-API-C in Figure 4.6.1-1 above.)
The MBMS Client receives media and other objects from the BM-SC according to the MBMS Download Delivery Method specified in clause 7 of TS 26.346. If an uplink is available to the MBMS Client, and if associated delivery procedures as specified in clause 9.3 of TS 26.346 are activated, the MBMS Client uses the associated delivery procedures to recover damaged media objects received from the BM-SC for xMB-C Session type Files.
The Media Server function interfaces with the MBMS Client per Figure 5.1 of TS 26.347, and shall expose the content received (and possibly repaired) by the MBMS Client to the 5GMSd Client via the HTTP client-to-application interface specified in clause 7.2 of TS 26.347. (This interaction is labelled MBMS-API-U in Figure 4.6.1-1 above.)
The media player sends requests according to the signalled object availability times in the manifest. In case a media object transmitted via the MBMS User Service is not received by the MBMS Client by the object availability times, or if it cannot be repaired in time for consumption by the 5GMS Client, the Media Server returns an error or a partial object in response to the Media Player's request for the media object, and the Media Player may instead attempt to retrieve the media object, or ranges of it, from the 5GMSd AS at reference point M4d, if available. The object shall be available for the application for a well-defined time duration.
The usage of existing reference points to support these scenarios is documented in the following clauses. Procedures for 5GMS via eMBMS are defined in clause 5.10.
Reference point M1d is used as defined in clauses 4.1 to 4.4.
In addition, the content provider shall authorize via M1d that 5GMS content may be distributed via eMBMS.
The translation of M1d information to eMBMS delivery provisioning is left to implementation.
Reference point M5d is used as defined in sub-clauses 4.1 to 4.4.
In addition, for 5GMS content to be distributed via eMBMS:
The 5GMS Service Access Information shall include the relevant information of the eMBMS Service Announcement in order to bootstrap reception of the MBMS service, typically via a service identifier (i.e., the serviceId attribute of the bundleDescription.userServiceDescription element of the USD - see TS 26.346). This is passed by the Media Session Handler to the MBMS Client via reference point MBMS-API-C TS 26.347.
When this information is present in the Service Access Information and when the UE is MBMS-capable, the 5GMSd Client shall invoke the MBMS Client to initiate reception of the corresponding MBMS User Service.
The 5GMS Service Access Information shall include relevant information from the eMBMS Service Announcement in order for the Media Session Handler to:
Collect metrics of the MBMS service from the MBMS Client and report them to the 5GMSd AF using an appropriate metrics reporting scheme.
Collect media consumption information from the MBMS Client and submit it to the 5GMSd AF in 5GMS consumption reports..
The MBMS User Service Announcement as defined in TS 26.346 is used to advertise the availability of 5GMS content delivered via eMBMS.
A Generic application service (as defined in clause 5.7 of TS 26.346) is provisioned in the BM-SC and the application service entry point instance is a downlink 5GMS streaming manifest, for example a DASH MPD or HLS playlist.
The MBMS Client operates according to the procedures defined in clause 6.3 of TS 26.347 at reference point MBMS-API-C when communicating with the 5GMSd Client.
The MBMS Client exposes information to the Media Session Handler to manage the reception of MBMS User Services.
The Media Session Handler configures the MBMS Client for consumption and QoE metrics reporting.
The MBMS Client provides consumption and QoE metrics reports to the Media Session Handler.
The MBMS Client operates according to the procedures defined in clause 7 of TS 26.347 at reference point MBMS-API-U when communicating with the 5GMSd Client.
The MBMS Client provides the streaming manifest, as well as updates of the manifest, to the 5GMSd Client and implements policies for hybrid services based on clause 7 of TS 26.347.
The MBMS Client exposes fully- and partially-received media objects to the Media Player in the 5GMSd Client.