4 Functional architecture

23.4793GPPRelease 17Technical Specification Group Services and System AspectsTSUE MBMS APIs for Mission Critical Services

4.1 General

This clause specifies the functional model of the MC MBMS API within the MC service UE (as described in clause 4.3), and the system architecture (as described in clause 4.2).

4.2 System architecture

This clause demonstrates the end-to-end MC service architecture with the use of MC MBMS API for MC multicast operations.

Figure 4.2-1 shows the system architecture for mission critical communications. In the system architecture GCSE communications as defined in 3GPP TS 23.468 [2] is supported. When representing the MC service client, the MC application accesses the MBMS resource on MC MBMS user agent through the MC MBMS API, based on information in application signalling over MCPTT-1, MCVideo-1 or relevant interfaces of MCData service. Some multicast related information acquired through the MC MBMS API are used by the MC application to report to the MC service server over application signalling.

Figure 4.2-1: System architecture for MC MBMS API

4.3 Functional model

4.3.1 Functional model of MC MBMS API

Figure 4.3.1-1 shows the functional model of the MC MBMS API which resides between the MC application and MC MBMS user agent on the MC service UE.

Figure 4.3.1-1: MC MBMS API functional model

In the functional model the MC application can represent an MC service client.

The MC MBMS user agent supports the MC service client functions in receiving the MBMS bearer data for the use of MBMS transmission defined in 3GPP TS 23.280 [3], 3GPP TS 23.379 [4], 3GPP TS 23.281 [5] and 3GPP TS 23.282 [6].

4.3.2 MC application

The MC application invokes the MC MBMS API to access and manage the MBMS bearers to support MC services.

The MC application supports the following functions:

– Registration and deregistration to the MC MBMS user agent;

– Reception of application level control signalling messages;

– Activation and termination of MBMS bearer quality monitoring;

– Obtaining MBMS bearer availability through the MC MBMS API;

– Obtaining MBMS bearer suspension and resumption status through the MC MBMS API;

– Reception of media with or without FEC encoding and media with or without ROHC compression from the MC MBMS user agent;

– Obtaining location information for MBMS usage through the MC MBMS API;

– Configuration of the MC MBMS user agent; and

– Retrieve capabilities of MC MBMS user agent.

4.3.3 MC MBMS user agent

The MC MBMS user agent may provide MBMS media with FEC and ROHC to the MC application.

One or more MC application(s) use the MC MBMS API provided by the MC MBMS user agent.

The MC MBMS user agent supports the following functions:

– Detection of location information for MBMS usage;

– Detection of MBMS bearer availability;

– Report of MBMS bearer quality to the MC application;

– Reception of MBMS data from a lower layer of the UE;

– Detection of suspension of MBMS bearer; and

– Delivery of media with or without FEC encoding and media with or without ROHC compression to the MC application.