4.1 Overall Media Architecture

26.5013GPP5G Media Streaming (5GMS)General description and architectureRelease 18TS

Streaming in the context of this specification is defined as the delivery of time-continuous media as the predominant media. Streaming points to the fact that the media is predominantly sent only in a single direction and consumed as it is received. Additionally, the media content may be streamed as it is produced, referred to as live streaming. If content is streamed that is already produced, it is referred to as on-demand streaming.

The overall 5G Media Streaming Architecture is shown in Figure 4.1-1 below.

NOTE: The functions indicated by the yellow filled boxes are in scope of stage 3 specifications for 5GMS. The functions indicated by the grey boxes are defined in 5G System specifications. The functions indicated by the blue boxes are neither in scope of 5G Media Streaming nor 5G System specifications.

Figure 4.1-1: 5G Media Streaming within the 5G System

The 5GMS Application Provider uses 5GMS for streaming services. It provides a 5GMS Aware-Application on the UE to make use of 5GMS Client and network functions using interfaces and APIs defined in 5GMS.

The architecture in Figure 4.1-1 represents the specified 5GMS functions within the 5G System (5GS) as defined in TS 23.501 [2]. Three main functions are defined:

– 5GMS AF: An Application Function similar to that defined in TS 23.501 [2] clause 6.2.10, dedicated to 5G Media Streaming.

– 5GMS AS: An Application Server dedicated to 5G Media Streaming.

– 5GMS Client: A UE internal function dedicated to 5G Media Streaming. The 5GMS Client is a logical function and its subfunctions may be distributed within the UE according to implementation choice.

5GMS AF and 5GMS AS are Data Network (DN) functions and communicate with the UE via N6 as defined in TS 23.501 [2].

Functions in trusted DNs, e.g. a 5GMS AF in the Trusted DN, are trusted by the operator’s network as illustrated in Figure 4.2.3-5 of TS 23.501 [2]. Therefore, such AFs may directly communicate with the relevant 5G Core functions.

Functions in external DNs, e.g. a 5GMS AF in the External DN, may only communicate with 5G Core functions via the NEF using N33.

The present document specifies the according network architectures for 5GS. The 5GMS architecture may be applied to an EPS although such an application is not specified in the present document and is left to the discretion of deployments and implementations.

The 5G Media Services Architecture maps the overall high-level architecture shown in Figure 4.1-1 above to the general architecture shown in Figure 4.1-2 below.

NOTE: The 5GMS Client in the UE is depicted in the form of Media Session Handler and Media Stream Handler constituent functions which expose APIs to one another in the same way that those APIs are exposed to 5GMS-Aware Applications. This UE architecture is not applicable generally; it is just as valid to implement a 5GMS Client that does not expose interfaces M6 and M7 within the 5GMS Client. It is also valid for a 5GMS Client inside a UE to be completely self-contained, such that all functionality typically implemented in the 5GMS-Aware Application is embedded in the UE and thus interfaces M6 and M7 are not exposed at all.

Figure 4.1-2: 5G Media Streaming General Architecture

The remainder of the present document specifies stage 2 aspects of the media streaming functional entities shown in the general architecture of Figure 4.1-2.

This architecture specification addresses two main scenarios as concerns each individual media streaming operation:

– Downlink streaming: The network is the origin of the media and the UE acts as the consumption device.

– Uplink streaming: The UE is the origin of the media and the network acts as the consumption entity.

The functional entities and interfaces of the media streaming general architecture need to be elaborated with specificities relating to downlink and uplink streaming. For this purpose, corresponding descriptions add the suffix "d" for downlink and "u" for uplink functionality as appropriate in each case.

Clause 4.2 introduces the 5G Unicast Downlink Media Streaming architecture.

Clause 4.3 introduces the 5G Unicast Uplink Media Streaming architecture.