The 5GMSu Application Provider uses 5GMSu functions for uplink streaming services. It provides a 5GMSu-Aware Application on the UE the ability to make use of 5GMSu Client and network functions using 5GMSu interfaces and APIs.
The architecture in Figure 4.3.1-1 above represents the specified 5GMSu functions within the 5G System (5GS) as defined in TS 23.501. Three main functions are defined:
5GMSu AF: An Application Function similar to that defined in TS 23.501, clause 6.2.10, dedicated to 5G Uplink Media Streaming.
5GMSu AS: An Application Server dedicated to 5G Uplink Media Streaming.
5GMSu Client: A UE-internal function dedicated to 5G Uplink Media Streaming.
5GMSu AF and 5GMSu AS are Data Network (DN) functions and communicate with the UE via N6 as defined in TS 23.501.
Functions in trusted DNs, e.g., a 5GMSu AF in the Trusted DN, are trusted by the operator's network as illustrated in Figure 4.2.3-5 of TS 23.501. Therefore, such AFs may directly communicate with relevant 5G Core functions.
Functions in external DNs, e.g., a 5GMSu AF in the External DN, may only communicate with 5G Core functions via the NEF using N33.
The architecture in Figure 4.3.1-2 below represents the media architecture connecting UE internal functions and related network functions for 5G Uplink Media Streaming.
5G Media Streaming Client for uplink (5GMSu Client) on UE: Originator of 5GMSu service that may be accessed through well-defined interfaces/APIs. The UE may also be implemented in a self-contained manner such that interfaces M6u and M7u are not exposed at all.
The 5GMSu Client contains two subfunctions:
Media Session Handler: A function on the UE that communicates with the 5GMSu AF in order to establish, control and support the delivery of a media session, and that may perform QoE metrics reporting. The Media Session Handler exposes APIs that can be used by the 5GMSu-Aware Application.
Media Streamer: A function on the UE that communicates with the 5GMSu AS in order to perform uplink streaming of media content and provides a service to both the 5GMSu-Aware Application for media capturing and uplink streaming and the Media Session Handler for media session control.
5GMSu-Aware Application: The 5GMSu Client is typically controlled by an external media application, e.g. an App, which implements external application or content service provider specific logic and enables a media session to be established. The 5GMSu-Aware Application is not defined within the 5G Media Streaming specifications, but the function makes use of 5GMSu Client and network functions using 5GMSu interfaces and APIs.
5GMSu AS: An Application Server which hosts 5G media functions. Note that there may be different realizations of a 5GMSu AS, for example a Content Delivery Network (CDN) server.
5GMSu Application Provider: External application or content-specific media functionality, e.g., media storage, consumption, transcoding and redistribution that uses 5GMSu interfaces to receive streaming media from 5GMSu Aware Applications.
5GMSu AF: An Application Function that provides various control functions to the Media Session Handler on the UE and/or to the 5GMSu Application Provider. It may relay or initiate a request for different Policy or Charging Function (PCF) treatment or interact with other network functions via the NEF.
The following interfaces are defined for 5G Uplink Media Streaming:
M1u (5GMSu Provisioning API): External API, exposed by the 5GMSu AF and which enables the 5GMSu Application Provider to provision the usage of the 5G Media Streaming system for uplink media streaming and to obtain feedback.
M2u (5GMSu Publish API): Optional External API exposed by the 5GMSu AS used when the 5GMSu AS in the trusted DN is selected to receive the content for the streaming service.
M3u: (Internal and NOT SPECIFIED): Internal API used to exchange information for content hosting on a 5GMSu AS within the trusted DN.
M4u (Uplink Media Streaming APIs): APIs exposed by a 5GMSu AS to the Media Streamer to stream media content.
M5u (Media Session Handling API): APIs exposed by a 5GMSu AF to the Media Session Handler for media session handling, control and assistance that also include appropriate security mechanisms e.g. authorization and authentication, and QoE metrics reporting.
M6u (UE Media Session Handling APIs): APIs that may be exposed by a Media Session Handler to the Media Streamer for client-internal communication, and to the 5GMSu-Aware Application to make use of 5GMSu functions.
M7u (UE Media Streamer APIs): APIs that may be exposed by a Media Streamer to the 5GMSu-Aware Application and Media Session Handler to make use of the Media Streamer, including configuration of QoE metrics to be measured and logged, and the collection of metrics measurement logs.
M8u: (Application API): application interface used for information exchange between the 5GMSu-Aware Application and the 5GMSu Application Provider, for example to provide Service Access Information to the 5GMSu-Aware Aapplication. This API is external and not specified in the 5GMS architecture.
The UE may include many detailed subfunctions that can be used individually or controlled individually by the 5GMSu-Aware Application. This clause breaks down several relevant identified subfunctions for which stage 3 specification is available.
The 5GMSu-Aware Application itself may include many functions that are not provided by the 5GMSu Client or to the 5G UE. Examples include peripheral discovery, notifications and social network integration. The 5GMSu-Aware Application may also include functions that are equivalent to ones provided by the 5GMSu Client and may only use a subset of the 5GMSu Client functions.
With respect to the Media Streamer and Media Handler functions, Figure 4.3.2-1 shows more detailed functional components of a 5GMSu Client.
The following subfunctions are identified as part of a more detailed breakdown of the UE 5G Uplink Media Streaming functions:
5GMSu-Aware Application: application which is out of scope of the present specification and which uses the UE 5G Uplink Media Streaming functions and APIs.
Media Capturing: Devices such as video cameras or microphones that transform an analog media signal into digital media data.
Media Encoder(s): Compresses the media data.
Metrics Measurement and Logging: execution of QoE metrics measurement and logging by the Media Streamer in accordance with the metrics configuration.
Metrics Collection and Reporting: execution of the collection of QoE metrics measurement logs from the Media Streamer by the Media Session Handler for subsequent metrics reporting to the 5GMSu AF, in accordance with the metrics configuration.
Media Upstream Client: encapsulates encoded media data and pushes it upstream.
Network Assistance: uplink streaming delivery assisting functions provided by the network to the 5GMSu Client and Media Streamer in the form of bit rate recommendation (or throughput estimation) and/or delivery boost. Network Assistance functionality may be supported by 5GMSu AF or ANBR-based RAN signaling mechanisms.
Media Remote Control: receives control commands from a 5GMSu AF.
Core Functions: configures the 5GMSu AS for uplink streaming reception.
Here are the roles of the different APIs of the UE 5G Uplink Media Streaming functions:
M6u: API used to control the Core Functions and the Remote Control function.
M7u: API used to configure, activate and stop the Media Capturing, Media Encoding(s) and Media Upstream Client functions, and also to support metrics configuration and collection functionality.
The 5GMS architecture offers the option to create aContent Hosting Configuration for external 5GMSd AS(s) through a provisioning interface, as described in clause 5.4. A Content Hosting Configuration is a 5GMS-optimized configuration that is tailored to a third-party content or service provider to leverage the capabilities of the 5G System to achieve optimized delivery of media content.
Upon successful setup of a Content Hosting Configuration, the 5GMSd AF uses the NSaaS to create or use an existing corresponding network slice, and assigns the Content Hosting Configuration domain as the network slice selection assistance information rule. This allows any traffic to and from the Content Hosting Configuration domain to be mapped to the correct network slice instance.
The concept of Network Slice as a Service (NSaaS) is defined in TS 28.530. NSaaS can be offered by an MNO to third-party providers in the form of a service. This service allows the providers to use the network slice instance as the end user and to manage the network slice instance via a management interface exposed by the MNO. In turn, these providers offer their own services, e.g. OTT service, on top of the network slice instance obtained from the MNO.
The NSaaS offered by the MNO can be characterized by certain properties (capabilities to satisfy service level requirements), e.g.
radio access technology,
guaranteed / non-guaranteed QoS,
security level, etc.
The interface that is used for the creation and management of network slices is defined in TS 28.531 and the information elements are defined in TS 28.541.
The network (HPLMN) may provision the UE with Network Slice Selection Policy (NSSP) as part of the UE Route Selection Policy rules as described in TS 23.503. This ensures that the UE will request a particular network slice when establishing the PDU session. Note that this mapping can also be established through associating an Application with the Content Hosting Configuration and the network slice, which in turn will be associated with a PDU session that includes the Content Hosting Configuration domain as a matching domain.
Once the PDU session is established using the network slice instance that corresponds to the Content Hosting Configuration, the media distribution to the UE may start. The network slice instance may be provisioned to support processing and edge computing in addition to the appropriate QoS allocation. The 5GMSd AF is responsible for ensuring appropriate traffic routing, e.g. request the routing of traffic to a local access to a Data Network (identified by a DNAI) that hosts the media processing compute instances.