The functional model for the MC services architecture is defined as a series of planes to allow for the breakdown of the architectural description. Each plane is expected to operate in an independent manner, providing services to the connected planes as and when requested by the connected plane, and requesting services from other planes as required.
In this context, each plane manages on its own behalf:
Use of identities: Each plane is responsible for the privacy of that plane's own identities; and
Security for that plane: It does not preclude a plane requesting security services from another plane, but that is a decision made within the plane, as to whether to use offered security services or mechanisms within the plane itself.
application plane: The application plane provides all of the services (e.g. call control, floor control, video control, data control, conferencing of media, provision of tones an announcements) required by the user together with the necessary functions to support MC service. It uses the services of the signalling control plane to support those requirements.
signalling control plane: The signalling control plane provides the necessary signalling support to establish the association of users involved in an MC service, such as an MCPTT call or other type of MC services. The signalling control plane also offers access to and control of services across MC services. The signalling control plane uses the services of session connectivity.
The corresponding session connectivity supporting these planes are defined for the use of 5GS within TS 23.501. The associated resource control to support these planes is defined within TS 23.503.
Each MC service can be represented by an application plane functional model. The corresponding functional model across MC services may be similar but is described by the individual functional entities and reference points that belong to that MC service. Within the application plane for an MC service, a common set of functions as well as reference points is shared across MC services and is referred as the common services core.
Figure 5.3.1-1 shows the common functional model for the application plane for an MC system using 5GS.
Figure 5.3.1-1 shows the common functional model for the application plane for an MC system using 5GS.
The common services core functions and reference points shown in Figure 5.3.1-1 are shared across each MC service.
Figure 5.3.1-2 shows the common functional model for the signalling control plane using 5GS.
In the model shown in Figure 5.3.1-2, the SIP core may interact directly with 5GS via the N5 reference point or Rx reference point to control QoS on a per communication flow in accordance with TS 23.501.
Figure 5.3.1-3 shows the relationships between the reference points of the common application plane of an MC service server and the common signalling plane.
The protocols on any reference point that is exposed for MC service interoperability with other SIP core or other IMS entities in other systems shall be compatible with the protocols defined for the corresponding reference point defined in TS 23.002.
The SIP-1 reference point, which exists between the signalling user agent and the SIP core for establishing a session in support of MC service, shall use the Gm reference point as defined in TS 23.002 (with necessary enhancements to support MC service requirements and profiled to meet the minimum requirements for support of MC services). The SIP-1 reference point fulfils the requirements of the 5G-GC1 reference point, and is used for:
SIP registration (including the UE's capabilities, for example eMBMS capable, or MBS capable UE);
authentication and security to the service layer;
event subscription and event notification;
overload control;
MBS session management; e.g., MBS session announcement and de-announcement; and
The SIP-2 reference point, which exists between the SIP core and the SIP AS for establishing a session in support of MC service, shall use the ISC and Ma reference points as defined in TS 23.002. The SIP-2 reference point is used for:
notification to the MC service server(s) of SIP registration (including the UE's capabilities, for example eMBMS capable, or MBS capable UE) by the MC service UE;
The N5 reference point and Rx reference point, which exist between the SIP core and the 5GS, are used for resource management of MC service sessions, e.g. QoS control, as defined in TS 23.501, TS 23.502 and TS 23.503.
The description of functional model for off-network operation in clause 7.3.2 of TS 23.280 applies.
The description of functional model for off-network operation of MCPTT service in clause 7.3.2 of TS 23.379 applies.
The description of functional model for off-network operation of MCVideo service in clause 6.1.2 of TS 23.281 applies.
The description of functional model for off-network operation of MCData service in clause 6.4.2 of TS 23.282 applies.