The MCVideo client functional entity acts as the user agent for all MCVideo application transactions. The MCVideo client is responsible for remote device control. This functional entity is located in the UE for both on-network and off-network operations.

The MCVideo server functional entity provides centralised support for MCVideo services. All the MCVideo clients supporting users belonging to a single group are required to use the same MCVideo server for that group. An MCVideo client supporting a user involved in multiple groups can have relationships with multiple MCVideo servers. The MCVideo server is an instantiation of a MC service server in accordance with TS 23.280. The MCVideo server functional entity represents a specific instantiation of the GCS AS described in TS 23.468 to control multicast and unicast operations for group communications. The MCVideo server functional entity is supported by the SIP AS, HTTP client and HTTP server functional entities of the signalling control plane. This MCVideo server provides support for centralised media transmission control for on-network and distributed media transmission control for off-network operation. The MCVideo server is responsible for managing and providing the device information that can participate in MCVideo communications. The device information is further associated to MCVideo users to manage remote device control authorization. The device information is provisioned to the MCVideo server by the MCVideo service provider, mission critical organization and the MCVideo user. The MCVideo server performing the functional alias controlling role is responsible for:

• interfacing with the functional alias management server for functional alias policy;
• functional alias activation, deactivation, take over and interrogation support for MCVideo user.

The controlling roles for group call, private call and functional alias are independent with each other.

The media distribution function is responsible for the distribution of media to MCVideo clients. By means of information provided by the MCVideo server (e.g. IP addresses, transport layer ports), it will provide the following functionality:

• provide for the reception of uplink MCVideo UE media transmission by means of the MCVideo-7 reference point;
• storing the received media stream as MCVideo content files;
• replicate the media as needed for distribution to those participants using unicast transport;
• distribute downlink media to MCVideo UEs by IP unicast transmission to those participants utilizing unicast transport by means of the MCVideo-7 reference point;
• distribute downlink media to MCVideo UEs using multicast downlink transport of media for the call by means of the MCVideo-8 reference point; and
• provide a media mixing function where multiple media streams are combined into a single media stream for transmission to the MCVideo UE.

This functional entity exists on the UE and provides support for sending and receiving one or multiple media streams. It also provides support for combining multiple media streams into one media stream through the enforcement of media policy information. It supports the storing of a media stream as MCVideo content files.

This functional entity contains information of the MCVideo user profile associated with an MCVideo ID that is held by the MCVideo service provider at the application plane. The MCVideo user profile is determined by the mission critical organization, the MCVideo service provider, and potentially the MCVideo user. The MCVideo ID is a MC service ID as described in clause 8 of TS 23.280. The MCVideo user profile is a MC service user profile as described in clause 10.1.4 of TS 23.280. The MCVideo user profile can be co-located with other MC service user profiles and stored in a common MC service user database.

This functional entity provides support for centralised transmission control for on-network and distributed transmission control for off-network operation. It may schedule transmission requests according to uplink criteria from different transmission control participants, send an notification to all transmission control participants to allow them to receive the video according to downlink criteria if the transmission request is granted, and provide queuing in cases of contention. Transmission control applies to all MCVideo communications including group call and private call. For on-network operation, this functional entity is located with the MCVideo server. For off-network operation, this functional entity is located in the UE.

The transmission control participant functional entity is responsible for handling outgoing transmission requests and the incoming video stream invitations and notifications. This functional entity is located in the UE for both on-network and off-network operations.

The MC gateway server provides support for MCVideo interconnection services with a partner MCVideo system in a different trust domain whilst providing topology hiding. It acts as a proxy for one or more MCVideo servers in the partner MCVideo system without needing to expose the MCVideo servers in the primary MCVideo system outside the trusted domain of the primary MCVideo system. It may be a role of the MCVideo server described in subclause 6.2.2.3.2 of the present document. The MC gateway server is responsible for relaying call control and floor control signalling messages, and media between MCVideo servers within the MCVideo system and the interconnected MCVideo system.