Content for TS 23.289 Word version: 19.3.0

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7.3 MC service over 5G MBS 7.3.1 General 7.3.2 Information flows for 5G MBS 7.3.2.1 MBS session announcement 7.3.2.2 UE session join notification 7.3.2.3 MapGroupToSessionStream 7.3.2.7 UnMapGroupFromSessionStream 7.3.2.8 Discover MBS Session request 7.3.2.9 Discover MBS Session response 7.3.2.10 MBS listening status report 7.3.2.11 MBS session de-announcement 7.3.2.12 MBS session de-announcement acknowledgement 7.3.2.13 Media distribution request 7.3.2.14 Media distribution response 7.3.2.15 Media distribution release 7.3.2.16 MBS session announcement acknowledgement
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7.3 MC service over 5G MBS |R18| p. 52

7.3.1 General p. 52

This subclause defines information flows and procedures for 5G MBS usage that applies to MC services. 5G MBS session can be used by any MC service for any MC service group.

The following subclauses specify the procedures and information flows for the usage of 5G MBS transmission that are utilized by the following MC services:

MCPTT (as specified in TS 23.379);
MCVideo (as specified in TS 23.281); and
MCData (as specified in TS 23.282).

MC service specific pre-requisites and resultant behaviour by functional entities in performing these procedures are specified in the respective MC service TSs as listed above.

The first phase to utilize MBS sessions for MC service media transmission is to have the sessions created hence the network resources are reserved. The MC service server may consider the UE's capabilities and service related information e.g., UE's MBS capabilities, location, MBS listening status report sent by group members when it decides to create or use MBS sessions. The MC service server needs to interact with the 5GC for this matter. During the interaction, the necessary information related to the requested session is determined, e.g., MBS session mode (either a broadcast or a multicast session) and the required QoS profile. This interaction depends on the configuration option under consideration, i.e., whether the MC service server is in trusted domain (limited operations), and whether the session creation is done with or without a dynamic PCC rule.

The information elements describing the MBS session under consideration is then sent to the MC service clients via MBS session announcement, where the latter need to react according to the announced session mode.

If eMBMS and 5G MBS co-exist for MC services, the MC service server may decide to trigger the establishment of an eMBMS bearer to deliver the MC media associated to the MC service group communications, if the target MC service group(s) consists of members with eMBMS capable UE. As a result, the MC service server subsequently needs to send an eMBMS bearer announcement towards the clients camping on LTE.

7.3.2 Information flows for 5G MBS p. 53

7.3.2.1 MBS session announcement p. 53

Table 7.3.2.1-1 provides the information elements during MBS session announcement, which are sent by the MC service server to the clients. The MBS session announcement includes information elements related to the announced MBS session. Optionally, it includes eMBMS related information elements, if eMBMS and 5G MBS co-exist.

Table 7.3.2.1-1: MBS session announcement

Information element	Status	Description
5G MBS session information	M	Providing the MBS session related information if MC service server decides to use 5G MBS session to deliver MC service group communication data.
>MBS session ID	M	The identity of the MBS session used to deliver MC service group communication data. It is either TMGI for broadcast MBS and multicast MBS sessions, or source specific IP multicast address for multicast MBS session.
>MBS session mode	M	Indicate the service type of the MBS session, either a multicast MBS session or a broadcast MBS session.
>MC service group ID	O	Indicate the MC service group ID associated to the MBS session.
>MBS related SDP information	M	SDP related to application-level control signalling or media to be transmitted over the MBS session (e.g., codec, protocol ID, FEC information, IP address and ports).
>List of MBS Service Area information (see NOTE 5)	O	For the case of local MBS services, it indicates either multicast service area identifier(s) for multicast MBS session, or broadcast service area identifier(s) for broadcast MBS session.
>MBS session announcement acknowledgement	O	Indicate if the MC service server requires an acknowledgement to the MBS session announcement.
>Multicast MBS session related information (see NOTE 1)	O	Additional information to be used by the MC service client to join the multicast MBS session such as PLMN ID of the default PLMN service provider, NID (for the case of SNPN deployments) in case of source specific IP multicast address, DNN, and SNSSAI of the PDU session associated with the multicast MBS session
>UE session join notification (see NOTE 2)	O	Indicate if the MC service server requires a notification from the MC service client once it has joined the multicast MBS session.
>Monitoring state	O	Indicate if the MC service client is required to actively monitor the MBS session quality and report it to the MC service server. This is applicable for both multicast and broadcast eMBMS session.
>Frequency (see NOTE 3)	O	Identification of frequency associated with a broadcast MBS session, if multi carrier support is provided.
>MBS Frequency Selection Area ID (MBS FSA ID) (see NOTE 3)	O	The frequency associated to a certain broadcast area, if multi carrier support is provided.
eMBMS bearer information	O	Providing the 4G eMBMS bearer related information if MC service server decides to use 4G eMBMS additionally with 5G MBS session to deliver MC service group communication data.
>TMGI (see NOTE 4)	M	TMGI information
>Alternative TMGI	O	A list of additional alternative TMGI may be included and used in roaming scenarios.
>QCI	O	QCI information used by the ProSe UE-Network Relay to determine the ProSe Per-Packet Priority value to be applied for the multicast packets relayed to Remote UE over PC5.
>List of service area identifier	M	A list of service area identifier for the applicable eMBMS broadcast area.
>Frequency	O	Identification of frequency if multi carrier support is provided
>eMBMS related SDP information	M	SDP with media and floor control information applicable to groups that can use this eMBMS bearer (e.g., codec, protocol id, FEC information).
>Monitoring state	O	Indicate if the MC service client is required to actively monitor the eMBMS bearer quality and report it to the MC service server.
>ROHC information	O	Indicate the usage of ROHC over the eMBMS bearer and provide the parameters of the ROHC channel to signal to the ROHC decoder.
NOTE 1: Such information may be pre-configured in the MC service UE, or provided in any other implementation specific way NOTE 2: It is applicable for multicast MBS session NOTE 3: It is applicable for broadcast MBS session NOTE 4: TMGI for 4G eMBMS bearer can be the same or different with 5G MBS session ID. NOTE 5: Details of MBS service area information is defined in TS 23.247.

7.3.2.2 UE session join notification p. 56

Table 7.3.2.2-1 describes the information flow of UE session joining notification from the MC service client to the MC service server after successfully joining a certain multicast MBS session procedure as defined in TS 23.247.

Table 7.3.2.2-1: UE session join notification

Information element	Status	Description
MBS session ID(s)	M	The identity of the multicast MBS session(s) being joined. It is either TMGI or source specific IP multicast address.
MC service ID	M	Identity of the MC service user who is reporting the session status
MBS multicast joining status	M	The multicast listening status can be joined if successfully joined MBS session.

7.3.2.3 MapGroupToSessionStream p. 56

Table 7.3.2.3-1 defines the MapGroupToSessionStream to be sent from the MC service server to MC service clients to provide specific required information to receive the media related to a group communication within an MBS session. The MC service can either be MCPTT, MCVideo or MCData services.

Table 7.3.2.3-1: MapGroupToSessionStream

Information element	Status	Description
MC service group ID	M	This element identifies the MC service group related to a group communication to be delivered over the MBS session. The MC service group ID is either MCPTT group ID, MCVideo group ID, or MCData group ID.
Media stream identifier	M	This element identifies the media stream of the SDP used for the group communication within the MBS session. In case separate media streams are used for the audio and video media components in MCVideo services, separate identifiers can be used.
MBS session ID	O	The MBS session identifier if the MapGroupToSessionStream message is not sent on the same session as the MC media

7.3.2.4 Void

7.3.2.5 Void

7.3.2.6 Void

7.3.2.7 UnMapGroupFromSessionStream p. 56

Table 7.3.2.7-1 describes the information flow to disconnect an MC group communication call from a MBS session. It is sent from the MC service server to the MC service client, where the MC service can either be MCPTT, MCVideo or MCData services.

Table 7.3.2.7-1: UnMapGroupFromSessionStream

Information element	Status	Description
MCPTT group ID	M	This element identifies the MC service group related to a group call to be dissociated over the MBS session. The MC service group ID is either MCPTT group ID, MCVideo group ID, or MCData group ID.
Media stream identifier	M	This element identifies the media stream of the SDP, which is no longer used for the group call within the MBS session. In case separate media streams are used for audio and video stream in MCVideo services, a separate identifier is optinally used to identify the audio stream, which is no longer used.
MBS session ID	O	Indicating the MBS session ID, if the information is sent over another MBS session or unicast path

7.3.2.8 Discover MBS Session request p. 57

The usage of Discover MBS Session request is similar to Discover Bearer request for eMBMS as it defined in TS 23.280.

Table 7.3.2.8-1 describes the information flow discover MBS session request from the MC service server to another MC service server (MBS session control role).

Table 7.3.2.8-1: Discover MBS session request

Information element	Status	Description
List of MBS service area information	O	A list of MBS service area information for the applicable MBS session service area.
Bandwidth	M	Maximum bandwidth required
5QI	O	Desired 5QI

7.3.2.9 Discover MBS Session response p. 57

The usage of Discover MBS Session response is similar to Discover Bearer response for eMBMS as it defined in TS 23.280.

Table 7.3.2.9-1 describes the information flow discover MBS session response from an MC service server (MBS session control role) to the MC service server.

Table 7.3.2.9-1: Discover MBS session response

Information element	Status	Description
MBS Session ID(s)	M	List of MBS session IDs and related information
List of MBS service area information (see NOTE)	O	A list of MBS service area identifiers for the applicable MBS session service areas, corresponding to the listed MBS session IDs, over which the request was successful.
Frequency	O	Identification of the frequency if multi-carrier support is provided
5QI	O	Providing feedback related to the applicable 5QI information.
NOTE: List of MBS service area information is optional and needed once it is applicable with the MBS session ID under consideration.

7.3.2.10 MBS listening status report p. 58

Table 7.3.2.10-1 describes the information flow of MBS listening status report from the MC service client to the MC service server. The MBS listening status report is applicable to both broadcast and multicast MBS sessions.

Table 7.3.2.10-1: MBS listening status report

Information element	Status	Description
MBS session ID(s)	M	The identity of the MBS session(s) being monitored.
MC service ID	M	Identity of the MC service user who is reporting the session status. It may either be the MCPTT ID, MCVideo ID, or MCData ID.
MBS listening status	O	The listening status per MBS session ID.
MBS reception quality level	O	The reception quality level
Unicast listening status	O	The unicast listening status associated with the unicast delivery.
NOTE: The set of quality levels helps service continuity in broadcast and multicast scenarios. A reception quality level may help to make an efficient switching decision to unicast delivery. How these levels are used is implementation specific.

7.3.2.11 MBS session de-announcement p. 58

Table 7.3.2.11-1 describes the information flow of an MBS session de-announcement sent from the MC service server to the MC service clients.

Table 7.3.2.11-1: MBS session de-announcement.

Information element	Status	Description
MBS session ID(s)	M	The identity of the MBS session(s) to be de-announced.
MBS session de-announcement acknowledgement	O	Indicate if the MC service server requires an acknowledgement to the MBS session de-announcement.

7.3.2.12 MBS session de-announcement acknowledgement p. 58

Table 7.3.2.12-1 describes the information flow of an MBS session de-announcement acknowledgement message sent from the MC service clients to the MBS service server, to acknowledge the reception of the MBS session de-announcement.

Table 7.3.2.12-1: MBS session de-announcement acknowledgement

Information element	Status	Description
MC service ID	M	The MC service identity of the MC service client, whose group is no longer associated to the MBS session(s)
MBS session ID(s)	M	The identity of the MBS session(s) to be de-announced.
MBS session de-announcement status	M	The de-announcement status per MBS session ID.

7.3.2.13 Media distribution request p. 58

Table 7.3.2.13-1 describes the information flow media distribution request from the MC Service server to an MC service server (5G MBS Session control role) that has a desired 5G MBS session.

The difference compared with the information flow defined in TS 23.280 is that in 5G MBS, the information element for QoS is 5QI.

Table 7.3.2.13-1: Media distribution request

Information element	Status	Description
MBS session ID	M	MBS session identifier
Bandwidth	M	Maximum bandwidth required
Separate floor control	M	Whether or not a separate session is required for floor control
SDP information	M	SDP with media and floor control information applicable to groups that can use this MBS session (e.g. codec, protocol id)
5QI	O	Desired 5QI
MC Group ID	O	The MC group id for when the request is sent for a specific group call

7.3.2.14 Media distribution response p. 59

Table 7.3.2.14-1 describes the information flow media distribution response from an MC Service server (5G MBS session control role) that has a desired 5G MBS session to the MC service server.

Table 7.3.2.14-1: Media distribution response

Information element	Status	Description
MBS session ID	M	MBS session identifier
Bandwidth	M	Maximum bandwidth required
SDP information	M	SDP with media and floor control information applicable to groups that can use this session (e.g. codec, protocol id)
5QI	O	Actual 5QI
Media stream identifier	O	This element identifies the media stream of the SDP used for the group call
Media distribution indicator	O	Indicates to the MC service server whether the media in the ongoing group communication should be sent or not

7.3.2.15 Media distribution release p. 59

Information flow for Media distribution release is reused without modification as specified in clause 10.7.2.10 of TS 23.280.

7.3.2.16 MBS session announcement acknowledgement p. 59

Table 7.3.2.16-1 describes the information flow of an MBS session announcement acknowledgement message sent from the MC service clients to the MBS service server, to acknowledge the reception of the MBS session announcement.

Table 7.3.2.16-1: MBS session announcement acknowledgement

Information element	Status	Description
MC service ID	M	The MC service identity of the MC service client.
MBS session ID(s)	M	The identity of the MBS session(s) whose announcement information is received.