6.4 Participating MCPTT function floor control procedures

24.3803GPPMission Critical Push To Talk (MCPTT) media plane controlProtocol specificationRelease 18TS

6.4.1 General

Once an on-demand MCPTT session is established or a pre-established session is in use when the participating MCPTT function receives floor control messages from the floor participant in the MCPTT client or from the floor control server in the controlling MCPTT function, the behaviour of the participating MCPTT function is described in the following clauses.

6.4.2 Receive floor control messages

Upon receiving a floor control message the participating MCPTT function:

1. shall immediately forward the floor control message to the floor control server if the message is received from the floor participant;

2. if an MBMS subchannel is not used for a conversation in the session the floor control message is associated with, shall immediately forward the floor control message to the floor participant if the message is received from the floor control server; and

3. if an MBMS subchannel is used for a conversation in the session the floor control message is associated with:

a. if

i. the floor control message is not a Floor Idle message or a Floor Taken message or a Floor Release Multi Talker message;

ii. the MCPTT client has not reported "listening" status as specified in 3GPP TS 24.379 [2] clause 14.2.3;

iii. the MCPTT client has reported "not-listening" status as specified in 3GPP TS 24.379 [2] clause 14.2.3 in the latest received MBMS bearer listening status report; or

iv. the floor control message is a Floor Idle message or a Floor Taken message or a Floor Release Multi Talker message, protection of floor control messages sent over the MBMS subchannel from the participating MCPTT function to the served MCPTT clients is required, and the participating MCPTT function determined that the MCPTT client does not support MuSiK as specified in 3GPP TS 24.379 [2];

shall immediately forward the floor control message to the floor participant; and

b. if

i. the MCPTT client has reported "listening" status as specified in 3GPP TS 24.379 [2] clause 14.2.3 in the latest received MBMS bearer listening status report; and

ii if the floor control message is the Floor Idle message or the Floor Taken message or the Floor Release Multi Talker message, and:

– protection of floor control messages sent over the MBMS subchannel from the participating MCPTT function to the served MCPTT clients is not required; or

– the participating MCPTT function determined that the MCPTT client supports MuSiK as specified in 3GPP TS 24.379 [2];

shall perform actions as specified in clause 10.2.

NOTE: When the Floor Idle, Floor Taken, or Floor Release Multi Talker messages are discarded the messages are sent to the MCPTT clients over the MBMS subchannel allocated for the conversation as specified in clause 10.2.

6.4.3 Receive RTP media packets (R: RTP Media)

Upon receiving RTP media packets the participating MCPTT function:

1. shall immediately forward the RTP media packet to the controlling MCPTT function if the RTP packet is from an MCPTT client; and

2. if an MBMS subchannel is not used for a conversation in the session the RTP media packets are associated with, shall immediately forward the RTP media packets to the MCPTT client if the RTP packet is from the controlling MCPTT function or the non-controlling MCPTT function.

3. if an MBMS subchannel is used for a conversation in the session the RTP media packets are associated with and if RTP media packets are received from the controlling MCPTT function or the non-controlling MCPTT function:

a. if

i. the MCPTT client has not reported "listening" status as specified in 3GPP TS 24.379 [2] clause 14.2.3; or

ii. the MCPTT client has reported "not-listening" status as specified in 3GPP TS 24.379 [2] clause 14.2.3 in the latest received MBMS bearer listening status report,

shall immediately forward the RTP media packets to the MCPTT client; and

b. if the MCPTT client has reported "listening" status as specified in 3GPP TS 24.379 [2] clause 14.2.3 in the latest received MBMS bearer listening status report, shall perform actions as specified in clause 10.2.

6.4.4 Release of session

When the participating function receives an indication from the application and signalling plane that session release is initiated, the participating MCPTT function:

1. shall stop sending floor control messages towards the floor participant and the floor control server; and

2. shall stop sending RTP media packets towards the MCPTT client and towards the controlling MCPTT function.

When the participating MCPTT function receives an indication from the application and signalling plane that the session is released, the participating MCPTT function:

1. in case of a pre-established session, shall perform the actions in clause 9.3.2; and

2. in case of an on-demand session, shall release the media resources associated with the session.