6.3.3 Floor control procedures at MCPTT call release

29.3803GPPMission Critical Push To Talk (MCPTT) media plane control interworking with Land Mobile Radio (LMR) systemsRelease 17Stage 3TS

When an MCPTT media endpoint leaves an MCPTT call and the MCPTT call remains ongoing with the other media endpoints, the IWF floor control server follows a two-step procedure.

Step 1 The IWF stops sending floor control messages and RTP media packets to the MCPTT media endpoint leaving the MCPTT call and, the IWF discards floor control messages and RTP media packets received from the MCPTT media endpoint leaving the MCPTT call.

Step 2 When the application and signalling plane has determined that the MCPTT call with this MCPTT floor participant has been released, the corresponding instance of the IWF floor control server state machine for ‘basic floor control operation towards the floor participant’ is released.

When an MCPTT call is released, the IWF floor control server follows a two-step procedure.

Step 1 The IWF stops sending floor control messages and RTP media packets to all floor participants in the MCPTT call.

Step 2 When the application and signalling plane has determined that the MCPTT call has been released, the corresponding instance of the floor control server state machine for ‘general floor control operation’ are also terminated, along with any ‘basic floor control operation towards the floor participant’ state machines for the floor participants of this call.

The floor control server state machine for general floor control operation initiates the MCPTT call release depending on the release policy specified in 3GPP TS 29.379 [26].