10.5.5 Floor control on an interworking group homed in the LMR system

23.2833GPPMission Critical Communication Interworking with Land Mobile Radio SystemsRelease 18TS

Figure 10.5.5‑1 shows the procedure for floor control on an interworking group homed in the LMR system. Simultaneous floor requests are included to show various aspects of interworking floor control.

Pre-conditions:

1. The interworking group is homed in the LMR system.

2. The MCPTT server is configured to locally filter competing floor control requests before communicating with the IWF.

3. MCPTT client 1, MCPTT client 2, and LMR users (represented by the IWF) are affiliated to that group.

4. An interworking group call is ongoing involving MCPTT users and LMR users (represented by the IWF). The floor is currently idle.

Figure 10.5.5-1: Floor control on a group homed in the LMR system

1. The users of MCPTT Client 1 and MCPTT Client 2 both want to send voice media over the session.

2. MCPTT Clients 1 and 2 send floor request messages to the floor control server.

3. The MCPTT floor control server determines to accept the floor request from MCPTT Client 1 based on local arbitration results (e.g., according to priority information versus the competing request from MCPTT client 2).

4. The user of MCPTT client 2 is notified that their floor request was rejected.

5. Since the group is homed in the LMR system the MCPTT floor control server forwards the floor request to the IWF for final floor control determination. The IWF performs floor arbitration in conjunction with the LMR system (not shown). The IWF determines that the floor can be granted to the MCPTT user.

6. The IWF sends a floor granted message to the MCPTT floor control server.

7. The MCPTT floor control server sends a floor granted message to MCPTT client 1.

8. The MCPTT floor control server sends a floor taken message to MCPTT client 2 to notify the user of who is granted the floor.

9. MCPTT Client 1 notifies the user that he/she has been granted the floor and may begin speaking.

10. MCPTT Client 1 begins sending voice media over the established session. The media is distributed to affiliated group members including the IWF.