5 Roles

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

5.1 General

This clause associates the IWF with the MCPTT roles described in the stage 2 architecture document (see 3GPP TS 23.379 [5]).

5.2 Client

The IWF acts on behalf of all users homed in the IWF. There are no client procedures specified in the present document and specific client handling within the LMR system is out of scope.

5.3 IWF performing the controlling role

An IWF performing the controlling role shall:

1. support the role of a controlling MCPTT function as specified in 3GPP TS 23.379 [5];

2. support negotiating media plane control channel media level attributes as specified in clause 4.3;

3. provide floor control arbitration logic with an interface to MCPTT clients as described in clause 4.2.1 and support the related procedures as specified in clause 6.3;

4. provide a network media interface as described in clause 4.2.1 and support associated procedures as specified in clause 6.3;

5. provide a media distributor with a floor control interface towards the MCPTT clients as described in 3GPP TS 24.380 [25] clause 4.2.1 and support associated procedures in clause 6.3;

6. support the on-network mode floor control protocol elements as specified in clause 8: and

7. support media plane security as specified in clause 13.

An IWF performing the controlling role may:

1. provide a floor request queue as described in clause 4.2.1 and support the related procedures as specified in clause 6.3 and clause 4.3.

5.4 IWF performing the participating role

An IWF performing the participating role shall:

1. support the role of a participating MCPTT function;

2. distribute floor control messages as described in clause 6.3 and support associated procedures as specified in clause 6.4;

3. perform endpoint floor control signalling as the floor participant on behalf of users homed in the IWF; and

NOTE: Floor control is modelled as a floor participant that is part of the IWF performing the participating role, and sits "behind" the participating role. This is for modelling purposes only and does not impose any particular structure or implementation on the IWF.

4. support media plane security as specified in clause 13.

5.5 IWF performing the non-controlling role

An IWF performing the non-controlling role of an MCPTT group shall:

1. support floor control involving groups from multiple MCPTT systems as specified in 3GPP TS 29.379 [26];

2. provide a floor control interface towards the controlling MCPTT function as described in clause 4.2.4 and support the related procedures as specified in clause 6.5;

3. provide a media interface towards the controlling MCPTT function as described in clause 4.2.4 and support the related procedure as specified in clause 6.5;

4. provide a media distributor as described in clause 4.2.4 and the related procedures as specified in clause 6.5; and

5. support media plane security as specified in clause 13.