The procedure in this sub clause specify how request for resource for floor control (or transmission control in MCVideo and MCData) and for the media plane can be handled independently. This procedure utilizes the Rx reference point both between from the MC service server to the PCRF and from the SIP core to the PCRF.
Resource for the transmission control are requested at session establishment, in this case the IMS standard procedures as specified in TS 23.228
are used. The session description shall in this procedure include bandwidth information applicable for the transmission control traffic requirement. At group call setup the request for resources for the media plane is triggered. This request is sent directly from the MC service server to the PCRF.
The procedure is optional and is suitable when the procedures for pre-established sessions are used, it may also be used to setup and tear down the media plane used by between consecutive group calls in one communication session using the chat call model.