Group call service using broadcast radio bearer

1. A method for a wireless communication network to establish a wireless group call by at least one base transceiver system from one of a plurality of communication units to others of the plurality of communication units that are in the service coverage area of the at least one base transceiver system, the method comprising the steps of:

establishing a group page identity for the plurality of communication units of the group;

determining whether there are a sufficient number of communication units for the group call to enable Forward Access Channel (FACH) broadcast mode whereupon the communication units for the group are placed in a CELL_FACH state;

providing a single group paging message using the group page identity on a paging channel (PCH) to the group of the plurality of communication units with information for group call set up;

receiving, from a requesting communication unit of a group on a Random Access Channel (RACH), a request for a group call with other communication units of the group;

allocating the Secondary Common Control Physical Channel (S-CCPCH) as a common downlink channel for the group call at each base transceiver system of the at least one base transceiver systems that is providing communication service to the others of the plurality of communication units of the group;

allocating a dedicated forward access channel (FACH) for the requesting communication unit by a base transceiver system that is providing communication service to the requesting communication unit; and

switching one of the communication units between a common forward access channel (CELL_FACH) state and a dedicated channel (CELL_DCH) state depending upon performance criteria measured for the group call.

2. The method of claim 1 , wherein the performance criteria of the switching step is a number of communication units in the group, wherein if the number is greater than a predetermined number threshold then at least one of the plurality of communication units of the group are switched to a dedicated channel (CELL_DCH) state.

3. The method of claim 1 , wherein the performance criteria of the switching step is a talk time on the common downlink channel, wherein if the talk time is greater than a predetermined time threshold then that communication unit is switched to a dedicated channel (CELL_DCH) state.

4. The method of claim 1 , wherein the performance criteria of the switching step is a transmission traffic volume for the group, wherein if the transmission traffic volume is greater than a predetermined transmission traffic volume threshold then at least one of the plurality of communication units of the group are switched to a dedicated channel (CELL_DCH) state.

5. The method of claim 1 , wherein the performance criteria of the switching step is a quality of signal on the common downlink channel to a communication unit in the group, wherein if the quality is less than a predetermined quality threshold then that communication unit is switched to a dedicated channel (CELL_DCH) state.

6. The method of claim 5 , wherein the switching to a (CELL_DCH) state is predicated on that communication unit being in a soft handoff mode.

7. The method of claim 5 , wherein the predetermined quality threshold is selected such that the common channel broadcast will provide a lower quality than the threshold at a location of a communication unit within a cell edge of the serving base transceiver system.

8. The method of claim 1 , wherein the switching step includes a hysteresis in the switching between the common channel state and the dedicated channel state.

9. The method of claim 1 , wherein the allocating a common downlink channel step includes determining whether a communication unit is in soft handoff mode, wherein the same common downlink channel is used by the base transceivers of adjacent cells for soft-combining of macro diversity branches for that communication unit.

10. The method of claim 1 , further comprising the step of releasing a traffic plane radio resource for a group if the session activity for that group is idle beyond a predefined timer expiration value.

11. The method of claim 1 , wherein in the providing step the paging channel is a paging control channel (PCCH).

12. The network of claim 1 , wherein the controller is operable to release a traffic plane radio resource for a group if the session activity for that group is idle beyond a predefined timer expiration value.

13. A wireless communication network to establish a wireless group call, the network comprising:

a plurality of communication units comprising a group;

at least one base transceiver system servicing the group, the at least one base transceiver system providing a group call from one of a plurality of communication units to others of the plurality of communication units that are in the service coverage area of the at least one base transceiver system; and

a controller for controlling the at least one base transceiver system, wherein the controller is operable to: establish a group page identity for the plurality of communication units of the group; determine whether there are a sufficient number of communication units for the group call to enable Forward Access Channel (FACH) broadcast mode whereupon the communication units for the group are placed in a CELL_FACH state; provide a single group paging message using the group page identity on a paging channel (PCH) to the group of the plurality of communication units with information for group call set up; receive, from a requesting communication unit of a group on a Random Access Channel (RACH), a request for a group call with other communication units of the group, allocate the Secondary Common Control Physical Channel (S-CCPCH) as a common downlink channel for the group call at each base transceiver system of the at least one base transceiver systems that provides communication service to the others of the plurality of communication units of the group, allocate a dedicated forward access channel (FACH) for the requesting communication unit by a base transceiver system that provides communication service to the requesting communication unit, and switch one of the communication units between a common forward access channel (CELL_FACH) state and a dedicated channel (CELL_DCH) state depending upon performance criteria measured for the group call.

14. The network of claim 13 , wherein the performance criteria is a number of communication units in the group, wherein if the number is greater than a predetermined number threshold then at least one of the plurality of communication units of the group are switched to a dedicated channel (CELL_DCH) state.

15. The network of claim 13 , wherein the performance criteria is a talk time on the common downlink channel, wherein if the talk time is greater than a predetermined time threshold then that communication unit is switched to a dedicated channel (CELL_DCH) state.

16. The network of claim 13 , wherein the performance criteria is a transmission traffic volume for the group, wherein if the transmission traffic volume is greater than a predetermined transmission traffic volume threshold then at least one of the plurality of communication units of the group are switched to a dedicated channel (CELL_DCH) state.

17. The network of claim 13 , wherein the performance criteria is a quality of signal on the common downlink channel to a communication unit in the group, wherein if the quality is less than a predetermined quality threshold then that communication unit is switched to a dedicated channel (CELL_DCH) state.

18. The network of claim 17 , wherein the switch to a CELL_DCH state is predicated on that communication unit being in a soft handoff mode.

19. The network of claim 17 , wherein the predetermined quality threshold is selected such that the common channel broadcast will provide a lower quality than the threshold at a location of a communication unit within a cell edge of the serving base transceiver system.

20. The network of claim 13 , wherein the controller includes a hysteresis in the switching between the common channel state and the dedicated channel state.

21. The network of claim 13 , wherein the controller is operable to determine whether a communication unit is in soft handoff mode, wherein the controller directs that the same common downlink channel is used by the base transceivers of adjacent cells for soft-combining of macro diversity branches for that communication unit.

22. The network of claim 13 , wherein the paging channel is a paging control channel (PCCH).