The invention refers to traffic controller in a cellular radio system comprising at least one radio base station (BTS) associated with a plurality of traffic channels (T) for serving a cell (C1), and a plurality of mobile stations (MS) within the cell. The traffic controller is arranged to delicate one of the downlink traffic channels (TCHdl1) for a selected group of mobile stations (MS) and is also arranged to delicate one of the uplink traffic channels (TCHul1) for the selected group of mobile stations (MS). Each of the mobile stations (MS1-MS3) in the selected group of mobile stations comprises communication means for inter group communication via the delicated downlink channel (TCHdl1) and the delicated uplink channel (TCHul1) only.