Mobile communication system having a control station which selects speech coding schemes for a mobile station

Abstract

Communication is carried out on the basis of an optimum speech coding scheme that is matched to the speech coding schemes provided by the radio zones, and to the speech coding capabilities of the mobile stations. To achieve this, when a traffic channel is set up between a mobile station and a switch, a traffic channel selection condition that has been specified by the switch on the basis of the speech coding capabilities of the mobile station that made the SETUP request and of the mobile station to which the call is made, is stored in the control station. The control station grasps which speech coding scheme is currently being used in the radio zone which it controls. Moreover, by transferring the selection conditions specified by the switch and using these conditions as information required for channel setup by another control station, communication can be carried out using a high-priority speech coding scheme when handover occurs. This happens when channel selection takes place in another radio zone spanning control stations, or when a mobile station has moved to a radio zone in which a high-priority speech coding scheme can be used. As a result, traffic channels based on the optimum speech coding scheme can be changed over smoothly.