A time slot for a connection request sent from a mobile station includes the mobile station ID and the application discrimination word of the object application for which the mobile station requests the connection. By referring to the database, a base station assigns a MDC preferentially to a mobile station issuing a connection request for calling a high priority application. The base station monitors the MDCs used for ongoing communications. If a MDC assigned to a mobile station does not satisfy a predetermined radio communication quality, other MDCs for lower priority application are freed and reassigned to the mobile station. A plurality of MDCs including the reassigned MDCs into which the same contents are encapsulated are transmitted to the mobile station.