Patent ID: 6735446
Filing Date: 2004-05-11
Classification: H04W

Abstract:
A mobile communication system in which a central control unit assigns pairs of upstream and downstream channels to mobile station units located in a radio zone of a base station unit to carry out a two-way communication between the mobile station units, and the central control unit assigns pairs of upstream and downstream channels to the mobile station units to carry out a one-to-multiple group communication between the mobile station units, comprising:a memory unit, provided in the central control unit, storing vacant channel data indicative of the presence of a vacant channel with respect to the group communication carried out by the channel assignment of the central control unit; a broadcast message unit, provided in the base station unit, transmitting a broadcast message containing the vacant channel data, stored in the memory unit, to each of the mobile station units; a message receiving unit, provided in one of the mobile station units, receiving the broadcast message transmitted by the broadcast message unit; and a call request transmission unit, provided in said one of the mobile station units, transmitting, when the vacant channel data of the received message indicates the presence of the vacant channel, a call request for a one-way communication using the vacant channel, to the base station unit, wherein the central control unit assigns the vacant channel to said one of the mobile station units in response to a call request for a one-way communication using the vacant channel, which is sent by said one of the mobile station units, and updates the vacant channel data, stored in the memory unit, as a result of the assignment of the vacant channel.