Patent ID: 7965696

Claim:
A slave station which transmits signals to a master station servicing a plurality of service areas and receives signals from the master station, the slave station being located in any one of the service areas and the slave station comprising: a transmitting unit adapted to transmit a signal to the master station; a receiving unit adapted to receive a signal transmitted from the master station; a storing unit adapted to store information which is included, in the signal received from the master station; an input unit adapted to input data operated by a user of the slave station; and a control unit adapted to control these units of the slave station, wherein under a control by the control unit, the transmitting unit transmits a transmission request for transmitting multicast data, to the master station in accordance with a timing of power-on or an input by the input unit, wherein the slave station further includes a number of times of multicast transmission storing unit for storing information of a number of times of transmission for requested multicast data, the number of times of multicast transmission being set by the master station for each of service areas based on a number of slave stations transmitting the transmission request in each of service areas and a predetermined calculation manner, and being received from the master station, wherein after receiving the multicast data the number of times of multicast transmission for the service area in which own slave station is located, the number of times being stored in the number of times of multicast transmission storing unit, the control unit determines presence or absence of lacking data which have not been received, and transmits a retransmission request for requesting the lacking data to the master station in a case of presence the lacking data.