Patent ID: 7346021

Claim:
A master station for use in a communications system including at least one slave station in a system environment in which the communications system and a plurality of other communications systems share a same channel, each of the other communications systems comprising a respective other master station and at least one slave station, said master station comprising: a communication section for performing communications using a first communication band which is divided into: a beacon period in which said master station and all other master stations transmit a beacon packet in competition with one another; a time division multiple access (TDMA) period in which only specific permitted stations are allowed access using a communication band which is allocated through time division; and a carrier sense multiple access (CSMA) period in which every station is allowed access in competition with one another, the communications being performed in a cycle comprising the beacon period, the TDMA period, and the CSMA period; an acquisition section for acquiring a state of used communication band in each of the other communications systems; and a determination section for, based on the states of used communication band in the other communications systems acquired by the acquisition section, calculating a second communication band available in the communications system to which said master station belongs, in the TDMA period, and determining whether a communication which is requested by the at least one slave station of the communications system to which said master station belongs is granted or rejected in accordance with the calculated second communication band; wherein a ratio between the TDMA period and the CSMA period dynamically varies in accordance with a total communication band required by a station.