A communications system for exchange of information between a base station and a terminal by a multicarrier transmission mode using a plurality of subcarriers. The communication system includes a base station, a transmission data generator configured to generate frequency band information indicating which frequency band is to be used for transmission of data between said communication apparatuses; and a transmitter configured to transmit the frequency band information, using a specific frequency band, set from among a plurality of frequency bands assigned to the communications system, and to transmit data by using at least one frequency band set from among said plurality of frequency bands, and at the time of establishing the wireless channel, the frequency band usable by the communications apparatus is restricted, and said specific frequency band and said at least one frequency band set, other than the specific frequency band, are assigned within that restricted frequency band.