A communications system for exchange of information between communications apparatuses by a multicarrier transmission mode using a plurality of subcarriers, the communication system includes a transmission data generator configured to generate frequency band information indicating which frequency band is to be used for transmission of data information between said communication apparatuses and a transmitter configured to transmit the frequency band information by using a specific frequency band which is set from among a plurality of frequency band assigned to the communications system, and to transmit data information by using at least one frequency band set from among said plurality of frequency bands; and a receiver configured to receive the frequency band information by using the specific frequency band, wherein said specific frequency band also transmits data information and said specific frequency band is made variable.