Communications apparatus and communications system using multicarrier transmission mode

A communications system for exchange of information between a base station and a terminal by a multicarrier transmission mode using a plurality frequency bands, the communication system comprising:

• a transmission data generator configured to generate frequency band set information indicating which frequency band is to be used for transmission of dedicated user data information between said base station and said terminal, wherein the frequency band set is made variable;
• a transmitter configured to transmit the frequency band set 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 dedicated user data information by using the frequency band set and the specific frequency band at a time;
• and
• a receiver configured to receive the frequency band set information by using the specific frequency band, wherein
• the frequency band set as at least one frequency band set from among said plurality of frequency bands without the specific frequency band.