Base station, terminal, band allocation method, and downlink data communication method

An integrated circuit comprising:

• at least one input, which, in operation, inputs data;
• and
• circuitry, which is coupled to the at least one input and which, in operation:
• controls reception of information including both:
• (i) first information related to a reference frequency of a communication band, the communication band including a first component carrier and a second component carrier added to the first component carrier, in which a synchronization signal is mapped around a center of each of the first component carrier and the second component carrier, and (ii) second information used for determining the second component carrier, said information including both the first information and the second information being received in the first component carrier on a Physical Downlink Shared Channel (PDSCH), and
• sets the reference frequency of the communication band based on the first information, to acquire a Physical Downlink Control Channel (PDCCH) in the second component carrier based on the second information, and to perform communication simultaneously on the first component carrier and the second component carrier,
• wherein the second information includes a downlink frequency bandwidth of the second component carrier, a number of antennas for use in the second component carrier, and resources used to receive a response signal in the second component carrier responsive to an uplink data signal.