A method for communicating in a communication apparatus includes receiving an orthogonal frequency division multiplexing (OFDM) signal transmitted from a base station, the OFDM signal including a plurality of carrier groups, each carrier group including a plurality of carriers. The plurality of carrier groups are assigned transmission data for a plurality of communication apparatuses, and each of the plurality of carrier groups adopts one of a first transmission mode in which the transmission data is transmitted using one modulated signal and a second transmission mode in which the transmission data is transmitted using a plurality of modulated signals. A carrier group, to which transmission data for the communication apparatus is assigned, is specified based on control information included in the received OFDM signal. Reception data associated with the specified carrier group is generated by decoding the one modulated signal used in the first transmission mode, when the first transmission mode is adopted for the specified carrier group, and reception data associated with the specified carrier group is generated by decoding the plurality of modulated signals used in the second transmission mode when the second transmission mode, is adopted for the specified carrier group.