Provided are a base station, a terminal, a band allocation method, and a downlink data communication method in which a mapping method for synchronization signals and report signals is implemented with high resource usage efficiency when a first system in which an independent single communication is allocated to a unit band co-exists with a second system in which a plurality of unit bands can be allocated to a single communication. In a base station, an OFDM signal generation unit maps primary synchronization channel (P-SCH), secondary synchronization channel (S-SCH), primary broadcast channel (P-BCH), and dynamic broadcast channel (D-BCH), which can be decoded by both an LTE terminal and an LTE+ terminal, to some of a plurality of unit bands. The OFDM signal generation unit also maps D-BCH+, which can be decoded only by an LTE+ terminal, to all of the plurality of unit bands to produce a multiplexed transmission signal.