Communication radio transmitter

In some embodiments, a communication apparatus can transmit OFDM signals that include at least a first period and a second period. The communication apparatus can include a transmitting section and a signal processing section. The transmitting section can transmit the OFDM signals to an additional communication apparatus by using multiple subcarriers allocated a set of two or more contiguous frequency channels. The contiguous frequency channels can be used simultaneously by the additional communication apparatus. The signal processing section is configured to not use at least all subcarriers positioned in the respective centers of these frequency channels when allocating data to the subcarriers in the frequency channels used to transmit the OFDM signals for a first period.