A first communication apparatus (1) transmits a signal to a second communication apparatus (2) in one of a plurality of time frames contained in each of radio frames, and the second communication apparatus (2) replies to the first communication apparatus (1) with information indicating whether or not the signal has been successfully decoded. The first communication apparatus (1) transmits signals to the second communication apparatus (2) in a plurality of frequency bands in an identical time frame. The second communication apparatus (2) receives from the first communication apparatus (1), the signals transmitted in the plurality of frequency bands in the identical time frame, generates a reply signal for a signal received in each of the plurality of frequency bands, the reply signal indicating whether the received signal has been successfully decoded, and transmits a plurality of the reply signals separately in a plurality of time frames, each of the plurality of reply signals being generated for each of sign
