<p>A transmitting apparatus can be used in a first communication system of single-carrier format and a second communication system of multicarrier format. This apparatus comprises a first retransmitting means that transmits a single-carrier packet via a downstream channel and retransmits the single-carrier packet in response to a request after the lapse of a first retransmission standby interval; and a second retransmitting means that transmits a multicarrier packet via the downstream channel and retransmits the multicarrier packet in response to a request after the lapse of a second retransmission standby interval. The second retransmitting means transmits at least one multicarrier packet during the first retransmission standby interval.</p>
