The responder causes the sixth SSW packet to include the sector identification information on the transmission sector used in transmitting the SSW packet with the highest reception quality, which is one of the first to fifth SSW packets and hereinafter referred to as the “most-desirable transmission sector”, and to include the quality information indicating the respective reception qualities of the SSW packets.
After that, in a third period 5213, the initiator transmits a sector sweep feedback (SS-Feedback) packet using the most-desirable transmission sector notified from the responder on the basis of the sixth SSW packet. Further, the responder receives the SS-Feedback packet using the sector 0.
The initiator causes the SS-Feedback packet to include the sector identification information on the transmission sector used in transmitting the SSW packet with the highest reception quality (the most-desirable transmission sector), which is one of the sixth to tenth SSW packets, and to include the quality information indicating the respective reception qualities of the SSW packets.
Lastly, in a fourth period 5214, the responder transmits a sector sweep acknowledge (SS-ACK) packet using the most-desirable transmission sector notified from the initiator on the basis of the SS-Feedback packet. Further, the initiator receives the SS-ACK packet using the sector 0.