Random access operation is performed under a communication environment in which a plurality of communication modes having different transmission rate coexist with small overhead. A high-grade communication station spoofs information of a packet length and a rate in a decoding portion so that a value of (packet length)/(rate) corresponds to a duration where the communication is hoped to be stopped. The other station receiving the spoofed information receives the rest of the packet with the designated rate during the interval designated by the value of (packet length)/(rate). In this case, the packet length and the rate are not those of actually transmitted packet so that this packet is discarded.