A wireless communication system includes a first communication station configured to operate according to a first communication protocol, and a second communication station capable of operating according to both the first communication protocol and a second communication protocol. When the second communication station transmits a packet according to the second communication protocol, at least a first signal field compliant with the first communication protocol and a second signal field compliant with the second communication protocol are attached to a header of the packet, and the first signal field includes a parity bit. When the second communication station receives a packet from another communication station, the second communication station performs a parity check on the first signal field of the packet, and when no parity error is detected, the second communication station further checks whether content of the first signal field is compliant with the first communication protocol.