In a wireless LAN system, each wireless terminal device determines whether or not the wireless terminal device has entered into a wireless LAN domain established by a base station, and if it has entered, transmits an entry terminal identification information update control frame including identification...http://www.google.com.hk/patents/US5982762?utm_source=gb-gplus-share專利 US5982762 - Wireless LAN system, base station device and wireless terminal device therefor, and method for relaying information frame
