Date Added: Dec 2010
The effective coverage distance of Wireless LAN (WLAN) being small, users may leave the coverage area of the specific Access Point (AP) from time to time while roaming. However, the wireless network is a shared medium. The air is open for everyone. In general there is collision if a few users attempt to transmit with the same channel that is more rigorous during handoff period because of active scan mode. The active scan will perform requests for searching available AP. Unfortunately, this function consumes too much resource in wireless communication, and also affect total performance.