An Access Point Coordination System for Improved VoIP/WLAN Handover Performance

With layer 2 and 3 handover algorithms, wireless LAN can allow users to roam between different access points without breaking the connection to the Internet. However, one of the biggest problems in roaming is the latency in the handoff process. Recently, Ramani and Savage (2005) have proposed a new scheme called SyncScan which can reduce the overall handoff latency in layer 2 by more than 80%. However, this scheme assumes that the beacon transmission schedule among the access points is known a priori, and the beacons are transmitted on time. In this paper, we will propose a self-organized access point coordination system to generate and maintain a conflict-free beacon transmission schedule. Also, we will present a performance evaluation of the SyncScan scheme by studying the effect of beacon transmission delay due to data traffic, and mobility on handover performance