A Zone Based Interleaved Scanning Technique for Fast Handoff in IEEE 802.11 Wireless Networks

IEEE 802.11 is a popular wireless LAN standard and because of its low cost and good bandwidth, it is widely used now a days. Due to the small cell size frequent handoffs may occur while roaming in an area covered by several access points and a high handoff latency may cause disruptions in ongoing communications. To support voice and multimedia applications, handoff latency needs to be within 50 ms. Earlier works to reduce handoff latency either did not achieve this limit or are restrictive in some way. In this paper we propose a handoff mechanism where scanning is interleaved with data communication before actual handoff. Only authentication and association/reassociation are done during handoff. Handoff latency is reduced to a value well within 50 ms. The scheme does not require any extra hardware or modification to the protocol stack.