Novel MAC Layer Handoff Schemes for IEEE 802.11 Wireless LANs

Handoff in the IEEE 802.11 wireless LANs (WLANs) occurs whenever the mobile station (STA) changes its association from one access point (AP) to another owing to poor link quality. In a WLAN, small coverage areas of APs create frequent handoffs. Previous studies have shown that the typical handoff latency is high enough to hamper the service quality of multimedia streams like VoIP (voice over IP). In this paper, a novel scheme to reduce the handoff latency is proposed by using inter-AP communication to receive the probe response(s). Another adaptive scheme to enhance the quality of service (QoS) for multimedia streams during handoff is presented which builds upon the first scheme and adaptively distributes the total handoff latency. Through extensive simulations, we prove that our adaptive scheme decreases handoff latency significantly and achieves both fast and smooth hand-off that multimedia applications entail.