A fast handoff algorithm using intelligent channel scan for IEEE 802.11 WLANs

In order to support mobility, WLANs must provide smooth handoff mechanism. Recent studies show, however, handoff delay of WLANs is very large and often it exceeds 300ms. The major reason is the slow scanning mechanism finding a new AP. With this handoff delay, current WLANs are not suitable to provide seamless real-time interactive services such as VoIP service. In this paper, we analyze the current handoff method of IEEE 802.11 and propose a new handoff algorithm which can reduce the time needed for searching a new AP and thus reduce overall handoff delay. We show by simulation that the proposed algorithm can significantly reduce handoff delay compared with the current handoff method.