As VoIP applications become popular over IEEE 802.11-based Wireless Local Area Networks (WLANs), it is important to support fast, seamlesss handoff when a mobile station (MS) roams from one access point (APs) to another. Our goal is to reduce the handoff latency so that the impact of lost packets on a voice conversation is unnoticeable. In this paper, we present a fast handoff solution where an MS can stealthily scan channels of the neighboring APs during a VoIP communication without skipping packet receiption/transmission. Using our method, maybe only one packet is lost during a handoff process on our VoIP test-bed.
