Enhanced Scanning Scheme for Delay-Constrained Fast Handoff in IEEE 802.11 WLANs

Since channel scanning time in IEEE 802.11 handoff is dominant in total handoff delay time, attention has to be paid to the reduction of channel scanning time for effectively supporting delay sensitive applications such as voice over IP (VoIP). Therefore, this paper proposes a new channel scanning scheme that adaptively adopts full channel scanning before, and first satisfaction first reservation scanning after a required delay time obtained from the application layer. Simulation results substantiate that the proposed scheme can keep the total handoff delay as low as possible compared to the required delay while maintaining acceptable Received Signal Strength (RSS) to a Mobile Host (MH) and thus the Quality of Service (QoS) of the applications can be more guaranteed than the conventional and previous schemes.