HaND: Fast Handoff with Null Dwell Time for IEEE 802.11 Networks

How to reduce the handoff delay and how to make appropriate handoff decisions are two fundamental challenges in designing an effective handoff scheme for 802.11 networks to provide seamless and satisfactory data roaming services to mobile users. In this paper, we propose a unique fast handoff scheme called HaND (Handoff with Null Dwell time). HaND adopts a novel zero-channel-dwell-time architecture which leverages on the communication backbone between APs to relay the information about wireless channels, and allows the AP (rather than the station) to make appropriate handoff decisions aiming at providing fair service satisfaction to all stations. HaND is a software-only solution and compatible with the 802.11 standard without modifying the 802.11 protocol or introducing new wireless frames. We have implemented it in the Madwifi device driver and demonstrated its effectiveness via experiments.