Using Shared Beacon Channel for Fast Handoff in IEEE 802.11 Wireless Networks

Abstract—Handoff process in IEEE 802.11 wireless networks must be accomplished with as little interruption as possible to maintain the required quality of service (QoS). Previous research reported that channel scanning phase accounts for more than 90 % of the overall link-layer handoff latency, ranging from 350 to 500 msec. In order to eliminate the time-consuming channel scanning latency we propose a stand-alone, shared beacon channel, where stations (STAs) can update information about neighboring access points (APs) via an extra receiver. Our proposed method contributes to completely eliminate the channel scanning phase, therefore, realizing fast handoff in IEEE 802.11 wireless networks. In this paper, we implement our proposed method on FreeBSD 6.1R kernel with Atheros AR5212-based 802.11 a/b/g chipsets. From experimental results, we find that it takes 6.063 msec delay on average during handoff from 802.11b AP to 802.11a AP while transmitting/receiving 480 byte ICMP frames with an interval of 10 msec. I