Scanning through Authentication for IEEE 802.11 WLAN Fast Handoff

摘要

Handoff procedure in IEEE 802.11 wireless networks must be accomplished with as little interruption as possible to maintain the required quality of service (QoS). We have developed a fast handoff scheme, called Auth-Scan, to reduce the time-consuming channel scanning latency. AuthScan comprises two steps: First, a client caches its handoff history with beacon information. Second, when in need of handoff, a client transmits Authentication Request frames to the selected Access Points (APs) from the cache instead of broadcasting Probe Request frames like in active scan to discover the next AP. Our proposed method does not require any support from the infrastructure network and contributes to finish the handoff procedure with the lowest latency when compared to approaches that improve the efficiency of channel scanning. Furthermore, AuthScan requires neither hardware upgrades to the client, nor any modification to currently deployed APs. In this paper, we present the theoretical handoff latency of AuthScan with comparison to other approaches, and show the effectiveness of our system through experiments.