An Efficient Channel Scanning Scheme With Dual-Interfaces for Seamless Handoff in IEEE 802.11 WLANs

In this letter, we propose an efficient channel scanning scheme for IEEE 802.11 WLANs to reduce the handoff delay. The proposed scheme is fundamentally different from existing channel scanning schemes in that access points (APs), not mobile stations, switch channels. Specifically, each AP is equipped with dual wireless network interfaces, one of which is used for normal AP operations and the other is dedicated to the channel scanning assistance. In this circumstance, mobile stations do not perform active scans and stay on their operating channel, while APs switch channels and broadcast beacon frames by using the additional interface. Thus, mobile stations can maintain up-to-date information on neighboring APs without scanning other channels. Consequently, the service disruption during channel scanning is eliminated and the quality of ongoing data communication is not degraded. Our performance evaluation results show that the proposed scheme outperforms existing channel scanning schemes.