Directional antennas have been intensively studied in wireless local area networks (WLANs) in order to increase space reuse rate, reduce interference, and extend transmission range, etc. However, the handoff techniques of directional antennas still need improvement. One critical problem is to reduce the extremely long handoff latency of directional antennas caused by the sequential search of sectors in the channel scanning phase. In this paper, we propose a moving-direction-oriented handoff scheme which prioritizes the scanning of sectors by the moving direction of a mobile station. The moving direction is calculated by an analytical method utilizing the direction-of-arrival information of the mobile station. Simulation results show that the calculated moving direction can achieve an accuracy of over 98%. The proposed scheme can significantly reduce the channel scanning latency without degrading the searching range. Moreover, the handoff frequency of stations is also reduced, which is beneficial in saving network resources.
['Xiaoqian Lyu', 'Jiang Xie']
A Moving-Direction-Oriented Handoff Scheme for Directional Antennas in Wireless Local Area Networks