IEEE 802.11 無線網路快速換手的自適性行動預測

Abstract

Handoff latency is a severe bottleneck to guarantee the service continuity in IEEE 802.11 WLAN Network, which is a requirement for voice and multimedia applications. The handoff latency of IEEE 802.11 can be classified into four types of latency phases, Scanning Latency, Authentication Latency, Association Latency and IEEE 802.11i Authentication Latency. Several schemes have been proposed to reduce the handoff latency. However, these schemes result in redundant messages overhead in the network, lack of handoff zone initialization mechanism or require computing power in the AAA (Authentication, Authorization, and Access control) Server. In this paper, we propose an Adaptive Mobility Prediction method to achieve low handoff latency, a self-configure predictability index to create a Candidate Node List of popular roaming Access Points, which balance the pre-authentication key distribution message overhead in the WLAN network and computing capability requirement on the AAA Server. Simulation results present up to 82.4% message reduction in comparison to the Proactive Neighbor Caching scheme and 33.2% enhancement in accuracy in comparison to the Selective Neighbor Caching schemes,meanwhile maintaining 54.1% of messages overhead.