Adaptive Neighbor Caching for Fast BSS Transition Using IEEE 802.11k Neighbor Report

Handoff latency is a severe bottleneck impacting the service continuity for voice and multimedia applications in WLAN. IEEE 802.11k neighbor report defines the neighbor APs which are potential transition candidates for the roaming target. But the selection method for the roaming target AP is left undefined. Several schemes have been proposed for fast handoff with neighbor APpsilas information. However, these schemes result in huge redundant transition messages overheads in the WLAN and require high computing power for the AAA (Authentication, Authorization, and Access control) server. In this paper, we propose an adaptive neighbor caching (ANC) method to achieve higher handoff prediction accuracy for selecting proper candidate APs in the Neighbor Report. An adaptive predictability index is introduced for selecting those potential roaming APs, which can mitigate the scanning latency and the pre-authentication key distribution message overhead in the WLAN as well as computing loading for the AAA server. Simulation results present up to 83.5% of transition messages are reduced in comparison to the Proactive Neighbor Caching (PNC), 56.4% of candidate AP selection accuracy is improved and 37.5% of transition messages are reduced in comparison to the Selective Neighbor Caching (SNC).