SNC

Mobility support is one of the most challenging issues in IEEE 802.11 networks. In the proactive neighbor caching (PNC) scheme, when a mobile host is connected to an access point (AP), its context (e.g. security association or QoS information) is propagated in advance to all of the AP's neighbors to reduce handoff processing time. In this paper, we propose a selective neighbor caching (SNC) scheme, which propagates a mobile host's context only to the selected neighbor APs considering handoff patterns. Therefore, the SNC scheme can reduce the message overhead on the links among APs. We evaluate the performance of the SNC and PNC schemes in terms of the cache hit probability and the signaling cost. Especially, we investigate the effect of mobility and cache size through extensive simulations. The results reveal that the SNC scheme provides a comparable cache hit probability while significantly reducing the signaling overhead in IEEE 802.11 networks. Moreover, although the SNC propagates relatively a small number of contexts to neighbor APs, the SNC scheme outperforms the PNC scheme when the cache size is small and the mobility is low.