Random Route Discovery Packet Drop Using Load Factor of MAC Layer in IEEE 802.11 Ad Hoc Networks

摘要

Recent research has shown that the original DCF access mode of IEEE 802.11 has low performance in heavy traffic and multi-hop environment. In this paper, the research focus is placed on the improvement of IEEE 802.11 networks in asymmetric contention condition multi-hop environment. Performance enhancement is implemented by the interaction of MAC layer and ad hoc routing mechanism. Different from previous mechanisms that are realized by routing layer metric measurement (e.g. delay, link state), the proposed Random Route Discovery Packet Drop (R~2DPD) mechanism introduces a MAC parameter to evaluate current wireless media contention state (i.e. load factor) to be adaptive to the MAC layer contention. This new mechanism drops ad hoc routing packets in the MAC layer according to the on-line measuring of local contention state (i.e., load factor). Stations in heavy contention environment drop route discovery packets with high probability so that the congestion is relieved. Simulation results have shown that the new MAC algorithm can achieve better performance than the original DCF algorithm.