Random route discovery packet drop using load factor of MAC layer in IEEE 802.11 ad hoc networks

Recent research has shown that the original DCF access mode of IEEE 802.11 has low performance in heavy traffic and multi-hop environment [Yong Peng, et al., ICII 2001] [Shugong Xu, et al., IEEE GLOBECOM, 2001]. In this paper, our research focus is placed on the improvement of 802.11 networks in multi-hop environment with heavy contention area. We implement system performance enhancement through the interaction of MAC layer and ad hoc routing mechanism. We have first introduced a MAC parameter to evaluate current wireless media contention state (i.e. load factor). In order to be adaptive to the MAC layer contention, we propose a new DCF based MAC mechanism with the name of random route discovery packet drop (R/sup 2/DPD). 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 our new MAC algorithm can achieve better performance than the original DCF algorithm.