Fairness issues in multihop wireless ad hoc networks

Abstract

In this thesis, we investigate the fairness of bandwidth allocation in multihop wireless ad hoc networks (MANETs) at two levels: the MAC/link layer and the network layer with focus on MAC/link layer fairness. We demonstrate that IEEE 802.11 operating in a MANET could suffer from a severe fairness problem. To remedy the fairness problem, a new protocol EHATDMA (extended hybrid asynchronous time division multiple access) is proposed. Simulation results show that EHATDMA strikes a good balance between throughput and fairness. In addition, we identify the non-work-conserving mechanism as the most important mechanism affecting fairness. A three-dimensional Markov model is proposed to further analyze the throughput and fairness properties of IEEE 802.11 in MANETs. The model confirms the conclusion that non-work-conserving principles will MAC/link layer fairness. Our preliminary results indicate that a fair MAC protocol also improves fairness as well as other performance aspects of TCP flows in MANETs.