Abstract: In multi-rate ad hoc networks，with the advantage of adaptive rate control algorithm，nodes can transmit at different data rates，which leads to better capacities of ad hoc networks.In this paper，the MAC layer fairness is analyzed in multi-rate ad hoc networks.The simulation results show that there is a serious fairness problem in IEEE 802.11 based multi-rate ad hoc networks.After thorough discussion on throughput fairness and temporal fairness，the result shows that temporal fairness is better in the research of MAC layer fairness in multi-rate ad hoc networks.In addition，an Enhanced Fair Back-off（EFB） algorithm for multi-rate ad hoc networks is proposed in this paper.The simulation result shows that the proposed algorithm can achieve far better MAC layer fairness in multi-rate ad hoc networks.

摘要： 在多速率Ad hoc网络中，利用自适应速率调整算法，网络节点可以根据信道质量选择不同的传输速率，从而提高网络的总体通信能力。对多速率Ad hoc网络MAC层公平性进行了仿真和分析，实验结果表明基于IEEE 802.11的多速率Ad hoc网络中存在严重的公平性问题。通过对吞吐率公平和时间公平的讨论，指出在多速率Ad hoc网络中进行MAC层公平性研究，时间公平性标准是较优的选择。另外提出一种针对多速率Ad hoc网络的改进公平回退（EFB）算法，仿真实验的结果表明该算法能够明显提高多速率Ad hoc网络的MAC层公平性。