在多跳无线网中 ,MAC(media access control)层的公平性虽然是一个局部特性 ,但影响网络的整体性能。后退算法是制约 MAC层公平性的关键之所在 ,Bharghavan等人通过试验方法提出了 MIL D算法 ,试验结果表明 MIL D算法的公平性比 BEB算法好 ,但作者没有进行理论分析。本文给出了分析后退算法的简单模型 ,并根据公平性约束、有效性约束和分布性约束给出 MIL D算法的理论分析。 In multi-hop wireless networks, although the fairness of the MAC layer is a partial feature, it affects the overall network performance. Backward algorithm is the key to restrain the fairness of MAC layer. Bharghavan et al. Propose MIL D algorithm through experimental method. The experimental results show that the fairness of MIL D algorithm is better than that of BEB algorithm, but the author does not make theoretical analysis. In this paper, we give a simple model to analyze backtracking algorithm, and give a theoretical analysis of MIL D algorithm according to fairness constraints, validity constraints and distribution constraints.