中文摘要：

IEEE 802.11p协议是针对车载环境应用制定的物理层与MAC层标准。车载网络中节点的高移动性和拓扑结构的频繁变更导致网络丢包率增加。为解决车辆移动特性引发的信道访问不公平性问题及降低网络丢包率,提出一种基于相对速度的自适应退避算法RSBA,依据移动节点间相对速度差异优化退避机制。通过NC-TUns模拟实验表明,RSBA减少了丢包率,提高了信道访问公平性,改善了IEEE 802.11p协议的网络性能。

英文摘要：

IEEE 802.11p is the standard for PHY and MAC protocol that the IEEE workgroups made for VANETs.According to the main features of vehicular networks such as the high speed and dynamic network topology,the ratio of the loss packets is increasing.In order to reslove the unfairness problem of channel access and decrease the loss ratio,proposed a relative-speed-based self-adaptive backoff algorithm（RSBA）.Based on the deviation of the relative speeds,the backoff mechanism got optimized.Through simulation with NCTUns,RSBA is proved to decrease the ratio of dropped packets,enhance the fairness of channel access and help improving the performance of the IEEE 802.11p MAC protocol.