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应用于车载自组网的IEEE 802.11p媒体接入控制(MAC)层采用增强型分布信道接入机制,为验证该机制能否满足不同类型消息的服务质量(QoS),在考虑不同竞争窗口值、消息内部碰撞和信道忙时的退避挂起机制的基础上,构建了基于二维Markov链的分析模型,该模型综合了饱和情况和非饱和情况.通过该模型,分析了不同类型队列消息的归一化吞吐量和丢包率性能指标.结果表明,归一化吞吐量随车辆数的增加而减小,随不同类型数据包产生量的增加而增加;丢包率随车辆数的增加而增加;高优先级队列始终有较大归一化吞吐量值.验证了IEEE 802.11p能保证不同类型消息的QoS.
IEEE 802.11p Media Access Control (MAC) layer applied to in-vehicle ad hoc networks adopts an enhanced distributed channel access mechanism. In order to verify whether this mechanism can satisfy the QoS of different types of messages, considering different contention window values , Internal collision of messages and backoff and suspension mechanism when the channel is busy, an analysis model based on two-dimensional Markov chain is constructed, which combines the situation of saturation and non-saturation.Through this model, the analysis of different types of queue messages Normalized throughput and packet loss rate performance index.The results show that the normalized throughput decreases with the increase of the number of vehicles and increases with the increase of different types of data packets.The packet loss rate increases with the increase of the number of vehicles Increasing; high-priority queues always have larger normalized throughput values verifying that IEEE 802.11p guarantees QoS for different types of messages.