基于时序网络的VANETs拓扑特征分析

动态性是车载自组织网络（VANETs）拓扑结构的重要特征之一，研究拓扑结构的时序特征对VANETs协议开发和网络管理具有重要意义。采用复杂网络理论研究VANETs拓扑结构的时序特性。建立了VANETs时序网络模型- 可达图模型，该模型不仅考虑了信息传输时间，而且能够刻画VANETs中信息的存储转发机制。通过仿真实验研究VANETs时序网络的拓扑特征，分析信息传输时间 和最大可容忍延迟时间 与网络的节点出度、非对称性、数据包到达率等时序拓扑参数之间的关系。研究结果表明与瞬时和静态网络模型相比，本文提出的时序网络模型能更合理的刻画VAENTs中信息传输过程，并且降低信息传输时间 和增大最大可容忍时间 有利于提高整个网络的时序连通性，从而提高数据包传输效率，该结论可为优化VANETs拓扑控制和网络协议开发提供新的指导。

Topology Characteristics Analysis of VANETs Based on Temporal Network

The topology dynamic is one of the important characteristics of vehicular ad hoc networks (VANETs). The study of the temporal topology of VANETs plays a significant role in network protocol development and management. The temporal characteristics of topology for VANETs is studied based on complex network theory. The temporal model of VANETs as reachability graph model is built. This model not only describes the information transmission time, but also can capture the store-and-forward mechanism in VANETs. The characteristics of temporal topology of VANETs are studied by simulation experiment. The relations of the information transmission time and the maximum tolerated delay time to the out-degrees, asymmetry and reachability ratio of packets are analyzed. The results show that compared to the instantaneous and the static network model, the temporal network model can capture the information transmission process in VANETs better, and the decrease of transmission time or the increase of maximum tolerated delay time contributes to the improvement of temporal connectivity in VANETs, thus raising the transmission efficiency of VANETs topology control and protocol development with new guidance.