中文摘要：

为了解决由于道路上车辆密度快速变化，而传输半径却保持不变所带来的不稳定的连通性和较高的误比特率。提出一种车载自组织网络中基于车辆密度的可变传输范围路由（VRR）协议，节点根据道路车辆密度调节信息最大传输距离，降低信息传输时延，确保网络的高连通性。在齐次泊松点过程模型的基础上推导出传输半径随着车辆密度的变化条件，验证其可行性，理论分析获得平均时延的数学计算式，最后仿真比较VRR协议与固定传输范围路由（FRR）协议的性能。仿真结果表明，VRR协议能够应用到实际环境中，且在高连通概率的前提下．使信息从源节点快速地传输到目的节点。

英文摘要：

In order to solve the problem of unstable connectivity and high bit error rate, which are caused by rapid changes in the density of vehicles on the road, while the transmission radius remained unchanged, a variable transmission range routing protocols based on vehicle density in vehicular Ad-Hoc network was proposed. According to different vehicle density, node could adjust the farthest transmission distance and reduce the transmission latency of the message, which could ensure high connection probability of the network. Based on homogeneous poisson point process model, the change conditions of transmission range with different vehicle density were deduced, and its feasible was proved. Furthermore, mathematical calculate formula of average latency was obtained according to the theoretical analysis. At last, variable transmission range routing protocol based on vehicle density and fixed transmission range routing protocol were compared by simulation. The simulated results show that the proposed protocol can be applied in actual environments, and the message can be transmitted fast from source node to destination node under the condition of high connection probability.