Abstract: Data transmission technology in VANETs（Vehicular Ad-hoc Networks） obtains more attention since that VANETs is able to provide road safety, vehicle traffic management and infotainment service. However, the changed topology and fast moving vehicle accelerate the fracture of communication link between vehicles, and reduce the reliability of communication links. Therefore,the multi-hop connectivity properties of VANETs based on a physical layer based Quality of Service（QoS） criterion in terms of average end-to-end path outage probability are analyzed.Under this approach, a multi-hop path joining a pair of vehicles is considered to be connected if and only if the average end-to-end path outage probability meets a target requirement. An analytical model to compute the average end-to-end path outage probability of a connected path is presented. This paper then investigates the minimum transmit power and maximum number of hops satisfying an average path outage probability constraint. The validity of the theoretical analysis is verified by simulation.Simulation results show that a suitable power control algorithm can improve the data transmission path.

Key words: connectivity, minimum transmit power, path outage probability, Vehicular Ad hoc Networks（VANETs）

摘要： 车载网VANETs（Vehicular Ad hoc Networks）在道路安全、车流量管理和娱乐应用具有广阔的前景，而这些应用依赖数据有效的传输。为此，VANETs的数据传输技术成为研究的焦点。然而，VANETs的拓扑动态变化、车辆快速移动加速了车间通信链路的断裂，降低了链路的可靠性，为数据有效传输提出了挑战。据此，分析了VANETs的多跳通信连接特性。通过研究端到端中断概率，提出多跳连接的分析模型。通过模型，可得出在一定的平均端到端中断概率所需的最小发射功率以及最大传输跳数。通过仿真，验证理论模型的正确性。仿真进一步表明，通过合适的功率控制算法有利于改善数据传输路径。

关键词: 连接性, 最小发射功率, 路径中断概率, 车载网