VANET协助下载策略研究

Study on cooperative downloading strategy in VANET

互联网的普及,使得人们对网络的依赖日益加深,人们希望能够随时随地连接网络,即使是在行驶的汽车里。然而,目前高速公路两旁稀疏的AP分布及有限的通信范围很难满足用户在车联网环境下对网络的需求。针对这一问题,提出了一种基于目标车组的车联网协助下载方法,利用同向车之间相对速度小、连接质量好的特点在局部范围内形成车组,并选择一组合适的对向车辆携带用户所需数据为其提供协助下载。该方法利用同向车组有效延长了对向协助车与目标车的通信时间,从而在减少对向车辆的协助次数的同时保证网络的吞吐量。仿真结果表明该方法可以使下载吞吐量提高30%以上,且降低了盲区通信时延,并能在车流密度较低的情况下保持较好的性能。

With the development of Internet,there is increasing need for people to be connected. The rapid expansion of the Internet of things makes the VANET（ vehicular ad-hoc network） more and more attractive.Nowadays,people expect to be able to connect to the network anytime and anywhere,even in a car. However,the sparse AP distribution and the restricted communication coverage are far away for meeting the demand of users on the network under expressway VANET environment. To solve this problem,a vehicle-string-based cooperative downloading strategy is proposed. A vehicle string including the one that needs data is formed with the homodromous vehicles so to leverage the characteristic of less relative velocity and better connection quality.Meanwhile,a set of suitable opposite vehicle is selected to carry data user needed for cooperative downloading. The method utilizes the vehicle string to extend communication time between the opposite assistant vehicles and the target vehicle effectively,thereby obtains notable benefit while with a less opposite cooperative vehicles in terms of throughput. The simulation results show that this proposed method significantly improves downloading throughput by30% and reduces communication delay in dead area. And also,it has a good performance in the case of low traffic density.