中文摘要：

随着人们对互联网依赖性的日益提高，人们希望随时随地接人Internet，即使在行驶中的汽车里．虽然通过3G或4G网络可以达到此目标，但是通过路边接入点AP（Access Point）接入互联网具有高带宽低延迟的特点．该文针对AP通信范围有限的问题提出了一套适应于高速公路场景下，通过AP接人点以及其它车辆进行协助下载的方法DSRelay．使用文中提出的算法，移动用户在一个AP区内不能完成它的下载任务时，下一个AP点计算用户和注册车辆在AP间盲区（DarkArea，DA）中的相遇时间和通信时长，选择一组协助车辆来携带用户所需数据．每辆协助车在DA中不同时间段内将数据传给用户，从而达到利用DA延伸移动用户的下载区域的目的．同时，文中对车速变化带来的影响进行了分析，并提出了相应解决方案．作者最后对该方法进行了仿真实验，实验结果表明该方法显著提高了下载的吞吐量，减少了间歇性连接带来的影响．

英文摘要：

Internet is playing a more and more important role in shaping our lives, which raises the demand for anytime and anywhere connection, even while on driving cars. Although 3G or 4G networks can be used to achieve this goal, roadside Access Points （APs） have the advantages of low cost and high bandwidth. At present, however, APs cannot cover all the areas, which causes intermittent connectivity. In this paper, we propose DSRelay, a scheme of cooperative download- ing in highway scenarios. When a mobile client leaves a AP coverage area without finishing its downloading, with the proposed algorithm, APs compute meeting time and communication dura- tion between client car and other registered cars, and choose a series of cars to carry data client needed, so that the data can be transmitted to the client at different time slot in Dark Areas （DA） out of AP coverage areas. This scheme utilizes DAs for extending the downloading areas of the client as much as possible, which improves the total amount of data transferred and minimizes the delay. Also, we analyze the influence of changeable car speeds and give a solution. Simulation results indicate that the benefits of the proposed scheme in terms of increasing throughput and reducing the delay.