With the development of smart cities, Internet services will be pervasively accessible for moving vehicles. It is envisioned that the video content demand of vehicles will explode in the near future. However, the strategy to efficiently distribute video content in large-scale vehicular networks is still absent due to challenges arising from the huge video population, heavy bandwidth consumption, heterogeneous user devices and vehicles' mobility. In this work, we propose to collaboratively replicate video content on Roadside Units (RSUs) to enhance video distribution services based on the fact that the contact period between moving vehicles and a single RSU is not long enough to complete video downloading. In our design, a video file is split into multiple chunks. Each RSU replicates a small number of original chunks and chunks encoded by network coding. Replicating encoded chunks can reduce redundancy of chunks on different RSUs so that RSUs can complement each other better, whereas original chunks can be transrated to chunks with lower bitrates flexibly to fit in users' devices. Therefore, we replicate both original and encoded chunks on RSUs to take advantages of both sides. Stochastic models are employed to analyze chunk download processes and a convex optimization problem is formulated to determine the optimal partition of space allocated to each kind of chunks. Furthermore, we extend our strategy to support video streaming services and empirically prove that the influence caused by limitations of network coding is moderate. In the end, we conduct extensive simulations which not only validate the accuracy of our models but also demonstrate that our strategy can effectively boost video distribution services.

中文翻译：

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协作复制 RSU 上的编码内容以增强车辆视频服务

随着智慧城市的发展，移动车辆将普遍接入互联网服务。可以预见，车辆的视频内容需求将在不久的将来爆发。然而，由于庞大的视频数量、大量带宽消耗、异构用户设备和车辆移动性带来的挑战，在大规模车载网络中有效分发视频内容的策略仍然不存在。在这项工作中，我们建议基于移动车辆和单个 RSU 之间的接触时间不足以完成视频下载的事实，在路边单元 (RSU) 上协作复制视频内容以增强视频分发服务。在我们的设计中，一个视频文件被分成多个块。每个 RSU 复制少量的原始块和通过网络编码编码的块。复制编码的块可以减少不同 RSU 上块的冗余，以便 RSU 可以更好地相互补充，而原始块可以灵活地转换为较低比特率的块以适应用户的设备。因此，我们在 RSU 上复制原始块和编码块以利用双方的优势。采用随机模型来分析块下载过程，并制定凸优化问题来确定分配给每种块的空间的最佳分区。此外，我们扩展了我们的策略以支持视频流服务，并凭经验证明网络编码限制造成的影响是中等的。到底，