Physics and Computer Architecture Department, Miguel Hernández University, 03202 Elche, Spain.
Sensors (Basel). 2018 Oct 17;18(10):3495. doi: 10.3390/s18103495.
Nowadays, more and more vehicles are equipped with communication capabilities, not only providing connectivity with onboard devices, but also with off-board communication infrastructures. From road safety (i.e., multimedia e-call) to infotainment (i.e., video on demand services), there are a lot of applications and services that may be deployed in vehicular networks, where video streaming is the key factor. As it is well known, these networks suffer from high interference levels and low available network resources, and it is a great challenge to deploy video delivery applications which provide good quality video services. We focus our work on supplying error resilience capabilities to video streams in order to fight against the high packet loss rates found in vehicular networks. So, we propose the combination of source coding and channel coding techniques. The former ones are applied in the video encoding process by means of intra-refresh coding modes and tile-based frame partitioning techniques. The latter one is based on the use of forward error correction mechanisms in order to recover as many lost packets as possible. We have carried out an extensive evaluation process to measure the error resilience capabilities of both approaches in both (a) a simple packet error probabilistic model, and (b) a realistic vehicular network simulation framework. Results show that forward error correction mechanisms are mandatory to guarantee video delivery with an acceptable quality level , and we highly recommend the use of the proposed mechanisms to increase even more the final video quality.
如今，越来越多的车辆配备了通信功能，不仅提供了与车载设备的连接，还提供了与车外通信基础设施的连接。从道路安全（例如多媒体 e-呼叫）到信息娱乐（例如视频点播服务），有许多应用程序和服务可以部署在车载网络中，其中视频流是关键因素。众所周知，这些网络受到高干扰水平和低可用网络资源的影响，因此，部署提供高质量视频服务的视频传输应用程序是一项巨大的挑战。我们专注于为视频流提供纠错能力，以应对车载网络中高丢包率的问题。因此，我们提出了将源编码和信道编码技术相结合的方法。前者通过使用 Intra 刷新编码模式和基于瓦片的帧分区技术应用于视频编码过程。后者则基于使用前向纠错机制来尽可能多地恢复丢失的数据包。我们进行了广泛的评估过程，以在（a）简单的数据包错误概率模型和（b）现实的车载网络仿真框架中测量这两种方法的纠错能力。结果表明，前向纠错机制对于保证具有可接受质量水平的视频传输是必需的，我们强烈建议使用所提出的机制来进一步提高最终的视频质量。
