A wide variety of works have been conducted in vehicle-to-everything (V2X) communications to enable a variety of applications for road safety, traffic efficiency and passenger infotainment. Although dedicated short-range communications (DSRC) based V2X is already in the deployment phase, cellular based V2X is gaining more interest in academia and industry most recently. This article surveys the existing work and challenges on LTE and 5G to support efficient V2X communications. First, we present the motivations for cellular based V2X communications. Second, we summarize the LTE V2X architecture and operating scenarios being considered. Third, we discuss the challenges in existing LTE for supporting V2X communications such as physical layer structure, synchronization, multimedia broadcast multicast services (MBMS), resource allocation, security and survey the recent solutions to these challenges. We further discuss the challenges and possible solutions for 5G based vehicular communications. Finally, we discuss the open research issues and possible research directions in cellular based vehicular communications.

中文翻译：

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基于蜂窝的V2X通信的挑战和解决方案

车辆到所有（V2X）通信中已经进行了各种各样的工作，以实现道路安全，交通效率和乘客信息娱乐的各种应用。尽管基于专用短距离通信（DSRC）的V2X已经处于部署阶段，但基于蜂窝的V2X最近在学术界和工业界引起了越来越多的兴趣。本文调查了LTE和5G在支持高效V2X通信方面的现有工作和面临的挑战。首先，我们介绍了基于蜂窝的V2X通信的动机。其次，我们总结了正在考虑的LTE V2X架构和操作方案。第三，我们讨论了现有LTE支持V2X通信的挑战，例如物理层结构，同步，多媒体广播多播服务（MBMS），资源分配，安全性，并调查针对这些挑战的最新解决方案。我们将进一步讨论基于5G的车载通信的挑战和可能的解决方案。最后，我们讨论了基于蜂窝的车辆通信中的开放性研究问题和可能的研究方向。