Vehicle-to-vehicle (V2V) communication plays a pivotal role in intelligent transport systems (ITS) with cellular-vehicle to everything (C-V2X) and IEEE 802.11p being the two competing enabling technologies. This paper presents multi-dimensional discrete-time Markov chain (DTMC) based models to study the medium access control (MAC) layer performance of the IEEE 802.11p standard and C-V2X Mode 4. These models are coupled with an appropriate DTMC based queuing model, and traffic generators for periodic cooperative awareness messages (CAMs) and event-driven decentralized environmental notification messages (DENMs). Closed-form solutions for the steady-state probabilities of the models are obtained, which are then utilized to derive expressions for several key performance metrics. An application for a highway scenario is presented to provide numerical results and to draw insights on the performance. In particular, a performance comparison between IEEE 802.11p and C-V2X Mode 4 in terms of the average delay, the collision probability, and the channel utilization is presented. The results show that IEEE 802.11p is superior in terms of average delay, whereas C-V2X Mode 4 excels in collision resolution. The paper also includes design insights on possible future MAC layer performance enhancements of both standards.

中文翻译：

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基于离散时间马尔可夫链的 C-V2X 模式 4 和 IEEE 802.11p 的 MAC 层性能比较

车对车 (V2V) 通信在智能交通系统 (ITS) 中发挥着举足轻重的作用，蜂窝车联网 (C-V2X) 和 IEEE 802.11p 是两种相互竞争的使能技术。本文提出了基于多维离散时间马尔可夫链 (DTMC) 的模型，以研究 IEEE 802.11p 标准和 C-V2X 模式 4 的媒体访问控制 (MAC) 层性能。这些模型与基于 DTMC 的适当排队相结合模型，以及用于周期性协作感知消息 (CAM) 和事件驱动的分散环境通知消息 (DENM) 的流量生成器。获得模型稳态概率的封闭形式解，然后将其用于导出几个关键性能指标的表达式。提出了高速公路场景的应用程序，以提供数值结果并深入了解性能。特别地，给出了 IEEE 802.11p 和 C-V2X 模式 4 在平均延迟、冲突概率和信道利用率方面的性能比较。结果表明，IEEE 802.11p 在平均延迟方面更胜一筹，而 C-V2X 模式 4 在冲突解决方面表现出色。该论文还包括对两种标准未来可能的 MAC 层性能增强的设计见解。而 C-V2X 模式 4 在冲突解决方面表现出色。该论文还包括对两种标准未来可能的 MAC 层性能增强的设计见解。而 C-V2X 模式 4 在冲突解决方面表现出色。该论文还包括对两种标准未来可能的 MAC 层性能增强的设计见解。