With the high data rates and ultra-low latency it provides, millimeter-wave (mmWave) communications will be a key enabler for future vehicular networks. However, due to high penetration losses and high mobility, mmWave links experience frequent blockages. We present an analytical framework to evaluate the performance of vehicular relaying, where vehicles on a highway exchange data with the network, either over direct vehicle-to-infrastructure (V2I) links with roadside units or a combination of a vehicle-to-vehicle (V2V) sidelink and a V2I link. Both V2V and V2I line-of-sight links can be blocked by other vehicles. We establish continuous-time Markov chain models of the blockage events that V2I links and vehicular relays experience, and use their steady-state solution to obtain analytical expressions for the blockage probability, average blockage duration and the SINR distribution. We demonstrate through numerical examples that relays are helpful, especially when the traffic density is high, since they can provide intermittent but more frequent connection opportunities and reduce the blockage duration. We show that relays that are far from a vehicle only have a marginal benefit since they are blocked with higher probability, compared to the closer relays. The proposed analytical framework enables fast and accurate assessment of a given deployment scenario, which will benefit researchers exploring mmWave-enabled vehicular networks.

中文翻译：

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通过车载中继减轻毫米波车载网络阻塞的影响

凭借其提供的高数据速率和超低延迟，毫米波 (mmWave) 通信将成为未来车载网络的关键推动因素。然而，由于高穿透损耗和高移动性，毫米波链路经常遇到阻塞。我们提出了一个评估车辆中继性能的分析框架，其中高速公路上的车辆与网络交换数据，通过与路边单元的直接车辆到基础设施（V2I）链接或车辆到车辆的组合（ V2V) 侧链和 V2I 链路。V2V 和 V2I 视线链接都可以被其他车辆阻挡。我们建立了 V2I 链路和车辆中继所经历的阻塞事件的连续时间马尔可夫链模型，并使用它们的稳态解来获得阻塞概率的解析表达式，平均阻塞持续时间和 SINR 分布。我们通过数值例子证明中继是有帮助的，尤其是在交通密度高的时候，因为它们可以提供间歇但更频繁的连接机会并减少阻塞持续时间。我们表明远离车辆的中继仅具有边际收益，因为与较近的中继相比，它们被阻塞的概率更高。所提出的分析框架能够对给定的部署场景进行快速准确的评估，这将有利于研究人员探索支持毫米波的车载网络。因为它们可以提供间歇性但更频繁的连接机会并减少阻塞持续时间。我们表明远离车辆的中继仅具有边际收益，因为与较近的中继相比，它们被阻塞的概率更高。所提出的分析框架能够对给定的部署场景进行快速准确的评估，这将有利于研究人员探索支持毫米波的车载网络。因为它们可以提供间歇性但更频繁的连接机会并减少阻塞持续时间。我们表明远离车辆的中继仅具有边际收益，因为与较近的中继相比，它们被阻塞的概率更高。所提出的分析框架能够对给定的部署场景进行快速准确的评估，这将有利于研究人员探索支持毫米波的车载网络。