The digital transformation within the automotive industry is accelerating towards an era dominated by autonomous vehicles, with vehicle-to-everything (V2X) communications being a fundamental enabler for this advancement. As vehicular networks evolve to meet the complex demands of autonomous driving, traditional communication systems encounter limitations in bandwidth and data transfer rates. Millimeter-wave (mmWave) communication emerges as a pivotal solution, offering the extensive bandwidth required for the high data throughput and low latency essential in modern vehicular communications. However, challenges loom, with beam alignment in mmWave V2X becoming a time-consuming process and the mmWave’s blockage effect impeding consistent and reliable vehicular communication links. Therefore, the development of efficient, real-time, and robust beam alignment technology is crucial for mmWave V2X communication. In this paper, we present a comprehensive survey of beam alignment techniques in mmWave V2X communication. We explore various approaches including beam sweeping, angle of arrival (AoA)/angle of direction (AoD) estimation, black-box optimization, and side information. Subsequently, we introduce performance metrics for assessing beam alignment performance and compare the performance of four beam alignment methods under different metrics. Finally, we summarize the future research directions and challenges faced by beam alignment techniques in mmWave V2X communication, offering valuable insights for researchers in this field.

中文翻译：

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毫米波 V2X 通信中的光束对准：调查


汽车行业的数字化转型正在加速迈向自动驾驶汽车主导的时代，而车联网 (V2X) 通信是这一进步的基本推动力。随着车辆网络不断发展以满足自动驾驶的复杂需求，传统通信系统在带宽和数据传输速率方面遇到了限制。毫米波 (mmWave) 通信作为一种关键解决方案出现，提供现代车辆通信所必需的高数据吞吐量和低延迟所需的广泛带宽。然而，挑战迫在眉睫，毫米波 V2X 中的波束对准成为一个耗时的过程，而且毫米波的阻塞效应阻碍了一致且可靠的车辆通信链路。因此，开发高效、实时、鲁棒的波束对准技术对于毫米波V2X通信至关重要。在本文中，我们对毫米波 V2X 通信中的波束对准技术进行了全面的调查。我们探索了各种方法，包括波束扫描、到达角 (AoA)/方向角 (AoD) 估计、黑盒优化和辅助信息。随后，我们介绍了评估光束对准性能的性能指标，并比较了四种光束对准方法在不同指标下的性能。最后，我们总结了毫米波V2X通信中波束对准技术的未来研究方向和面临的挑战，为该领域的研究人员提供了宝贵的见解。