Unmanned aerial vehicles (UAVs) have found widespread commercial, civilian, and military applications. Wireless communication has always been one of the core technologies for UAV. However, the communication capacity is becoming a bottleneck for UAV to support more challenging application scenarios. The heavily-occupied sub-6 GHz frequency band is not sufficient to meet the ultra high-data-traffic requirements. The utilization of the millimeter-wave (mmWave) frequency bands is a promising direction for UAV communications, where large antenna arrays can be packed in a small area on the UAV to perform three-dimensional (3D) beamforming. On the other hand, UAVs serving as aerial access points or relays can significantly enhance the coverage and quality of service of the terrestrial mmWave cellular networks. In this paper, we provide a comprehensive survey on mmWave beamforming enabled UAV communications and networking. The technical potential of and challenges for mmWave-UAV communications are presented first. Then, we provide an overview on relevant mmWave antenna structures and channel modeling. Subsequently, the technologies and solutions for UAV-connected mmWave cellular networks and mmWave-UAV ad hoc networks are reviewed, respectively. Finally, we present open issues and promising directions for future research in mmWave beamforming enabled UAV communications and networking.

中文翻译：

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毫米波波束赋形无人机通信和网络调查


无人机 (UAV) 已广泛应用于商业、民用和军事领域。无线通信一直是无人机的核心技术之一。然而，通信能力正在成为无人机支持更具挑战性的应用场景的瓶颈。严重占用的 6 GHz 以下频段不足以满足超高数据流量的要求。毫米波（mmWave）频段的利用是无人机通信的一个有前途的方向，其中可以将大型天线阵列封装在无人机上的小区域中以执行三维（3D）波束成形。另一方面，无人机作为空中接入点或中继可以显着增强地面毫米波蜂窝网络的覆盖范围和服务质量。在本文中，我们对支持毫米波波束成形的无人机通信和网络进行了全面调查。首先介绍了毫米波无人机通信的技术潜力和挑战。然后，我们概述了相关毫米波天线结构和信道建模。随后，分别回顾了无人机连接的毫米波蜂窝网络和毫米波无人机自组织网络的技术和解决方案。最后，我们提出了毫米波波束赋形无人机通信和网络未来研究的未决问题和有希望的方向。