In this paper, a full-duplex unmanned aerial vehicle (FD-UAV) relay is employed to increase the communication capacity of millimeter-wave (mmWave) networks. Large antenna arrays are equipped at the source node (SN), destination node (DN), and FD-UAV relay to overcome the high path loss of mmWave channels and to help mitigate the self-interference at the FD-UAV relay. Specifically, we formulate a problem for maximization of the achievable rate from the SN to the DN, where the UAV position, analog beamforming, and power control are jointly optimized. Since the problem is highly non-convex and involves high-dimensional, highly coupled variable vectors, we first obtain the conditional optimal position of the FD-UAV relay for maximization of an approximate upper bound on the achievable rate in closed form, under the assumption of a line-of-sight (LoS) environment and ideal beamforming. Then, the UAV is deployed to the position which is closest to the conditional optimal position and yields LoS paths for both air-to-ground links. Subsequently, we propose an alternating interference suppression (AIS) algorithm for the joint design of the beamforming vectors and the power control variables. In each iteration, the beamforming vectors are optimized for maximization of the beamforming gains of the target signals and the successive reduction of the interference, where the optimal power control variables are obtained in closed form. Our simulation results confirm the superiority of the proposed positioning, beamforming, and power control method compared to three benchmark schemes. Furthermore, our results show that the proposed solution closely approaches a performance upper bound for mmWave FD-UAV systems.

中文翻译：

---

毫米波全双工无人机中继：联合定位、波束成形和功率控制

在本文中，采用全双工无人机（FD-UAV）中继来增加毫米波（mmWave）网络的通信容量。在源节点（SN）、目的节点（DN）和FD-UAV中继配备大型天线阵列，以克服mmWave信道的高路径损耗并帮助减轻FD-UAV中继的自干扰。具体来说，我们制定了一个最大化从 SN 到 DN 的可实现速率的问题，其中联合优化了无人机位置、模拟波束成形和功率控制。由于问题是高度非凸的，并且涉及高维、高耦合的变量向量，我们首先获得 FD-UAV 中继的条件最优位置，以最大化封闭形式的可实现速率的近似上限，在视距 (LoS) 环境和理想波束成形的假设下。然后，将无人机部署到最接近条件最佳位置的位置，并为两个空对地链路提供视距路径。随后，我们提出了一种交替干扰抑制 (AIS) 算法，用于波束成形矢量和功率控制变量的联合设计。在每次迭代中，波束赋形矢量被优化以最大化目标信号的波束赋形增益和干扰的连续减少，其中最优功率控制变量以闭合形式获得。与三种基准方案相比，我们的仿真结果证实了所提出的定位、波束成形和功率控制方法的优越性。此外，