In this paper, the joint design of power allocation (PA), beamforming (BF) and positioning is studied for unmanned-aerial-vehicle (UAV) aided millimeter-Wave (UAV-mmWave) systems, with the objective of maximizing the energy efficiency (EE), under the constraints of maximum transmitting power, minimum data rate from the ground users and positioning range of the UAV. To address the above problem, we first obtain the positioning of the UAV, with the help of approximate beam pattern. Then, near-optimal BF and closed-form PA are derived given the obtained position, with the help of block coordinate descent method. To reduce the complexity, two suboptimal BF schemes with one-loop iteration and closed-form solutions are respectively derived. Furthermore, we propose the simplified algorithms for two special cases, i.e., only line-of-sight (LoS) path and Non-LoS (NLoS) path exist between the users and the UAV. Simulation results verify the effectiveness of the developed joint schemes and show the superior EE performance. Moreover, they can obtain almost the same performance as the existing benchmark schemes but with lower complexity.

中文翻译：

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节能无人机辅助多用户毫米波系统的功率分配、波束成形和定位联合设计


本文研究了无人机辅助毫米波（UAV-mmWave）系统的功率分配（PA）、波束成形（BF）和定位的联合设计，目标是最大化能源效率（EE），在最大发射功率、地面用户最小数据速率和无人机定位范围的约束下。为了解决上述问题，我们首先借助近似波束方向图获得无人机的定位。然后，在给定所获得的位置的情况下，借助块坐标下降法导出近最优 BF 和闭合形式 PA。为了降低复杂度，分别推导了两种具有单循环迭代和闭式解的次优BF方案。此外，我们针对两种特殊情况提出了简化算法，即用户和无人机之间仅存在视距（LoS）路径和非视距（NLoS）路径。仿真结果验证了所开发的联合方案的有效性并显示出优越的EE性能。此外，它们可以获得与现有基准方案几乎相同的性能，但复杂度较低。