Owing to the recent advances of non-orthogonal multiple access (NOMA) and millimeter-wave (mmWave), these two technologies are combined in unmanned aerial vehicle (UAV) networks in this paper. However, energy efficiency has become a significant metric for UAVs owning to their limited energy. Thus, we aim to maximize the energy efficiency for mmWave-enabled NOMA-UAV networks by optimizing the UAV placement, hybrid precoding and power allocation. However, the optimization problem is complicated and intractable, which is decomposed into several sub-problems. First, we solve the UAV placement problem by approximating it into a convex one. Then, the hybrid precoding with user clustering is performed to better reap the multi-antenna gain. Particularly, three schemes are proposed, where the cluster head selection algorithm is adopted while considering different equivalent channels of users. Finally, the power allocation is optimized to maximize the energy efficiency, which is converted to convex and solved via an iterative algorithm. Simulation results are provided to evaluate the performance of the proposed schemes.

由于非正交多路访问（NOMA）和毫米波（mmWave）的最新发展，本文将这两种技术结合到了无人机（UAV）网络中。然而，对于拥有有限能量的无人机而言，能源效率已成为一项重要指标。因此，我们旨在通过优化UAV放置，混合预编码和功率分配，最大程度地提高启用mmWave的NOMA-UAV网络的能源效率。然而，优化问题是复杂且棘手的，它分解为几个子问题。首先，我们通过将其近似为凸面来解决无人机放置问题。然后，执行带有用户聚类的混合预编码，以更好地获得多天线增益。特别是，提出了三种方案，在考虑不同的用户等效信道的同时采用簇头选择算法。最后，优化功率分配以最大程度地提高能量效率，将其转换为凸形并通过迭代算法求解。提供仿真结果以评估所提出方案的性能。