1. Dalian University of Technology, Dalian University of Technology , Dalian China 116024
2. South China University of Technology, South China University of Technology , Guangzhou Guangdong China 510640
3. University of Nebraska-Lincoln, University of Nebraska-Lincoln , Lincoln Nebraska United States 68588
Due to the recent advances of non-orthogonal multiple access (NOMA) and millimeter-wave (mmWave), these two technologies are combined to study 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 enhance 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.
This work was supported by National Natural Science Foundation of China (Grant No. 61871065 and 61971194).