Joint Trajectory Design and Transmit Power Control in NOMA-Aided UAV Communication Systems

Unmanned aerial vehicles (UAVs) are becoming increasingly prevalent in wireless communications scheme with theirs inherent advantages of convenience, low cost and flexibility. However, due to the maneuverability of UAVs, the decoding sequence changes frequently, which generates the difficulty in accomplishing the method of joint optimization of UAVs track and transmitting energy in non-orthogonal multiple access (NOMA) assisted UAVs wireless communication scheme. Therefore, based on the aggregate energy constraint and maximum speed constraint in UAV flight, we investigate into maximizing the minimum aggregate reachable rate of data signalling of the user by optimizing UAV trace and transmitting power jointly. Faced with this nonconvexity problem, we firstly make it convexification, while making the objective function smooth. Then, we develop a track design and transmission power control algorithm (TDPCA) with low complexity. Next, alternate optimization and continuous convex programming are used to solve the transformation problem. Specifically, we convert this problem into two independent sub-problems: transmission power control problem and UVA trace design problem. Then, one of the subproblems is solved iteratively, while the other subproblems keep fixed until the TDPCA converges. Finally, we present lots of simulation results to verify that the TDPCA can effectively enhance the aggregate reachable data rate compared with the reference algorithms that have fixed track and transmit power.