Unmanned aerial vehicles (UAVs) are gaining widespread use in wireless relay systems due to their exceptional flexibility and cost-effectiveness. This paper focuses on the integrated design of UAV trajectories and the precoders at both the transmitter and UAV in a UAV-assisted relay communication system, accounting for transmit power constraints and UAV flight limitations. Unlike previous works that primarily address multiple-input single-output (MISO) systems with Gaussian inputs, we investigate a more realistic scenario involving multiple-input multiple-output (MIMO) systems with finite-alphabet inputs. To tackle the challenging and inherently non-convex problem, we propose an efficient solution algorithm that leverages successive convex approximation and alternating optimization techniques. Simulation results validate the effectiveness of the proposed algorithm, demonstrating its capability to optimize system performance.

翻译：无人机因其卓越的灵活性和成本效益，在无线中继系统中正获得广泛应用。本文聚焦于无人机辅助中继通信系统中无人机轨迹、发射端预编码器及无人机端预编码器的联合设计，同时考虑了发射功率约束与无人机飞行限制。与以往主要针对高斯输入的多输入单输出系统研究不同，本文探讨了一种更贴近实际的场景，即涉及有限字母输入的多输入多输出系统。为应对这一具有挑战性且本质非凸的优化问题，我们提出了一种高效的求解算法，该算法利用了逐次凸逼近与交替优化技术。仿真结果验证了所提算法的有效性，证明了其优化系统性能的能力。