This article investigates an unmanned aerial vehicle (UAV)-enabled wireless communication network with multiple pairs of source-destination ground users (GUs), where the rotary-wing UAV acts as an aerial mobile relay to transfer information from the source GUs to corresponding destination GUs when the direct terrestrial communication is blocked. On the premise of satisfying the communication requirements of all GUs, we intend to minimize the total energy consumption of supporting the propulsion and communication by jointly optimizing communication time, UAV transmit power allocation and UAV trajectory. To tackle the formulated non-convex problem, we first transform the original problem into a more tractable form with a finite number of optimization variables using the path discretization approach. Then, we decompose the joint optimization problem into three subproblems to find a near optimal solution. Finally, these subproblems can be efficiently solved via the proposed iterative algorithm based on block coordinate descent and successive convex approximation (SCA) techniques. As the initial UAV trajectory has significant influence on the final results, we put forward a novel trajectory initialization scheme by combining the classic Pickup-and-Delivery Problem with fly-hover-communication protocol. Numerical results demonstrate that our proposed design contributes to significant performance enhancement compared with other two benchmarks.

中文翻译：

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具有多对用户的 UAV 中继网络的联合能量和轨迹优化

本文研究了具有多对源-目的地地面用户 (GU) 的无人机 (UAV) 无线通信网络，其中旋翼无人机充当空中移动中继，将信息从源 GU 传输到相应的目的地当直接地面通信被阻塞时的 GU。在满足所有GU的通信需求的前提下，我们打算通过联合优化通信时间、无人机发射功率分配和无人机航迹，将支撑推进和通信的总能耗降到最低。为了解决公式化的非凸问题，我们首先使用路径离散化方法将原始问题转换为具有有限数量优化变量的更易于处理的形式。然后，我们将联合优化问题分解为三个子问题，以找到接近最优的解决方案。最后，这些子问题可以通过所提出的基于块坐标下降和连续凸逼近 (SCA) 技术的迭代算法有效地解决。由于初始无人机轨迹对最终结果有显着影响，我们通过将经典的拾取和交付问题与飞行悬停通信协议相结合，提出了一种新颖的轨迹初始化方案。数值结果表明，与其他两个基准相比，我们提出的设计有助于显着提高性能。这些子问题可以通过提出的基于块坐标下降和连续凸逼近 (SCA) 技术的迭代算法有效地解决。由于初始无人机轨迹对最终结果有显着影响，我们通过将经典的拾取和交付问题与飞行悬停通信协议相结合，提出了一种新颖的轨迹初始化方案。数值结果表明，与其他两个基准相比，我们提出的设计有助于显着提高性能。这些子问题可以通过提出的基于块坐标下降和连续凸逼近 (SCA) 技术的迭代算法有效地解决。由于初始无人机轨迹对最终结果有显着影响，我们通过将经典的拾取和交付问题与飞行悬停通信协议相结合，提出了一种新颖的轨迹初始化方案。数值结果表明，与其他两个基准相比，我们提出的设计有助于显着提高性能。