Recently, unmanned aerial vehicles (UAVs) have attracted lots of attention because of their high mobility and low cost. This article investigates a communication system assisted by multiple UAV-mounted base stations (BSs), aiming to minimize the number of required UAVs and to improve the coverage rate by optimizing the three-dimensional (3D) positions of UAVs, user clustering, and frequency band allocation. Compared with the existing works, the constraints of the required quality of service (QoS) and the service ability of each UAV are considered, which makes the problem more challenging. A three-step method is developed to solve the formulated mixed-integer programming problem. First, to ensure that each UAV can serve more number of users, the maximum service radius of UAVs is derived according to the required minimum power of the received signals for the users. Second, an algorithm based on artificial bee colony (ABC) algorithm is proposed to minimize the number of required UAVs. Third, the 3D position and the frequency band of each UAV are designed to increase the power of the target signals and to reduce the interference. Finally, simulation results are presented to demonstrate the superiority of the proposed solution for UAV-assisted communication systems.

中文翻译：

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用于无人机通信的多个无人机安装基站的3D部署

近来，无人飞行器（UAV）由于其高机动性和低成本而引起了很多关注。本文研究了由多个安装在无人机上的基站（BS）辅助的通信系统，旨在通过优化无人机（3D）的3D位置，用户群集和频率来最大限度地减少所需的无人机数量并提高覆盖率。频段分配。与现有工作相比，考虑了每个无人机所需的服务质量（QoS）和服务能力的约束，这使问题更具挑战性。开发了一种三步法来解决公式化的混合整数规划问题。首先，为了确保每个无人机都能为更多用户提供服务，无人机的最大服务半径是根据用户接收信号所需的最小功率得出的。其次，提出了一种基于人工蜂群算法的算法，以减少所需的无人机数量。第三，每个无人机的3D位置和频带被设计为增加目标信号的功率并减少干扰。最后，仿真结果表明了所提出的解决方案在无人机辅助通信系统中的优越性。