Communication is a key aspect of modern life. Unfortunately, when natural disasters occur, the communication system and infrastructure of a city may be partially or even completely destroyed. In this case, communication becomes a crucial part of search-and-rescue missions. This study develops an aerial communication relay platform as an effective solution for communication loss during a natural disaster. The model used considers the aircraft altitude and attitude, which affect the energy acquisition and consumption, and the signal fading effects. The flight path is planned by adopting a nonlinear optimization technique, i.e., the Hermite-Simpson collocation method. For a realistic communication model regarding urban signal loss and path propagation, the building deployment of an area of radius 2km in two cities in South Korea (Seoul and Jeonju) was obtained. Simulation experiments for the different urban environments were performed to test the communication reliability, focusing on the relation between the unmanned aerial vehicle and ground users. Through the simulation, the optimal flight paths in high-rise urban and urban microcell environment were obtained. The obtained results were later compared with a baseline simulation composed of a steady-flight circular path. The generated flight path proves the feasibility of endurance flights for low-altitude communication aid aircrafts using a unified model for signal fading alongside solar power energy acquisition into the case study.

中文翻译：

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用于可持续通信中继的太阳能无人机飞行路径规划

沟通是现代生活的一个重要方面。不幸的是，当自然灾害发生时，城市的通信系统和基础设施可能会部分甚至完全被破坏。在这种情况下，通信成为搜救任务的关键部分。本研究开发了一种空中通信中继平台，作为自然灾害期间通信丢失的有效解决方案。所使用的模型考虑了影响能量获取和消耗的飞机高度和姿态，以及信号衰落效应。飞行路径规划采用非线性优化技术，即Hermite-Simpson搭配法。对于关于城市信号损失和路径传播的现实通信模型，获得了韩国两个城市（首尔和全州）半径2km区域的建筑部署。进行了不同城市环境的仿真实验以测试通信可靠性，重点关注无人机与地面用户之间的关系。通过仿真，得到了高层城市和城市微蜂窝环境下的最优飞行路径。获得的结果随后与由稳定飞行圆形路径组成的基线模拟进行了比较。生成的飞行路径证明了使用统一模型进行信号衰落和太阳能采集的低空通信辅助飞机耐力飞行的可行性。进行了不同城市环境的仿真实验以测试通信可靠性，重点关注无人机与地面用户之间的关系。通过仿真，得到了高层城市和城市微蜂窝环境下的最优飞行路径。获得的结果随后与由稳定飞行圆形路径组成的基线模拟进行了比较。生成的飞行路径证明了使用统一模型进行信号衰落和太阳能采集的低空通信辅助飞机耐力飞行的可行性。进行了不同城市环境的仿真实验以测试通信可靠性，重点关注无人机与地面用户之间的关系。通过仿真，得到了高层城市和城市微蜂窝环境下的最优飞行路径。获得的结果随后与由稳定飞行圆形路径组成的基线模拟进行了比较。生成的飞行路径证明了使用统一模型进行信号衰落和太阳能采集的低空通信辅助飞机耐力飞行的可行性。获得的结果随后与由稳定飞行圆形路径组成的基线模拟进行了比较。生成的飞行路径证明了使用统一模型进行信号衰落和太阳能采集的低空通信辅助飞机耐力飞行的可行性。获得的结果随后与由稳定飞行圆形路径组成的基线模拟进行了比较。生成的飞行路径证明了使用统一模型进行信号衰落和太阳能采集的低空通信辅助飞机耐力飞行的可行性。