Flight Path Planning of Solar-Powered UAV for Sustainable Communication Relay

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.