HAPS Trajectory Optimization Based on Throughput Heat Map

High altitude platform station (HAPS) is a platform that provides direct communication to wireless devices such as smart phones by equipping unmanned aerial vehicles (UAVs) flying in the stratosphere with cellular base station functions. In this paper, we propose a HAPS trajectory optimization method based on a throughput heat map, where the HAPS trajectory is designed considering the trajectory constraints of HAPS as an aircraft. The HAPS trajectory is optimized according to the throughput characteristics to be improved, such as the average throughput of each UE (user equipment). Computer simulations using actual UE distributions for Tokyo, Osaka, and Nagoya showed that the sub-optimized figure-8 trajectory improved the 50th percentile throughput by 15-16% and the 5th percentile throughput by 3–20% for each city, respectively, compared to the non-optimized circular trajectory. Trajectories aimed at improving the 50th, 75th, and 95th percentiles improved throughput characteristics around the 50th percentile, around the 75th-95th percentile, and above the 96th percentile, respectively.