3D Trajectory Optimization for Energy-Efficient UAV Communication With Obstacle Constraints

In this paper, we address the challenges faced by a UAV in multi-obstacle environments, where frequent flight path adjustments increase energy consumption and obstacles impede communication. To tackle these issues, we propose a UAV-assisted ground user communication system, where a fixed-wing UAV navigates a complex multi-obstacle environment. Based on this model, we formulate an optimization problem to maximize the UAV's energy efficiency by optimizing its 3D trajectory. This problem is a mixed-integer non-convex optimization problem, with dual effects of obstacles on the UAV. To tackle this challenge, we introduce an obstacle avoidance factor to optimize the UAV's flight height, thereby avoiding obstacles of specific heights. Additionally, we consider the impact of obstacles on the UAV communication link and derive an equation for determining the blocking region. In response to the influence of obstacles and flight height on UAV energy efficiency, we propose an optimization method based on the DOB-DSCA algorithm. Experimental results show that optimizing flight height can improve energy efficiency by 12.6%, while the presence of obstacles reduces energy efficiency by 17.7%. Furthermore, considering the limited research in the existing literature on factors affecting UAV energy efficiency, we focus on how variations in transmission power, total flight time, and obstacle height can enhance UAV energy efficiency.