Communication Quality Optimization for UAV Trajectory in Irregular Topography

Unmanned Aerial Vehicles (UAVs) are becoming increasingly popular for both civil and military missions, and communication link establishment between the UAV and ground/aerial stations is a crucial factor for mission success. However, topography greatly affects the communication link, particularly when the UAV is flying at a low altitude between mountains of varying elevations. This paper proposes a system model based on the diffraction phenomenon with Multiple Knife Edges (MKE) to model the UAV-station channel when the Line of Sight (LoS) is absent. The objective is to optimize the trajectory of low/mid-altitude flying UAVs in complex propagation environments. To maximize communication quality, the paper also proposes an optimization formulation using Mixed Integer Linear Programming (MILP). The proposed approach is validated through simulations that limit LoS propagation using real terrain profiles. The approach finds the optimal UAV trajectory with the "best feasible" communication quality within physical limitations.