A survey on UAV placement and trajectory optimization in communication networks: From the perspective of air-to-ground channel models

Abstract

Unmanned aerial vehicles (UAVs) have been utilized extensively in communication networks due to their versatility and maneuverability. It is also necessary to optimize their locations or trajectories. Moreover, it is important to adopt an appropriate air-to-ground (A2G) channel model that can reflect the practical environment well. In this paper, we first introduce the representative A2G channel models widely adopted in the literature and then review recent works on UAV placement and trajectory optimization from the perspective of A2G channel models. Finally, we present future research directions based on trends and lessons derived from our review of the existing studies.