Power-Efficient Formation of UAV Swarm: Just Like Flying Birds?

Recently, unmanned aerial vehicles (UAVs) have been the subject of much attention, and UAV swarms are a promising solution to resolve the limitations of a single UAV. In terms of aerodynamics, fixed-wing UAV swarms fly in a V-formation to reduce their energy usage via upwash. UAVs in the V-formation are typically in close proximity, reducing power consumption aerodynamically. However, these formations lack spatial separability, degrading the performance of communication employing non-orthogonal multiple access schemes. In this paper, to tackle this problem, the formation of UAV swarms considering both aerodynamics and communications employing the beam division multiple access (BDMA) scheme is examined. Problems related to the minimization of power consumption of UAVs and the ground control station (GCS) are formulated separately, after which we optimize the beamforming vector, power, and formation of the UAV swarm and propose a novel UAV swarm formation, termed the O-formation, that is power-efficient for communications. Numerical results show that formation of the UAV swarm affects the power consumption related to communications and that the proposed O-formation improves the power efficiency compared to the V-formation and a random formation.