Energy-Efficient Ground Base Station Antenna Array System for Wireless Back-Hauling and Two State Charging of Drone Base Stations.

A ground base station (GBS) antenna array system (AAS) geometry and feed technique are proposed for 360 degrees azimuth beam scan, elevation beam scan, azimuth beam-width control, elevation beam-width control, and in existing AASs these four capabilities do not coexist. First, the results confirm that the number of active radio-frequency (RF) switches in the proposed AAS feed network is reduced by more than 99%, and the AAS achieves a power consumption reduction of up to 50% without fully connected (FC) architecture and 35% with FC architecture compared to the existing AAS. Also, an independent GBS AAS azimuth and elevation plane beam-width control can be achieved from 65 degrees to 0.01 degrees which makes it suitable for GBS-assisted wireless back-hauling plus wireless charging of unmanned aerial vehicle base stations (UAV-BSs), dynamic GBS sectorisation order control, and millimeter wave beam tracking. Also, a parallel concurrent UAV-BS battery charging configuration with power source swap capability is proposed to charge UAV-BS using the GBS back-haul and onboard power amplifier (PA) system as the power sources. The results show that the proposed charging configuration improves hovering time by 180.7% compared to the existing onboard PA system configuration for battery charging. Furthermore, the proposed charging configuration can recharge the battery of the inactive state UAV-BS to increase the state of charge of two 16-Ah batteries to 80% in 180.13 min, and UAV-BS's inactive state charging was not proposed in the existing onboard PA system configuration for UAV-BS's battery charging.