FSO as backhaul and energizer for drone-assisted mobile access networks

Drone mounted base stations (DBSs) can be flexibly deployed over some areas (such as hotspots and disaster struck areas) to speed up the communication between terrestrial base stations (TBSs) and users. In order to increase the capacity of the backhaul link between a DBS and its TBS, free space optical (FSO) communications is applied as the backhaul solution. However, the DBS and its TBS should be in line-of-sight (LoS). Thus, a new DBS placement method is introduced to maximize the number of served users while guaranteeing the LoS between the DBS and its TBS. In addition, in order to prolong the hovering time of a DBS, we propose to deploy an optical beam to facilitate simultaneous communications and charging. That is, an optical beam transmitted from a TBS to its DBS carries not only data but also energy. The DBS mounted with a solar panel and an FSO receiver receives both the data and energy carried by the optical beam simultaneously. Numerical results demonstrate that using an optical beam to charge and communicate with a DBS can gain 25% extra hovering time of the DBS and achieve high network throughput.