An FSO-Based Drone Charging System for Emergency Communications

In a disaster struck area (DSA), macro base stations (MBSs) are usually damaged, and thus the wireless network becomes dysfunctional. To efficiently recover the communications, drone mounted base stations (DBSs) are deployed to relay data between the mobile users (MUs) in a DSA and working MBSs in the proximity of the DSA. However, a DBS may be deployed far away from a working MBS, thus limiting the backhaul link capacity between the DBS and the MBS. Also, the hovering time of current drones is limited, and thus caps the usage of DBSs. In order to increase the backhaul link capacity and prolong the hovering time of a DBS, we propose to apply free space optics to enable an MBS to simultaneously transmit data streams and energy to a DBS with high efficiency. The problem of jointly optimizing the DBS placement as well as the access link bandwidth allocation is formulated to maximize the hovering time of a DBS and guarantee the data rate requirements of the MUs. The joint bandwidth allocation DBS placement (TWIST) algorithm is proposed to solve the problem. The performance of TWIST is demonstrated through simulations.