Laser Charging Enabled DBS Placement for Downlink Communications

Drone-mounted base-station (DBS) can empower 5G and beyond networks with additional flexibility and maneuverability, and laser charging can potentially extend the DBS's flight time. We propose a laser charging enabled DBS framework in which a laser charging station on the ground constantly transmits energy to a quadrotor DBS in the air and the DBS provides communications for all users. The DBS is to be intelligently placed in the optimal location to provide service to the ground users in each time slot. We thus formulate the joinT powEr and bandwidth assignment, LasEr Charing enAbled DBS placemenT (TELECAST) problem to jointly maximize the flight time and communications data rate. Since the TELECAST problem is NP-hard, we decompose it into two sub-problems: the joint power and bandwidth allocation problem (JPB) and the DBS placement problem. A recursive algorithm is employed to solve the JPB problem and a counting placement algorithm is used to tackle the DBS placement problem. The performance of our algorithm is superior to fixed placement algorithms and greedy resource allocation algorithm and lagrange resource allocation algorithm upon which the user data rate is improved by more than 6% and the total flight time is extended by 20%, as demonstrated in our simulation results.