Efficient Scheduling of Charger-UAV in Wireless Rechargeable Sensor Networks: Social Group Optimization Based Approach

Wireless power transfer (WPT) technology enables the replenishment of rechargeable battery energy by the sensor nodes (SNs) in wireless rechargeable sensor networks (WRSNs). The deployment of unmanned aerial vehicles (UAVs) as flying chargers to replenish battery energy is established as an emerging technique, especially in harsh environments. The UAV is also operated by limited battery power and, hence, is also power-constrained. Therefore, the UAV has to timely return to the depot to be fully recharged for the next cycle. The SNs should also be timely recharged before they completely deplete their energy. The design of an efficient charging schedule for the charger-UAV for WRSNs is challenging due to the above-mentioned constraints. Moreover, the problem is non-deterministic polynomial hard (NP-hard). This paper addresses the problem of scheduling the charger-UAV to replenish the energy of SNs in WRSNs. A population-based, nature-inspired algorithm, social group optimization (SGO), is employed to design an efficient charging schedule. The flying energy of the UAV is considered to ensure that the UAV will safely and timely return back to the depot. The fitness function is designed with a novel reward-based approach. The proposed work is extensively simulated, and performance comparisons are done along with statistical analysis.