RF energy harvesting for WSNs via dynamic control of unmanned vehicle charging

Numerous applications of wireless sensor networks (WSNs) are hindered by the limited battery power of the sensors. Instead of using the fixed amount of battery power, in this paper, we propose to integrate supercapacitors into the sensors, and let the sensors wirelessly harvest the relatively unlimited Radio Frequency (RF) energy for the perpetual operation of WSNs. To further facilitate the energy harvesting of WSNs in harsh terrains, we employ an unmanned vehicle to provide dedicated RF signals, and develop a dynamic optimization scheme to control the moving of the vehicle. Specifically, we propose to amount a dedicated RF energy source on a mobile unmanned vehicle, and let the vehicle periodically localize sensors, dynamically select the sensors to recharge, and find its optimal sojourn time, so that the overall operation of the WSN is optimized. Based on the RF energy harvesting equipment of Powercast Corp., we establish the testbed and conduct a series of experiments to verify the effectiveness of the proposed scheme.