Wireless Charging Energy-Relay Scheme for Wireless Sensor Networks

Owing to the development of the Fifth Generation (5G) Communication and Internet of Things (IoT), Wireless Sensor Network (WSN) has received unprecedented attention from modern society. Wireless Power Transfer (WPT) is a promising technique to alleviate the energy sustainment issue of WSN. WPT enables WSN playing significant roles in smart farmland, intelligent factory and smart city. In these application scenarios, in order to save the on-grid power and protect natural environment, green charging base station (GBS) is proposed to first harvest green energy and then wirelessly power the wireless sensors with WPT. However, when a GBS omnidirectionally power its surrounding wireless sensors, the sensors closer to the GBS may be overcharged, while the sensors far from the GBS may not receive enough energy supply. Therefore, we propose a scheme to leverage the sensors with abundant energy replenishment to relay energy for the sensors with less residual energy. Then, we further propose an heuristic algorithm to efficiently solve the relay assignment problem. By this algorithm, the sensors far from the GBS can also receive considerable energy transmitted by the relays. Extensive simulations have validated that, compared to the conventional wireless charging scheme without energy relay, our proposed scheme can dramatically improve wireless charging performance in reducing the Dead Sensors Percentage (DSP) in the local WSN by around 50%.