Cluster-based Efficient Wireless Charging for Wireless Rechargeable Sensor Networks

With the rapid development of the fifth generation (5G) communication and Internet of Things (IoT) technology, the applications of Wireless Rechargeable Sensor Networks (WRSNs) have been widely adopted in modern society. Wireless Power Transfer (WPT) technology enables WRSNs to play important roles in target detection, environment monitoring and other IoT application scenarios. In certain areas, especially when Sensor Nodes (SNs) are deployed on a large scale, Mobile Charging Vehicles (MCVs) with large-capacity batteries are usually adopted to replenish wireless energy to the SNs. During the charging process, the closer an MCV is to an SN, the higher the wireless charging efficiency achieves. However, if an MCV travels a lengthy distance before reaching the SNs, its energy will direly waste during the movement. Thus, the total charging efficiency in the network is diminished. In order to improve the MCV's charging efficiency in WRSN, this work proposes to enable the MCV to wirelessly power the SNs cluster by cluster. Then, the MCV's charging efficiency maximization problem is formulated as an optimization problem. Since this formulated problem is NP-hard, we further propose the Efficiency-driven Path Selection (EPS) algorithm to effectively reduce the MCV's charging time and traveling distance, thus conserving more energy to power the SNs. Extensive simulations validate that our proposed algorithm preeminently improves the MCV's charging efficiency.