Multi-Type Charging Scheduling Based on Area Requirement Difference for Wireless Rechargeable Sensor Networks

Charging scheduling plays a crucial role in ensuring durable operation for wireless rechargeable sensor networks. However, previous methods cannot meet the strict requirements of a high node survival rate and high energy usage effectiveness. In this article, we propose a multi-type charging scheduling strategy to meet such demands. In this strategy, the network is divided into an inner ring and an outer ring to satisfy different demands in different areas. The inner ring forms a flat topology, and adopts a periodic and single-node charging pattern mainly for a high node survival rate. A space priority and a time priority are designed to determine the charging sequence of the nodes. The optimal charging cycle and the optimal charging time are achieved by mathematical derivations. The outer ring forms a cluster topology, and adopts an on-demand and multi-node charging pattern mainly for high energy usage effectiveness. A space balancing principle and a time balancing principle are designed to determine the charging positions of the clusters. A gravitational search algorithm is designed to determine the charging sequence of the clusters. Several simulations verify the advantages of the proposed solution in terms of energy usage effectiveness, charging failure rate, and average task delay.