Optimizing Charging Station Placement in Energy-Harvesting Wireless Sensor Networks

Wireless Sensor Networks (WSN) have emerged as the defacto enabler for different systems, such as Internet of Things (IoT), Fifth and Sixth Generation (5G/6G) Mobile Communication, and beyond, due to their advantages of low cost, wide range of applications, versatility and ease of deployment. However, WSN still suffer from a main disadvantage represented by the lack of energy resources. To this end, current research is directed toward providing energy sources to the sensors, including equipping the sensors with renewable energy capabilities or harvesting energy from the received wireless signal. Recent work in energy harvesting techniques is focused on providing statistical models for the energy harvesting, or suggesting routing and scheduling schemes for energy harvested WSN, given a fixed sensors and charging stations deployment. In this paper, we investigate the effective placement of the charging base stations for such networks, as bringing the stations closer to the sensors enables faster charging, and thus more data to be routed. The problem is formulated as an Integer Linear Program (ILP) that minimizes a cost function related to the average charging time of the sensor nodes. The simulation results show the proposed scheme can achieve at least 40% increase in the total harvested energy while reducing the total costs by at least 12% when compared to the state-of-the-art scheme.