Maximizing Sensor Lifetime in a Rechargeable Sensor Network via Partial Energy Charging on Sensors

The wireless energy transfer technology based on magnetic resonant coupling has emerged as a promising technology for wireless sensor networks, by providing controllable yet perpetual energy to sensors. In this paper we study the use of a mobile charger to wirelessly charge sensors in a rechargeable sensor network so that the sum of sensor lifetimes is maximized while the traveling distance of the mobile charger is minimized. Unlike existing studies that assumed a mobile charger must charge a sensor to its full energy capacity before moving to charge the next sensor, in this paper we assume that each sensor can be partially charged so that more sensors can be charged by the mobile charger before their energy depletions. Under this new charging model, we first formulate a novel optimization problem of scheduling the mobile charger to charge life-critical sensors with an objective to maximize the sum of sensor lifetimes, while minimizing the traveling distance of the mobile charger. Due to NP-hardness of the problem, we then propose an efficient algorithm for it. We finally evaluate the performance of the proposed algorithm through experimental simulations. Simulation results demonstrate that the proposed algorithm is very promising.