Efficient dispatch of mobile sensors in a WSN with wireless chargers

Abstract

Hybrid wireless sensor networks (WSNs) contain static and mobile sensors to support various applications. Static sensors monitor environment to find where events occur. Mobile sensors (MSs) move to event locations (ELs) to do advanced analysis. Since MSs are powered by batteries, how to dispatch them to visit ELs in an energy-efficient manner is critical. Moreover, as the technology of wireless chargers (WCs) is mature, it is feasible to use WCs to replenish energy of MSs during their working time. The paper addresses the multi-round sensor dispatch problem in a hybrid WSN with WCs, whose goal is to schedule the paths of MSs to visit ELs and WCs in each round, such that their lifetime is maximized. The problem is NP-hard and we propose a group-based mobile sensor dispatch (G-MSD) algorithm, which clusters ELs into groups by their positions. G-MSD dispatches MSs to visit each group of ELs to save and balance their moving energy costs. Besides, it schedules MSs to call at WCs to recharge batteries on demand. Simulation results verify that the G-MSD algorithm greatly extends lifetime of MSs, as comparing with other methods.