Towards perpetual sensor networks via Overlapped Mobile Charging

Abstract

Wireless power transfer has given a promising alternative to replenish battery-powered wireless sensor networks (WSNs). We can employ mobile vehicles, robots, or unmanned aerial vehicle as mobile chargers to wirelessly charge sensor nodes. Most of previous works either assume that a mobile charger can charge only one sensor node at a time, or optimize for charging delay, radiation safety, etc. In this paper, we consider a fundamental problem: given one mobile charger that can charge multiple sensor nodes simultaneously, how we can schedule it to charge a given WSN to maximize the energy usage effectiveness (EUE)? We propose a novel charging paradigm, Overlapped Mobile Charging (OMC), the first of its kind to the best of our knowledge. Firstly, OMC clusters sensor nodes into multiple non-overlapped sets using k-means evaluated by the Davies–Bouldin Index, such that the sensor nodes in each set have similar recharging cycles. Secondly, for each set of sensor nodes, OMC further divides them into multiple overlapped groups, and charges each group at different locations for different time durations to make sure that each overlapped sensor node just receives its required energy from multiple charging locations. Simulations confirm the advantages of OMC in terms of EUE.