Charger Placement With Wave Interference

To guarantee the reliability for WRSNs, placing sufficient static chargers effectively ensures charging coverage for the entire network. However, this approach leads to a considerable number of sensors located within charging overlaps. The destructive wave interference caused by concurrent charging in these overlaps may weaken sensors received power, thereby negatively impacting charging performance. This work addresses a CHArging utIlity maximizatioN (CHAIN) problem, which aims to maximize the overall charging utility while considering wave interference among multiple chargers. Specifically, given a set of stationary sensors, we investigate how to determine optimal positions for a fixed number of chargers. To tackle this problem, we first develop a charging model with wave interference, then propose a two-step charger placement scheme to identify the optimal charger positions. In the first step, we maximize the overall additive power of the waves involved in interference by selecting an appropriate initial position for each charger. Then, in the second step, we maximize the overall charging utility by finding the optimal final position for each charger around its initial position. Finally, to evaluate the performance of our scheme, we conduct extensive simulations and field experiments and the results suggest that CHAIN performs better than the existing algorithms.

I. Introduction

Nowadays, Wireless Power Transfer (WPT) technology has aroused widespread attention from researchers due to its merits: no wiring, reliability, and ease of maintenance [1]. Benefiting from WPT, we can place power transmitters (i.e., wireless chargers) at proper positions in the network to construct Wireless Rechargeable Sensor Networks (WRSNs), providing sustainable energy supply for sensors [2], [3], [4], [5], [6], [7], [8], [9]. WRSNs have experienced extensive applications in healthcare [10], [11], industrial tasks [12] and oceanic monitoring [13], owing to the great ease of overcoming the energy limitations in Wireless Sensor Networks (WSNs).