EMR Safety in Multiple Wireless Chargers Powered IoT Networks

In order to actualize maintenance-free and energy-sustainable Internet of Things (IoT) networks, far-field wireless charging has been prevalently applied to power the IoT devices (IoTDs). However, electromagnetic radiation (EMR) safety becomes the increasing concern when multiple wireless chargers simultaneously power surrounding IoTDs. In this letter, we derive accurate Non-Linear Superposition models for both specific absorption ratio (SAR) and wireless charging utility in scenarios with multiple wireless chargers. Considering EMR safety, we formulate the overall wireless charging utility maximization problem based on our proposed models. We then propose the tiMe domaIn sampliNg safE chaRging (MINER) algorithm to efficiently solve it. Hardware-based experiments have been conducted to validate the effectiveness of our proposed models and algorithm.