Concurrent Wireless Power Transfer in the Internet of Batteryless Things: Experiment and Modeling

The advancement of energy harvesting technologies, coupled with the adoption of ultra-low-power IoT devices, have enabled the emergence of the Internet of Batteryless Things (IoBT). This innovative paradigm envisions a sustainable future by employing radiative wireless power transfer (RWPT) to support battery-free IoT device operation. Despite significant progress in optimizing one-to-one RWPT, a systematic understanding of the dynamics of concurrent RWPT is still lacking. This includes addressing complex situations such as one-to-many, many-to-one, and many-to-many concurrent power transfer. These gaps hinder the scalability and practical implementation of distributed RWPT networks in real-world IoBT environments. This study addresses these challenges by conducting comprehensive experimental evaluations and developing detailed theoretical models for concurrent RWPT across all four fundamental scenarios. By leveraging state-of-the-art wireless power development kits, the novel experimental observations provide key insights into spatial power distribution. For instance, the movement of a neighboring IoT node can either double a battery-free IoT node's received power or reduce it to nearly zero. Furthermore, analytical models grounded in electromagnetic field theory, circuit principles, and wave propagation dynamics are proposed to predict and optimize RWPT performance across diverse scenarios, and are validated by MATLAB simulation. This work represents the first unified framework for concurrent RWPT, offering valuable contributions to the design of scalable, energy-efficient IoBT systems.