# Theory and Experiment for Wireless-Powered Sensor Networks: How to Keep Sensors Alive

## TL;DR

This paper presents a real-time multi-node wireless-powered sensor network with a novel beam-splitting beamforming technique and an energy management algorithm, demonstrating perpetual sensor operation through experimental validation.

## Contribution

It introduces a practical multi-antenna beam-splitting beamforming method and an energy neutral control algorithm for sustained sensor operation in wireless-powered networks.

## Key findings

- Beam-splitting beamforming achieves Pareto optimality.
- The energy neutral control algorithm maintains sensor node longevity.
- Experimental results confirm perpetual sensor operation.

## Abstract

In this paper, we investigate a multi-node multi-antenna wireless-powered sensor networks (WPSN) comprised of one power beacon and multiple sensor nodes. We have implemented a real-life multi-node multi-antenna WPSN testbed that operates in real time. We propose a beam-splitting beamforming technique that enables a power beacon to split microwave energy beams towards multiple nodes for simultaneous charging. We experimentally demonstrate that the beam-splitting beamforming technique achieves the Pareto optimality. For a perpetual operation of the sensor nodes, we adopt an energy neutral control algorithm that keeps a sensor node alive by balancing the harvested and the consumed power. The joint beam-splitting and energy neutral control algorithm is designed by means of the Lyapunov optimization technique. By experiments, we have shown that the proposed algorithm can successfully keep all sensor nodes alive by optimally splitting energy beams towards multiple sensor nodes.