Single versus Multi-Tone Wireless Power Transfer with Physically Large Array

TL;DR

This paper compares single-tone and multi-tone wireless power transfer methods using large arrays, highlighting the effectiveness of adaptive single-tone signals for rapid energy delivery to energy-neutral devices.

Contribution

It provides experimental insights into the feasibility of using adaptive single-tone signals for efficient wireless power transfer to unknown ENDs with large arrays.

Findings

Adaptive single-tone signals outperform multi-tone at low power levels.

Response time for ENDs can extend to tens of seconds without prior location info.

Adaptive signals enhance power transfer efficiency in large-array systems.

Abstract

Distributed beamforming is a key enabler to provide power wirelessly to a massive amount of energy-neutral devices (ENDs). However, without prior information and fully depleted ENDs, initially powering these devices efficiently is an open question. This work investigates and assesses the feasibility of harvesting sufficient energy to transmit a backscatter pilot signal from the END, which can be then used for coherent downlink transmission. We experimentally evaluated adaptive single-tone and multi-tone signals during initial charging. The results indicate that the response time for ENDs with unknown locations can extend to several tens of seconds. Notably, the adaptive single-tone excitation shows, among others, better performance at lower transmit power levels, providing a faster response. These findings underscore the potential of adaptive single-tone signals in optimizing power delivery to END in future networks.