Waveform Optimization and Beam Focusing for Near-field Wireless Power Transfer with Dynamic Metasurface Antennas and Non-linear Energy Harvesters

TL;DR

This paper introduces a waveform optimization and beam focusing method for near-field wireless power transfer using dynamic metasurface antennas and non-linear energy harvesters, significantly improving efficiency and focusing energy on intended receivers.

Contribution

It develops a mathematical framework and optimization approach for waveform and beam design in near-field RF-WPT with DMA and non-linear harvesters, enhancing power transfer efficiency.

Findings

Increasing transmit tones reduces power consumption.

Longer antennas improve performance.

DMA outperforms fully-digital architectures.

Abstract

Radio frequency (RF) wireless power transfer (WPT) is a promising technology for future wireless systems. However, the low power transfer efficiency (PTE) is a critical challenge for practical implementations. One of the main inefficiency sources is the power consumption and loss introduced by key components such as high-power amplifier (HPA) and rectenna, thus they must be carefully considered for PTE optimization. Herein, we consider a near-field RF-WPT system with a dynamic metasurface antenna (DMA) at the transmitter and non-linear energy harvesters. We provide a mathematical framework to calculate the power consumption and harvested power from multi-tone signal transmissions. Based on this, we propose an approach relying on alternating optimization and successive convex approximation for waveform optimization and beam focusing to minimize power consumption while meeting energy harvesting requirements. Numerical results show that increasing the number of transmit tones reduces the power consumption by leveraging the rectifier's non-linearity more efficiently. Moreover, they demonstrate that increasing the antenna length improves the performance, while DMA outperforms fully-digital architecture in terms of power consumption. Finally, our results verify that the transmitter focuses the energy on receivers located in the near-field, while energy beams are formed in the receivers' direction in the far-field region.