On the Beneficial Roles of Fading and Transmit Diversity in Wireless Power Transfer with Nonlinear Energy Harvesting

Bruno Clerckx; Junghoon Kim

doi:10.1109/TWC.2018.2870377

On the Beneficial Roles of Fading and Transmit Diversity in Wireless Power Transfer with Nonlinear Energy Harvesting

Bruno Clerckx, Junghoon Kim

Research output: Contribution to journal › Article › peer-review

57 Citations (Scopus)

Abstract

We study the effect of channel fading in wireless power transfer (WPT) and show that fading enhances the RF-to-DC conversion efficiency of nonlinear RF energy harvesters. We then develop a new form of signal design for WPT, denoted as transmit diversity, that relies on multiple dumb antennas at the transmitter to induce fast fluctuations of the wireless channel. Those fluctuations boost the RF-to-DC conversion efficiency thanks to the energy harvester nonlinearity. In contrast with (energy) beamforming, transmit diversity does not rely on channel state information at the transmitter (CSIT) and does not increase the average power at the energy harvester input, even though it still enhances the overall end-to-end power transfer efficiency. Transmit diversity is also combined with recently developed (energy) waveform and modulation to provide further enhancements. The efficacy of the scheme is analyzed using physics-based and curve fitting-based nonlinear models of the energy harvester and demonstrated using circuit simulations, prototyping and experimentation. Measurements with two transmit antennas reveal gains of 50% in harvested DC power over a single transmit antenna setup. The work (again) highlights the crucial role played by the harvester nonlinearity and demonstrates that multiple transmit antennas can be beneficial to WPT even in the absence of CSIT.

Original language	English
Article number	8470248
Pages (from-to)	7731-7743
Number of pages	13
Journal	IEEE Transactions on Wireless Communications
Volume	17
Issue number	11
DOIs	https://doi.org/10.1109/TWC.2018.2870377
Publication status	Published - 2018 Nov

Bibliographical note

Funding Information:
Manuscript received April 12, 2018; revised July 19, 2018; accepted September 1, 2018. Date of publication September 24, 2018; date of current version November 9, 2018. This work was supported by the EPSRC of U.K. under Grant EP/P003885/1. The associate editor coordinating the review of this paper and approving it for publication was M. Di Renzo. (Corresponding author: Bruno Clerckx.) The authors are with the EEE Department, Imperial College London, London SW7 2AZ, U.K. (e-mail: [email protected]; [email protected]).

Publisher Copyright:
© 2002-2012 IEEE.

Keywords

Fading
energy beamforming
energy modulation
energy waveform
nonlinear energy harvesting
transmit diversity
wireless power transfer

ASJC Scopus subject areas

Computer Science Applications
Electrical and Electronic Engineering
Applied Mathematics

Access to Document

10.1109/TWC.2018.2870377

Cite this

@article{88cfb02efdf54fbba9788f12c6844218,

title = "On the Beneficial Roles of Fading and Transmit Diversity in Wireless Power Transfer with Nonlinear Energy Harvesting",

abstract = "We study the effect of channel fading in wireless power transfer (WPT) and show that fading enhances the RF-to-DC conversion efficiency of nonlinear RF energy harvesters. We then develop a new form of signal design for WPT, denoted as transmit diversity, that relies on multiple dumb antennas at the transmitter to induce fast fluctuations of the wireless channel. Those fluctuations boost the RF-to-DC conversion efficiency thanks to the energy harvester nonlinearity. In contrast with (energy) beamforming, transmit diversity does not rely on channel state information at the transmitter (CSIT) and does not increase the average power at the energy harvester input, even though it still enhances the overall end-to-end power transfer efficiency. Transmit diversity is also combined with recently developed (energy) waveform and modulation to provide further enhancements. The efficacy of the scheme is analyzed using physics-based and curve fitting-based nonlinear models of the energy harvester and demonstrated using circuit simulations, prototyping and experimentation. Measurements with two transmit antennas reveal gains of 50% in harvested DC power over a single transmit antenna setup. The work (again) highlights the crucial role played by the harvester nonlinearity and demonstrates that multiple transmit antennas can be beneficial to WPT even in the absence of CSIT.",

keywords = "Fading, energy beamforming, energy modulation, energy waveform, nonlinear energy harvesting, transmit diversity, wireless power transfer",

author = "Bruno Clerckx and Junghoon Kim",

note = "Funding Information: Manuscript received April 12, 2018; revised July 19, 2018; accepted September 1, 2018. Date of publication September 24, 2018; date of current version November 9, 2018. This work was supported by the EPSRC of U.K. under Grant EP/P003885/1. The associate editor coordinating the review of this paper and approving it for publication was M. Di Renzo. (Corresponding author: Bruno Clerckx.) The authors are with the EEE Department, Imperial College London, London SW7 2AZ, U.K. (e-mail: [email protected]; [email protected]). Publisher Copyright: {\textcopyright} 2002-2012 IEEE.",

year = "2018",

month = nov,

doi = "10.1109/TWC.2018.2870377",

language = "English",

volume = "17",

pages = "7731--7743",

journal = "IEEE Transactions on Wireless Communications",

issn = "1536-1276",

publisher = "Institute of Electrical and Electronics Engineers Inc.",

number = "11",

}

TY - JOUR

T1 - On the Beneficial Roles of Fading and Transmit Diversity in Wireless Power Transfer with Nonlinear Energy Harvesting

AU - Clerckx, Bruno

AU - Kim, Junghoon

N1 - Funding Information: Manuscript received April 12, 2018; revised July 19, 2018; accepted September 1, 2018. Date of publication September 24, 2018; date of current version November 9, 2018. This work was supported by the EPSRC of U.K. under Grant EP/P003885/1. The associate editor coordinating the review of this paper and approving it for publication was M. Di Renzo. (Corresponding author: Bruno Clerckx.) The authors are with the EEE Department, Imperial College London, London SW7 2AZ, U.K. (e-mail: [email protected]; [email protected]). Publisher Copyright: © 2002-2012 IEEE.

PY - 2018/11

Y1 - 2018/11

N2 - We study the effect of channel fading in wireless power transfer (WPT) and show that fading enhances the RF-to-DC conversion efficiency of nonlinear RF energy harvesters. We then develop a new form of signal design for WPT, denoted as transmit diversity, that relies on multiple dumb antennas at the transmitter to induce fast fluctuations of the wireless channel. Those fluctuations boost the RF-to-DC conversion efficiency thanks to the energy harvester nonlinearity. In contrast with (energy) beamforming, transmit diversity does not rely on channel state information at the transmitter (CSIT) and does not increase the average power at the energy harvester input, even though it still enhances the overall end-to-end power transfer efficiency. Transmit diversity is also combined with recently developed (energy) waveform and modulation to provide further enhancements. The efficacy of the scheme is analyzed using physics-based and curve fitting-based nonlinear models of the energy harvester and demonstrated using circuit simulations, prototyping and experimentation. Measurements with two transmit antennas reveal gains of 50% in harvested DC power over a single transmit antenna setup. The work (again) highlights the crucial role played by the harvester nonlinearity and demonstrates that multiple transmit antennas can be beneficial to WPT even in the absence of CSIT.

AB - We study the effect of channel fading in wireless power transfer (WPT) and show that fading enhances the RF-to-DC conversion efficiency of nonlinear RF energy harvesters. We then develop a new form of signal design for WPT, denoted as transmit diversity, that relies on multiple dumb antennas at the transmitter to induce fast fluctuations of the wireless channel. Those fluctuations boost the RF-to-DC conversion efficiency thanks to the energy harvester nonlinearity. In contrast with (energy) beamforming, transmit diversity does not rely on channel state information at the transmitter (CSIT) and does not increase the average power at the energy harvester input, even though it still enhances the overall end-to-end power transfer efficiency. Transmit diversity is also combined with recently developed (energy) waveform and modulation to provide further enhancements. The efficacy of the scheme is analyzed using physics-based and curve fitting-based nonlinear models of the energy harvester and demonstrated using circuit simulations, prototyping and experimentation. Measurements with two transmit antennas reveal gains of 50% in harvested DC power over a single transmit antenna setup. The work (again) highlights the crucial role played by the harvester nonlinearity and demonstrates that multiple transmit antennas can be beneficial to WPT even in the absence of CSIT.

KW - Fading

KW - energy beamforming

KW - energy modulation

KW - energy waveform

KW - nonlinear energy harvesting

KW - transmit diversity

KW - wireless power transfer

UR - http://www.scopus.com/inward/record.url?scp=85054220156&partnerID=8YFLogxK

U2 - 10.1109/TWC.2018.2870377

DO - 10.1109/TWC.2018.2870377

M3 - Article

AN - SCOPUS:85054220156

SN - 1536-1276

VL - 17

SP - 7731

EP - 7743

JO - IEEE Transactions on Wireless Communications

JF - IEEE Transactions on Wireless Communications

IS - 11

M1 - 8470248

ER -

On the Beneficial Roles of Fading and Transmit Diversity in Wireless Power Transfer with Nonlinear Energy Harvesting

Abstract

Bibliographical note

Keywords

ASJC Scopus subject areas

Access to Document

Other files and links

Fingerprint

Cite this