Experimenting Waveforms and Efficiency in RF Power Transfer

Ayir, Nachiket; Fierro, Marcelo Fabián Trujillo; Riihonen, Taneli; Allén, Markus

doi:10.1109/mwsym.2019.8700791

Cited by 10 publications

(14 citation statements)

References 8 publications

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“…η DC-to-DC = P DC out P DC in = η DC-to-RF • η RF-to-RF • η RF-to-DC (1) which is further split into the RF waveform generation efficiency at the source transmitter (η DC-to-RF ), the overall RF transmission efficiency between antenna connectors (η RF-to-RF ), and the power conversion efficiency at the destination energyharvesting (EH) receiver (η RF-to-DC ).…”

Section: A Motivationmentioning

confidence: 99%

“…For our study, we employ a USRP while operating in the 863-873-MHz European unlicensed band. 1 The block diagram of our test bed along with a few preliminary results is presented in Fig. 1.…”

Section: Contributions and Organizationmentioning

confidence: 99%

“…Finally, for a given N, we examine the effect of varying the PAPR of the RF waveform (before the PA I stage) on η DC-to-DC . Here, we present the observations for N = 4, in which we vary the PAPR from 4 to 8 by successively decrementing A from 1 to 1 4 and the results are shown in Fig. 7(c).…”

Section: B End-to-end Efficiency Of Multisine Waveforms Versus Gmentioning

confidence: 99%

“…The conclusions of this work are applicable to other ultrahigh-frequency (UHF) bands as well whenever bandwidth is not large. Some related results for the American 902-928-MHz ISM band have been presented in[1].…”

mentioning

confidence: 99%

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Waveforms and End-to-End Efficiency in RF Wireless Power Transfer Using Digital Radio Transmitter

Ayir

Riihonen

Allén

et al. 2021

IEEE Trans. Microwave Theory Techn.

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We study radio frequency (RF) wireless power transfer (WPT) using a digital radio transmitter for applications where alternative analog transmit circuits are impractical. An important parameter for assessing the viability of an RF WPT system is its end-to-end efficiency. In this regard, we present a prototype test bed comprising a software-defined radio (SDR) transmitter and an energy-harvesting receiver with a low resistive load; employing an SDR makes our research meaningful for simultaneous wireless information and power transfer (SWIPT). We analyze the effect of clipping and nonlinear amplification at the SDR on multisine waveforms. Our experiments suggest that when the direct current (dc) input power at the transmitter is constant, high peak-to-average power ratio (PAPR) multisines are unsuitable for RF WPT over a flat-fading channel, due to their low average radiated power. The results indicate that the end-to-end efficiency is positively correlated with the average RF power of the waveform and that it reduces with increasing PAPR. Consequently, digital modulations, such as phase shift keying (PSK) and quadrature amplitude modulation (QAM), yield better end-to-end efficiency than multisines. Moreover, the end-to-end efficiency of PSK and QAM signals is invariant to the transmission bit rate. An in-depth analysis of the end-toend efficiency of WPT reveals that the transmitter efficiency is lower than the receiver efficiency. Furthermore, we study the impact of a reflecting surface on the end-to-end efficiency of WPT and assess the transmission quality of the information signals by evaluating their error vector magnitude (EVM) for SWIPT. Overall, the experimental observations of end-to-end efficiency and EVM suggest that, while employing an SDR transmitter with fixed dc input power, a baseband quadrature PSK signal is most suitable for SWIPT at large, among PSK and QAM signals.Index Terms-Nonlinear distortion, radio frequency (RF) energy harvesting (EH), simultaneous wireless information and power transfer (SWIPT), software-defined radio (SDR), wireless power transfer (WPT).

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Section: A Motivationmentioning

confidence: 99%

Section: Contributions and Organizationmentioning

confidence: 99%

Section: B End-to-end Efficiency Of Multisine Waveforms Versus Gmentioning

confidence: 99%

mentioning

confidence: 99%

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Waveforms and End-to-End Efficiency in RF Wireless Power Transfer Using Digital Radio Transmitter

Ayir

Riihonen

Allén

et al. 2021

IEEE Trans. Microwave Theory Techn.

Self Cite

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“…Recent research developments in the area of wireless power transfer (WPT) using RF signals have focused on laying important theoretical foundations pertaining to several key aspects in the domain, such as, waveform designing, rectifierbased modeling, beamforming algorithms, co-existence with traditional wireless communications systems, etc., [5]. While the theoretical findings motivates towards the use of multi-sine type waveform designs (e.g., Orthogonal Frequency Division Multiplexing (OFDM)) for WPT [5], recent experimental findings still back the adoption of traditional Sinusoidal waveform in the 915MHz operation regime [6]. Additionally, the Square waveform [7] and extended Square, i.e., Rectangular waveform [8] are also potential candidates to be considered as possible inputs for efficient WPT.…”

Section: Introductionmentioning

confidence: 99%

Analyzing standard RF Waveform Designs for WPT

Gautam¹,

Kumar²,

Chatzinotas³

et al. 2021

Preprint

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The possibility to harvest energy from ambient radio-frequency (RF) sources has intrigued humankind since past several decades. In this context, there has been a tremendously growing research interest in the field of wireless power transfer (WPT) using the RF regime of the electromagnetic (EM) spectrum. In this paper, we investigate the aspect of real-time energy harvesting (EH) via different types of waveform designs such as Orthogonal Frequency Division Multiplexing (OFDM), Square, Triangular, Sinusoidal, and Sawtooth. We make use of a Software Defined Radio (SDR) and a Powercast P21XXCSREVB EH module to carry out the experiments on practical device performance. Specifically, we are interested in obtaining some insights based on the comparison between the aforementioned waveform designs from the perspectives of separation distance between the USRP and P21XXCSR-EVB EH module, and power emission via USRP. Correspondingly, the demonstration of the EH is provided in terms of the above-mentioned investigation metrics, while seeking the best waveform to support WPT.

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Experimental Evaluation of RF Waveform Designs for Wireless Power Transfer Using Software Defined Radio

et al. 2021

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The possibility to harvest energy from ambient radio-frequency (RF) sources has intrigued humankind for the past several decades. In this context, there has been a tremendously growing research interest in the field of wireless power transfer (WPT) using the RF range of the electromagnetic (EM) spectrum. In this paper, we experimentally investigate the aspect of real-time energy harvesting (EH) via different types of waveform designs such as orthogonal frequency division multiplexing (OFDM), square, triangular, sinusoidal, and sawtooth. We make use of a Software Defined Radio (SDR) and a Powercast P21XXCSR-EVB EH module to carry out the experiments on a practical device to assess performance. Specifically, we are interested in obtaining some insights based on the comparison between the aforementioned waveform designs from the perspectives of the separation distance between the USRP and P21XXCSR-EVB EH module, and power emission via USRP. In this vein, we perform additional subsequent experiments after reporting the practical effectiveness of the OFDM waveform, which also follows our intuitive analysis. Correspondingly, we study the effect on WPT with variable USRP transmit power, the separation distance between the USRP and EH antennas, number of OFDM sub-carriers, and multipath setting. As an application of OFDM, the effectiveness of fifth generation-new radio (5G-NR) and long-term evolution (LTE) waveforms are also tested for the WPT mechanism. The demonstration of the EH is provided in terms of the above-mentioned investigation metrics while seeking the best waveform to support WPT.

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Experimenting Waveforms and Efficiency in RF Power Transfer

Cited by 10 publications

References 8 publications

Waveforms and End-to-End Efficiency in RF Wireless Power Transfer Using Digital Radio Transmitter

Waveforms and End-to-End Efficiency in RF Wireless Power Transfer Using Digital Radio Transmitter

Analyzing standard RF Waveform Designs for WPT

Experimental Evaluation of RF Waveform Designs for Wireless Power Transfer Using Software Defined Radio

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