Simultaneous Wireless Information and Power Transfer in a two-user OFDM Interference Channel

IEEE Trans. Signal Process.

Bayguzina

2016

Self Cite

346

767

Abstract-Far-field Wireless Power Transfer (WPT) has attracted significant attention in recent years. Despite the rapid progress, the emphasis of the research community in the last decade has remained largely concentrated on improving the design of energy harvester (so-called rectenna) and has left aside the effect of transmitter design. In this paper, we study the design of transmit waveform so as to enhance the DC power at the output of the rectenna. We derive a tractable model of the non-linearity of the rectenna and compare with a linear model conventionally used in the literature. We then use those models to design novel multisine waveforms that are adaptive to the channel state information (CSI). Interestingly, while the linear model favours narrowband transmission with all the power allocated to a single frequency, the non-linear model favours a power allocation over multiple frequencies. Through realistic simulations, waveforms designed based on the non-linear model are shown to provide significant gains (in terms of harvested DC power) over those designed based on the linear model and over non-adaptive waveforms. We also compute analytically the theoretical scaling laws of the harvested energy for various waveforms as a function of the number of sinewaves and transmit antennas. Those scaling laws highlight the benefits of CSI knowledge at the transmitter in WPT and of a WPT design based on a non-linear rectenna model over a linear model. Results also motivate the study of a promising architecture relying on large-scale multisine multi-antenna waveforms for WPT. As a final note, results stress the importance of modeling and accounting for the non-linearity of the rectenna in any system design involving wireless power.

“…Such a strategy has also appeared in the SWIPT literature with OFDM transmission, e.g. [14], [15]. Remark 1: For the extreme case where the channel is perfectly flat magnitude-wise, i.e.…”

Section: A Linear Model-based Designmentioning

confidence: 99%

Waveform Design for Wireless Power Transfer

IEEE Trans. Signal Process.

Bayguzina

2016

Self Cite

346

767

“…Note that this ASS strategy has already appeared in the WIPT literature, e.g. in [11], [41] with OFDM transmission.…”

Section: A Wpt-only: Energy Maximizationmentioning

confidence: 99%

Wireless Information and Power Transfer: Nonlinearity, Waveform Design, and Rate-Energy Tradeoff

IEEE Trans. Signal Process.

2018

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199

260

The design of Wireless Information and Power Transfer (WIPT) has so far relied on an oversimplified and inaccurate linear model of the energy harvester. In this paper, we depart from this linear model and design WIPT considering the rectifier nonlinearity. We develop a tractable model of the rectifier nonlinearity that is flexible enough to cope with general multicarrier modulated input waveforms. Leveraging that model, we motivate and introduce a novel WIPT architecture relying on the superposition of multi-carrier unmodulated and modulated waveforms at the transmitter. The superposed WIPT waveforms are optimized as a function of the channel state information so as to characterize the rate-energy region of the whole system. Analysis and numerical results illustrate the performance of the derived waveforms and WIPT architecture and highlight that nonlinearity radically changes the design of WIPT. We make key and refreshing observations. First, analysis (confirmed by circuit simulations) shows that modulated and unmodulated waveforms are not equally suitable for wireless power delivery, namely modulation being beneficial in single-carrier transmissions but detrimental in multi-carrier transmissions. Second, a multicarrier unmodulated waveform (superposed to a multi-carrier modulated waveform) is useful to enlarge the rate-energy region of WIPT. Third, a combination of power splitting and time sharing is in general the best strategy. Fourth, a non-zero mean Gaussian input distribution outperforms the conventional capacity-achieving zero-mean Gaussian input distribution in multi-carrier transmissions. Fifth, the rectifier nonlinearity is beneficial to system performance and is essential to efficient WIPT design.

“…The maximization of E subject to the transmit power constraint would lead to a single-sinewave transmission strategy where the power is allocated to the strongest sinewave, i.e. the one corresponding to the strongest channel [10]. This contrasts with RF experiments that highlight the usefulness of allocating power to multiple sinewaves [5]- [7].…”

Section: Output DC Currentmentioning

confidence: 99%

Waveform optimization for Wireless Power Transfer with nonlinear energy harvester modeling

2015 International Symposium on Wireless Communication Systems (ISWCS)

Bayguzina

Yates

et al. 2015

Self Cite

Abstract-Far-field Wireless Power Transfer (WPT) and Simultaneous Wireless Information and Power Transfer (SWIPT) have attracted significant attention in the RF and communication communities. Despite the rapid progress, the problem of waveform design to enhance the output DC power of wireless energy harvester has received limited attention so far. In this paper, we bridge communication and RF design and derive novel multisine waveforms for multi-antenna wireless power transfer. The waveforms are adaptive to the channel state information and result from a posynomial maximization problem that originates from the non-linearity of the energy harvester. They are shown through realistic simulations to provide significant gains (in terms of harvested DC power) over state-of-the-art waveforms under a fixed transmit power constraint.