Sequential asymmetric superposition windowing for Crest Factor Reduction and its effects on Doherty power amplifier

Nair, M. V. Deepak; Giofrè, Rocco; Colantonio, Paolo; Giannini, F.

doi:10.1109/inmmic.2015.7330380

Cited by 3 publications

(5 citation statements)

References 9 publications

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“…In order to quantitatively reveal the identification ability of FFT and ACF, the Crest Factor is introduced as an evaluation index [46,47]. Crest Factor (aka Peak-to-Average Ratio) is defined as peak value divided by the effective value of a signal [48]: However, the reflected pulse is easily identified by ACF. Normally, the computer software locates the liquid level by extracting the reflected pulse, so for an algorithm, the ability of identifying the acoustic pulse is what we are concerned about.…”

Section: Experimental Schemesmentioning

confidence: 99%

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A Novel Acoustic Liquid Level Determination Method for Coal Seam Gas Wells Based on Autocorrelation Analysis

Zhang

Fan

et al. 2017

Energies

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Abstract:In coal seam gas (CSG) wells, water is periodically removed from the wellbore in order to keep the bottom-hole flowing pressure at low levels, facilitating the desorption of methane gas from the coal bed. In order to calculate gas flow rate and further optimize well performance, it is necessary to accurately monitor the liquid level in real-time. This paper presents a novel method based on autocorrelation function (ACF) analysis for determining the liquid level in CSG wells under intense noise conditions. The method involves the calculation of the acoustic travel time in the annulus and processing the autocorrelation signal in order to extract the weak echo under high background noise. In contrast to previous works, the non-linear dependence of the acoustic velocity on temperature and pressure is taken into account. To locate the liquid level of a coal seam gas well the travel time is computed iteratively with the non-linear velocity model. Afterwards, the proposed method is validated using experimental laboratory investigations that have been developed for liquid level detection under two scenarios, representing the combination of low pressure, weak signal, and intense noise generated by gas flowing and leakage. By adopting an evaluation indicator called Crest Factor, the results have shown the superiority of the ACF-based method compared to Fourier filtering (FFT). In the two scenarios, the maximal measurement error from the proposed method was 0.34% and 0.50%, respectively. The latent periodic characteristic of the reflected signal can be extracted by the ACF-based method even when the noise is larger than 1.42 Pa, which is impossible for FFT-based de-noising. A case study focused on a specific CSG well is presented to illustrate the feasibility of the proposed approach, and also to demonstrate that signal processing with autocorrelation analysis can improve the sensitivity of the detection system.

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Section: Experimental Schemesmentioning

confidence: 99%

Section: Experimental Schemesmentioning

confidence: 99%

A Novel Acoustic Liquid Level Determination Method for Coal Seam Gas Wells Based on Autocorrelation Analysis

Zhang

Fan

et al. 2017

Energies

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“…To mitigate them, clipping & filtering techniques can be used. However, such techniques are not able to fully restrict the peak-regrowth, and, above all, to properly control the in-band noise (i.e., avoiding EVM degradation) [9,16,17].…”

Section: Clipping and Filteringmentioning

confidence: 99%

“…Crest Factor Reduction (CFR) techniques [8,9], in conjunction with Digital Predistortion (DPD) techniques are considered to be a promising solution to simultaneously achieve higher linearity and efficiency [10][11][12][13][14][15]. However, a complete experimental validation of both benefits and drawbacks induced by their application on a DPA is not yet reported in literature.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, for an in-depth performance analysis two different DPD approaches, i.e., Generalized Memory Polynomial (GM P DP D ), and Volterra series based Digital Predistortion (V DP D ) are adopted and applied onto two different signal standards: Long-Term Evolution (LT E) and multicarrier Wideband Code Division Multiple Access (W CDM A) with varying bandwidth. In particular, to reduce the PAPR of the signals, CF R W B technique [9,10] based on peak windowing is used and its performance in conjunction with GM P DP D and V DP D techniques is evaluated through several parameters such as Adjacent Channel Power ratio (ACPR), Error Vector Magnitude (EVM), and power efficiency increment. This paper is organized as follows.…”

Section: Introductionmentioning

confidence: 99%

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Enhancing Power Efficiency of Doherty Power Amplifiers Using Windowing Based Crest Factor Reduction Technique

Vikraman¹,

Giofrè²,

Colantonio³

2016

PIER C

Self Cite

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Abstract-This paper investigates the performance of a Windowing Based Crest Factor Reduction (CF R W B ) technique, to enhance the power efficiency of Radio Frequency (RF) power amplifiers. In particular, CF R W B is implemented on a Doherty Power Amplifier (DP A) in conjunction with Generalized Memory Polynomial (GM P DP D ), and Volterra series based Digital Predistortion (V DP D ) techniques. Key features like spectral regrowth, Peak to Average Power Ratio (P AP R) reduction, efficiency improvement and Error Vector Magnitude (EV M ) have been used to measure the efficacy of the proposed method. Both simulation and experimental results show that the proposed combination of CF R W B technique with GM P DP D and V DP D is able to reduce the P AP R of the complex input signals by nearly 60%, with minimal degrading of the EV M and spectral regrowth. Moreover, such signal with reduced P AP R can be used to overdrive the DPA, allowing for a relevant average efficiency enhancement (i.e., up to 25%), while fulfilling the requirements of modern communication standards such as Wideband Code Division Multiple Access (W CDM A) and long-term evolution (LT E).

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Spectral Re-Growth Suppression in the FBMC-OQAM Signal Under the Non-linear Behavior of a Power Amplifier

Jake¹,

Mwangi

Langat

2019

Eng. Technol. Appl. Sci. Res.

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Typically, the filter bank multicarrier with offset quadrature amplitude modulation (FBMC-OQAM) bears some impressive properties that make it popular as one of the substitutes to orthogonal frequency division multiplexing (OFDM) for the upcoming technology of broadband wireless communication systems. Although FBMC-OQAM preserves the multicarrier modulation (MCM) features, its spectrum usually suffers from impairments when subjected to the nonlinear behavior of a power amplifier (PA) which results in spectral re-growth. Due to the spectrum limitation and low energy efficiency foreseen in the forthcoming 5G networks, it is vital to confine the spectrum of the FBMC-OQAM signal within the allocated band of interest. In this paper, the suppression of the spectral re-growth experienced on the FBMC-OQAM signal due to the nonlinear distortion effects introduced by the PA is investigated. The crest factor reduction (CFR) method in combination with an adaptive digital pre-distortion (DPD) are used. The peak windowing technique based on sequential asymmetric superposition windowing (SASW) algorithm is used in the CFR part while the least square estimation with QR-decomposition (LSE/QR) has been used as the coefficient’s estimator and adaptation algorithm in the DPD part. The performance of the two combined techniques has been evaluated on SystemVue2018 simulation platform. The adjacent channel leakage ratio (ACLR) and the error vector magnitude (EVM) have been considered as the performance merits. The simulation results show that the proposed techniques significantly improve the spectrum, first by reducing the PAPR of the FBMC-OQAM signal by about 1.5dB. Secondly, the spectral re-growth has been reduced by about -45.74dB adjacent channel leakage suppression and the error vector magnitude measure has been obtained to be about 7.12%. (-22.95dB). These values lead to better average input power of the FBMC-OQAM signal and improvement in the spectral efficiency and they are in accordance with the 3GPP standard for wideband signals in nonlinear systems.

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Sequential asymmetric superposition windowing for Crest Factor Reduction and its effects on Doherty power amplifier

Cited by 3 publications

References 9 publications

A Novel Acoustic Liquid Level Determination Method for Coal Seam Gas Wells Based on Autocorrelation Analysis

A Novel Acoustic Liquid Level Determination Method for Coal Seam Gas Wells Based on Autocorrelation Analysis

Enhancing Power Efficiency of Doherty Power Amplifiers Using Windowing Based Crest Factor Reduction Technique

Spectral Re-Growth Suppression in the FBMC-OQAM Signal Under the Non-linear Behavior of a Power Amplifier

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