On Iterative Compensation of Clipping Distortion in OFDM Systems

Liang, Shansuo; Tong, Jun; Li, Ping

doi:10.1109/lwc.2018.2874935

Cited by 17 publications

(10 citation statements)

References 16 publications

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“…According to [19], the number of iterations for the converged BER dominates the complexity of receiver-based solutions due to the usage of FFT/IFFT pairs. There are usually one or two iterations in most schemes, except for in the case of ISR (e.g., [12][13][14][15][16]). In this example, the proposed scheme further enhances the converged BER to 10 −5 within five iterations, which consumes two to five times more complexity when compared with the consumption of other schemes.…”

Section: Performance Evaluationmentioning

confidence: 99%

“…The receiver-side remedies for PA nonlinearity in OFDM systems have been widely investigated in the literature [12][13][14][15][16]; however, the increase in processing time makes such iterative methods infeasible due to the high data rate requirement of mobile broadband. Nevertheless, these techniques may come in handy for LPWA uplinks to support machine-type communications, which need to leave all possible complicated operations at base stations for power saving [17,18].…”

Section: Introductionmentioning

confidence: 99%

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Improved ISR for IEEE 802.11ah Nonlinearity Compensation via Adjustable Constellation Borders

2021

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Iterative subcarrier regularization (ISR) has been recently proposed as a receiver-side remedy for orthogonal frequency division multiplexing (OFDM) nonlinearity. It allows the power amplifier of OFDM transmitters to operate at a lower input back-off for more efficient uplinks. However, the compensation ability cannot align with increasing channel quality, because the standard quadrature amplitude modulation (QAM) used in ISR may eliminate compensation due to erroneous decisions. To solve this issue, an improved version of ISR was proposed to flexibly adjust the constellation borders of QAM and numerically optimize it based on IEEE 802.11ah (hereinafter referred to as 802.11ah) specifications. Simulations show that the proposed scheme not only improves the converged bit error rate of ISR but also accelerates its own convergence, especially in a high channel quality, thereby achieving better power efficiency for Internet of Things clients without additional computational complexity.

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Section: Performance Evaluationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Improved ISR for IEEE 802.11ah Nonlinearity Compensation via Adjustable Constellation Borders

2021

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“…The receiver-side signal linearization approaches are particularly suitable for MTC type systems where the IoT-CD traffics are UL-dominated [18]. With the abovementioned advantages, the studies on receiver-side compensation have been extensively reported in literature in the following two categories: (1) maximum-likelihood (ML) detection-based (e.g., [24]- [26]), and (2) signal compensation (SC)-based (e.g., [27]- [30]). The former can achieve a better bit error rate (BER) performance than the latter at the expense of exponentially growing computational complexity with the FFT size that leads to infeasibility.…”

Section: Introductionmentioning

confidence: 99%

Mitigation of PA Nonlinearity for IEEE 802.11ah Power-Efficient Uplink via Iterative Subcarrier Regularization

Cho

Yu²,

Hsu³

et al. 2021

IEEE Access

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An orthogonal frequency division multiplexing (OFDM) transmitter for 802.11ah uplink may consume unnecessarily high power due to the malicious effect of a large peak-to-average power ratio (PAPR). This is particularly a problem for client devices (CDs) under the low-power wide-area (LPWA) technology in an Internet of thing (IoT) system, where high PAPR signals may drive the power amplifier (PA) to operate with large input back-off (IBO). This article focuses on receiver-side signal compensation (SC) techniques and introduces a novel scheme called iterative subcarrier regularization (ISR), which is based on the generalization of Papoulis-Gerchberg algorithm (GPGA). We claim that the proposed scheme is completely compatible with 802.11ah as it only exploits the prior information available in the standard operations and popular system-build-in functions in the iterative signal reconstruction process. Extensive numerical evaluations demonstrate that the proposed scheme can improve PA efficiency by 4-9 dB for uplink signaling.INDEX TERMS Orthogonal frequency division multiplexing (OFDM), nonlinear noise, Papoulis-Gerchberg algorithm, peak-to-average power ratio (PAPR), 802.11ah.

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“…Throughout the paper, we focus on the fundamental perfor-mance of the uncoded OFDM system over both additive white Gaussian noise (AWGN) and frequency-selective Rayleigh fading channels. Our analytical results on SNDR may be also valid for coded OFDM systems (e.g., [18]- [21]), but their precise analysis is beyond the scope of this work. We note that most of the conventional TD compensation schemes such as the original work of DAR [11] as well as [14], [16], [18], [19], [21] have been focused on the clipped OFDM signal (without filtering), but as mentioned above, clipping should be applied to oversampled OFDM signals together with filtering for lower PAPR and higher SDR.…”

Section: Introductionmentioning

confidence: 99%

“…Our analytical results on SNDR may be also valid for coded OFDM systems (e.g., [18]- [21]), but their precise analysis is beyond the scope of this work. We note that most of the conventional TD compensation schemes such as the original work of DAR [11] as well as [14], [16], [18], [19], [21] have been focused on the clipped OFDM signal (without filtering), but as mentioned above, clipping should be applied to oversampled OFDM signals together with filtering for lower PAPR and higher SDR. It will be shown that in the presence of CAF, the TD reconstruction process fails to take into account the effect of filtering on the resulting signals and thus should lead to some degradation in terms of its achievable performance.…”

Section: Introductionmentioning

confidence: 99%

Performance Analysis and Comparison of Clipped and Filtered OFDM Systems With Iterative Distortion Recovery Techniques

Sun

Ochiai

2021

IEEE Trans. Wireless Commun.

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A well-known drawback of orthogonal frequencydivision multiplexing (OFDM) is its signal with high peakto-average power ratio (PAPR). Among a number of PAPR reduction techniques, clipping and filtering (CAF) is the simplest approach, which effectively reduces the PAPR of band-limited OFDM signals at the cost of increasing in-band distortion. In order to mitigate the performance degradation caused by the inband distortion, several iterative distortion recovery techniques have been proposed in the literature, and they are largely classified into time-domain (TD) and frequency-domain (FD) compensation approaches: The former and latter are represented by the decision-aided reconstruction (DAR) and clipping noise cancellation (CNC), respectively. To date, however, their theoretical performance limits have not been studied. In this work, we revisit the performance limits of CAF and derive a closed-form signal-to-distortion power ratio (SDR) expression. Furthermore, we introduce a time-domain distortion model for characterizing the OFDM signal with CAF, based on which we make performance comparison between the two compensation approaches. Theoretical analysis and simulations in terms of their achievable symbol error rate (SER) reveal that, unlike the FD counterpart, the TD compensation may suffer from unrecoverable distortion when filtering after clipping is applied at the transmitter.

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On Iterative Compensation of Clipping Distortion in OFDM Systems

Cited by 17 publications

References 16 publications

Improved ISR for IEEE 802.11ah Nonlinearity Compensation via Adjustable Constellation Borders

Improved ISR for IEEE 802.11ah Nonlinearity Compensation via Adjustable Constellation Borders

Mitigation of PA Nonlinearity for IEEE 802.11ah Power-Efficient Uplink via Iterative Subcarrier Regularization

Performance Analysis and Comparison of Clipped and Filtered OFDM Systems With Iterative Distortion Recovery Techniques

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