Generalised precoding method for PAPR reduction with low complexity in OFDM systems

Hsu, Chau-Yun; Liao, Hsuan-Chun

doi:10.1049/iet-com.2017.0824

Cited by 17 publications

(20 citation statements)

References 25 publications

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“…where X P k mod P are the periodically extended coefficients of P-point DFT of {v r } P−1 r=0 . Since 14is basically an SS process, the frequency-domain data received after inverse-shaping Y P r at the receiver can be obtained using the equation [21]:…”

Section: Frequency-domain Aspectmentioning

confidence: 99%

“…DFT-s-OFDM signaling is expected to be a more robust waveform for uplink through adjustable PAPR reduction schemes. Hence, several data-independent schemes such as spectral shaping (SS) [20], which use extra subcarriers to further reduce PAPR, have been investigated to overcome the need for a flexible countermeasure to the PAPR problem [16,21]. Although the results in [16] successfully achieved 2-3 dB PAPR reduction compared with conventional DFT-s-OFDM with 10%-20% spectral efficiency loss, further spectral efficiency loss does not improve the PAPR performance more, and instead degrades it.…”

Section: Introductionmentioning

confidence: 99%

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Polynomial Cancellation Coded DFT-s-OFDM for Low-PAPR Uplink Signaling

Cho

Kuo

et al. 2019

Electronics

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The physical layer signaling of the 5G new radio still utilizes cyclic prefix orthogonal frequency division multiplexing (CP-OFDM) and discrete Fourier transform-spread-OFDM (DFT-s-OFDM) to support 5G services for the sake of system-backward compatibility. However, the transmission requirements among these services differ, and this poses a challenge to the adaptability of the waveforms with regard to the peak-to-average power ratio (PAPR) issue. In particular, DFT-s-OFDM serving as a low-PAPR option for uplink signaling still has room for PAPR improvement in cases such as machine-type and device-to-device communications. We propose polynomial cancellation coded (PCC)-DFT-s-OFDM to flexibly reduce the PAPR of conventional DFT-s-OFDM. The principle of the proposed method, including its transform, is analyzed in the time domain. The results show that it can also be regarded as a novel spectral shaping scheme for PAPR reduction. Through a parameter designed for adjusting the cost of spectral efficiency, the proposed method can regulate the extent of improvement compared with the conventional DFT-s-OFDM, not only in the PAPR, but also for the spectral radiation and bit error rate when considering the nonlinearity of the power amplifier. The increase in computational complexity is neglectable owing to the simplicity of generalized PCC, making it apt to be deployed in existing systems.

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Section: Frequency-domain Aspectmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Polynomial Cancellation Coded DFT-s-OFDM for Low-PAPR Uplink Signaling

Cho

Kuo

et al. 2019

Electronics

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“…Note that the current LTE UL, DFT-s-OFDM, uses N p = 0 (g = 1) for rate-lossless transmission which can be a special case in GPC [7]. Although the contribution of PAPR reduction is almost gained fromŨ where G only maintains the energy between input and output symbols, we still can reselect and reposition the N p duplicates of U elements to improve the diversity of signal phase for further PAPR reduction without increasing any computational complexity.…”

Section: Tx Bitsmentioning

confidence: 99%

Adjustable PAPR reduction for DFT‐s‐OFDM via improved general precoding scheme

2018

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An improved and specification-compatible general precoding scheme (GPC) for adjustable peak-to-average power ratio (PAPR) reduction in discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-s-OFDM) is proposed. Through the rearrangement of periodic padding for precoded data symbols in the GPC precoding matrix, the proposed algorithm does not increase any computational complexity compared to the original GPC. The LTE-based simulation shows the proposed algorithm has a better improvement of PAPR reduction especially in low-order modulations and the performances can be scaled to the other transmission bandwidth. These works contribute to the flexibility of DFT-s-OFDM for supporting 5G transmission over miscellaneous power amplifiers. Introduction: As a low peak-to-average power ratio (PAPR) variant of orthogonal frequency division multiplexing (OFDM), discrete Fourier transform (DFT) spread OFDM (DFT-s-OFDM) has been standardised as fourth generation (4G) long term evolution (LTE) for uplink (UL) transmission [1] due to its easy implementation and high symmetry to LTE OFDM downlink. Gradually, DFT-s-OFDM has been widely used for three 5G scenarios: enhanced mobile broadband, massive machine-type communication (mMTC), and ultra-reliable and lowlatency communication (uRLLC); and therefore has adopted for the UL waveform of 5G non-standalone new radio (NR) [2]. However, the services in 5G become more diverse which challenge the flexibility of DFT-s-OFDM [3]. In the viewpoint of signal linearity, 5G NR should be flexible for fitting the different-quality power amplifiers (PAs) of miscellaneous 5G devices. It is worth mentioning that the PA efficiency grows exponentially around the margin of linear and compression region [4, Fig. 5]. Within this region, even a slight improvement of PAPR reduction may significantly enhance the power efficiency. In addition, since the device-to-device (D2D) communications as an enabling 5G issue in LTE has been enthusiastically studied for improving the spectral efficiency, system capacity, and transmission range [5], the PA non-linearity and non-uniform UL power increase the inter-resource block (RB) interference and restrict the coverage dynamicity of the user equipment for D2D power control [6]. As known, lowering PAPR can ameliorate the flexibility of UL power for D2D power control especially in low-complexity PA devices. Fortunately, the mMTC and uRLLC devices in the D2D network are allowed to a low-speed transmission. This motivates us to exploit the merits of general precoding scheme (GPC) [7] on the trade-off between further PAPR reduction and transmission rate by an adjustable parameter. GPC was proposed for generalising all famous precoding transform, such as DFT [1], discrete Hartley transform [8], and Zadoff-Chu transform [9], into a scalable form consisted of periodic extended transform matrix and energy conservation matrix. In this Letter, we propose an improved version of GPC for better PAPR reduction without any increase of computational complexit...

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“…In order to mitigate PAPR, there have been many techniques proposed in literature either to reduce the peak power with fixed average power or alter the distribution so that the average power produced has smaller peak power [2][3][4][5][6]. Due to this, there are two categories of PAPR reduction techniques which are called as signal distortion technique and signal scrambling technique.…”

Section: Introductionmentioning

confidence: 99%

Wavelet Based Multicarrier Modulation (MCM) Systems: PAPR Analysis

Zakaria¹,

Salleh²

2021

Wavelet Theory

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Orthogonal frequency division multiplexing (OFDM) is a prominent system in transmitting multicarrier modulation (MCM) signals over selective fading channel. The system offers to attain a higher degree of bandwidth efficiency, higher data transmission, and robust to narrowband frequency interference. However, it incurs a high peak-to-average power ratio (PAPR) where the signals work in the nonlinear region of the high-power amplifier (HPA) results in poor performance. Besides, an attractive dynamic wavelet analysis and its derivatives such as wavelet packet transform (WPT) demonstrates almost the same criteria as the OFDM in MCM system. Wavelet surpasses Fourier based analysis by inherent flexibility in terms of windows function for non-stationary signal. In wavelet-based MCM systems (wavelet OFDM (WOFDM) and Wavelet packet OFDM (WP-OFDM)), the constructed orthogonal modulation signals behaves similar to the fast Fourier transform (FFT) does in the conventional OFDM (C-OFDM) system. With no cyclic prefix (CP) need to be applied, these orthogonal signals hold higher bandwidth efficiency. Hence, this chapter presents a comprehensive study on the manipulation of specified parameters using WP-OFDM, WOFDM and C-OFDM signals together with various wavelets under the additive white Gaussian noise (AWGN) channel.

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Generalised precoding method for PAPR reduction with low complexity in OFDM systems

Cited by 17 publications

References 25 publications

Polynomial Cancellation Coded DFT-s-OFDM for Low-PAPR Uplink Signaling

Polynomial Cancellation Coded DFT-s-OFDM for Low-PAPR Uplink Signaling

Adjustable PAPR reduction for DFT‐s‐OFDM via improved general precoding scheme

Wavelet Based Multicarrier Modulation (MCM) Systems: PAPR Analysis

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