Peak-to-average Power Ratio Reduction Method Research Articles

Performance Analysis of Layered ACO-OFDM

Layered asymmetrically clipped optical orthogonal frequency division multiplexing (LACO-OFDM) has been proposed for improving the spectral efficiency of conventional asymmetrically clipped optical OFDM. Multiple base layers that are orthogonal in the frequency domain are sequentially superimposed to form LACO-OFDM, where each superimposed layer fills the empty subcarriers left by the previous layer. As our contribution, the bit error ratio (BER) considering the effect of thermal noise, clipping distortion, inter-layer interference, and the bit rate difference between layers is analysed in this paper. Since the BER performance of LACO-OFDM is closely related to its peak-to-average power ratio (PAPR) distribution, we also provide the analytical expression of the PAPR distribution in this paper, which quantifies how the number of layers in LACO-OFDM reduces the PAPR. As a further advance, we propose a tone-injection aided PAPR reduction design for LACO-OFDM, which in turn improves the BER performance. Simulations are provided for verifying both the analytical BER performance and the PAPR distribution of LACO-OFDM. The results show that the expressions derived match well with the simulations. Furthermore, the PAPR reduction method proposed attains a 5 dB PAPR reduction at the $10^{-3}$ probability-point of the complementary cumulative distribution function, as well as a better BER performance than the original LACO-OFDM scheme.

PAPR reduction in OFDM system using hybrid PTS-RCMN scheme

Orthogonal Frequency Division Multiplexing (OFDM) is a widely accepted multi-carrier transmission scheme which is used for high data rate applications like Long-Term Evolution (LTE). It offers higher data transmission rate by efficient bandwidth usage. OFDM offers greater resistance and immunity towards inter-symbol interference (ISI) and Inter-Carrier Interference (ICI). However the major drawback associated with OFDM is high Peak to Average Power Ratio (PAPR) which forces high power amplifier (HPA) to work in the non-linear region resulting in harmonic distortions in the output. Partial transmit sequence (PTS) is a widely employed and tested method for PAPR reduction in 4G systems. In this paper we have proposed a novel scheme which uses a combination of PTS and Reduced Complexity Maximum Norm (RCMN) method to improve PAPR reduction performance of PTS system. This scheme has effectively reduced PAPR as compared to conventional PTS technique with insignificant increase in computational complexity.

PAPR reduction in OFDM system using hybrid PTS-RCMN scheme

Orthogonal Frequency Division Multiplexing (OFDM) is a widely accepted multi-carrier transmission scheme which is used for high data rate applications like Long-Term Evolution (LTE). It offers higher data transmission rate by efficient bandwidth usage. OFDM offers greater resistance and immunity towards inter-symbol interference (ISI) and Inter-Carrier Interference (ICI). However the major drawback associated with OFDM is high Peak to Average Power Ratio (PAPR) which forces high power amplifier (HPA) to work in the non-linear region resulting in harmonic distortions in the output. Partial transmit sequence (PTS) is a widely employed and tested method for PAPR reduction in 4G systems. In this paper we have proposed a novel scheme which uses a combination of PTS and Reduced Complexity Maximum Norm (RCMN) method to improve PAPR reduction performance of PTS system. This scheme has effectively reduced PAPR as compared to conventional PTS technique with insignificant increase in computational complexity.

PAPR Reduction in OFDM Systems using Partial Transmit Sequence combined with Cuckoo Search Optimization Algorithm (ICAT16-0286)

Partial transmit sequence (PTS) scheme is one of the efficacious tool for lessening peak-to-average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) system. However, computational cost for the optimum phase factors searches of PTS scheme entails huge computational requirements and limits its applicability to practical applications especially for high-speed data transmissions. This study proposes a PAPR reduction method with a low computational complexity based on a combination of cuckoo search optimization algorithm with PTS scheme in OFDM system. In terms of PAPR and computational cost reductions, the performance of the cuckoo-PTS scheme is comparatively investigated by performing a set of simulations with different PTS schemes.

A novel constellation amplitude modification method for PAPR reduction in OFDM systems

AbstractIn this paper, we propose a constellation amplitude modification (CAM) method to reduce the peak‐to‐average power ratio (PAPR) in orthogonal frequency division multiplexing systems. The key idea of the proposed CAM method is to modify the original constellation amplitude and choose the constellation points with the minimum PAPR as the transmitted constellation points. The CAM method formulates the PAPR reduction as a convex optimization problem, and then, it applies the customized interior‐point method to solve the optimization problem. Compared with the traditional methods, the CAM method does not increase the transmit power, and the receiver has no additional operations. Simulation results show that the CAM method converges fast and offers significant PAPR reduction. Copyright © 2016 John Wiley & Sons, Ltd.

Linear Precoding for PAPR Reduction of GFDMA

Similar to the widely used orthogonal frequency division multiplexing systems, generalized frequency division multiplexing suffers from a high peak-to-average power ratio (PAPR). In this letter, we propose a data-independent precoder to minimize the variance of the instantaneous power (IP), subject to the constraint of unchanged average IP as a means for PAPR reduction. Simulation results show that the proposed precoder can reduce PAPR without any increase in out of band radiation or bit error rate degradation. Compared with the existing solutions, the proposed technique provides an improved PAPR performance. Furthermore, an efficient implementation of the proposed precoding technique is introduced. A thorough computational complexity analysis of different PAPR reduction methods is also presented in this letter.

An Efficient Bayesian PAPR Reduction Method for OFDM-Based Massive MIMO Systems

We consider the problem of peak-to-average power ratio (PAPR) reduction in orthogonal frequency-division multiplexing (OFDM) based massive multiple-input multiple-output (MIMO) downlink systems. Specifically, given a set of symbol vectors to be transmitted to $K$ users, the problem is to find an OFDM-modulated signal that has a low PAPR and meanwhile enables multiuser interference (MUI) cancelation. Unlike previous works that tackled the problem using convex optimization, we take a Bayesian approach and develop an efficient PAPR reduction method by exploiting the redundant degrees of freedom of the transmit array. The sought-after signal is treated as a random vector with a hierarchical truncated Gaussian mixture prior, which has the potential to encourage a low PAPR signal with most of its samples concentrated on the boundaries. A variational expectation-maximization (EM) strategy is developed to obtain estimates of the hyperparameters associated with the prior model, along with the signal. In addition, the generalized approximate message passing (GAMP) is embedded into the variational EM framework, which results in a significant reduction in computational complexity of the proposed algorithm. Simulation results show our proposed algorithm achieves a substantial performance improvement over existing methods in terms of both the PAPR reduction and computational complexity.

On the Shift Value Set of Cyclic Shifted Sequences for PAPR Reduction in OFDM Systems

Orthogonal frequency division multiplexing (OFDM) signals have high peak-to-average power ratio (PAPR), which causes distortion when OFDM signal passes through a nonlinear high power amplifier. A partial transmit sequence (PTS) scheme is one of the typical PAPR reduction methods. A cyclic shifted sequences (CSSs) scheme is evolved from the PTS scheme to improve the PAPR reduction performance, where OFDM signal subsequences are cyclically shifted and combined to generate alternative OFDM signal sequences. The shift value (SV) sets in the CSS scheme should be carefully selected because those are closely related to the PAPR reduction performance of the CSS scheme. In this letter, we propose some criteria to select the good SV sets and verify its validness through simulations.

On Joint Compressed Sensing Based Channel Estimation and Nonuniform PTS PAPR Reduction without Side Information

In this paper, nonuniform partial transmit sequences (NPTS) method has been proposed, for peak to average power ratio (PAPR) reduction in OFDM systems. Pilot assisted compressed sensing (CS) based channel estimation has been utilized jointly with the proposed PAPR reduction method to avoid sending any side information. CS recovery algorithms such as orthogonal matching pursuit are used for estimation of the channel taps. Simulation results demonstrate that the proposed technique decreases the PAPR of OFDM systems and has accurate channel estimation.

A Low-Complexity Architecture for PAPR Reduction in OFDM Systems With Near-Optimal Performance

Selected mapping (SLM) schemes are widely used to reduce the peak-to-average power ratio (PAPR) in orthogonal frequency-division multiplexing (OFDM) systems. Various time-domain approaches have been proposed for reducing the number of inverse fast Fourier transform (IFFT) operations required to generate the candidate signals in traditional SLM schemes. However, the resulting time-domain-generated signals are somewhat correlated, and thus, the PAPR reduction performance is seriously degraded. Accordingly, this paper proposes a novel PAPR reduction method in which frequency-domain phase rotation, cyclic shifting, complex conjugate, and subcarrier reversal operations are all employed to increase the diversity of the candidate signals. Furthermore, to circumvent the multiple-IFFT problem, all of the frequency-domain operations are converted into time-domain equivalents. It is shown that the subcarrier partitioning and reassembling processes are key to realizing low-complexity time-domain equivalent operations. Moreover, it is shown theoretically and numerically that the computational complexity of the proposed scheme is significantly lower than that of the traditional SLM method and that the PAPR reduction performance is within 0.001 dB of that of SLM. Overall, the results indicate that among all of the low-complexity architectures proposed in the literature, the method proposed in this paper most closely approximates the PAPR reduction performance of the traditional SLM scheme.

Overlapped Scaling Tone Reservation Method for PAPR Reduction in OFDM/OQAM Systems

Peak-to-Average Power Ratio (PAPR) reduction using Tone Reservation (TR) method is studied for the application in Offset Quadrature Amplitude Modulation based Orthogonal Frequency Division Multiplexing (OFDM/OQAM) transmission using bank of filtered subcarriers. The novel TR method for the filtered subcarriers is presented, which takes into consideration the overlapping nature of the OQAM signals. To eliminate the peaks of the OFDM/OQAM signals effectively, the proposed Overlapped Scaling Tone Reservation (OS-TR) method generate the peak cancelling signal by considering the least square approximation algorithm with possible adjacent symbol overlap. Simulation results show that the proposed method used in OFDM/OQAM system can provide better performance than Controlled Clipping Tone Reservation (CC-TR) method directly used in the OFDM/OQAM system and even outperform Multi Block-Tone Reservation (MB-TR) method.

Peak-to-Average Power Ratio Reduction based Varied Phase for MIMO-OFDM Systems

One of the severe drawbacks of orthogonal fre-quency division multiplexing (OFDM) is high Peak-to-Average Power Ratio (PAPR) of transmitted OFDM signals. During modulation the sub-carriers are added together with same phase which increases the value of PAPR, leading to more interference and limits power efficiency of High Power Amplifier (HPA), it’s requires power amplifier’s (PAs) with large linear oper-ating ranges but such PAs are difficult to design and costly to manufacture. Therefore, to reduce PAPR various methods have been proposed. As a promising scheme, partial transmit sequences (PTS) provides an effective solution for PAPR reduction of OFDM signals. In this paper, we propose a PAPR reduction method for an OFDM system with variation of phases based on PTS schemes and Solid State Power Amplifiers (SSPA) of Saleh model in conjunction with digital predistortion (DPD), in order to improve the performance in terms of PAPR, the HPA linearity and for the sake of mitigating the in-band distortion and the spectrum regrowth. The simulation results show that the proposed algorithm can not only reduces the PAPR significantly, but also improves the out-of-band radiation and decreases the computational complexity.

PAPR reduction using genetic algorithm in lifting-based wavelet packet modulation systems

Wavelet packet modulation (WPM) is a potential candidate in wireless communication systems by virtue of its exibility and modular implementation capability. However, WPM suffers from high peak-to-average power ratio (PAPR), which results in signal distortion when a high-power amplier is employed at the transmitter. The partial transmit sequence (PTS) is an attractive PAPR reduction method, but its computational complexity is high. In this paper, we propose a PTS based on the genetic algorithm (GA) scheme (GA-PTS) to reduce the computational complexity of the PTS in the lifting-based WPM (LBWPM) systems. Simulation results show that the proposed GA-PTS scheme provides signicant improvement in PAPR reduction while maintaining a low computational load. The cumulative distribution function performance of the LBWPM system is better than the performance of the classical WPM.

A novel generalized oppositional biogeography-based optimization algorithm: application to peak to average power ratio reduction in OFDM systems

Abstract A major drawback of orthogonal frequency division multiplexing (OFDM) signals is the high value of peak to average power ratio (PAPR). Partial transmit sequences (PTS) is a popular PAPR reduction method with good PAPR reduction performance, but its search complexity is high. In this paper, in order to reduce PTS search complexity we propose a new technique based on biogeography-based optimization (BBO). More specifically, we present a new Generalized Oppositional Biogeography Based Optimization (GOBBO) algorithm which is enhanced with Oppositional Based Learning (OBL) techniques. We apply both the original BBO and the new Generalized Oppositional BBO (GOBBO) to the PTS problem. The GOBBO-PTS method is compared with other PTS schemes for PAPR reduction found in the literature. The simulation results show that GOBBO and BBO are in general highly efficient in producing significant PAPR reduction and reducing the PTS search complexity.

Peak-to-Average Power Ratio Performance Analysis for Orthogonal Chirp Division Multiplexing Multicarrier Systems Based on Discrete Fractional Cosine Transform

In doubly selective fading channels, the orthogonal frequency division multiplexing (OFDM) multicarrier system may fail. Chirp like basis (fractional Fourier transform-fractional cosine transform) may be used instead of complex exponential basis in this case to improve the system performance. However, in multicarrier transmission, the high peak to average power ratio (PAPR) of the transmitted signal is one of the difficult problems that face both the chirp and the exponential basis. In this paper, an evaluation for the PAPR performance of a multicarrier system based on the fractional cosine transform (FrCT) is introduced and then compared with DFrFT and FFT. Moreover, applying the SLAM technique over these systems is provided to understand the behaviour of these systems when applying SLAM. Simulations verify that this system obtains a better PAPR performance. Moreover, further PAPR reduction can be gained using the well-known PAPR reduction methods. Moreover, applying SLAM technique improves the performance of (dB) by 4 dB to 5 dB and all systems become as competitive to each other when SLAM is applied. Finally, BER performance comparison among OFDM, Discrete Cosine Transform MCM (DCT- MCM), Discrete Hartley Transform MCM (DHT-MCM), DFrFT-OCDM and DFrCT- OCDM MCM systems was done by means of simulation over 100,000 multicarrier blocks for each one and showed that our proposed scenario gave the best performance.

An Enhanced Partial Transmit Sequence Segmentation Schemes to Reduce the PAPR in OFDM Systems

Although the orthogonal frequency division multiplexing system (OFDM) is widely used in high-speed data rate wire and wireless environment, the peak-to- average-power-ratio (PAPR) is one of its major obstacles for the real applications. The high PAPR value leads some devices of the OFDM system such as power amplifiers and analog to digital converters to work out of band of these devices. Thus the system efficiency is degraded. Many techniques have been proposed to overcome the high PAPR in OFDM systems such as partial transmit sequences (PTS), selected mapping and interleaving technique. PTS is considered as one of the effective PAPR reduction methods; this scheme depends on segmentation of the input data into several subblocks and then combined again. The three well-known segmentation schemes are pseudo-random, adjacent and interleaving; each scheme has PAPR reduction performance, and computational complexity differs from one to another. In this paper, five types of segmentation schemes are proposed to improve the PAPR reduction execution including sine and cosine shape as well as hybrid interleaving and adjacent schemes in new approaches. From the simulation results, the proposed methods can achieve PAPR reduction performance greater than that of the adjacent and interleaving partition schemes, without increasing the computational complexity of the system. Moreover, the enhanced schemes can realize better PAPR performance with any number of subcarriers.

Peak-to-average Power Ratio Methods to Improve the Performance of Multicarrier Modulation Systems

The objective of this review is Comprehensive description for Peak to Average Power Ratio (PAPR) reduction methods in Orthogonal Frequency Division Multiplexing (OFDM) multicarrier modulation systems to provide the researchers in this field with a broader understanding of the high PAPR problem in OFDM systems and Classification of the available solutions to mitigate the problem. Also, we discuss and make some remarks on the criteria for PAPR reduction methods. In wireless multicarrier communication systems, the major drawback of transmit signal is high Peak to Average Power Ratio. Transmitters have a lot of devices such as Power Amplifiers (PA), PAs are often designed to operate at non-linear region to reduce power consumption. However, non-linear transfer functions of PAs may be led to high peaks of amplitude levels resulting a high peak levels of multicarrier signal while average power still approximately fixed depended on PA specifications. This mean, PAPR will be increased caused high complexity, bandwidth expansion, spectral spillage and degradation of system performance. One important type of multicarrier modulation systems is OFDM.

A Novel Multi-Block Tone Reservation Scheme for PAPR Reduction in OQAM-OFDM Systems

Due to the overlapping structure of the offset quadrature amplitude modulation-based orthogonal frequency-division multiplexing (OQAM-OFDM) signals, the peak-to-average power ratio (PAPR) in OQAM-OFDM systems cannot be efficiently reduced by existing PAPR reduction methods, which independently consider the PAPR reduction in each data block. In this paper, a novel multiblock tone reservation (MB-TR ) scheme is proposed for the PAPR reduction in OQAM-OFDM systems. The key idea of the MB-TR scheme is to exploit the overlapping structure of the OQAM-OFDM signals and jointly consider the adjacent data blocks to obtain the clipping noise. To effectively eliminate the peaks of the OQAM-OFDM signals, the MB-TR scheme generates the peak-canceling signal by employing the weighted least square algorithm to fit the waveform of the peak-canceling signal to the waveform of clipping noise. Simulation results and analysis show that the MB-TR scheme could offer better PAPR reduction with lower computational complexity than the clipping control tone reservation scheme directly employed in OQAM-OFDM systems.

A combined technique for carrier frequency offset estimation and peak-to-average power ratio reduction in OFDM systems using null subcarriers and Cuckoo search algorithm

This paper presents a novel generic method for the carrier frequency offset (CFO) estimation and reduction of peak-to-average power ratio (PAPR) in orthogonal frequency division multiplexing based wireless communication systems. Estimation of CFO using null subcarriers embedded in one or more pilot symbol is one of the best known CFO estimation techniques that achieve an estimation range of inverse of the sampling interval with low implementation complexity. We propose to exploit a few null subcarriers in the pilot symbol for PAPR reduction by switching with some data subcarriers in the data block of which the PAPR is intended to be minimized. We define a new cost function for the PAPR reduction at the transmitter and CFO estimation at the receiver and the computational complexity of its evaluation is made significantly low by applying Cuckoo search optimization algorithm. Also, the proposed method requires less side information to be send to the receiver as compared to many of the prevailing PAPR reduction methods. Computer simulation studies reveal that the proposed combined technique offers significant performance advantage for both PAPR reduction and CFO estimation concurrently.

A low-complexity peak cancellation scheme and its FPGA implementation for peak-to-average power ratio reduction

The power amplifier (PA) is the most power-hungry component in a wireless base station transmitter, and reducing the peak-to-average power ratio (PAPR) of wireless signals is an important issue for its effective use. In this paper, we focus on a field-programmable gate array (FPGA) implementation of the peak cancellation (PC) technique, which is known as the simplest method for PAPR reduction. The design issue of effective peak-cancelling pulses under the constraint on the out-of-band emission is addressed. In order to reduce its hardware complexity, a novel approach for generating peak-cancelling pulses is also presented. The experimental results based on long-term evolution (LTE)/LTE-Advanced and multi-band Wideband Code Division Multiple Access (WCDMA) signals demonstrate the validity of the proposed scheme. It has been shown that the proposed PC scheme can achieve lower in-band distortion than the conventional PC with an acceptable loss in out-of-band performance. Our study also includes mapping the signal processing methods onto a Xilinx virtex-7 FPGA device running at 245.76 MHz and addresses the resource utilization and the hardware design in detail.