Peak-to-average Power Ratio Reduction Performance Research Articles

Two-stage collaborative information interaction reliability improvement for the distribution grid

The impulse noise generated by a large volume of power electronics devices imposes a hazardous impact on information interaction reliability in low-voltage distribution grids. In this paper, we propose a two-stage collaborative information interaction reliability improvement algorithm to minimize the bit error rate (BER) of the information interaction under impulse noise. In the first stage, the transmission-side peak-to-average power ratio (PAPR) is reduced based on the adaptive particle swarm optimization (PSO)-enabled partial transmit sequence (PTS). In the second stage, the reception-side dual-signal blanking is proposed based on the transmission-side PAPR and reception-side useful signal power estimation and peak median ratio. The transmission–reception collaborative information interaction reliability improvement is realized through two aspects. First, transmission-side PAPR reduction improves the performance of reception-side signal blanking by making it easier to distinguish useful signals from impulse noise. Second, the transmission-side PAPR is utilized to improve the estimation accuracy of both coarse and precise thresholds in dual-signal blanking. Simulation results show that the proposed algorithm outperforms existing algorithms in both PAPR reduction and BER performances to achieve information interaction reliability improvement effectively.

Enhanced PAPR reduction in DCO-OFDM using multi-point constellations and DPSO optimization

DC-biased optical OFDM (DCO-OFDM) is a commonly used method of OFDM in visible light communication (VLC). Unfortunately, VLC systems that use OFDM often experience a high peak-to-average power ratio (PAPR). To address this issue, this study proposes a novel method called the multi-point constellation method (MPC) to reduce PAPR in DCO-OFDM. The MPC method involves adding extra alternative constellation points around the existing points and using the discrete particle swarm optimization (DPSO) algorithm to select the constellation points with the lowest PAPR. The proposed MPC method is also combined with selective mapping (SLM), a well-known PAPR reduction technique in the literature. Simulation results show that the proposed MPC method outperforms the SLM method in reducing PAPR in 4-QAM and 16-QAM modulations when used in combination with SLM. Furthermore, increasing the number of iterations and particles in the DPSO algorithm improves the PAPR reduction performance of the proposed method even further.

Improved Algorithm of Partial Transmit Sequence Based on Discrete Particle Swarm Optimization

Orthogonal frequency division multiplexing (OFDM) in 5G has many advantages; however, one of the disadvantages is that the superposition of a large number of subcarriers leads to a high peak-to-average power ratio (PAPR) of the transmit signal. A high PAPR results in high-power amplifier distortion and performance degradation. The partial transmit sequence (PTS) algorithm is commonly used for PAPR reduction. It enumerates all combinations of phase factors, weighs the signal using each phase factor combination, and finds the set of phase factors that minimizes the PAPR value of the OFDM signal. The advantage of the PTS is that it determines the optimal solution through enumeration; however, its major drawback is the higher complexity caused by the use of enumeration. Some studies have introduced the discrete particle swarm optimization (DPSO) algorithm instead of enumeration to determine the optimal solution of the PTS algorithm. As an excellent optimization method, the DPSO algorithm represents each individual as a solution during the optimization. Through iterative updates of the initial population, individuals in the population continuously move closer to the optimal solution. This approach significantly reduces complexity compared with the exhaustive enumeration used in the traditional PTS algorithm. However, the disadvantage of the general DPSO algorithm is that it can result in premature and early convergence, which leads to degradation of the PAPR reduction performance. In this study, we propose an improved method based on the general DPSO-based PTS algorithm, and the improved algorithm MDPSO-PTS adopts dynamic time-varying learning factors, which can find the optimal combination of phase factors more efficiently. The MDPSO-PTS algorithm expands the search space when seeking the optimal combination of phase factors. This avoids the drawback of premature convergence commonly observed in general DPSO-PTS algorithms, preventing early consideration of local optima as global optima. A comparative simulation of the improved MDPSO-PTS algorithm with the general DPSO-PTS algorithm shows that the improved algorithm has stronger PAPR reduction, whereas the complexity remains basically unchanged. A comparative simulation with the traditional PTS algorithm shows a significant reduction in complexity, with only a slight, acceptable loss of reduction performance.

Local PAPR-Aware Precoding for Energy-Efficient Cell-Free Massive MIMO-OFDM Systems

Orthogonal frequency-division multiplexing (OFDM) based Cell-free massive multiple-input multiple-output (CF-mMIMO) is the most promising technology that, compared to cellular technology, provide uniformly better quality of service for users in sub-6GHz bands. To make OFDM based CF-mMIMO more cost-effective and power-efficient, the access points (APs) should be equipped with low-cost and low-quality transceiver hardware. However, transmitting OFDM signals with high peak-to-average power ratio (PAPR) via such hardware causes severe hardware impairments (HWI), damaging the system performance. In this paper, we present an energy-efficient downlink transmission scheme adequate to the emerging CF-mMIMO-OFDM technology. Specifically, we introduce a smart PAPR-aware precoding scheme, referred to as localPAPRfree, adequate for cell-free architecture. Interestingly, the proposed technique can be implemented in a distributed and scalable manner, demonstrating benefits of CF-mMIMO-OFDM. The PAPR-aware precoding scheme is formulated as a simple convex optimization problem solved via an efficient and steepest iterative algorithm. In addition, we present a theoretical study to analyze the downlink (DL) spectral-efficiency (SE) and energy-efficiency (EE) performance of CF-mMIMO-OFDM under power amplifier (PA) non-linearity, providing important insights into the practical impact of nonlinear PA. Numerical results show that the proposed localPAPRfree algorithm offers excellent PAPR reduction performance, guaranteeing high EE.

Adaptive-Mode PAPR Reduction Algorithm for Optical OFDM Systems Leveraging Lexicographical Permutations

In direct current optical orthogonal frequency division multiplexing (DCO-OFDM) systems, the high peak-to-average power ratio (PAPR) has been a significant challenge. Recently, lexicographical symbol position permutation (LSPP) using random permutations has been introduced as an efficient solution to reduce high PAPR. In this paper, we aim to evaluate the effectiveness of LSPP by comparing both adjacent and interleaved lexicographical permutation sequences with random lexicographical permutation sequences. Our findings demonstrate that random permutation yields superior PAPR reduction performance results when compared to adjacent and interleaved permutation. However, in scenarios with a limited number of sub-blocks, the use of adjacent and interleaved permutation becomes more favorable, as they can eliminate the possibility of generating identical permutation sequences, a drawback of random permutation. Additionally, we propose a novel algorithm to determine the optimal number of candidate permutation sequences that can achieve acceptable PAPR reduction performance while adhering to computational complexity constraints defined by the system requirements.

PAPR Reduction in OFDM System Using Metaheuristic Algorithm

The advancement of technology necessitates the development of more sophisticated modulation strategies for wideband digital communication systems. The requirements for high-speed data transmissions can be effectively met by utilizing orthogonal frequency division multiplexing, which is an effective technique. However, a high peak-to-average power ratio (PAPR) is one of the key limits that OFDM systems face, both in terms of their performance and their power efficiency. The evaluation of the PAPR reduction has become a topic of widespread interest in this present decade due to the relevance it holds in the industrial and scientific communities. The purpose of this study is to show the combination of the bat algorithm with the partial transmit sequence scheme as an effective way for reducing PAPR that also eases the burden of computing work. For the purpose of providing a comparative evaluation of the PAPR reduction performance, a number of simulations using various partial transmit sequence schemes have been carried out. The findings of the simulation show that the BA-PTS scheme has the potential to provide superior PAPR reduction performance while simultaneously reducing the computational load.

A Low-Complexity SLM PAPR Reduction Scheme for OFDMA

In orthogonal frequency division multiplexing (OFDM) systems, selected mapping (SLM) techniques are widely used to minimize the peak to average power ratio (PAPR). The candidate signals are generated in the time domain by linearly mixing the original time-domain transmitted signal with numerous cyclic shift equivalents to reduce the amount of Inverse Fast Fourier Transform (IFFT) operations in typical SLM systems. The weighting factors and number of cyclic shifts, on the other hand, should be carefully chosen to guarantee that the elements of the appropriate frequency domain phase rotation vectors are of equal magnitude. A low-complexity expression is chosen from among these options to create the proposed low-complexity scheme, which only requires one IFFT. In comparison to the existing SLM technique, the new SLM scheme achieves equivalent PAPR reduction performance with significantly less computing complexity. MATLAB tool is used for simulating the proposed work.

Low complexity partition-recombined SLM scheme for reducing PAPR in coherent optical OFDM systems

High peak-to-average power ratio (PAPR) remains the main challenge of coherent optical orthogonal frequency division multiplexing (CO-OFDM) systems. Selective mapping (SLM) is a well-known effective PAPR reduction technique, but it suffers from high computational complexity. To reduce the PAPR of OFDM signals, a low-complexity, partition-recombined SLM (PRSLM) scheme is proposed. The PRSLM scheme can generate more candidate signals than that of the conventional-original SLM (COSLM) scheme. The real and imaginary components of time-domain symbols are first partitioned, and then recombined to generate new candidate signals, which reduces computational complexity significantly. A 40-GBaud single-polarization CO-OFDM transmission system is set up to evaluate the performance of the PRSLM scheme. Simulation results show that the proposed scheme achieves 61.9% reduction in complex multiplication complexity, and 60.3% reduction in addition complexity compared with the COSLM scheme when the FFT size is 128. Furthermore, the proposed scheme achieves a similar PAPR reduction performance to the COSLM scheme without bit error rate degradation. In a nutshell, the PRSLM scheme improves noise tolerance and implementation efficiency of high-speed optical communication as well as alleviates nonlinear impairments.

Comparison of PAPR Reduction Using ABC-FF Algorithm and OGWO in MIMO-OFDM

In the transmitted signal, the high peak-to-average power ratio (PAPR) is the real disadvantage of multiple input, multiple output (MIMO) orthogonal frequency division multiplexing (OFDM) systems. Among different PAPR reduction techniques, selected mapping (SLM) is a famous strategy that accomplishes good PAPR reduction performance without signal distortion. Likewise, Partial transmit sequence (PTS) is additionally solitary of the successful techniques to decrease the PAPR in OFDM. Though, result an optimal segment issue in PTS system is measured to exist a critical concern. To progress the existing PAPR reduction techniques, we have incorporated ideal SLM and PTS based PAPR reduction strategy in parallel. By utilizing, the OGWO algorithm; the transmit succession was chosen with least PAPR above all communication antennas. The proposed PAPR reduction approach is applied independently on each transmitted antenna, and so the PAPR can be extremely reduced. Moreover, the OGWO optimization based PAPR reduction technique will provide better performance and it was been promoted as an uncomplicated way for PAPR reduction. The proposed approach will be analyzed with ABC-FF Algorithm PAPR reduction scheme to show the effectiveness

A Hybrid PAPR Reduction Scheme in OFDM-IM Using Phase Rotation Factors and Dither Signals on Partial Sub-Carriers

As a multi-carrier modulation technique, a high peak-to-average power ratio (PAPR) is a common issue suffered by orthogonal frequency division multiplexing with index modulation (OFDM-IM) due to its system structure. High PAPR may cause signal distortion, which affects correct symbol transmission. This paper tries to inject dither signals to the inactive (idle) sub-carriers, which is a unique transmission structure of OFDM-IM, to reduce PAPR. Unlike the previous works, which utilize all idle sub-carriers, the proposed PAPR reduction scheme utilizes selected partial sub-carriers. This method performs well in terms of bit error rate (BER) performance and energy efficiency, which are obvious drawbacks of the previous PAPR reduction works due to the introduction of dither signals. In addition, in this paper, phase rotation factors are combined with the dither signals to compensate for the PAPR reduction performance degradation due to the insufficient use of partial idle sub-carriers. Moreover, an energy detection scheme is designed and proposed in this paper in order to distinguish the index of phase rotation factor used for transmission. It is shown by extensive simulation results that the proposed hybrid PAPR reduction scheme is able to implement an impressive PAPR reduction performance among existing dither signa-based schemes as well as classical distortion-less PAPR reduction schemes. In addition, the proposed method obtains better error performance and energy efficiency than that of the previous works. At the error probability , the proposed method can achieve around 5 dB gain compared to the conventional dither signal-based schemes

A novel differential evolution algorithm for tone reservation based peak to average power ratio reduction technique in orthogonal frequency division multiplexing systems

A critical problem in the Orthogonal Frequency Division Multiplexing (OFDM) framework for 5G communication is the high Peak to Average Power Ratio (PAPR) of the transmitted signal. The Tone Reservation (TR) scheme is employed to minimize the OFDM signal’s PAPR in time domain. It is comprised of some reserved subcarriers to generate a Peak Reduction Tone (PRT) set. The selection of these PRT set and the optimal target clipping level are the depending parameters of the PAPR reduction performance. A novel Differential Evolution based Tone Reservation (DE-TR) scheme is proposed to find an optimal PRT set and then the PAPR is reduced by employing an Optimized Iterative Clipping and Filtering (OICF) technique. Compared to other related techniques like Clipping Control Tone Reservation (CC-TR), Curve Fitting based Tone Reservation (CF-TR) and Parallel Tabu Search Tone Reservation (PTS-TR), the proposed technique DE-TR(Pro.) contributes to a substantial PAPR reduction output with lower computational complexity and maintaining an adequate bit error rate (BER) and spectral spreading efficiency. In addition, the theoretical relationship between the Error Vector Magnitude (EVM) and PAPR as well as CCDF performance with EVM are analyzed.

Hybrid clipping and companding techniques based peak to average power ratio reduction in orthogonal frequency division multiplexing based differential chaos shift keying system

In this paper, a hybrid approach using clipping and companding techniques is introduced to reduce the peak to average power ratio (PAPR) of orthogonal frequency division multiplexing based differential chaos shift keying (OFDM-DCSK), which is the major drawback of the OFDM-DCSK. The hybrid function is processed at the end of the transmitter before transmitting the signal. However, there is no need for an inverse function at the receiver, which decreases the system complexity. Several techniques have been proposed in the literature for decreasing the PAPR value. Clipping and companding are active methods in terms of reducing the PAPR. Finally, the PAPR reduction and bit error rate (BER) performances are evaluated. The simulation results show that this technique gives better performance as compared with the clipping and companding techniques.

Hybrid-Domain Evaluation PTS with Adaptive Selection Methods for PAPR Reduction

The partial transmit sequence (PTS) technique is a fairly suitable scheme to mitigate the high peak-to-average power ratio (PAPR) problem inherent in 5G multicarrier systems, especially considering a high-order QAM modulation design. However, the high computational complexity level and the speed of the convergence for optimizing the phases of the transmitting signal restrict this technique in practical applications. In this paper, a low-complexity frequency-domain-evaluated PTS (F-PTS) based on a spacing multiobjective (SMO) processing algorithm is proposed to reduce the PAPR values. The PAPR performance are accurately predicted in terms of modifying relative dispersion in the frequency domain. As a result, the complexity of searching the optimal phase factors and IFFT computing is simplified. Moreover, a frequency-domain- and time-domain-evaluating PTS (FTD-PTS) is employed to search the optimal solution with a reasonable complexity. Simulation results verify that the operation rate of F-PTS is significantly improved after transferring the exhaustive search strategy of PTS into the SMO algorithm, and the F-PTS PAPR reduction performance is just 0.3 dB away from theoretical optimal performance. The FTD-PTS spends an acceptable operation rate to obtain optimal PAPR reduction performance, which subtracts 0.5 and 0.6 dB more than PSO-PTS and conventional PTS at CCDF=10−3, respectively.

A Novel Selective Mapping Method based on Cumulative Symbol Optimization for PAPR Minimization in Low Complexity GFDM Transmitter

In this paper, the problem of high peak-to-average power ratio (PAPR) in the low complex version of the generalized frequency division multiplexing (LC-GFDM) is handled by developing a novel PAPR reduction method called cumulative symbol optimization-selective mapping (CSO-SLM). With this new method, the disadvantage caused by the symbol addition process that greatly reduces the SLM performance in the LC-GFDM transmitter was eliminated thanks to the combination of SLM technique with the cumulative symbol optimization procedure. In order to demonstrate the benefit of integrating the CSO procedure into the SLM scheme, our proposed CSO-SLM strategy was compared to the conventional SLM technique with regard to both PAPR reduction and power spectral density (PSD) performance in the simulations. Moreover, the CSO-partial transmit sequence (CSO-PTS) technique, which was specially developed for the LC-GFDM system as the CSO-SLM strategy, and a robust PAPR reduction method named GreenOFDM were also used for comparison. According to the simulation results, the proposed CSO-SLM technique clearly outperforms each of the benchmark strategies considered in this paper by leaving them behind with regard to the amounts of PAPR and PSD improvements achieved in the LC-GFDM transmission signal.

Reduction of PAPR in OTFS using normalized μ‐law and A‐law companding transform

In this letter, we propose a normalized ‐law and ‐law companding transform to reduce the peak‐to‐average power ratio (PAPR) of the orthogonal time‐frequency space (OTFS) signal. The normalized ‐law and ‐law transforms reduce the peak power while keeping the same average power before and after the companding transform, which leads to lowering the PAPR. This letter also presents a theoretical analysis of PAPR and transform gain for validating the companding transforms. Simulations demonstrate that the normalized ‐law obtains better PAPR reduction and BER performance than the normalized ‐law and exhibits superior BER performance than the existing ‐law transform.

A Construction Method of Phase Sequences for the Selected Mapping Scheme

In this paper, a construction method of phase sequences is proposed for the selected mapping (SLM) scheme. Three principles are applied to the construction process: periodicity, binary (±1), and maximization of the minimum Hamming distance between different sequences. Using the first and second principle, except the original frequency signal, the calculation process of other candidate time signals can be simplified as the linear addition of some intermediate signals, which are obtained in the inverse fast Fourier transform (IFFT) operation of the original frequency signal. Using the third principle, greater differences can be generated between different candidate signals, which is helpful to improve the peak-to-average power ratio (PAPR) reduction performance. Theoretical analysis and simulation results show that, with the help of new phase sequences, the SLM scheme can effectively reduce the computational complexity, while it shows almost the same performance of PAPR reduction as that of the traditional SLM scheme, whose phase sequences are from the odd row vectors in the Hadamard matrix.

Novel PAPR Reduction Algorithms for OFDM Signals

This paper proposes two efficient peak-to-average power ratio (PAPR) reduction algorithms for OFDM signals based on the principle of tone reservation. The first algorithm is performed in the time domain, whereas the second algorithm is a new clipping-and-filtering method. Both algorithms consist of two stages. The first stage, which is done off-line, precomputes a set of canceling signals based on the settings of the OFDM system. In particular, these signals are constructed to cancel signals at different levels of maximum instantaneous power that are above a predefined threshold. The second stage, which is online and iterative, reduces the signal peaks using modified versions of the canceling signals constructed in the first stage. When the reserved tones are distributed among the data tones, analysis and simulation results obtained with Data Over Cable Service Interface Specifications (DOCSIS) parameters show that the proposed algorithms achieve slightly better PAPR reduction performance and with significantly lower complexity when compared to the conventional algorithms.

Minimizing the PAPR for FBMC/OQAM Signals Using Enhanced-PTS with Low Complexity Search

The filter bank multicarrier with offset quadrature amplitude modulation (FBMC/OQAM) scheme has recently become a focus of interest for many scholars and researchers. Despite its impressive advantages over Orthogonal Frequency Division Multiplexing (OFDM), the FBMC/OQAM system exhibits high Peak-to-Average Power Ratio (PAPR) which could plague its performance if it is not properly managed. In this paper, we proposed a PAPR reduction scheme that improves the Partial Transmit Sequence (PTS) to an enhanced PTS (EPTS), then employs a low complexity search to determine the optimal combination of phase factors. In the enhanced PTS, the FBMC/OQAM data blocks are partitioned into sub-blocks by taking into account their overlapping arrangement, then a segmentation operation is performed to the overall overlapping partitioned data blocks in order to form several segments of sub-blocks. After that, the segments are optimized consecutively by applying a phase factor search approach. Referred to as enhanced PTS with iterative flipping (EPTS-IF), the proposed scheme optimizes consecutively the segments of sub-blocks by employing Iterative Flipping approach. The PAPR reduction performance and the computational complexity of the proposed scheme have been evaluated through computer simulations and theoretical analysis which revealed a significant PAPR reduction gain of approximately 30.48%, and at a low computational cost.

Partial transmit sequence based on discrete particle swarm optimization with threshold about PAPR reduction in FBMC/OQAM system

Partial transmit sequence (PTS) is an effective method to reduce the peak-to-average power ratio (PAPR) of orthogonal frequency division multiplexing (OFDM) system, but it is not suitable for the filter bank multi-carrier with offset quadrature amplitude modulation (FBMC/OQAM) system because of the overlapping structure of FBMC/OQAM signals. And PTS needs the traversal method to search for the optimal solution, which will increase the complexity of the system. To overcome this shortcoming, a PTS based on discrete particle swarm optimization with threshold (PTS-DPSO-TH) is proposed and applied to FBMC/OQAM system in this paper. PTS-DPSO-TH uses discrete particle swarm optimization (DPSO) to search for the optimal solution, effectively reducing the excessively high PAPR of the FBMC/OQAM system and avoiding the increase of system complexity. Secondly, the threshold is introduced to decrease the number of iterations and further reduce the system's complexity on the premise of guaranteeing the performance of PAPR reduction. Furthermore, through simulation, the effects of multiple parameters on PAPR reduction performance of PTS-DPSO-TH are compared and analysed.

PEAK-TO-AVERAGE POWER RATIO (PAPR) REDUCTION IN MULTIPLE-INPUT MULTIPLE OUTPUT (MIMO) WITH ORTHOGONAL FREQUENCY DIVISION MULTIPLEXING (OFDM) SYSTEMS: A REVIEW

Multiple-input multiple-output technology together with orthogonal frequency division multiplexing (MIMO-OFDM) is one of the most appealing techniques for mobile radio communications. It is an effective technique to combat multi-channel fading and to improve bandwidth efficiency. Simultaneously, it also increases the system's ability to provide reliable transmission. However, the main disadvantage of OFDM is the high peak-to-average-power ratio (PAPR), which, if not mitigated, will negatively impact practical applications. Algorithms to mitigate PAPR generally increase the complexity and an increase in the Bit Error Rate. Coding, phase rotation, and clipping are among the many techniques employed to reduce the PAPR. In this review, we will mainly investigate the advantages and disadvantages of MIMO-OFDM system and PAPR reduction performance with different PAPR reduction methods in MIMO-OFDM system. The main objective of this review is to enable researchers entering this field become familiar with the problem as well as the techniques to mitigate this problem. We classify MIMO-OFDM PAPR methods into three categories: Signal Distortion, Signal Scrambling, and Coding. This review discusses each category and its impact on the transmitter and receiver and summarizes the discussion in a table. We also briefly describe some of the methods used to reduce PAPR in MIMO-OFDM.