Orthogonal Frequency Division Multiplexing Peak-to-average Power Ratio Research Articles

Enhancing PAPR reduction efficiency in MIMO-OFDM systems via selective mapping and metaheuristic algorithms

The relentless evolution of communication systems, driven by the demands of 5G and the impending 6G networks, necessitates heightened data rates and spectral efficiency. orthogonal frequency division multiplexing (OFDM), a form of multicarrier modulation employed in multi-input multi-output (MIMO) systems, stands as a pivotal technology. Yet, OFDM grapples with challenges, notably the peak-to-average power ratio (PAPR) issue. Selective mapping (SLM) has been a favored technique for mitigating PAPR in OFDM, albeit challenged by computational complexities in its pursuit of discovering optimal phase factors. This paper pioneers a transformative approach by integrating metaheuristic algorithms genetic algorithm (GA), particle swarm optimization (PSO), and the innovative fireworks algorithm (FWA) into SLM for PAPR reduction while minimizing computational complexity. Simulation results not only affirm the efficacy of SLM-based techniques but also spotlight the potential of metaheuristic algorithms in addressing PAPR challenges in modern communication systems. The study transcends single-antenna systems, extending to MIMO-OFDM systems based on WiMAX standards, validating the efficacy of these techniques in multi-antenna configurations. Crucially, the FWA, proposed for the first time in this paper, emerges as a robust candidate, striking an enviable balance between computational efficiency and performance, achieving a notable PAPR reduction with a favorable search number.

Deep learning based asymmetrical autoencoder for PAPR reduction of CP-OFDM systems

Adoption of Orthogonal Frequency Division Multiplexing (OFDM) in 5th Generation New Radio (5G NR) as a multicarrier modulation technique allows high data rate transmission with lower complexity. However, problem such as peak to average power ratio (PAPR) has decreased the transmitter efficiency. Recently, several attempts have been made to reduce the high PAPR in OFDM utilizing deep learning (DL) based on autoencoder architecture. However, the proposed autoencoder using symmetrical autoencoder (SAE) is followed by high computational complexity at both transmitter and receiver as well as BER performance degradation. Since 5G NR focuses on massive 5G internet of things eco-system, a flexible carrier spacing is used to support diverse spectrum bands which is afterward named as Cyclic Prefix OFDM (CP-OFDM). In this study, we aimed to contribute to this growing area of research by exploring the potential of our proposed asymmetrical autoencoder (AAE) to reduce high PAPR in the CP-OFDM system. Four AAE models have been developed in this study and the performance of the models were evaluated based on comprehensive conditions such as data training at different corruption levels, cyclic prefix length, upsampling factors and loss function levels. The investigation of AAE in 5G CP-OFDM system has shown superior performance using a 5×1 AAE model that can reduce a substantial amount of PAPR, BER degradation and computational complexity compared to conventional SAE. This study lays the groundwork for future research into the asymmetrical approach of autoencoder especially in 5G and beyond networks.

PAPR, Spectral Efficiency, BER and SNR Analysis of OFDM: A Novel Partial Transmit Sequence-Particle Swarm Optimization Technique

Orthogonal frequency division multiplexing (OFDM) is a widely used multicarrier modulation (MCM) technique in the field of wireless communications, specifically designed to facilitate high-speed data transmission. The use of several subcarriers inside an OFDM system for the transmission of modulated symbols results in the generation of OFDM signals with a significant peak-to-average power ratio (PAPR). In this study, we propose a novel approach for mitigating the high PAPR in wireless communication systems (WCS). Our method utilizes a partial transmit sequence (PTS) strategy, which is enhanced by using an adaptive particle swarm optimization (PSO) algorithm. In this study, we present a description of an OFDM system employing the standard PTS technique in conjunction with PSO. To mitigate computational complexity, the suggested methodology efficiently explores the optimal amalgamation of phase rotation components. Experimental findings demonstrate that the computational complexity and PAPR have been greatly minimized by the suggested method.

A Comprehensive Analysis of PAPR Reduction in Scrambled UFMC and OFDM Using Artificial Bee Colony Algorithm for 5G Communications

ABSTRACT With the advent of 5G communications, the demand for high data rates and improved spectral efficiency has necessitated the exploration of advanced modulation techniques. Orthogonal Frequency Division Multiplexing (OFDM) and Universal Filtered Multi-Carrier (UFMC) are two prominent modulation schemes for 5G systems. However, both OFDM and UFMC suffer from a high Peak-to-Average Power Ratio (PAPR), leading to signal distortion and inefficient power amplification. The Partial Transmit Sequence (PTS) approach is a promising strategy to minimize PAPR in OFDM and is applied to UFMC to minimize PAPR in UFMC and is known as scrambled UFMC (S-UFMC). PTS, however, involves an extensive search to identify the best phase factors that increase computational complexity. The artificial bee colony algorithm is proposed to reduce the computational complexity S-UFMC and OFDM. A novel modulation scheme, amplitude phase shift keying (APSK), is used instead of quadrature phase shift keying (QPSK) and quadrature amplitude modulation (QAM) in S-UFMC and OFDM, which has better performance than conventional modulation schemes. In this research, OFDM, PTS OFDM, UFMC and S-UFMC are compared and it is found that the proposed scrambled UFMC with APSK modulation using ABC algorithm performs better than OFDM and UFMC in terms of PAPR, spectral efficiency and computational complexity.

LADMM-Based PAPR-Aware Precoding for Massive MIMO-OFDM Downlink Systems

We tackle the peak to average power ratio (PAPR) reduction of an orthogonal frequency division multiplexing (OFDM)-based massive multi-user (MU) multiple-input multiple-output (MIMO) downlink systems in this paper. Utilizing the redundant degree of freedom (DOF) provided by a large number of antennas equipped at the base station, we first formulate OFDM modulation, MU precoding, and PAPR reduction into a non-convex optimization problem. By using the linearized alternating direction method of multipliers (LADMM), we directly address the non-convex PAPR-aware precoding problem without any relaxation in terms of PAPR and multi-user interference (MUI), which is completely different from the existing convex optimization methods based on relaxations. At the same time, the paper is also the first work to directly solve the non-convex PAPR-aware precoding optimization. The experimental results demonstrate that the LADMM method gets the comparable PAPR reduction and symbol error rate (SER), faster convergence, and lower complexity than the existing relaxed methods.

PAPR Analysis of OFDM using Partial Transmit Sequence Method

Orthogonal Frequency Division Multiplexing (OFDM) is one of the most widely used multicarrier transmission and effective technologies in today's communication networks. OFDM has many benefits and drawbacks. High Peak to Average Power Ratio (PAPR) is one of its main drawbacks. The spectral efficiency of the high-power amplifiers decreases with increasing PAPR. Therefore, maintaining a wireless system's efficiency is required to lower the PAPR. A possible method for lowering the high PAPR in OFDM systems is Partial Transmit Sequence (PTS). PTS generates a number of candidate signals, and the best signal with the lowest PAPR is chosen for transmission. The results shows that the PTS technique achieves greater PAPR minimization with less complexity. MATLAB simulation has been used to examine the OFDM system's PSD, spectral efficiency, BER performance, and PAPR analysis.

PAPR Analysis of OFDM using Selective Mapping Method

A common standard modulation for several high data rate wireless communication systems is Orthogonal Frequency-Division Multiplexing (OFDM). It operates by splitting up large streams of data into several parallel streams with minimal data rates. Compared to single carrier modulation systems, OFDM offers various benefits. Some of these benefits are high transmission bit rates, great spectral efficiency, and sensitivity to frequency fading channels. However, there are drawbacks with OFDM. Among the major issues is the high Peak to Average Power Ratio (PAPR), due to which the system complexity increases. The Selective Mapping approach is used in this study to lower the OFDM PAPR. In this article, simulation has been done using MATLAB, evaluated PSD, spectral efficiency, BER performance and PAPR analysis of OFDM system.

Simultaneous minimization of side‐band power and PAPR in OFDM based cognitive radio without additional bandwidth requirement for sending SI

AbstractCognitive radio (CR) incorporating orthogonal frequency division multiplexing (OFDM) is an intelligent spectrum sharing technique that acquires high data rate in frequency selective fading environment. OFDM has been successfully used for 4G and specific version of OFDM is being considered as the multiple access technology for 5G as well. However OFDM signal is more likely to have high peak‐to‐average power ratio (PAPR). Similarly, the sideband power of secondary or temporary users (SU) in CR can lead to interference to the licensed or primary users of the neighboring bands. In this work, an improved technique for the joint minimization of sideband power and PAPR using Zadoff‐Chu (ZC) sequence is proposed for CR based on OFDM technology. Furthermore, we propose a detection algorithm based on a binary hypothesis testing problem to recover the chosen ZC sequence at the receiver side eliminating the requirement of side information (SI) transmission. Simulation studies of the proposed method exhibits the efficiency of the concurrent reduction of PAPR and sideband power along with a huge bandwidth saving by the omission of the SI transmission.

Minimizing Peak to Average Power Ratio in OFDM System with WHT and Log Companding

Orthogonal Frequency Division Multiplexing (OFDM) suffers the effect of Peak to Average Power Ratio (PAPR) that reduces the strength or power of radio frequency (RF) signal at the transmitter and which also pushes the performance of transmitter amplifier into distortion. In order to minimize the effect of PAPR in OFDM, this paper proposed a system that precodes the OFDM signal using Walsh-Hadamard Transform (WHT) and Log function companding algorithm. Simulations were conducted in MATLAB environment while varying the number of subcarriers, N = 16, 64, 128, 256. simulation results indicated original OFDM revealed high PAPR in transmitted signal for the different number of subcarriers (N) such that for N =16, 64, 128, and 256, resulting in 7.964dB, 8.885 dB, 9.548 dB, and 9.961 dB respectively. With the introduction of WHT-Log companding scheme, the PAPR of OFDM signal was significantly reduced to 4.775 dB, 4.285 dB, 4.517 dB, and 4.602 dB by a percentage improvement of 40%, 51.8%, 52.7%, and 57.8% for N = 16, 64, 128, and 256 respectively. As a result, from the simulation results, the proposed system can be said to have largely reduced PAPR in OFDM system using a scheme with significant computational complexity.

Precoded SLM and PTS Scheme for Reduced PAPR in OFDM for Wireless Communications

Orthogonal Frequency Division Multiplexing (OFDM) contribute high data rates in current as well as future wireless communication systems but it aches from high Peak to Average Power Ratio (PAPR). But this high PAPR makes the High-Power Amplifier (HPA) complex which increases the cost of it and leads to the drawbacks like Inter Carrier Interference (ICI) and rise in out of band radiation. Even though many techniques are there to decrease the complexity of HPA by reducing the PAPR, Selected Mapping (SLM) and the Partial Transmit Sequence (PTS) provides less PAPR with low complexity. In this paper, both PTS and SLM are combined with Discrete Sine Transform (DST) and their PAPR and efficiencies are also compared with OFDM signal. The proposed hybrid DST-PTS and DST-SLM provides less PAPR compared to OFDM, SLM and PTS techniques with low complexity. Also, the bit error rate for DST-SLM and DST-PTS techniques are compared for different values of SNR. In future wireless communication systems, these proposed techniques can be used as they provide less bit error rate and less PAPR with low complexity

OFDM PAPR Reduction via Time-Domain Scattered Sampling and Hybrid Batch Training of Synchronous Neural Networks

Peak-to-average power ratio (PAPR) reduction in multiplexed signals in orthogonal frequency division multiplexing (OFDM) systems has been a long-standing critical issue. Clipping and filtering (CF) techniques offer good performance in terms of PAPR reduction at the expense of a relatively high computational cost that is inherent in the repeated application of fast Fourier transform (FFT) operations. The ever-increasing demand for low-latency operation calls for the development of low-complexity novel solutions to the PAPR problem. To address this issue while providing an enhanced PAPR reduction performance, we propose a synchronous neural network (NN)-based solution to achieve PAPR reduction performance exceeding the limits of conventional CF schemes with lower computational complexity. The proposed scheme trains a neural network module using hybrid collections of samples from multiple OFDM symbols to arrive at a signal mapping with desirable characteristics. The benchmark NN-based approach provides a comparable performance to conventional CF. However, it can underfit or overfit due to its asynchronous nature which leads to increased out-of-band (OoB) radiations, and deteriorating bit error rate (BER) performance for high-order modulations. Simulations’ results demonstrate the effectiveness of the proposed scheme in terms of the achieved cubic metric (CM), BER, and OoB emissions.

A Novel Companding Technique to Reduce High Peak to Average Power Ratio in OFDM Systems

The reduction of the high peak-to-average-power ratio (PAPR) is important to the efficiency of the orthogonal frequency division multiplexing (OFDM) technique. Excessive PAPR contributes to nonlinear clipping induced harmonic distortions that reduce system reliability. In this article, a new technique for decreasing the high PAPR in OFDM with minimum effects on the system performance is proposed. The technique uses the image adjust (IMADJS) function to reduce the high PAPR of transmitted OFDM signals by compressing large signals and expanding small signals. In comparison, the IMADJS strategy has the advantage of maintaining a constant average power level before and after companding. A comparative analysis is provided between the proposed (IMADJS) technique and well-known companding techniques such as μ-law, absolute exponential (AEXP), and the new error function (NERF). The comparison is based on PAPR, bit error rate (BER), power spectral density (PSD), and average power performance metrics. Simulation results confirm that the IMADJS technique significantly improved the drawbacks of the PAPR. Furthermore, the PAPR is reduced by 2.81dB. The IMADJS technique has less impact on the original power spectrum than on other companding schemes. The average out-of-band radiation of the IMADJS technique reaches about -50dB at the frequency of 0MHz. In contrast, the average of the original OFDM signal is that the out-of-band radiation reaches around -52dB. The AEXP and NERF companding techniques reach about -46dB, while the μ-law companding technique hits about -37dB.

PAPR reduction in OFDM system using combined MCS and DHMT precoding

Orthogonal Frequency Division Multiplexing (OFDM) has become a preferable scheme for most high data rate wireless communication standards. However, the non-linear power amplifier effect experienced in the OFDM system has increases the peak-to-average power ratio (PAPR). This paper proposed a Median Codeword Shift (MCS) as a new solution to alleviate the effect of high PAPR. MCS takes advantage of the codeword structure and bit position changes through the manipulation of the codeword structure and permutation process to achieve a low PAPR value. Additionally, the enhanced version of MCS is also being proposed by merging MCS with the Discrete Hartley matrix transform (DHMT) precoding method to boost the PAPR reduction. Simulation results show that MCS is capable of minimizing PAPR of conventional OFDM with 24% improvement and at the same time outperform Selective Codeword Shift (SCS) with a 0.5 dB gap. A remarkable result was also achieved by MCS-DHMT with a 15.1% improvement without facing any bit error rate (BER) degradation.

PAPR reduction in OFDM system using combined MCS and DHMT precoding

Orthogonal Frequency Division Multiplexing (OFDM) has become a preferable scheme for most high data rate wireless communication standards. However, the non-linear power amplifier effect experienced in the OFDM system has increases the peak-to-average power ratio (PAPR). This paper proposed a Median Codeword Shift (MCS) as a new solution to alleviate the effect of high PAPR. MCS takes advantage of the codeword structure and bit position changes through the manipulation of the codeword structure and permutation process to achieve a low PAPR value. Additionally, the enhanced version of MCS is also being proposed by merging MCS with the Discrete Hartley matrix transform (DHMT) precoding method to boost the PAPR reduction. Simulation results show that MCS is capable of minimizing PAPR of conventional OFDM with 24% improvement and at the same time outperform Selective Codeword Shift (SCS) with a 0.5 dB gap. A remarkable result was also achieved by MCS-DHMT with a 15.1% improvement without facing any bit error rate (BER) degradation.

Application Framework Development for Algorithm Design of PAPR Reduction in OFDM

Orthogonal Frequency Division Multiplexing (OFDM) is a well-built candidate for Physical Layer of 5G Communications as like it was there in 3G and 4G. With many advantages OFDM has some limitations like synchronization, Peak to Average Power Ratio (PAPR) etc. PAPR in OFDM remained the hot topic in PHY design of modern wireless communication systems since decades. Researchers are working to solve this problem with various approaches. Being one of the problem solvers team we realized that for a new researcher major effort goes into development of framework rather than actual PAPR algorithm. With this paper we tried to solve this issue by designing a simplified framework for developing, testing and measurement of PAPR of OFDM in Laboratory Virtual Instrumentation Engineering Workbench (LabVIEW) Platform. LabVIEW is a cutting edge, state of the art graphical programming environment which makes programming more simplified by adapting icons and connectors instead of text instructions, which makes computer programming language least complex, so that one can focus more on algorithm design rather than solving syntactical issues of the programming language. There are numerous applications of LabVIEW platform such as Instrumentation, image processing, digital signal processing, digital communication and many more. We have used core programming, signal processing and digital communication modules of LabVIEW for this research work. This paper has three sections, in section one, we explained need of framework, in second section we have explained detailed explanation of framework and its deployment and in the third section result and conclusion has been described..

Peak Average Power Ratio Reduction Technique For Better Performance With Multi Input Multi Output

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 various novel PAPR reduction schemes to show the effectiveness.

In-Service BER Based Estimation of OFDM PAPR and CFO-induced Peak Phase Deviation

High Peak-to-Average Power Ratio (PAPR) of the transmitted OFDM signal is a well-known major drawback of the Orthogonal Frequency-Division Multiplexing (OFDM), so the High-Power Amplifier (HPA) is therefore necessary to operate in its linear region, i.e. with large back-off between the operating input power and its saturation region, so introducing not only in-band distortion, but also the adjacent channel interference. Specifically with the Long-Term Evolution (LTE) systems downlink, some sort of PAPR reduction, such as e.g. clipping, must be utilized. Considering that in many practical situations, determining PAPR demands complex test equipment, such as e.g. Vector Signal Analyzer (VSA), which might not be available, in this paper, we develop a simple Bit-Error-Rate (BER) based model for the (residual) PAPR estimation, by applying link abstraction, i.e. considering the easy measurable BER degradation due to HPA non-linearity, as if it were the consequence of the according level of additive white Gaussian noise (AWGN) abstracting the HPA distortion, while considering high Signal-to-Noise Ratio (SNR) and long enough cyclic prefix (CP), thus neglecting (real) additive noise and time dispersion (i.e. multipath fading). Moreover, the out-of-service BER testing, which requires network operator to interrupt its revenue-generating traffic, can be substituted by in-service BER estimation from in-phase and quadrature-phase eye diagram closures, measured on live traffic, by means of a simple oscilloscope. The analytical model is verified by the appropriate Monte-Carlo simulations.

Spectrum Efficient DSI-Based OFDM PAPR Reduction by Subcarrier Group Modulation

High peak-to-average power ratio (PAPR) is a long-standing problem of orthogonal frequency division multiplexing (OFDM) system. Although there have been a plethora of proposals presented to date, most of the proposals sacrifice spectral efficiency to attain low PAPR. In this paper, a concept of subcarrier group modulation (SGM) is proposed to transform those spectrum inefficient schemes into spectrum efficient ones. The SGM scheme groups available subcarriers, and assigns one extra bit to each group depending on one of two different sets of constellation, thereby freeing some subcarriers for PAPR reduction. At the receiver, the constellation set used in a particular group is determined by the maximum-likelihood detection. The SGM scheme can be integrated to different PAPR reduction schemes. In this paper, it is integrated with the dummy sequence insertion (DSI) scheme. The DSI with SGM can attain the same spectral efficiency as the conventional OFDM does. Through simulations, it is found that it can achieve PAPR almost similar to that the conventional DSI scheme does without degrading BER performance significantly over both additive white Gaussian noise and Rayleigh fading channels. In addition to the PAPR reduction application, the proposed scheme can be used to improve throughput of any conventional OFDM systems.

Implementation of Non Linear Companding Technique for Reducing PAPR of OFDM

High Peak-to-Average Power Ratio (PAPR) of transmitted signal is one of the foremost problems to implement Orthogonal Frequency Division Multiplexing (OFDM) System. To transform the OFDM signal into anticipated statistics form that are identified by a linear piecewise function, the new Non-Linear Companding transform (NCT) set of rules is used. The variable slopes and inflexion points are introduced inside the probability density function (PDF) while the PAPR and Bit Error Rate (BER) are compared to achieve efficiency in the overall performance and flexibility in the Non-Linear Companding (NCL) form. The expected transform gain and signal attenuation factor and all the theoretical value study of this set of rules are given. The main parameters are evaluated specifically based on the selection criteria of the transform parameters focusing on robustness and execution aspects. The exploration is exactly proved in Simulink.

Chaotic reconfigurable ZCMT precoder for OFDM data encryption and PAPR reduction

A secure orthogonal frequency division multiplexing (OFDM) transmission scheme precoded by chaotic Zadoff–Chu matrix transform (ZCMT) is proposed and demonstrated. It is proved that the reconfigurable ZCMT matrices after row/column permutations can be applied as an alternative precoder for peak-to-average power ratio (PAPR) reduction. The permutations and the reconfigurable parameters in ZCMT matrix are generated by a hyper digital chaos, in which a huge key space of ∼10800 is created for physical-layer OFDM data encryption. An encrypted data transmission of 8.9 Gb/s optical OFDM signals is successfully demonstrated over 20 km standard single-mode fiber (SSMF) for 16-QAM. The BER performance of the encrypted signals is improved by ∼2 dB (BER@10−3), which is mainly attributed to the effective reduction of PAPR via chaotic ZCMT precoding. Moreover, the chaotic ZCMT precoding scheme requires no sideband information, thus the spectrum efficiency is enhanced during transmission.