Peak-to-average Power Ratio Research Articles

Reduced resource competition based on mCAP and FD‐OZCZ code for VLCP system

AbstractThe advancement of smart cities and intelligent industries has accentuated the necessity for reliable indoor communication and precise indoor positioning. In response, this paper presents an innovative integrated system for indoor visible light communication and positioning, designed to facilitate robust communication and pinpoint accuracy in positioning for indoor applications. We incorporate multiband carrierless amplitude and phase (CAP) modulation to mitigate interference between communication and positioning subcarriers. Unlike the conventional orthogonal frequency division multiplexing‐based subcarrier modulation (OFDM‐SCM), CAP demonstrates reduced out‐of‐band interference and a diminished peak‐to‐average power ratio (PAPR). Moreover, we introduce the frequency domain optical zero correlation zone (FD‐OZCZ) code, integrated within the CAP signal to optimize the distribution of positioning subcarriers. Simulation outcomes substantiate that our proposed CAP, augmented with FD‐OZCZ, outperforms OFDM‐SCM systems in delivering reliable communication and exceptional positioning accuracy.

Advanced NOMA-aided indoor optical wireless communications using improved quantum optimized resource

At present, Non-Orthogonal Multiple Access (NOMA) has become the most efficient technique to solve Data Rate (DR) requirements in Visible Light Communication (VLC) systems. However, present NOMA systems show high interference and increase the Peak-to-Average Power Ratio (PAPR), especially in wider applications. To overcome this issue, several techniques have been undertaken in the past and proven to better communication performance. However, the existing studies fail to provide a better Quality of Services (QoS) for the recent multi-carrier Optical Communication System (OCS). Hence, this study put forth a novel Generalized Frequency Division Multiplexing (GFDM) scheme to minimize the PAPR in an indoor-based NOMA-VLC system. To enhance the performance of the GFDM system, a novel Offset-based Quadrature Amplitude Modulation (OQAM) technique is introduced that enhances the signal quality and prevents the Co-Channel Interference (CCI) problems effectively. Moreover, the proposed study introduces a novel Quantum-enabled Rabbit Optimization (QRO) technique for solving Resource Allocation (RA) problems in the NOMA-VLC system. The proposed method is processed via the MATLAB platform and various performance measures like Sum Rate (SR), Signal-to-Interference Noise Ratio (SINR), and Symbol Error Rate (SER) are analyzed and distinguished with various existing studies. In the simulation scenario, the proposed method achieves the SR of 178Mbps, SINR of 16 dB, and SER of compared to conventional techniques.

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.

Analysis of Filtered Multicarrier Modulation Techniques Using Different Windows for 5G and Beyond Wireless Systems

In contemporary wireless communication systems, multicarrier modulation schemes have become widely adopted over single-carrier techniques due to their improved capacity to address challenges posed by multipath fading channels, leading to enhanced spectral efficiency. Orthogonal frequency division multiplexing (OFDM), a prevalent multicarrier scheme in 4G, is favored for its ease of implementation, interference resilience, and high data rate provision. But it falls short of meeting the requirements for 5G and beyond due to limitations such as out-of-band (OOB) emissions and cyclic prefixes. This paper introduces the filter bank multicarrier (FBMC) and universal filtered multicarrier (UFMC) with quadrature amplitude modulation (QAM) and phase shift keying (PSK) waveforms through Additive White Gaussian Noise channel (AWGN), Rayleigh fading channel and Rician channel. The objective of this paper is to enhance the performance of UFMC with reduced complexity through the new filtering approach for achieving optimal outcomes. The proposed scheme, incorporating Tukey filtering technique, demonstrates superior performance in reducing peak-to-average power ratio (PAPR) and improving bit error ratio (BER) compared to the original UFMC signal without necessitating additional power increments. Specifically, the UFMC system with Tukey filtering achieves a notable net gain of 5 dB. Simulation results demonstrate that utilizing various filter types in FBMC and UFMC systems, combined with QAM modulation, significantly reduces OOB emissions compared to conventional systems. In aspect to BER, Tukey window showed almost 10−6 at 15 dB SNR in UFMC which is better than FBMC.

PAPR analysis in OTFS using the centre phase sequence matrix based PTS method

Orthogonal time–frequency space (OTFS) is a multicarrier modulation technique for high-speed data transfer in wireless communications. In an OTFS system, many subcarriers are used to send the modulated symbols. This makes OTFS signals have a high peak-to-average power ratio (PAPR). We suggest a partial transmit sequence (PTS) approach based on the Centre Phase Sequence Matrix (CPSM) to lower the high PAPR. Furthermore, the suggested method effectively searches for the best possible combination of phase rotation factors to reduce computing complexity. We examine the outcomes regarding bit error rate (BER), power spectral density (PSD), and PAPR to validate the competing transforms in the OTFS system. Along with non-orthogonal multiple access (NOMA), filter bank multi-carrier (FBMC), universal filter multi-carrier (UFMC), and orthogonal frequency division multiplexing (OFDM), the PAPR, BER, and PSD performance of OTFS were also compared. According to the data, the suggested PTS + CPSM reduces PAPR more effectively than the current PTS. It is also mentioned that by increasing the number of sub-blocks (s = 2 and 4), the suggested PTS + CPSM can achieve an even better PAPR rate. According to the experimental results, the suggested approach has dramatically decreased the PAPR while maintaining the BER and PSD performance with the least amount of computational complexity.

Chaotic discrete Fresnel transform for secure OFDM-PONs

A chaotic discrete Fresnel transform (DFnT) precoding scheme is proposed for physical-layer security enhancement in orthogonal frequency division multiplexing passive optical networks (OFDM-PONs). A multi-fold OFDM data encryption is applied in terms of the chaotic scale factor, and chaotic row/column permutations in the DFnT matrix, and the chaos sensitivity creates a huge key space of 10138. The peak-to-average power ratio (PAPR) performances of OFDM signals associated with a scale factor in DFnT are fully analyzed. A 38.2 Gb/s OFDM signal transmission with chaotic DFnT is successfully demonstrated over a 20 km standard single-mode fiber (SSMF), where the gain of receiver sensitivity is ∼2 dB (BER @10−3), compared with OFDM without precoding.

A Survey of PAPR Techniques Based on Machine Learning.

Orthogonal Frequency Division Multiplexing (OFDM) is the modulation technology used in Fourth Generation (4G) and Fifth Generation (5G) wireless communication systems, and it will likely be essential to Sixth Generation (6G) wireless communication systems. However, OFDM introduces a high Peak to Average Power Ratio (PAPR) in the time domain due to constructive interference among multiple subcarriers, increasing the complexity and cost of the amplifiers and, consequently, the cost and complexity of 6G networks. Therefore, the development of new solutions to reduce the PAPR in OFDM systems is crucial to 6G networks. The application of Machine Learning (ML) has emerged as a promising avenue for tackling PAPR issues. Along this line, this paper presents a comprehensive review of PAPR optimization techniques with a focus on ML approaches. From this survey, it becomes clear that ML solutions offer customized optimization, effective search space navigation, and real-time adaptability. In light of the demands of evolving 6G networks, integration of ML is a necessity to propel advancements and meet increasing prerequisites. This integration not only presents possibilities for PAPR reduction but also calls for continued exploration to harness its potential and ensure efficient and reliable communication within 6G networks.

PAPR reduction using model‐driven hybrid algorithms in the 6G NOMA waveform

AbstractIn the evolving landscape of sixth‐generation (6G) network technologies, Non‐Orthogonal Multiple Access (NOMA) systems are pivotal for achieving enhanced spectral efficiency and network capacity. However, a significant challenge in NOMA systems is the high Peak‐to‐Average Power Ratio (PAPR), which undermines system efficiency by necessitating high‐power amplifiers (HPAs) to operate in their less efficient, non‐linear range. Addressing this, we introduce a novel hybrid approach, the Selective Mapping‐Circular Transformation Method (SLM‐CTM), which ingeniously amalgamates the strengths of Selective Mapping (SLM) and the Circular Transformation Method (CTM) to mitigate PAPR issues. SLM is renowned for its peak power reduction capabilities without adding to system complexity, whereas CTM is valued for its simplicity and controlled signal distortion. The proposed SLM‐CTM strategy employs a blend of linear and nonlinear techniques to effectively lower PAPR in non‐orthogonal NOMA configurations, thereby reducing high‐power peaks while simultaneously enhancing signal quality. This paper delineates the application of the SLM‐CTM algorithm to evaluate critical NOMA parameters such as Power Spectral Density (PSD), Bit Error Rate (BER), and PAPR. Simulation results highlight the efficacy of SLM‐CTM over conventional SLM, demonstrating a significant throughput improvement of 3.2 dB and a PAPR reduction of 4.6 dB, underscoring the potential of SLM‐CTM in elevating the performance of NOMA systems within 6G network.

Clipping Noise Compensation for Overlapped Time Domain Multiplexing toward Low Peak-to-Average Power Ratio.

Overlapped Time Domain Multiplexing (OvTDM) is a high-rate transmission technology that employs the idea of superposition coded modulation (SCM) scheme for signal generation, aiming to achieve maximum channel capacity sharing. Meanwhile, it is also widely considered as a promising technique toward physical layer security. As a main drawback of such system, a high peak-to-average power ratio (PAPR) issue in this system, arising from multi-layer superposition, can be addressed through intentional clipping. However, the detection at the receiver side is vulnerable to nonlinear distortion caused by clipping, which can degrade the performance. To mitigate this distortion, this paper proposed an iterative scheme for estimating and partially canceling clipping distortion at the receiver. We managed to mitigate the impact of clipping noise as much as possible and minimize the cost of optimizing PAPR, thereby improving the transmission performance of OvTDM in the context of amplitude clipping.

DHT-based GFDM and STC-GFDM systems for beyond 5G wireless networks

This manuscript endeavours an exploration of Generalized Frequency Division Multiplexing (GFDM) as a promising alternative to the Orthogonal Frequency Division Multiplexing (OFDM) in next-generation cellular networks. GFDM’s exceptional performance in minimizing out-of-band emissions (OOBE) and maximizing spectral efficiency (SE) makes it a compelling candidate, especially when integrated with Multi-Input Multi-Output (MIMO) technology to enhance reliability through spatial diversity. However, ensuring GFDM’s resilience against frequency-selective channels (FSCs), especially in low-latency scenarios, is crucial.This research investigates Discrete Hartley Transform (DHT) based GFDM and Space-Time Coded GFDM (STC-GFDM) systems, proposing a comprehensive framework to enhance performance metrics such as Bit Error Rate (BER) and Achievable Rate (AR). Further enhancements are achieved through a Minimum BER-Power Allocation (MBER-PA) strategy, optimizing BER and AR in QAM-based GFDM and STC-GFDM systems employing a DHT precoding scheme. Analytical expressions for BER and AR are derived and validated via Monte Carlo simulations. Additionally, a comparative analysis against traditional GFDM systems is conducted, evaluating metrics including Peak-to-Average Power Ratio (PAPR), BER, and AR.

Design of an efficiency enhanced wideband Doherty power amplifier based on synthesising of a modified harmonic‐control load modulation network

AbstractA design of a broadband Doherty power amplifier (DPA) using a novel harmonic control network (HCN) is presented. The DPA structure focused on manipulating harmonic components using this new HCN to enhance the bandwidth of operation and power efficiency. The proposed HCN combines a third harmonic suppression network (THSN) with the second harmonic impedance inverter circuit (SHIIC). In the design, the second harmonic component of the main transistor and the peaking transistor are short‐circuited by their associated SHIIC. Additionally, the carefully designed SHIIC and THSN circuit placed between the main and peaking transistors realise open circuit conditions at the third harmonic for both transistors at the saturation state and back‐off regions. Side by side with the aid of the properly designed post‐matching tuned network (PMTN), these harmonic loading conditions make both amplifiers to operate in continuous Class‐F modes with enhanced‐added efficiencies over wideband conditions. As a result, a succession of highly efficient DPA modes can be formed over a continuous frequency range in the full Doherty region, resulting in a reduced‐size enhanced power efficiency wideband DPA. For verification, a wideband DPA operating from 1.1 to 1.8 GHz was designed and implemented using the proposed topology. The measured drain efficiency of the implemented DPA at 6‐dB back‐off is 52.5%–67.5%, while the saturated power across the specified bandwidth is 43–43.7 dBm. The fabricated DPA exhibits an average efficiency of 48.7%–59.4%, when supplied by a 40‐MHz long‐term evolution (LTE) signal with a 7.5‐dB peak‐to‐average power ratio (PAPR). Performing digital pre‐distortion (DPD) improves the adjacent channel power ratio (ACLR) from −25.8 dBc to −47.6 dBc.

Modified Error Function Companding for reduction of PAPR in GFDM signals

Generalized Frequency Division Multiplexing (GFDM) is a multicarrier modulation technique, nevertheless, it provides high peak to average power ratio (PAPR) which affects the power amplifier (PA) efficiency. In this work, the modified error function companding is proposed for reducing PAPR in GFDM signals. The power scaling parameter (η) and companding parameter (a) are used to reduce the peak power. The average power is not altered in the proposed method, so there is no need to adjust the dynamic gain of PA. The theoretical expressions for the transform gain, achievable PAPR reduction and closed form expression of attenuation factor are derived. Moreover, the transform gain, attenuation factor, power spectral density, PAPR and bit error rate (BER) performance of the proposed method is analysed for different values of companding parameter. The results ensure that the proposed mEFC method at a=1 provides significant PAPR reduction than existing companding methods.

A Novel Alternating μ-Law Companding Algorithm for PAPR Reduction in OFDM Systems

Orthogonal frequency division multiplexing (OFDM) inherits multi-carrier systems’ inevitable high peak-to-average power ratio (PAPR) problem. In this paper, a novel alternating companding technique is proposed to combat the harassment of high PAPR. The sequential μ-law companding (SULC) and a tone with a lower PAPR result in only partial tones needing companding. The SULC scheme’s PAPR and bit error rate (BER) performance has been balanced and improved. However, the computational complexity is still too high to be implemented. Therefore, this study sorted the transmission signals according to their amplitudes. Then, all the tones are divided into two groups by estimating the rough companding amount (around 54% of the subcarriers), using traditional parallel companding for the first group and the other group only by partial μ-law companding. This alternating μ-law companding (AULC) is proposed to improve the PAPR performance and simultaneously reduce complexity. Simulation results show that the proposed AULC method appreciably reduces the PAPR by about 5 dB (around 45%) compared with the original μ-law at complementary cumulative distribution function (CCDF) equal to 10−4. Moreover, it only requires a moderate complexity to outperform the other companding schemes without sacrificing the BER performance in the OFDM systems.

A novel piecewise nonlinear companding scaling scheme for FBMC PAPR reduction

The performance of offset quadrature amplitude modulation filter bank multi carrier (OQAM-FBMC) has been noticed to be affected by a high peak-to-average power ratio (PAPR). High PAPR causes the transmit power amplifier to become saturated, improving the bit error rate (BER) and causing out of band (OOB) distortions. In this paper, the PAPR of FBMC systems can be reduced by using shifting and scaling the trigonometric companding technique associated with a reduced BER performance and the power spectral density (PSD) with low OOB distortions. The characteristics of low peak signals are not changed by this companding scheme, while the characteristics of high peak signals are transformed into scaling piecewise nonlinear trigonometric functions. By tuning the parameters the suggested technique maintains the average signal power level unchanged. The theoretical analysis of the proposed scheme is also studied and also compared with the simulation results. The performance of the trigonometric companding scheme is also analysed with the μ-law and A-law existing companding methods and the suggested method obtaining 3 dB and 3.2 dB PAPR improvement respectively. The proposed technique determined to be better in terms of BER performance and spectrum efficiency.

An ADO‐OFDM with integrated precoding, companding and optimized power allocation methods for high‐speed data transmission in visible light communication

AbstractVisible light communications (VLC) has received a lot of attention in recent studies because of its benefits over radio‐frequency (RF) communications. It is a short‐range optical wireless communication system that uses light‐emitting diodes (LEDs) as transmitters. Optical orthogonal frequency division multiplexing (OFDM) is an auspicious technology for VLC high‐speed data transfer. The use of OFDM in a VLC system raises the system's peak‐to‐average power ratio (PAPR). The intrinsic non‐linearity of LED is a key concern in an asymmetrically clipped DC‐biased optical OFDM (ADO‐OFDM) system due to its high PAPR. Also, conventional ADO‐OFDM modulation scheme cannot be used for accommodating different demands of services in downlink multiple access due to the restriction of direct current biased optical OFDM (DCO‐OFDM) and asymmetrically clipped optical (ACO‐OFDM) transmission on odd and even subcarriers. To tackle this issue, a modified ADO‐OFDM (MADO‐OFDM) is proposed that adjusts the numbers of subcarriers required for the transmission of ACO‐OFDM and DCO‐OFDM adaptively based on the requests of services in downlink multiple access. Also, the proposed MADO‐OFDM is integrated with a discrete Hartley Matrix transform (DisHMT) precoder and Generalized Piecewise Linear Compander (GPLD) to provide high‐speed data transmission with less PAPR. In addition, the power is allocated to the proposed MADO‐OFDM system optimally by maximizing the channel capacity based on the Aquila optimizer algorithm. The simulation results reveal that the suggested system's PAPR is reduced by 2.4 dB and 0.8 dB, respectively, compared to conventional ADO and hybrid ADO‐OFDM. It also confirms that the suggested generalized PLC can greatly increase BER without affecting the PAPR performance.

A hybrid approach based on companding and PTS methods for PAPR reduction of 5G waveforms

ABSTRACT As a crucial enabler for the fifth-generation air interface, the filter bank multicarrier with offset quadrature amplitude modulation (FBMC/OQAM) is being investigated by several researchers. This article suggests using partial transmit sequence (PTS) and companding to create a hybrid peak-to-average power ratio (PAPR) reduction strategy for FBMC/OQAM signals. In the novel PTS Companding scheme, there are several segments to the data block signal, and the overlapping factor determines the number of data blocks in each segment. To obtain the lowest signal power in each segment, we choose the best data block to broadcast and examine the next overlapping data block concurrently. After that, the segment FBMC/OQAM signal peaks are compressed using companding. Based on simulation results and analysis, the proposed hybrid PTS Companding method in FBMC/OQAM systems may reduce PAPR more effectively than conventional PTS and Companding schemes. According to simulation results, the hybrid process can achieve around 5 dB greater PAPR performance than the conventional PTS and companding schemes.

Error analysis for face coded modulation system

AbstractThis paper discusses a new mapping scheme known as face coded modulation (FCM) system. In FCM, peak energy symbols are mapped onto an innermost ring according to the eight sockets in the human face, that is, brain, mouth, nostrils, eyes and ears. For example, FCM is formed when the constellation diagram from M‐ary quadrature amplitude modulation (MQAM) system is modified to reduce peak‐to‐average power ratio (PAPR) by relocating the four corner symbols of the MQAM, with peak energy, to the innermost ring in a way that forms the figure of a cross. Unlike APSK, FCM mapping introduces non‐uniform sequence of symbols on the ring, face width factor and multiple modulator circuits that can be used to lower power requirements for high power amplifiers (HPA) as used in MQAM transmission systems. Symbol error rate (SER) for FCM is calculated and the results compared with MQAM and MPSK. It is shown that at equal energy efficiency, FCM scheme has a better response to errors than both MPSK and MQAM and a better energy efficiency due to lowered PAPR than MQAM. Moreover, the simulation results exhibit a tight match for the proposed analytical framework when assessed under Additive White Gaussian Noise (AWGN) channel.

Timing synchronization of LACO-OFDM under non-linear distortions using ELM

Layered asymmetrically-clipped optical orthogonal frequency division multiplexing (LACO-OFDM) is a modulation technique for visible light communication (VLC) that provides power and spectral efficiencies. The LACO-OFDM technique utilizes all the available subcarriers and will have a relatively higher peak-to-average power ratio (PAPR). Hence, the modulated samples are prone to distortions caused by the non-linear devices and diffused channels, resulting in reduced accuracy of delay offset estimation for timing synchronization. In this paper, we propose a method to improve the timing synchronization accuracy of LACO-OFDM modulated systems using extreme learning machines (ELM). The ELM is trained offline to identify the delay offset using the timing metric (TM) as a feature identification problem. Among all types of neural networks that are used as classifiers and non-linear estimators, the ELMs are the least complex and require significantly less computational capacity. The simulations are performed to evaluate the accuracy of delay offset estimation in the presence of unknown non-linear effects of high-powered light-emitting diodes (LEDs) and diffused channel characteristics. The results show that the probability of error (PoE) of delay offset estimation and bit error rate (BER) is significantly reduced for scenarios like different frame lengths, channel coefficients, and unknown LED parameters in contrast to conventional methods. The proposed approach attains a PoE of 10−1 at signal-to-noise ratios (SNR)s of 4 dB and 6 dB with various TM, surpassing conventional methods which only achieve this beyond 15 dB. Moreover, the PoE remains below 10−2 for SNRs exceeding 7 dB and 10 dB in the proposed method, while conventional methods require SNRs above 25 dB to achieve comparable results.

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.

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.