Peak-to-average Power Ratio Reduction Method Research Articles

Cross-Antenna Polyphase Interleaving and Inversion scheme to reduce the PAPR of MIMO-FBMC/OQAM system

Filter Bank Multi-Carrier with Offset Quadrature Amplitude symbol mapping called as FBMC/OQAM is presented as a potential successor of Orthogonal Frequency Division Multiplexing OFDM. Combined with Multiple-Input Multiple- Output (MIMO), MIMO-FBMC/OQAM is a promising modulation scheme for high performance broadband wireless communications. However, one major drawback of MIMO-FBMC/OQAM is the high peak-to-average power ratio (PAPR) of the output signals. Latinovic et al. Proposed a PAPR reduction method called Polyphase Interleaving and Inversion (PII) for MIMOOFDM systems under the use of the space-frequency block coding (SFBC) [1]. In this investigation, we suggest two schemes called Cross Antenna Polyphase Interleaving and Inversion 1 and 2 (CAPII1/(CAPII2) PAPR reduction schemes for Space Frequency Block Coding MIMO-FBMC systems which consequently utilizes additional degrees of freedom by employing multiple antennas and generating more patterns leading to more signal candidates to transmit, while requiring a limited amount of side information. The simulation results show that both the proposed CAPII schemes experience remarkable gain in PAPR.

Leveraging Massive MIMO for Enhanced Energy Efficiency in High-Density IoT Networks

Maximizing energy efficiency (EE) in massive multiple-input multiple-output (MIMO) systems, while supporting the rapid expansion of Internet of Things (IoT) devices, is a critical challenge. In this paper, we delve into the intricate operations geared toward enhancing EE in such complex environments. To effectively support a multitude of IoT devices, we adopt a strategy of heavy reference signal (RS) reuse, and in this circumstance, we formulate the EE metrics and their corresponding inverses to determine pivotal operational parameters. These EE-centric parameters encompass factors such as the number of service antennas in the base station (BS), the number of IoT devices, and permissible coverage extents. Our objective is to calibrate these parameters to meet a predefined EE threshold, ensuring optimal system performance. Additionally, we recognize the indispensable role of Peak-to-Average Power Ratio (PAPR) reduction techniques, particularly in multicarrier systems, to further enhance EE. As such, we employ clipping-based PAPR reduction methods to mitigate signal distortions and bolster overall efficiency. Theoretical EE metrics are derived based on formulated signal-to-interference-plus-noise ratios (SINRs), yielding insightful closed-form expressions for the operational parameters. Leveraging two distinct EE metric models, we undertake parameter determinations, accounting for the levels of approximation. Intriguingly, our analysis reveals that even simplified models exhibit remarkable applicability in real-world scenarios, with a minimal margin of error. The results not only underscore the practical applicability of our theoretical constructs but also highlight the potential for significant EE enhancements in massive MIMO systems, thereby contributing to sustainable evolution in the IoT era.

A BACTERIA FORAGING ALGORITHM-BASED HYBRID A-LAW AND PTS PAPR REDUCTION METHOD FOR BEYOND 5G WAVEFORM

One of the most advanced waveforms available in the beyond-fifth-generation radio (B5GR) framework is nonorthogonal multiple access (NOMA). The power amplifier (PA) of the NOMA structure performs less efficiently when the signal is strong and the peak-to-average power ratio (PAPR) is high. This study applies a hybrid algorithm to the NOMA structure, combining fractal partial transmit sequence (PTS), A-law companding, and the bacterial foraging algorithm (BFA). Fractals are known for their self-repeating structures at different scales, allowing for efficient coverage and exploration of space. Fractals enhance the bacteria foraging algorithm (BFA) by improving search efficiency, enabling better exploration of complex, multi-dimensional optimization landscapes. Similarly, BFA balances exploring the search in promising areas. We utilized BFA to achieve optimal phase factors for the PTS algorithm and applied A-Law companding to the NOMA symbols to further enhance the structure’s performance. The intermediate computational complexity in the Rician and Rayleigh channels improves PAPR, bit error rate (BER), and power spectral density performance. Simulation results reveal that the performance of the proposed hybrid method is superior to that of existing PAPR reduction algorithms and substantially enhances the efficiency of NOMA.

Throughput improvement in ACO-OFDM-based VLC systems using noise cancellation and precoding techniques

One of the primary challenges faced by visible light communication (VLC) systems employing optical orthogonal frequency division multiplexing is the peak-to-average power ratio (PAPR). This study is dedicated to designing, simulating, and evaluating bit error rate (BER) and PAPR reduction methods tailored for the VLC broadcasting system. The asymmetric clipped optical orthogonal frequency division multiplexing (ACO-OFDM) scheme is highlighted in this work for its impressive performance. Therefore, the proposed PAPR mitigation methodologies applied to ACO-OFDM. The proposed PAPR reduction strategy involves 5 distinct precoding methodologies. The PAPR was mitigated by 3.485 dB after applying the DST precoding methodology. Still, the WHT precoding methodology can achieve PAPR reduction by 1.131 dB, without BER performance degradation, with respect to the conventional ACO-OFDM system. Furthermore, the work addresses another challenge in VLC systems: the bit error rate (BER). This is accomplished by introducing approaches to Time Domain Noise Cancelation and Frequency Domain Noise Cancelation (FDNC). The BER performance of these 2 receiver models is nearly the same. The simulation results indicate the system performance enhancement after applying noise cancellation approaches by 1.65 dB at the 4-QAM modulation scheme and 2.97 dB at the 1024-QAM modulation scheme. The 16-QAM modulation scheme, after applying DST and WHT methodologies alongside noise cancellation approaches, can enhance both PAPR by 20.83% and 6.76%, but the Eb/N0 performance enhancement by 10.10% and 14.64%, respectively. Additionally, the effectiveness and validity of the proposed schemes are verified by comparing them with relevant literature reviews on PAPR reduction techniques and selecting an optimal choice among them.

Performance Analysis of Hybrid Optical OFDM Schemes in terms of PAPR, BER and Spectral Efficiency using Various PAPR Reduction Methods

Orthogonal Frequency Division Multiplexing (OFDM) is an extremely important technique for transmitting data in both optical wireless and optical fiber communication. Optical wireless systems are limited to transmitting real and positive values to the optical transmitter, since they rely only on the intensity of a signal to convey information. Consequently, traditional OFDM is not suitable for direct implementation in optical systems. Various altered OFDM schemes have been examined to counteract multipath distortion, such as DC-biased optical OFDM (DCO-OFDM), asymmetrically clipped optical OFDM (ACO-OFDM), asymmetrically clipped DC biased optical OFDM (ADO-OFDM) and layered asymmetrically-clipped optical OFDM (LACO-OFDM) technique to improve the bit error rate (BER) performance and spectral efficiency of optical system. This article explores ways for reducing Peak-to-Average Power Ratio (PAPR). A mathematical model is formulated to account for clipping and Selective Mapping (SLM), as well as channel noise, in all of these approaches for received signal. LACO-OFDM has been determined to be a superior option when compared to other techniques. LACO-OFDM, a recently developed technique, demonstrates excellent performance in terms of PAPR, BER, and spectral efficiency. The simulation results demonstrate that the LACO-OFDM approach has greatly enhanced the spectral efficiency in comparison to previous approaches.

Exploring and Analyzing a Hybrid PAPR Reduction Method for OFDM Optimization

Orthogonal Frequency Division Multiplexing (OFDM) is a effective modulation technique widely used in modern communication systems, including 5G and wireless networks because of its high spectral efficiency and robustness towards multipath fading. However, OFDM signals are characterized by a high Peak-to-Average Power Ratio (PAPR), which can severely impact the power efficiency and operational cost of these systems. This research investigates and analyse effectiveness of two conventional PAPR reduction methods that is Selective Mapping (SLM), and Partial Transmit Sequence (PTS) with incorporating their approach of PAPR reduction to develop a hybrid variant: SLM-PTS. This study utilized MATLAB simulations to implement and test each PAPR reduction technique on a standard OFDM system model. Parameters such as the number of subcarriers, oversampling factor, and modulation types were systematically varied to analyze the impact on PAPR, BER, and computational complexity. The effectiveness of each technique was measured using the Complementary Cumulative Distribution Function (CCDF) of PAPR values and BER performance under different channel conditions. Key findings reveal that hybrid techniques, particularly SLM & PTS, offer significant improvements in PAPR reduction compared to traditional methods alone, without a corresponding increase in BER or computational overhead. The research underscores the potential of hybrid PAPR reduction techniques to significantly enhance the efficiency and reliability of OFDM systems. These findings have important implications for the design and optimization of next-generation wireless communication systems, suggesting that hybrid approaches can provide a balanced solution to the longstanding issue of PAPR in OFDM transmissions. This study contributes valuable insights into the practical application of combined PAPR reduction strategies, offering a pathway toward more power-efficient and robust OFDM technologies. Keywords : OFDM, PAPR, CCDF, SLM and PTS

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.

Performance enhancement and PAPR reduction for MIMO based QAM-FBMC systems.

Filter Bank Multi-Carrier (FBMC) is attracting significant interest as a multi-carrier modulation (MCM) approach for future communication systems. It offers numerous advantages in contrast to Orthogonal Frequency Division Multiplexing (OFDM). Nonetheless, similar to many other MCM techniques, FBMC encounters a significant challenge with a high Peak-to-Average Power Ratio (PAPR). Additionally, incorporating Multiple-Input and Multiple-Output (MIMO) into FBMC presents heightened difficulties due to the presence of complex interference and increased computational complexity. In this paper, we first study the performance analysis of MIMO based Quadrature Amplitude Modulation (QAM)-FBMC systems considering the system complexity and interference. To enhance coverage effectively using beamforming with multiple antennas, it is essential to reduce PAPR to minimize the input backoff (IBO) required by nonlinear power amplifiers. Therefore, we propose new PAPR reduction method for MIMO based QAM-FBMC systems leveraging the null space within the MIMO channel using clipping and filtering (CF) technique. The PAPR reduction signals generated in this process are then mapped to the null space of the overall MIMO channel for each frequency block. Through computer simulations using a nonlinear power amplifier model, we illustrate that the proposed method substantially enhances both PAPR and throughput of MIMO based FBMC systems compared to conventional methods.

Analysis of PAPR reduction of optical-OTFS for 256-QAM using companding and clipping–filtering algorithms

Abstract The article presents an investigation into Peak-to-Average Power Ratio (PAPR) reduction techniques in Optical Orthogonal Time Frequency Space (O-OTFS) modulation. Focusing on clipping and filtering as well as companding methods, the study explores their efficacy in mitigating PAPR challenges inherent in O-OTFS waveforms. The research evaluates the impact of these techniques on signal quality, particularly in the context of a Rician channel. Clipping and filtering (C&F) are examined for their ability to control amplitude peaks, while companding is analyzed for its role in optimizing dynamic range. The study conducts a comprehensive analysis of Bit Error Rate (BER) and power spectrum density (PSD) under varying conditions, shedding light on how these methods influence the reliability and robustness of OTFS communication. The investigation considers the interplay of these PAPR reduction methods with the unique characteristics of the Rician and Rayleigh channel, which includes a dominant line-of-sight component. The findings contribute valuable insights into designing efficient OTFS modulation systems for real-world scenarios. Ultimately, this research aims to provide a deeper understanding of PAPR reduction strategies in OTFS, offering guidance for optimizing signal processing techniques in communication systems where mitigating PAPR is crucial for achieving high performance and reliable data transmission. It is noted that the proposed C&F and companding algorithms outperform the conventional methods and achieved a PAPR gain of 1–3 dB and BER gain of 10.6–2 dB.

Iterative Filtering PAPR Reduction Method for OFDM Modulation in Fifth-generation Cellular Networks

Background & Objective: Orthogonal Frequency Division Multiplexing (OFDM) is an ordinarily used waveform in the fifth generation (5G) cellular networks for uplink links. However, there is a prominent disadvantage in the form of a high peak-to-average power ratio (PAPR) which yields distortion in the timing signal generated at the output of the high-power amplifier (HPA). Methods: A new method called Iterative Filtering PAPR Reduction (IFP) has been suggested in this paper and maintains backward compatibility. The basic concept behind this algorithm is to obtain a filter based on a constant-envelope signal that is intimate to the original signal as far as power is concerned. The constant-envelope signal is then compared to the output between the product of the convolution of the original signal with the filter in question, allowing for the calculation of the impulse response of the filter. Such a process can be repeated several times with different filters to realize the best reduction in PAPR. Results: The simulated results of the IFP method proved better performance in terms of PAPR reduction, Bit Error Rate (BER), and computational complexity requiring two iterations only. We can see a gain of 3.1dB in terms of PAPR reduction, 17dB in terms of BER, and a factor of 33 times in terms of computational complexity compared to the TR method. The Complementary Cumulative Complementary Density Function (CCDF) has assisted in measuring and improving the PAPR performance of the system. Conclusion: The theoretical analysis shows that a single iteration (NF= 1) is sufficient, and the simulation results exposed in this paper show a gain of 3.1 dB in PAPR reduction.

A Novel µ-law Nonlinear Companding with Modified Recoverable Upper Clipping Method for PAPR Reduction in ACO-OFDM VLC Systems

The high Peak-to-Average-Power Ratio (PAPR) is the major challenge that causes signal distortion at the output of a Light-Emitting-Diode (LED) due to the narrow dynamic region of a LED in an Optical Orthogonal Frequency Division Multiplexing (O-OFDM) based Visible Light Communication (VLC) systems. Although a μ-law Nonlinear Companding Transform (μ-NCT) in an Asymmetrically-Clipped O-OFDM (ACO-OFDM) architecture decreases the PAPR degree, generates undesired large signals that can enter the nonlinearity range of a LED. This paper proposes a novel PAPR reduction method referred to as μ-NCT with Modified Recoverable Upper-Clipping (μ-NCT+MoRoC) model. The μ-NCT+MoRoC model benefits from the PAPR reduction of μ-NCT, and later uses all the advantages of the newly designed MoRoC method to reduce the large signals’ amplitudes that rose after the μ-NCT. The MoRoC method stores the large signals without losing information at the transmitter within the existing bandwidth using the asymmetrical structure of ACO-OFDM. To recover the source signal at the receiver, the MoRoC method uses newly generated symbol-based threshold detection and recovery algorithms. Both MoRoC and proposed μ-NCT+MoRoC models provide PAPR reduction and 45% peak amplitude reduction for ACO-OFDM systems without additional bandwidth, loss of information, and extra IFFT/FFT.

A novel PAPR reduction method for hybrid beamforming transmitter

In orthogonal frequency division multiplexing (OFDM) systems, peak-to-average power ratio (PAPR) is one of the major factors that affect the power efficiency of transmitter. There exist many PAPR reduction methods for the conventional fully digital multiple-input multiple-output (MIMO) systems but there is little discussion on the PAPR reduction for the hybrid beamforming systems. When some output signals of the digital to analogue converter (DAC) are combined by the analogue beamforming network before power amplifier (PA), the one to one mapping between the digital signal and the signal passing through PAs is destroyed. In such hybrid beamforming architectures, the existing methods can only reduce the PAPR of DAC input signal but not PAPR of PA input signal. In this paper, we investigate whether and how we can extend existing PAPR reduction methods to the hybrid beamforming systems. We propose a novel PAPR reduction method, which extends the iteratively clipping and filtering (ICF) to the hybrid beamforming systems. To the best of our knowledge, our proposed algorithm is the first PAPR reduction algorithm dedicated for the hybrid beamforming systems. From the simulation, our proposed algorithm can achieve a smaller PAPR than the improved selective mapping (SLM) algorithm at the cost of minor signal distortion.

Performance Analysis of PAPR minimization in OFDM System Using Clipping, SLM and PTS Techniques

In wireless communications, Orthogonal Frequency Division Multiplexing (OFDM) is a method of modulating multicarrier signals to transmit high speed data. OFDM systems use multiple subcarriers to transmit the modulated symbols. There is a high peak to average power ratio (PAPR) in OFDM. PAPR can be reduced by using various methods. Different PAPR minimization techniques, like clipping, selective mapping (SLM) and partial transmit sequence (PTS) are presented in this project. This paper also focuses on Bit Error Rate (BER) and Signal to Noise Ratio (SNR) relative performance. A significant reduction in the PAPR and computational complexity can be seen from the results. The purpose of this study is to compare the results of an analysis recommended for PAPR reduction methods.

Modified [formula omitted]-law Root Companding for PAPR reduction in GFDM signals

Generalized Frequency Division Multiplexing (GFDM) is a multicarrier modulation technique and able to meet the requirements of next generation wireless systems. But it exhibits high peak to average power ratio (PAPR), which degrades the efficiency of the power amplifier (PA). In this work, modified Root Companding and modified μ-law Root Companding are proposed to reduce PAPR in GFDM signals. The existing methods alter the average power due to expansion of small signals, whereas the proposed method keeps the average power as constant by adjusting both small and large signals. Therefore, the adjustment of dynamic gain in PA is not required. Transform gain and achievable PAPR reduction of the proposed methods are compared by varying companding metrics such as companding root R and companding parameter μ. Also, bit error rate (BER) performance is analysed over AWGN channel and the value of R, μ is chosen such that companding distortion is small. The theoretical PAPR distribution of the proposed methods are derived and validated with Monte-Carlo simulations. The BER performance over multipath fading channel is also analysed. Further, the BER, PAPR and power spectral density performance of the proposed methods are compared with conventional OFDM, GFDM and existing PAPR reduction methods. The computational complexity is also analysed.

OFDM and MIMO wireless communication performance measurement using enhanced selective mapping based partial transmit sequences

The great spectral efficiency to mitigate multipath fading of OFDM (orthogonal frequency division multiplexing) made more accepted for broadband communication systems with some drawbacks such as high PAPR (Peak-to-Average Power Ratio), ISI (Inter-Symbol Interference) and ICI (Interiv Carrier Interference). High PAPR forces the operations of the HPA amplifier to work beyond its linear region causing in-band distortion as well as out-band noise and are overcome by using an amplifier with a large dynamic range. In this method, OFDM symbols are partitioned into multiple disjoint sub-blocks which are independently rotated in phase by optimum phase weighting factors. The resultant OFDM signal has less PAPR when compared to that of original OFDM signal in wireless communication. To minimize computational complexity, a modified PTS technique is proposed to enhance PAPR reduction and power amplifier efficiency in OFDM and MIMO (multiple inputs, multiple outputs)-OFDM methods through Selective Mapping based PTS (SMPTS) method combined with PAPR reduction methods.

VHDL implementation of circular shifting‐partial transmit sequence in MIMO OFDM systems

SummaryOne of the basic issues in orthogonal frequency‐division multiplexing (OFDM) frameworks is the peak‐to‐average power ratio (PAPR). There are several PAPR reduction methods available. The partial transmit sequence (PTS) technique is considered one of the superior techniques for overcoming this issue. In this study, an efficient VHSIC hardware description language VHDL implementation of the PTS design utilising roundabout circular shifting CS was planned. The proposed structured method was designed as a real‐time prototype circuit over a field programmable gate array (FPGA) utilising the VHDL language. The implementation results of the prototype circuit in terms of the resources used in the FPGA using the Xilinx synthesis tool on the Virtex‐5 board for SISO, 2 × 2 MIMO and 4 × 4 MIMO models for N‐IFFT 64 and 256 points are presented. The structured framework effectively combined to be a compact framework with low intricacy and high speed. Testing of the implemented circuit verified its functionality. A comparison of our proposed CS‐PTS scheme with previously used PTS schemes, such as the subblock scheme, showed that our proposed method is superior in terms of hardware complexity reduction.

Variable length error correcting code for image in OFDM and PAPR reduction

Data <span>transmission in orthogonal frequency division multiplexing (OFDM) system needs source and channel coding, the transmitted data suffers from the bad effect of large peak to average power ratio (PAPR). Source code and channel codes can be joined using different joined codes. Variable length error correcting code (VLEC) is one of these joined codes. VLEC is used in mat lab simulation for image transmission in OFDM system, different VLEC code length is used and compared to find that the PAPR decreased with increasing the code length. Several techniques are used and compared for PAPR reduction. The PAPR of OFDM signal is measured for image coding with VLEC and compared with image coded by Huffman source coding and Bose-Chaudhuri-Hochquenghem (BCH) channel coding, the VLEC code decreases the data transmitted size and keep the same level of PAPR reduction with respect to data coded by Huffman and BCH code when using PAPR reduction methods.</span>

Nonlinear companding transforms for reducing the PAPR of OTFS signal

In this paper, two non-linear companding transforms, namely exponential and sine hyperbolic, are proposed to reduce the peak to average power ratio (PAPR) of the orthogonal time frequency space (OTFS) modulation signal. The companding transforms are normalized such that the average power remains the same before and after companding. The resulting transforms have a saturation kind of characteristics for larger amplitudes of a signal while enhancing the smaller amplitudes slightly, which leads to a reduction of PAPR significantly. To validate the companding transforms in the OTFS system, we analyze the results in terms of PAPR, transform gain, attenuation factor, and bit error rate (BER). Also, compared the PAPR and BER performance of OTFS with OFDM, and the existing μ-law and clipping methods in OTFS. The results signify that the proposed companding transforms outperform the existing μ-law and clipping methods for PAPR reduction.

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.