Hybrid Peak-to-average Power Ratio Reduction Research Articles

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

Peak to Average Power Ratio Reduction in UFMC System Using Pre -Coding and Nonlinear Companding Techniques

Universal Filtered Multi-Carrier (UFMC) is a versatile fifth-generation communication technology that can be utilized in Internet of Things and Machine-to- Machine (M2M) communication to enhance connectivity and efficiency because of its spectral efficiency, low power consumption, reliability, and flexibility. The Internet of Things and Machine-to-Machine (M2M) communication enable devices to talk to each other, gather data, and make the world smarter and more efficient. However, the drawback of UFMC systems is they exhibit a very high peak -to-average-power-ratio which causes system Lower and latency on communication. Therefore, to lower the high peak -to-average-power-ratio of the UFMC system, this project proposes an efficient hybrid PAPR reduction approach that combines both non-linear companding techniques and precoding techniques. Key Words: Peak-to-average power ratio (PAPR), Hybrid PAPR reduction Techniques, Precoding Techniques, Non- Linear Companding Techniques (NCLTs), Universal Filtered Multi-Carrier (UFMC).

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 Joint Time-Domain Channel Estimation with Hybrid PAPR Reduction Scheme in UFMC Systems

In this paper, pilot-based time-domain channel estimation (CE) along with peak-to-average power ratio (PAPR) reduction is proposed for universal filtered multicarrier (UFMC) system. The pilots that are inserted in time domain not only estimate the channel behavior but also can be used in the reduction of PAPR. For PAPR reduction, a linear companding scheme, which can treat amplitudes of the UFMC signal separately with a different scale, is proposed. The proposed companding scheme offers more design flexibility and better performance gains by using two inflexion points. However, the proposed companding scheme requires side information (SI) to perform de-companding at the receiver. The transmission of SI decreases the data efficiency, so a pilot-assisted UFMC system that can perform both data recovery and PAPR reduction without the requirement of SI transmission is proposed. In pilot-assisted UFMC system, the inserted time-domain pilots can enable SI cancellation inherently. Furthermore, a hybrid transform, which improves PAPR performance by employing clipping scheme to the linear companded signal, is proposed. Simulation results confirm that the proposed joint CE with linear companding scheme achieves an improved net gain of 6.5[Formula: see text]dB. Additionally, the proposed hybrid scheme with clipping threshold of 1.4 provides an improved PAPR reduction of 8.8[Formula: see text]dB and enhanced net gain of 7.3[Formula: see text]dB. Moreover, the proposed joint time-domain CE with hybrid PAPR reduction scheme of UFMC system is validated over real time by employing wireless open-access research platform (WARP) board.

Analysis of Hybrid PAPR Reduction Methods of OFDM Signal for HPA Models in Wireless Communications

Orthogonal Frequency Division Multiplexing (OFDM) suffers from a high Peak-to-Average Power Ratio (PAPR). Designing a High Power Amplifier (HPA) with high PAPR is not a wise technique as it roots the amplifier to operate in a non-linear region which is intricate. Linearity and power efficiency are important constraints of HPA which cannot be achieved at the same time. Therefore, perfect linearity is observed when efficiency is low or vice versa and efficiency can be improved by decreasing the PAPR. In this paper, the PAPR is mitigated by using Partial Transmit Sequence (PTS), Selected Mapping (SLM), Hybrid and proposed methods. Analysis of OFDM with high PAPR passing through different HPA models is evaluated in terms of Power Spectral Density (PSD), gain and efficiency for all PAPR reduction methods considered in this work. The results are encouraging by using hybrid PAPR reduction method, HPAs can be operated in a linear region to provide higher efficiency compared to non-hybrid PAPR reduction methods. Hence, hybrid PAPR reduction methods can be used even in future wireless communications systems including 5G and beyond.

A Novel Hybrid PAPR Reduction Technique for NOMA and FBMC System and its Impact in Power Amplifiers

Non-orthogonal multiple access (NOMA) and filter bank multi carrier (FBMC) based on multi-carrier techniques are two best transmission schemes candidates for modern mobile communication systems. High peak to average power ratio (PAPR) is regarded as an important problem in implementing NOMA and FBMC systems. Several PAPR reduction techniques for FBMC have been presented in the literature review, but PAPR reduction techniques in NOMA are not explored so far. In that regard, there are several drawbacks of reduction methods presented in the literature. The disadvantages include a decrease in performance of bit error rate (BER), design complexity, minimum bit rate. In the present study, we have examined and compared the performance of the reduction techniques and proposed a selective mapping circular transformation hybrid (SLMCT) method. It is observed that SLMCT is the best method to enhance the PAPR and BER performance and minimizes the complexity of PTS technique. Further BER, PAPR, net gain, power reduction and CCDF parameters are examined. Finally, it is concluded that the performance of the proposed hybrid method is better than the existed peak power minimize techniques and plays an important role, when the objective is to maximize the performance of both PAPR and BER.

A Hybrid PAPR Reduction Scheme for OFDM Systems Using Perfect Sequences

In this paper, a peak to average power ratio (PAPR) reduction scheme with low complexity and high performance for orthogonal frequency division multiplexing (OFDM) signals is proposed. The proposed scheme is a hybrid PAPR scheme that employs a two-stage cascade structure. The first stage is a post-IFFT stage that can construct a set of high-order quadrature amplitude modulation (QAM) sequences from QPSK or BPSK sequences with the smallest possible number of IFFTs. The second stage is based on an optimal Class-III selected mapping (SLM) scheme which consists of a bank of parallel blocks. Each of these blocks generates more candidate sequences from each of QAM sequences by passing it through a set of parallel sub-blocks that perform circular convolution with perfect sequences and circular shifting with optimum shift values. Simulation results show that the proposed scheme can outperform existing schemes in terms of PAPR reduction with lower complexity.

Numerical Study of a Hybrid Optical DMT/DFT-S QAM Modulation

A hybrid modulation offers the peak-to-average power ratio (PAPR) robustness of discrete Fourier transform spread (DFT-S) quadrature amplitude modulation (QAM) with the bit rate optimization of discrete multi-tone (DMT) modulation. We examine via simulation under what circumstances this hybrid can increase achievable bit rate. Hybrid PAPR reduction allows us to increase the peak-to-peak voltage at the modulator electrical input to increase the signal mean power at the modulator output. We propose a methodology to identify the optimal driving strategy. We optimize the bit rate for the available spectrum, i.e., the spectral efficiency, taking into account the bandwidth limited nature of the transmitter. The final optimization we propose is the partition of the available spectrum into a lower frequency band for DFT-S QAM and a higher frequency band for DMT. The modulation level of the DFT-S QAM is also optimized. We compare the optimal hybrid performance versus DMT performance for a range of bit rates for a given modulation bandwidth. Improved performance comes at the cost of greater DSP complexity for the hybrid solution. We compare the number of complex multipliers required to implement hybrid versus DMT for both dispersive and non-dispersive systems.

Performance Analysis of Hybrid Peak to Average Power Ratio Reduction Techniques in 5G UFMC Systems

The universal filtered multi-carrier (UFMC) technique has been proposed as a prominent waveform candidate for fifth generation (5G) communication techniques. However, UFMC systems exhibit a high peak-to-average power ratio (PAPR), which causes serious degradation in the performance of the system. Therefore, this paper puts forward an effective hybrid PAPR reduction method to reduce the high PAPR of the UFMC system. The proposed hybrid scheme consists of a combination of precoding and non-linear companding techniques (NLCTs). A comparative analysis of the performance of different precoding methods, NLCTs, and hybrid methods are investigated in terms of the cumulative distribution function of the PAPR and the bit error rate (BER). The simulation results show that the proposed hybrid UFMC system has better PAPR reduction performance compared to conventional NLC and precoded UFMC systems. Moreover, the BER analysis of the UFMC system verifies that the proposed hybrid technique shows better BER performance compared to conventional companding techniques.

On Optimizing the PAPR of OFDM Signals With Coding, Companding, and MIMO

One main disadvantage of the multiple-input-multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM) system is that the signals transmitted on each antenna may experience high peak-to-average-power ratio (PAPR). We will present a new hybrid PAPR reduction technique that combines and optimizes three methods, namely convolutional code, successive suboptimal cross-antenna rotation and inversion (SS-CARI), and iterative modified companding and filtering. The results for the hybrid PAPR reduction technique show that this scheme significantly reduces the PAPR compared with SS-CARI alone; it can improve the bit error rate to levels better than what obtains with the space–time block coding MIMO-OFDM system, and the spectral splatter due to companding is also controlled by the use of frequency-domain filtering. In addition, it is a flexible technique in which the net gain can be optimized based on the requirements of scheme parameters, such as the code rate, the constraint length of the convolutional code, the number of subblocks for SS-CARI, and the companding parameters.

Novel hybrid PAPR reduction schemes for the MGFDM system

Fifth generation wireless communications are expected to serve future wireless needs such as machine-to-machine communications, tactile internet, be highly reliable, have low latency and perform satisfactorily in high speed communication links. Generalized Frequency Division Multiplexing (GFDM) is one of the promising and leading candidates proposed for the 5G physical layer waveform, to fulfill the above applications. Due to the non-orthogonal pulse shaping of individual subcarriers, GFDM suffers from self interference and also increased peak amplitude. The benefit of prolate windows can be exploited to convert a non-orthogonal GFDM system to an improved orthogonal Multi-taper GFDM (MGFDM) one. Similarly to other multicarrier (MC) techniques, MGFDM also suffers from high peak-to-average-power ratio (PAPR). In this article, we first explore some of the standard PAPR reduction approaches such as, Selective Mapping (SLM), Partial Transmit Sequence (PTS) and Zadoff–Chu Transform (ZCT) and a comparative performance is carried out in terms of the cumulative distribution function (CCDF). In addition, we propose in this article a novel hybrid Walsh–Hadamard precoding with both SLM and PTS PAPR reduction techniques to further reduce the PAPR level at the transmitter side. The Walsh–Hadamard kernel which is a square wave with values ±1 helps to reduce the PAPR without introducing distortion, compared to clipping based methods. Using these proposed schemes the results show a superior PAPR reduction improvement when compared to the conventional SLM and PTS techniques. Mathematical equations of the proposed systems were derived and the corresponding complexity analysis was carried out.

A Hybrid PAPR Reduction Method Based on SLM and Multi-Data Block PTS for FBMC/OQAM Systems

The filter bank multicarrier employing offset quadrature amplitude modulation (FBMC/OQAM) is a candidate transmission scheme for 5G wireless communication systems. However, it has a high peak-to-average power ratio (PAPR). Due to the nature of overlapped signal structure of FBMC/OQAM, conventional PAPR reduction schemes cannot work effectively. A hybrid PAPR reduction scheme based on selective mapping (SLM) and multi data block partial transmit sequence (M-PTS) methods is proposed for FBMC/OQAM signals in this paper. Different from the simple SLM-PTS method, the proposed hybrid algorithm takes into account the overlapping effect of multiple adjacent data blocks on its PTS process. From simulation results, it can be obtained that the proposed method can offer a significant PAPR reduction performance improvement compared with the SLM, PTS and SLM-PTS methods. The proposed method can effectively reduce the PAPR in FBMC/OQAM systems.

Non‐linear companding based hybrid PAPR reduction approach for DCT‐SCFDMA system

This study presents a new hybrid scheme that effectively reduces the peak-to-average power ratio (PAPR) of discrete cosine transform based single-carrier frequency division multiple access (DCT-SCFDMA) signal as well as improves the bit error rate (BER) performance of system. The method is to consolidate pulse shaping process with a novel hyperbolic tangent companding technique so that the PAPR of the SCFDMA signals can be further reduced by enabling the transformation of the amplitude of modulated signals into uniform distribution. Through extensive computer simulations, it has been shown that proposed scheme achieves significant improvements in BER and PAPR reduction over the existing standard pulse shaping methods when used alone in DCT-SCFDMA system as far as the lowest PAPR is concerned without degrading the error performance of the system.

Performance analysis of hybrid PAPR reduction technique for LTE uplink communications

Long Term Evolution standard implemented Single Carrier Frequency Division Multiple Access (SC-FDMA) in the uplink communications due to its low peak to average power ratio (PAPR). But for higher order modulations, there is a need for further reduction of PAPR in SC-FDMA systems. There are numerous techniques to decrease PAPR, but clipping and companding techniques are very simple to implement without any side information. μ law companding provides good PAPR reduction but increases the average power of companded signal. In this paper, the distribution of SC-FDMA signal is approximated, and a companding technique is proposed to transform the approximated distribution into a uniform distribution, which reduces PAPR without increasing average power of the signal. For further improvement in PAPR, a hybrid technique is also proposed where the companded signal is clipped to a specific threshold value. Simulation results show that PAPR reduction achieved by the proposed companding technique is better than that of μ law companding with a slight degradation in bit error rate (BER) performance. The proposed companding technique with no decompanding operation has better BER performance when compared to that with approximated decompanding operation. The hybrid technique further reduces PAPR with similar BER performance as that of proposed companding technique by carefully choosing the clipping ratio.

PAPR reduction in CO-OFDM systems using IPTS and modified clipping and filtering

Aiming at the problem of the peak to average power ratio (PAPR) in coherent optical orthogonal frequency division multiplexing (CO-OFDM), a hybrid PAPR reduction technique of the CO-OFDM system by combining iterative partial transmit sequence (IPTS) scheme with modified clipping and filtering (MCF) is proposed. The simulation results show that at the complementary cumulative distribution function (CCDF) of 10-4, the PAPR of proposed scheme is optimized by 1.86 dB and 2.13 dB compared with those of IPTS and CF schemes, respectively. Meanwhile, when the bit error rate (BER) is 10-3, the optical signal to noise ratio (OSNR) are optimized by 1.57 dB and 0.66 dB compared with those of CF and IPTS-CF schemes, respectively.

Hybrid PAPR Reduction Scheme for Universal Filter Multi-Carrier Modulation in Next Generation Wireless Systems

Universal filter multi carrier (UFMC) is one of the promising multi carrier modulation techniques for next generation wireless communication systems. UFMC seems to be most attractive because it provides better sub carrier separation like FBMC (Filer Bank Multi Carrier) and less complexity like OFDM (Orthogonal Frequency Division Multiplexing). But this technique suffers from limitation of higher Peak to Average Power Ratio (PAPR). In this paper a Hybrid PAPR reduction technique SC- UFMC have been proposed using SLM (Selective Mapping) and Clipping. The performance of proposed technique is evaluated for various design parameters including filter length, FFT size and Bits per sub carrier. The simulation results show that hybrid technique provides better PAPR reduction as compared with conventional SLM and clipping techniques.

Hybrid PAPR reduction scheme with Huffman coding and DFT-spread technique for direct-detection optical OFDM systems

Abstract High peak-to-average power ratio (PAPR) of the transmit signal is a major drawback in optical orthogonal frequency division multiplexing (OOFDM) system. In this paper, we propose and experimentally demonstrate a novel hybrid scheme, combined the Huffman coding and Discrete Fourier Transmission-Spread (DFT-spread), in order to reduce high PAPR in a 16-QAM short-reach intensity-modulated and direct-detection OOFDM (IMDD-OOFDM) system. The experimental results demonstrated that the hybrid scheme can reduce the PAPR by about 1.5, 2, 3 and 6 dB, and achieve 1.5, 1, 2.5 and 3 dB receiver sensitivity improvement compared to clipping, DFT-spread and Huffman coding and original OFDM signals, respectively, at an error vector magnitude (EVM) of −10 dB after transmission over 20 km standard single-mode fiber (SSMF). Furthermore, the throughput gain can be of the order of 30% by using the hybrid scheme compared with the cases of without applying the Huffman coding.

Hybrid PAPR Reduction Scheme for FBMC/OQAM Systems Based on Multi Data Block PTS and TR Methods

The filter bank multicarrier with offset quadrature amplitude modulation (FBMC/OQAM) is being studied by many researchers as a key enabler for the fifth-generation air interface. In this paper, a hybrid peak-to-average power ratio (PAPR) reduction scheme is proposed for FBMC/OQAM signals by utilizing multi data block partial transmit sequence (PTS) and tone reservation (TR). In the hybrid PTS-TR scheme, the data blocks signal is divided into several segments, and the number of data blocks in each segment is determined by the overlapping factor. In each segment, we select the optimal data block to transmit and jointly consider the adjacent overlapped data block to achieve minimum signal power. Then, the peak reduction tones are utilized to cancel the peaks of the segment FBMC/OQAM signals. Simulation results and analysis show that the proposed hybrid PTS-TR scheme could provide better PAPR reduction than conventional PTS and TR schemes in FBMC/OQAM systems. Furthermore, we propose another multi data block hybrid PTS-TR scheme by exploiting the adjacent multi overlapped data blocks, called as the multi hybrid (M-hybrid) scheme. Simulation results show that the M-hybrid scheme can achieve about 0.2-dB PAPR performance better than the hybrid PTS-TR scheme.

Hadamard Transform Combined with PTS for PAPR Reduction in Direct-Detection Optical OFDM System

High Peak-to-Average Power Ratio (PAPR) of the Orthogonal Frequency Division Multiplexing (OFDM) signal is one of the limitations to the transmission performance of optical OFDM system. In this paper, we propose a novel hybrid PAPR reduction technique called Hadamard Transform Combined with Partial transmit sequence (HTCP). The proposed HTCP scheme combines the merits of two complementary techniques, i.e., Hadamard transform and Partial Transmit Sequence (PTS), to improve the performance of the optical OFDM system in terms of PAPR and Bit Error Rate (BER). Simulation results show that the HTCP scheme has better performance with regard to PAPR and BER compared with the case of applying only the Hadamard transform or PTS technique.

PAPR Reduction in LTE Down Link using a Hybrid Repeated Clipping and SQRT Companding

The Orthogonal Frequency Division Multiplexing is one of the widely used modulation techniques in the broadband wireless technology. One of the main problems of the OFDM is the high peak-to-average power ratio of transmitting signal due to the superposition of many subcarriers. This paper presents a new hybrid peak-toaverage power ratio reduction technique, which repeated clipping and frequency domain filtering with SQRT companding over LET channel. The paper highlights the performance and advantages of the mixed technique. The simulations show that the proposed technique realizes an improved PAPR With acceptable BER.