An overview of peak-to-average power ratio reduction techniques for multicarrier transmission

High peak-to-average power ratio of the transmit signal is a major drawback of multicarrier transmission such as OFDM or DMT. This article describes some of the important PAPR reduction techniques for multicarrier transmission including amplitude clipping and filtering, coding, partial transmit sequence, selected mapping, interleaving, tone reservation, tone injection, and active constellation extension. Also, we make some remarks on the criteria for PAPR reduction technique selection and briefly address the problem of PAPR reduction in OFDMA and MIMO-OFDM.     

Adaptive PAPR Reduction Scheme for OFDM Using SLM with the Fusion of Proposed Clipping and Filtering Technique in Order to Diminish PAPR and Signal Distortion

One of the main disadvantages of multicarrier transmission is the high peak-to-average power ratio (PAPR) of the transmitted signal. If the highest transmitted power is confined by the application restrictions or regulatory, the result is to decrease the average power permitted under multicarrier transmission. Selected mapping (SLM) is a standard PAPR reduction scheme that is appropriate for orthogonal frequency division multiplexing (OFDM) scheme as it realizes the performance of PAPR reduction without signal distortion. This paper proposes a method in order to handle the difficulties of high PAPR in OFDM scheme. The offered system is an arrangement of two distinguished methods, such as clipping and SLM. Compared to other hybrid methods, where the individual methods are implemented sequentially, this paper integrates the clipping method in the SLM procedure. This produces a supplementary PAPR reduction associated to the serial arrangement. Simulation results specify that the offered scheme acquires the performance of appropriate PAPR reduction with low computational complexity. The PAPR reduction at different number of subcarriers is analyzed and compared with the existing research work. The performance of relative energy efficiency has also been focused on this paper.

     

A kind of PAPR reduction method based on pruning WPM and PTS technology

Wavelet packet multicarrier system gains widespread concern because of its better resistance performance to Inter-Symbol Interference (ISI) and Inter-Carrier Interference (ICI), as well as the higher spectrum efficiency. However, multicarrier system has a high Peak to Average Power Ratio (PAPR), which will lead to many problems such as lower system performance. In order to solve the problem, a kind of PAPR reduction method based on pruning Wavelet Packet Modulation (WPM) and Partial Transmit Sequences (PTS) technology is proposed in this paper, through proper pruning of the full-tree structure of wavelet packet modulation in the PTS technology to reduce the number of nodes in the system, and finally improve the reduction effect of PAPR. Simulation results show that when Complementary Cumulative Distribution Function (CCDF) is 10^?3, PTS based on pruning WPM compared with PTS technique and pruning technique has improved about 1 dB and 1.5 dB, which will not affect the system’s Bit Error Rate (BER) performance in the wavelet packet multicarrier system.     

Constrained Message Length Coding for Low Peak to Average Power Ratio in FBMC: OQAM Systems

The FBMC generation techniques are found to surmount the disadvantages of the IFFT/FFT based OFDM system. The minimization of PAPR is a much sought after solution by all multi-carrier methods. This paper investigates the possibility of a unified approach for error control coding and PAPR minimization in an FBMC-OQAM system. A new coding procedure called Constrained Message Length (CML) coding is presented in this paper. A new perspective on PAPR and an analytical framework for estimating the PAPR is also presented. Hybrid techniques using coding and companding are tested for different channel models, and their BER performance is on par with the BCH system. The proposed system is of low complexity and has a PAPR of only 3.81 dB, which is better than or comparable with the existing systems that are using complex methods. This paper has uniquely investigated the dependence of PAPR on the input data variation for a different set of random data loads. The CML coding proposed here can minimize the input data dependent PAPR deviation to a low variance of 0.045 dB, which provides an increased linear region of operation to the power amplifier in the RF section.

     

On the SER and spectral analyses of A-law companded multicarrier modulation

A peak-to-average power ratio (PAPR) reduction technique based on A-law companding is proposed for a multicarrier modulation (MCM) system. Multicarrier modulation is also known as orthogonal frequency-division multiplexing (OFDM) or digital multitone. The symbol error rate (SER) and spectral property of the companded MCM system are investigated. The SER and spectral performance of the proposed system are also compared with the uncompanded MCM system.     

A joint cross-layer transmission design with time–frequency coded cooperation HARQ for underground coal mine MC-CDMA WSNs

In this paper, multicarrier code division multiple access (MC-CDMA) modulation is adapted to constitute wireless sensors to improve the monitoring performance of wireless sensor networks (WSNs) for underground coal mine. A subcarrier phase compensation algorithm based on selective mapping (SLM) is proposed to reduce the relatively high PAPR of MC-CDMA signal. To further improve the monitoring performance of the underground MC-CDMA WSNs, a joint cross-layer transmission with time–frequency coded cooperation hybrid automatic repeat request (HARQ) is also proposed. The proposed cross-layer transmission combines time–frequency coded cooperation of physical layer with HARQ of media access control (MAC) layer. In the proposed transmission, the cooperative sensor utilizes time–frequency coded cooperation method to retransmit the monitoring information of source sensor at each retransmission time to obtain the coding gain and spatial diversity gain. Simulation results show that the proposed joint cross-layer transmission for underground coal mine MC-CDMA WSNs based on SLM phase compensation has significantly reduced the PAPR of MC-CDMA signal and improved the monitor performance of the coal mine MC-CDMA WSNs.     

Peak-to-average power reduction using partial transmit sequences: a suboptimal approach based on dual layered phase sequencing

A high peak-to-average power ratio (PAPR) is a major shortcoming in multicarrier systems, as it causes nonlinearity in the transmitter, degrading the performance of the system significantly. Partial transmit sequences (PTS) is one of the best methods in reducing PAPR, in which the information-bearing subcarriers are divided into M disjoint subblocks, each controlled by a phase rotation factor which brings PAPR down. Though PAPR reduction by PTS is more effective with more subblocks, there is a corresponding exponential increase in complexity. In this paper, a novel implementation of PTS is presented, in which a dual-layered approach is employed to reduce the complexity.     

一种基于快跳频技术的多载波CDMA系统

为进一步提高多载波CDMA系统的频带效率与抗干扰能力,提出了一种跳频多址技术结合多载波调制的传输方案,利用跳频技术将部分子载波传输与随机交织引入到多载波传输系统中,给出了系统实现的模型,并对该传输方案的系统带宽和误码性能进行了分析。理论分析与仿真结果表明：与以往的多载波CDMA系统相比,所建议系统的结构简单,性能优异,消除了已有系统中峰均功率比高和远近效应等问题,具有较强的抗多址干扰与窄带干扰的能力,并能有效地抗信道中突发错误的能力。     

A hybrid technique for the PAPR reduction of NOMA waveform

Non-orthogonal multiple access (NOMA) is a great contender for future cellular modulation due to its desirable properties like massive connectivity, high data rate transmission, and high spectral efficiency. However, its peak-to-average power ratio (PAPR) is significant, which becomes a significant disadvantage for the efficient operability of the NOMA waveform compared to current techniques. Several PAPR reduction algorithms like selective mapping (SLM), partial transmission sequence (PTS), and companding techniques have been proposed to lower the PAPR of multicarrier waveforms (MCWs). PTS reduces the PAPR but has high complexity. On the other hand, SLM has a less complex framework, but its PAPR performance is not as efficient as PTS. Companding methods reduce the PAPR by compressing the signals at the transmitter, which unfortunately reduces the dynamic range of the signal. In this work, we propose a hybrid algorithm (SLM + PTS) with a companding method for the first time for the NOMA waveform, which efficiently reduces the PAPR with low computational complexity. Furthermore, we compare the performances of a host of candidate algorithms like SLM, PTS, hybrid (SLM + PTS), hybrid + A law (SLM–PTS–A law), and hybrid + Mu law (SLM–PTS–Mu law). The results of the experiments show that the hybrid + Mu law did a better job than the existing PAPR reduction algorithms.     

A novel criterion for designing of nonlinear companding functions for peak-to-average power ratio reduction in multicarrier transmission systems

Nonlinear companding transform is a promising technique for the peak-to-average power ratio (PAPR) reduction in multicarrier transmission systems. However, conventional hard piecewise companding schemes often along with serious nonlinear distortion or complex companding parameters optimization embarrassment. In this paper, a novel designing criterion of nonlinear companding functions with more effective system performance is proposed. By transforming the Gaussian-distributed multicarrier signals into desirable statistics forms, we show that the smooth and differentiable concave probability distribution function of companded signals can obtain a better PAPR reduction and less out-of-band radiation as well as more simple companding parameters optimization than the traditional piecewise companding schemes. A detailed theoretical analysis and discussion is formulated, and then based on the analysis results, a novel trigonometric function companding scheme is presented and evaluated. Numerical results demonstrate that the companding schemes which consistent with the proposed criterion may significantly outperform conventional schemes by choosing the companding form and parameters appropriately.     

On the computation and reduction of the peak-to-average power ratioin multicarrier communications

For any code C defined over an equal energy constellation, it is first shown that at any time instance, the problem of determining codewords of C with high peak-to-average power ratios (PAPR) in a multicarrier communication system is intimately related to the problem of minimum-distance decoding of C. Subsequently, a method is proposed for computing the PAPR by minimum-distance decoding of C at many points of time. Moreover an upper bound on the error between this computed value and the true one is derived. Analogous results are established for codes defined over arbitrary signal constellations. As an application of this computational method, an approach for reducing the PAPR of C proposed by Jones and Wilkinson (1996) is revisited. This approach is based on introducing a specific phase shift to each coordinate of all the codewords where phase shifts are independent of the codewords and known both to the transmitter and the receiver. We optimize the phase shifts offline by applying our method for computing the PAPR for the coding scenario proposed by the ETSI BRAN Standardization Committee. Reductions of order 4.5 dB can be freely obtained using the computed phase shifts. Examples are provided showing that most of the gain is preserved when the computed optimal phase shifts are rounded to quantenary phase-shift keying (PSK), 8-PSK, and 16-PSK type phase shifts     

An efficient joint algorithm for reducing PAPR of SC-FDMA system in cognitive radio networks

Cognitive radio (CR) has been proposed as a solution for the spectrum scarcity problem. This paper investigates single-carrier frequency division multiple access (SC-FDMA) for cognitive radios. Recently, SC-FDMA has been suggested as a candidate for multicarrier based CR systems. In this paper, we propose enhanced techniques to reduce the peak to average power ratio (PAPR) in SC-FDMA for Cognitive Radio Network (CRN). We start by showing the effect of two standard PAPR reduction techniques (interleaver based and selective mapping) to reduce the PAPR in SC-FDMA based CR. Then, a proposed joint algorithm interleaver with selective mapping in a way that is suitable for SC-FDMA based CR will be proposed that results in a lower PAPR than using them individually. Simulation results show that the SC-FDMA with proposed techniques has a lower PAPR when compared with the conventional SC-FDMA system for CRN, while the complexity of the system slightly increases. Results also reveal that the no. of interleavers and SLM sequences must be chosen carefully in order to limit the PAPR with slightly increases in the complexity of the system.

     

PAPR Reduction in OFDM Signals: An Adaptive-Network-Based Fuzzy Inference Approach

In this paper, an adaptive-network-based fuzzy inference system (ANFIS) based scheme is analyzed and proposed for reducing the peak-to-average power ratio (PAPR) in multicarrier signals under additive white Gaussian noise and multipath fading (Raleigh) channel environment. This scheme involves training of ANFIS structure in time domain using Orthogonal Frequency Division Multiplexing signals with low PAPR, such as those obtained by approximate gradient project–null subcarrier switching (AGP–NCS) method. Once the ANFIS module is trained, the proposed scheme approximately offers similar reduction in PAPR as compared to AGP–NCS method, with significantly less convergence time and computational complexity. he results show that proposed approach is not only less complex but also maintains the data rate and bit error rate performance compared with other conventional schemes.     

Filter bank SCFDMA: an efficient uplink strategy for future communication systems

This paper develops a generalized system model for the precoded multicarrier communication system, using basic multirate building blocks. Mathematical analysis of the proposed model is carried out, and the results are utilized in developing an efficient uplink wireless communication standard filter bank single carrier frequency division multiple access. The proposed system combines the low peak to average power ratio (PAPR) advantage of a single carrier communication system with the reduced out of band emission (OBE) of filter bank multicarrier (FBMC) scheme. The sensitivity of the proposed system to carrier frequency offset (CFO) is analyzed, and the results are utilized in developing a CFO compensation scheme with reduced complexity. A Nyquist filter design approach, which strikes a balance between OBE and tail size, is developed and is incorporated into the proposed system to enhance the OBE and PAPR characteristics. The instantaneous power of the proposed system is theoretically analyzed using characteristic function based approach, and the effectiveness of modifications is substantiated. A detailed simulation study is carried out to validate the performance of the proposals.     

Improving PAPR performance of filtered OFDM for 5G communications using PTS

The filtered orthogonal frequency division multiplexing (F-OFDM) system has been recommended as a waveform candidate for fifth-generation (5G) communications. The suppression of out-of-band emission (OOBE) and asynchronous transmission are the distinctive features of the filtering-based waveform frameworks. Meanwhile, the high peak-to-average power ratio (PAPR) is still a challenge for the new waveform candidates. Partial transmit sequence (PTS) is an effective technique for mitigating the trend of high PAPR in multicarrier systems. In this study, the PTS technique is employed to reduce the high PAPR value of an F-OFDM system. Then, this system is compared with the OFDM system. In addition, the other related parameters such as frequency localization, bit error rate (BER), and computational complexity are evaluated and analyzed for both systems with and without PTS. The simulation results indicate that the F-OFDM based on PTS achieves higher levels of PAPR, BER, and OOBE performances compared with OFDM. Moreover, the BER performance of F-OFDM is uninfluenced by the use of the PTS technique.     

A Resource Allocation Framework for Scalable Video Broadcast in Cellular Networks

Video streaming is one of the most important applications that will make use of the high data rates offered by 4G networks. The current video transport techniques are already very advanced, and the more immediate problems lie in the joint optimization of video coding, AL-FEC, and PHY rate selection with the goal of enhancing the user perceived quality. In this work we provide an analysis of video broadcast streaming services for different combinations of layered coding and AL-FEC, using a realistic LTE PHY layer. Our simulation results show that the scalable content adaptation given by Scalable Video Coding (SVC) and the scheduling flexibility offered by the 3G-LTE MAC-layer provide a good match for enhanced video broadcast services for next generation cellular networks. Our proposed solution is compared to baseline algorithms and broadcast systems based on H.264/AVC streaming solutions. We emphasize the system quality improvement brought by our solution and discuss implications for a wide-scale practical deployment.     

Security aware hybrid precoding based peak‐to‐average power ratio reduction Approaches for telecommunication systems

In wireless telecommunication, one of the modulation approaches used is the orthogonal frequency division multiplexing (OFDM). Moreover, the high peak‐to‐average power ratio (PAPR) is the one notorious demerit in OFDM systems. Hence, the high power amplifier (HPA) is used in its linear region. Otherwise, the bit error rate (BER) will be increased. Several approaches are proposed in the wireless communications for reducing the PAPR issue. In this paper, we propose a hybrid Discrete Hartley Matrix Transform (DHMT) precoding using both selected mapping (SLM) and partial transmit sequence (PTS) PAPR reduction strategies. For the multicarrier modulation process, instead of Inverse Fast Fourier transform (IFFT) operation, the DHMT operation is used because of its low computational complexity. Based on multi‐chaotic, the time‐frequency domain encryption (TFDE) approach is adopted for physical layer security to confirm the security in data transmission. For enhancing the physical layer security, the proposed encryption system generates chaotic sequences based on Logistic maps and Lozi in the frequency and time domains together. In this study, the implementation of the DHMT‐based OFDM system is processed to reduce the maximum PAPR. Implementation is performed on the MATLAB platform, and the performances are calculated using complementary cumulative distribution function (CCDF), BER regards to signal‐to‐noise ratio (SNR), and the outputs are compared based on the computation time. However, compared with the existing models, the proposed model produced better PAPR minimization regarding SNR.     

A ZCMT Precoding Based Multicarrier OFDM System to Minimize the High PAPR

This paper presents a Zadoff-Chu matrix transform (ZCMT) precoding based multicarrier orthogonal-frequency-division-multiplexing (OFDM) system to minimize the high peak-to-average power ratio (PAPR). In the proposed system, ZCMT kernel is applied to the constellation symbols which not only reduces PAPR but also improves bit-error-rate (BER) performance. The ZCMT precoded OFDM signals allow the radio-frequency high-power-amplifier (HPA) to operate near its saturation level, thus maximize the power efficiency. Extensive computer simulations have been performed to analyze the PAPR, BER and power-spectral-density (PSD). Simulation results show that the proposed system has excellent PAPR gain and BER performance with no spectral distortion.     

A study on the PAPRs in multicarrier modulation systems with different orthogonal bases

This paper studies the peak‐to‐average power ratios (PAPRs) in multicarrier modulation (MCM) systems with seven different orthogonal bases, one Fourier base and six wavelet bases. It is shown by simulation results that the PAPRs of the Fourier‐based MCM system are lower than those of all wavelet‐based MCM (WMCM) systems. A novel threshold‐based PAPR reduction method is then proposed to reduce the PAPRs in WMCM systems. Both numerical and simulation results indicate that the proposed PAPR reduction method works very effectively in WMCM systems. Copyright © 2006 John Wiley & Sons, Ltd.     

New peak-to-average power-ratio reduction algorithms for multicarrier communications

New peak-to-average power-ratio (PAPR) reduction algorithms for multicarrier systems are developed by modifying the modulation constellation in active subcarriers and the modulation symbols in unused subcarriers. The proposed algorithms yield optimal PAPR-reduction solutions. For real-baseband multicarrier systems, the proposed PAPR-reduction algorithm is developed using a fast linear programming approach and considerable performance improvement can be achieved relative to that achieved with several existing algorithms. For passband multicarrier systems, a new PAPR-reduction algorithm is constructed whereby the associated minimax optimization problem is solved using an accelerated least-p th algorithm. Simulation results are presented which demonstrate that the proposed algorithm outperforms an algorithm due to Jones and that improved PAPR reduction can be achieved when the proposed algorithm is combined with another algorithm known as selective mapping scheme.