Peak-to-average Power Ratio Suppression Research Articles

A combination of DST precoder and ICF based-methods for PAPR suppression in OFDM signal

Abstract One well-known demerit of orthogonal frequency division multiplexing (OFDM) is its high peak-to-average power ratio (PAPR) which limits the efficiency of high-power amplifier (HPA) and also destroys its bit error rate (BER) performance. Hence, a method based on grouping of discrete sine transform (DST) precoder and iterative clipping and filtering (ICF) is proposed to reduce PAPR in this article. The DST precoder reduces PAPR to certain level by changing phase of the signal. Moreover, the ICF technique is also implemented in DST based-OFDM signal for additional minimization of PAPR. Therefore, the proposed method (DST-ICF) preserves BER performance also from other existing methods. At complementary cumulative distribution function (CCDF) = 10−3, the simulation results indicate the proposed technique that minimizes PAPR with iteration values (I = 1, I = 2, and I = 3) to 6.37 dB, 5.29 dB, and 4.81 dB respectively. Moreover, at same BER, the E b /N 0 of proposed technique with iteration value (I = 3) is achieved by 9.75 dB for quadrature phase shift keying (QPSK).

A new complexity reduction scheme in selective mapping‐based visible light communication direct current‐biased optical orthogonal frequency division multiplexing systems

Visible light communication (VLC) has emerged as a good accompaniment to radio-frequency (RF) technologies by deploying multicarrier schemes such as orthogonal frequency division multiplexing (OFDM). However, the coherent summation of carriers in the OFDM system leads to a high peak-to-average-power ratio (PAPR), causing non-linear clipping distortion at the transmitting light-emitting diode. This intricacy becomes a potential barrier for intensity modulation and limits the VLC systems' bandwidth. In the literature, non-distorting PAPR lowering approaches, such as the selective mapping (SLM) approach, have been confirmed as the most effective strategy for reducing ineludible high PAPR in optical OFDM systems among all other available techniques. Besides its astounding performance, the computational complexity also becomes a major complication in SLM due to the generation of multiple candidates. This paper proposes a computational complexity minimisation approach using inherit system properties in the SLM-based PAPR suppression method for VLC systems, where the phase sequence vectors are considered periodic. The alternative direct current-biased optical orthogonal frequency division multiplexing candidates for the single frequency-domain data block are generated with the periodic phase rotation vector. The evaluation of the complexity analysis and the simulation results shows that the mitigation of computational complexity surpasses the standard SLM technique.

IM/DD probabilistically shaped 64-QAM OFDM-PON transmission assisted by selective-mapping and flexible systematic polar code

Intensity-modulation direct-detection (IM/DD) orthogonal frequency division multiplexing (OFDM) has advantages of low cost and simple structure, which is a promising candidate for next-generation high-speed passive optical networks. In this work, we propose and experimentally demonstrate a look-up-table-based probabilistic shaping scheme assisted by selective-mapping (SLM) and flexible systematic polar code (SPC) to improve the performance of IM/DD 64-QAM OFDM transmission system. Meanwhile, we experimentally compare the performance between the proposed scheme and the joint constant composition distribution matching (CCDM) and low-density parity-check (LDPC). Here, abundant phase sequences in the SLM are generated by chaotic sequence to suppress peak-to-average power ratio (PAPR). The pre-set bits of SPC are utilized for the additional information of probabilistic shaping to reduce the redundancy and the cyclic redundancy check (CRC) aided successive cancellation list (CA-SCL) decoder is used for decoding. Joint probabilistic shaping and PAPR suppression have contributed 4.6-dB and 3-dB bit error ratio performance improvements for the IM/DD 64-QAM OFDM transmission system in the pre and post forward error correction (FEC), respectively.

A companding approach for PAPR suppression in OFDM based massive MIMO system

Abstract Orthogonal frequency division multiplexing (OFDM) based massive multiuser (MU) multiple input multiple output (MIMO) system is popularly known as high peak-to-average power ratio (PAPR) issue. The OFDM-based massive MIMO system exhibits large number of antennas at Base Station (BS) due to the use of large number of high-power amplifiers (HPA). High PAPR causes HPAs to work in a nonlinear region, and hardware cost of nonlinear HPAs are very high and also power inefficient. Hence, to tackle this problem, this manuscript suggests a novel scheme based on the joint MU precoding and PAPR minimization (PP) expressed as a convex optimization problem solved by steepest gradient descent (GD) with μ-law companding approach. Therefore, we develop a new scheme mentioned to as MU-PP-GDs with μ-law companding to minimize PAPR by compressing and enlarging of massive MIMO OFDM signals simultaneously. At CCDF = 10−3, the proposed scheme (MU-PP-GDs with μ-law companding for Iterations = 100) minimizes the PAPR to 3.70 dB which is better than that of MU-PP-GDs, (iteration = 100) as shown in simulation results.

Sparsity-Learning-Based Iterative Compensation for Filtered-OFDM With Clipping

This letter is concerned with the high peak-to-average power ratio (PAPR) problem in filtered orthogonal frequency-division multiplexing (f-OFDM) systems. Iterative clipping and filtering (ICF) is adopted as a simple and effective method to suppress PAPR but introduces signal distortion. At the receiver, we propose a sparsity-learning based iterative algorithm for distortion compensation by exploiting the sparsity of the distortion. Specifically, our iterative algorithm consists of a linear estimator, a soft demodulator, and a distortion estimator. The iteration between the three modules is based on turbo message passing. We show that our scheme outperforms the conventional iterative methods in both complexity and performance. Numerical results demonstrate that our algorithm achieves more effective PAPR suppression and better error rate performance.

A Novel Conversion Vector-Based Low-Complexity SLM Scheme for PAPR Reduction in FBMC/OQAM Systems

Filter bank multicarrier with offset quadrature amplitude modulation (FBMC/OQAM) is considered as a powerful supplementary waveform for future wireless communications. However, FBMC systems have the same high peak-to-average power ratio (PAPR) problem as other multi-carrier systems, and the PAPR reduction methods designed for orthogonal frequency division multiplexing (OFDM) systems cannot be directly applied to FBMC systems due to the unique overlapping structure of FBMC signals. Therefore, some PAPR suppression schemes tailored to FBMC systems have been proposed, but their computational complexity is prohibitively high for some practical applications. In this paper, we propose a conversion vector-based low-complexity dispersive selection mapping (DSLM) scheme, called the C-DSLM scheme, to reduce the PAPR of FBMC signals. In the C-DSLM scheme, a series of conversion vectors is first carefully designed for FBMC signals with overlapping structures, and then candidate signals are generated by multiplying the original signal by the cyclic shift of the conversion vectors with only a few nonzero elements. The complexity evaluation and simulation results show that the C-DSLM scheme's PAPR suppression performance is similar to that of the DSLM scheme with computational complexity is only approximately 10% of that of the DSLM scheme. Our proposed C-DSLM scheme is highly efficient and strongly applicable.

Recursive Carrier Interferometry Aided High Data Rate OFDM Systems With PAPR Suppression, Phase Noise Rejection, and Carrier Frequency Offsets Compensation

In this paper, we propose two groups of recursive codes, namely the Hadamard recursive carrier interferometry (HRCI) codes and diagonal recursive carrier interferometry (DRCI) codes, to simultaneously reduce the peak-to-average power ratio (PAPR) and suppress the phase noises and residual carrier frequency offset (RCFO) for high-speed orthogonal frequency division multiplexing (OFDM) systems. We exploit the recursion property of the Hadamard and diagonal matrices to constitute the proposed HRCI code and DRCI code using the carrier interferometry (CI) code, and present the system model in details to spread OFDM symbols in the frequency domain. Then, we prove that both HRCI and DRCI generation matrices keep their invertibility during the recursions. As a direct result of the new code design, the phase intervals are enlarged and the signals are shifted in the time domain, thus both the PAPR and the phase noises are reduced, and the RCFO can be mitigated. Moreover, the enlarged phase intervals enable the transceiver blocks including the channel estimator, which estimate the phase noise based on the received signals, to improve the performance. Furthermore, we present the expressions for the HRCI and DRCI embedded transmitted and received signals, and derive the analytical signal-to-interference-plus-noise ratio (SINR) expressions for bit error rate (BER) performance analysis. Then, we analyze the effects of presented codes on the phase differences and provide the computational complexity analysis. Numerical simulations verify the effectiveness of our theoretical analysis of SINR. Additionally, under different parameter settings, which consider the working conditions of practical systems, we demonstrate that the presented robust HRCI and DRCI coded OFDM systems can suppress the PAPR satisfactorily and better BER performances can be achieved by the recursive CI-aided spread OFDM systems with phase noise rejection and RCFO compensation when compared with counterpart systems.

Joint Time-Frequency Alignment for PAPR and OOBE Suppression of OFDM-Based Waveforms

Orthogonal frequency division multiplexing (OFDM) waveform has been adopted by many wireless standards due to its numerous advantages. However, OFDM symbols have two critical drawbacks: high out-of-band emission (OOBE) and high peak-to-average power ratio (PAPR). Cyclic prefix (CP) alignment is one of the promising methods that jointly suppresses the OOBE and PAPR of OFDM symbols without introducing extra receiver complexity. However, its suppression performance remains limited in practical scenarios as it only exploits the degrees of freedom (DoFs) provided by the CP part of the OFDM symbols. In this letter, we propose a novel approach which jointly exploits the time domain resources, i.e., CP, and the frequency domain resources that are not effectively used by the receiver, i.e., guard tones and the subcarriers faded by the multipath channel. Thus, the available DoFs are substantially increased and more efficiently utilized for alignment purpose. It is shown that the OOBE and PAPR suppression performance is significantly enhanced with the proposed method as compared with the original approach.

PAPR Reduction Schemes for Lifting Scheme based Orthogonal Wavelet Packet Multiplexing System

Lifting scheme based orthogonal wavelet packet multiplexing (LOWPM) system can increase computation ef- ficiency and save storage space, but as a new multicarrier modulation system, it also has the problem of high peak to aver- age power ratio (PAPR). In order to reduce computational complexity and improve the effect of PAPR suppression for Partial Transmit Sequence (PTS) technology, PAPR reduction schemes based on the technology of pruning wavelet packet modulation and the improved threshold search for PTS are put forward in the paper, through proper pruning of the full-tree structure of wavelet packet modulation in the PTS to reduce the number of nodes in the system, and finally im- prove the effect of PAPR reduction, on the other hand through improving threshold search to increase processing effi- cience. Simulation results show that the proposed algorithm compared with the original algorithm has corresponding per- formance improvement, and on the condition that not to affect the original bit error rate of system, can better reduce PAPR, while decrease the computational complexity.

Research on Suppression Technology of OFDM Peak-to-Average Power Ratio

OFDM has a high peak to average power ratio ( PAPR ), when the signal PAPR over power amplifier ( HPA ) linear dynamic range, will introduce nonlinear distortion, affecting the signal transmission performance. In order to overcome the defects, OFDM need to adopt the corresponding PAPR suppression technique, the signal amplitude changes of power amplifiers in the allowable range. This paper presents a new partial transmit sequence algorithm ( PTS ), double phase sequence reversal threshold algorithm, and simulation results show that the new algorithm on the PAPR suppression effectiveness, search depth of T, the inhibition on PAPR performance.