Large Peak-to-average Power Ratio Research Articles

Low-Complexity Blind PAPR Reduction for OFDM Systems With Rotated Constellations

The high Peak-to-Average Power Ratio (PAPR) of Orthogonal Frequency Division Multiplexing (OFDM) signals leads to a serious system performance degradation. To work around this issue, several algorithms have been proposed in the literature to reduce the PAPR, but, they often suffer from multiple limitations; in particular, the main issue with interleaving techniques is the spectral efficiency loss, as the transmission of a Side Information (SI) is generally required. In contrast to previous works, this article proposes a blind interleaving technique for OFDM systems with signal space diversity. Indeed, with Rotated and Cyclically Q-Delayed (RCQD) constellations, the In-phase (I) and Quadrature (Q) components of constellations symbols are correlated, which allows the receiver to estimate the interleaver index without any SI. Moreover, to lower down the complexity burden at the receiver side, we first design a blind decoder based on the Minimum Mean Square Error (MMSE) criterion and we then propose a low complexity decoder for the Uniformly Projected RCQD (UP-RCQD) QAM, as this constellation has several interesting structural properties and achieves near optimum BER performance. Simulation results show that our proposal leads to a large PAPR reduction and to a near optimum BER performance that outperforms, over various channels, the solution currently used in DVB-T2. They also underline the good performance of the blind decoding performed with up to 98% of complexity reduction compared to the max-log Maximum Likelihood (ML) estimation.

PAPR and BER Reduction on Improving Performance for Filtered-OFDM using MSM and PSO

Filtered-Orthogonal Division Multiplexing (F-OFDM) is one of the capable alternative candidate modulation methods for 5G communication systems. F-OFDM utilizes the allocated spectrum by having lower side-lobes, which leads to higher spectral efficiency. However, it experiences an elevated peak-to-average power ratio (PAPR). This influences the radio frequency components’ operation mode, such as the power amplifier and the digital-to-analog converter. Also, high PAPR builds the amplifiers to exertion in non-linear regions and enhance the Bit Error Rate (BER). Moreover, Large PAPR guides to spectral spreading and band distortion. Selective Mapping (SLM) provides enhanced PAPR reduction without the data rate loss and also exclusive of the signal distortion. Though, SLM has elevated computational complexity additionally. Numerous procedures have been suggested in the research for OFDM. In this thesis, a modified-SLM using Discrete Sine Transform (DST) is recommended to lessen the PAPR of filtered-OFDM. The idea of a Discrete Sine Transform is de-correlating the data in a sequence by compressed a large amount of signal energy into a few transform coefficients; consequently it provides an improved diminution in PAPR. Furthermore, the BER performance of the system has been enhanced by applying an optimization algorithm called Particle Swarm Optimization (PSO). This proposed model results illustrate that the proposed Modified Selective mapping using Discrete Sine Transform (MSLM-DST) technique can provide a PAPR reduction of about 4.4 dB. Moreover, the PSO improved the system performance as it significantly reduces the BER of the system.

Joint BER Optimization and Blind PAPR Reduction of OFDM Systems With Signal Space Diversity

This letter deals with a peak-to-average power ratio (PAPR) reduction scheme for orthogonal frequency division multiplexing (OFDM) systems with signal space diversity. An original algorithm for the selection of two rotated and cyclically Q-delayed (RCQD) QAM constellations is proposed to jointly optimize the bit error rate (BER) and the blind detection performance of a selected mapping (SLM) technique. Simulation results show that the proposed method achieves a large PAPR reduction with no spectral spoilage and also enhances the BER performance in the case of DVB-T2 over different channels.

Companding techniques for SC-FDMA and sensor network applications

ABSTRACT The large Peak-to-Average Power Ratio (PAPR) is a serious problem in wireless communication systems for mobile and sensor network applications. This paper presents efficient non-linear techniques to solve the large PAPR problem in Single-Carrier Frequency Division Multiple Access (SC-FDMA) system and Wireless Sensor Network (WSN) systems. The performance of the proposed techniques is investigated over a realistic channel model. Simulation results reveal PAPR reduction while preserving low Bit Error Rate (BER) levels.

BER Reduction Using Precoded OFDM in Power-line Channel

Power-line Communications (PLC) effectively uses the pervasive power grid as a high data rate communication medium. Despite its advantages, the presence of severe multipath fading and susceptibility to impulsive noise make reliable communication in a PLC system challenging. In PLC systems, orthogonal frequency-division multiplexing (OFDM) is an attractive choice mainly due to its resilience to multipath fading. However, OFDM signals suffers from large peak-to-average power ratio (PAPR) thus resulting in non-linear signal distortions at the transmitter. Therefore, for an OFDM-based PLC system, the combined effect of large PAPR and the presence of impulsive noise results in high bit error rate (BER). This paper proposes the use of precoding at the transmitter to reduce PAPR, and blanking non-linearity at the receiver to mitigate impulsive noise. Precoding is a data-independent and robust PAPR reduction scheme that essentially distributes the power of the individual OFDM symbols over the entire OFDM block. Blanking is an effective impulsive noise mitigation technique that results in better BER performance at the receiver. Simulation results show that, with the combination of precoding and blanking, significant gains in BER performance for an OFDM based PLC system can be obtained with minimal increase of transceiver complexity.

Adaptive Wavelet Packet Modulation

In this paper, we propose a new adaptive modulation based on the wavelet packet transform, which targets a good resistance against frequency selective channels while avoiding a large PAPR. Classical multi-carrier modulation schemes divide the channel bandwidth into narrowband sub-channels to improve its robustness against frequency selective fading. However, they suffer from the peak-to-average power ratio (PAPR) problem, which occurs due to a random constructive addition of sub-carriers. By contrast, single carrier modulation schemes, where each transmitted symbol fully occupies the bandwidth, are more sensitive to frequency selective environments and less affected by the PAPR problem. In this paper, we show how the bandwidth division can be reconfigurable and adapted to the channel properties, and we provide several examples to prove that the proposed adaptive modulation represents an alternative modulation which is adjustable between two extreme cases: single carrier modulation and classical multi-carrier modulation.

Peak-to-Average Power Ratio Reduction in OFDM Index Modulation Through Convex Programming

Orthogonal frequency division multiplexing (OFDM) index modulation (IM) is a new multi-carrier modulation where the sub-carriers have two states, active and idle, and the indices of the active sub-carriers carry information. Although showing many advantages over OFDM, OFDM-IM also inherits the high peak-to-average power ratio (PAPR) problem. In this letter, utilizing the signal feature of OFDM-IM, a high-efficient PAPR reduction method is proposed. Concretely, a small dither in the idle sub-carrier is introduced to reduce the PAPR, and the design of the optimal dither signal can be solved by the convex programming. Simulation results show that the proposed method can achieve a large PAPR reduction when a proper amplitude constraint on the dither signal is employed.

Peak-to-Average Power Ratio Reduction Using Adaptive Subcarrier Phase Adjustment Algorithm for OFDM-Based Cognitive Radio

Cognitive radio technology with orthogonal frequency-division multiplexing provides great flexibility in spectrum utilization. An efficient adaptive search algorithm for computing subcarrier phase adjustments is proposed in this paper. This algorithm leads to coherent cancellation of subcarriers, and hence peak-to-average power ratio (PAPR) reduction. In traditional subcarrier phase adjustment techniques for PAPR reduction, there is a need to send a large amount of side information that may deteriorate the system throughput. On the other hand, the proposed algorithm sets the side information adaptively with an updating phase vector. Simulation results reveal that the proposed algorithm achieves a large PAPR reduction for a wide range of operating conditions as the traditional algorithms, while reducing the amount of side information. This side information reduction is attributed to the independency of the side information of the number subcarriers.

Efficient Application of Selected Mapping with Clipping for PAPR Reduction in OFDM Systems

Orthogonal Frequency Division Multiplexing (OFDM) is an inimitable technology in wireless communication. High peak-to-average power ratio (PAPR) is a challenging issue in OFDM system. Large PAPR results in significant distortion in OFDM signal when passed through nonlinear high power amplifier. Selected mapping (SLM) is an efficient technique to reduce PAPR. In this work we efficiently apply SLM technique with clipping to reduce PAPR. And the simulation results show that the proposed techniques have better PAPR reduction performance than conventional Selected Mapping technique and SLM with interleaving.

Comparison and analysis of PAPR reduction techniques in OFDM

In this paper, different techniques for reducing Peak To Average Power Ratio (PAPR) is discussed. The performance of an orthogonal frequency division multiplexing(OFDM) system is degraded if the peak-toaverage power ratio(PAPR) is high. An OFDM system dynamic range is typically two or four times larger than a single carrier system increasing value of the dynamic range will lead to an increased cost, power consumption of transmitter amplifier and also lead to high peak to average power ratio (PAPR). This is one of the major drawbacks of OFDM system. A serious problem of large PAPR presents when energy-inefficient nonlinear power amplifiers are used. Several techniques have been proposed to reduce PAPR in OFDM system, out of that few are selective mapping (SLM), tone reservation and partial transmit sequence. SLM method could be used to reduce PAPR, however, it causes the BER degradation and increases computational complexity. The good improvement in PAPR given by the present techniques permits the reduction of the complexity and cost of the transmitter significantly.

Simple Alternative Multisequences for PAPR Reduction Without Side Information in SFBC MIMO-OFDM Systems

In this paper, we propose a novel alternative multisequence (AMS) scheme for the peak-to-average power ratio (PAPR) reduction in multiple-input-multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM) systems with space-frequency block coding (SFBC). The key idea of the proposed scheme is keeping the advantage of the SFBC structure to generate some AMSs via combining the signals at different transmit antennas. Specifically, when the proposed scheme is employed in SFBC MIMO OFDM systems with quadrature-amplitude modulation (QAM), one of the big advantages is that the side information (SI) does not need to be sent to the receiver. Theoretical analysis and simulation results validate that the proposed scheme has the ability to provide large PAPR reduction, a low bit error rate, and low computational complexity without SI in SFBC MIMO-OFDM systems.

Design and Performance of Overlap FFT Filter-Bank for Dynamic Spectrum Access Applications

An OFDMA-based (Orthogonal Frequency Division Multiple Access-based) channel access scheme for dynamic spectrum access has the drawbacks of large PAPR (Peak to Average Power Ratio) and large ACI (Adjacent Channel Interference). To solve these problems, a flexible channel access scheme using an overlap FFT filter-bank was proposed based on single carrier modulation for dynamic spectrum access. In order to apply the overlap FFT filter-bank for dynamic spectrum access, it is necessary to clarify the performance of the overlap FFT filter-bank according to the design parameters since its frequency characteristics are critical for dynamic spectrum access applications. This paper analyzes the overlap FFT filter-bank and evaluates its performance such as frequency characteristics and ACI performance according to the design parameters.

A Novel Dynamic Channel Access Scheme Using Overlap FFT Filter-Bank for Cognitive Radio

An OFDMA based channel access scheme is proposed for dynamic spectrum access to utilize frequency spectrum efficiently. Though the OFDMA based scheme is flexible enough to change the bandwidth and channel of the transmitted signals, the OFDMA signal has large PAPR (Peak to Average Power Ratio). In addition, if the OFDMA receiver does not use a filter to extract sub-carriers before FFT (Fast Fourier Transform) processing, the designated sub-carriers suffer large interference from the adjacent channel signals in the FFT processing on the receiving side. To solve the problems such as PAPR and adjacent channel interference encountered in the OFDMA based scheme, this paper proposes a novel dynamic channel access scheme using overlap FFT filter-bank based on single carrier modulation. It also shows performance evaluation results of the proposed scheme by computer simulation.

New Papr Reductionin Ofdm Systems By Hybrid Algorithm of Ptsand Appr Methods

In this paper, we propose a new peak to average power ratio (PAPR) reduction technique by a hybrid algorithm based on a partial transmit sequence (PTS) and adaptive peak power reduction (APPR ) methods. This technique is used in a system based on orthogonal frequency division multiplexing (OFDM). OFDM has orthogonally modulated sub-carriers which unexpectedly give large PAPR and tends to reduce the power efficiency of a RF amplifier. To reduce PAPR, the sequence of input data is rearranged by PTS for the reduction of PAPR and then fed to APPR process in the proposed system. The APPR method controls the peak level of the modulation signal by an adaptive algorithm. It reduces modulation signals over a predefined range. A proposed reduction method consists of these two methods and realizes both advantages at the same time. In simulation results, the proposed method shows the improvement on PAPR, PSD, and also the high performance on bit error rate of an OFDM system.

Performance of an adaptive predistorted power amplifier with peak limited baseband code‐division multiplexed signal

AbstractIn FDM and CDM systems, the peak‐to‐average power ratio (PAPR) increases as the number of signals to be multiplexed is increased. When a signal with a large PAPR is incident on a power amplifier, either the out‐of‐band radiation is increased or the power efficiency is degraded. Methods of resolving these problems are nonlinear distortion compensation techniques, one of which is the predistorter. Another conceivable solution is to suppress the PAPR of the input signal. In this paper, we first study the performance when a limiter is used for the CDM signal in the baseband. By computer simulation, it is shown that the PAPR is suppressed by using a limiter and that the deterioration of the SIR performance is small if the PAPR is more than 6 dB. Next, the characteristics are studied by numerical simulation when a CDM signal with a limiter in the baseband is input to an adaptive predistorter‐type distortion‐compensated power amplifier. By combining the CDM signal with a limiter in the baseband and the adaptive predistorter‐type distortion‐compensated power amplifier, it is possible to suppress the out‐of‐band radiated power and simultaneously increase the power efficiency. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 87(2): 37–45, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10154

PAPR reduction using soft clipping and ACI rejection in OFDM system

OFDM (orthogonal frequency division multiplexing) is usefully applied for DAB (digital audio broadcasting) and DVB (digital video broadcasting) systems due to its high spectral efficiency and robustness to ISI (intersymbol interference) and multipath fading. However, the OFDM signal has a large PAPR (peak-to-average power ratio), which results in significant nonlinear distortion when it passes through an HPA (high power amplifier) such as a TWTA (traveling wave tube amplifier) and a SSPA (solid state power amplifier). We propose a new PAPR reduction method using soft clipping and filtering. Unlike conventional hard clipping, soft clipping has non-zero slope in the clip region. Next, filtering, which uses additional FFT and IFFT processes, is applied in order to reject the out-of-band clip noise. Although the filtering removes the out-of-band noise, it oppositely increases PAPR by a small amount. Since an HPA increases the power consumption according to the linearity range, soft clipping for an SSPA lowers power consumption and is more efficient than the conventional hard clipping method. By the results of the proposed method, the wanted PAPR can be obtained and there is no out-of-band radiation caused by the clipping process.

Level clipped high-order OFDM

The asymptotic behavior of level clipped orthogonal frequency-division multiplexing when its order N approaches infinity is analyzed. It is shown that if the clipping level approaches infinity faster than /spl radic/lnN, then a zero bit-error rate penalty and arbitrarily large peak to-average power ratio (PAPR) gain are asymptotically obtained. Moreover, the expression for the probability of clipping is found, and using it, the upper bound of the probability of error is derived. This upper bound can be used to analyze the tradeoff between PAPR and probability of error.