Impacts des non-linéarités dans les systèmes multi-porteuses de type FBMC-OQAM

In our work, we have studied the impact of in-band non linear distortions caused by PA on both OFDM and FBMC/OQAM systems. A theoretical approach was proposed to evaluate the BER performance for the two systems. This approach is based on modeling the in-band non-linear distortion with a complex gain and an uncorrelated additive white Gaussian noise, given by the Bussgang theorem. Then, we have proposed different techniques to compensate this NLD either on the transmitter or the receiver sides.Dans cette thèse une étude des performances des systèmes OFDM et FBMC/OQAM en présence d'amplificateur de puissance sans mémoire en terme de TEB est présentée. Ensuite, nous avons proposé une technique de linéarisation d'AP par pré-distorsion adaptative neuronale. Aussi, nous avons proposé deux techniques de correction des non-linéarités au niveau du récepteur

OFDM-FBMC performance in presence of non-linear high power amplifier

Dans cette thèse une étude des performances des systèmes OFDM et FBMC/OQAM en présence d'amplificateur de puissance sans mémoire en terme de TEB est présentée. Ensuite, nous avons proposé une technique de linéarisation d'AP par pré-distorsion adaptative neuronale. Aussi, nous avons proposé deux techniques de correction des non-linéarités au niveau du récepteur.In our work, we have studied the impact of in-band non linear distortions caused by PA on both OFDM and FBMC/OQAM systems. A theoretical approach was proposed to evaluate the BER performance for the two systems. This approach is based on modeling the in-band non-linear distortion with a complex gain and an uncorrelated additive white Gaussian noise, given by the Bussgang theorem. Then, we have proposed different techniques to compensate this NLD either on the transmitter or the receiver sides

Memory CO-NNPD for the Compensation of Memory Crosstalk and HPA Nonlinearity

In [1] and [2], authors proposed two efficient crossoverpredistortion schemes which are capable to compensatesimultaneously HPA nonlinearity and crosstalk effects inMIMO systems. The crosstalk model considered in thesepapers was memoryless one. However, memory effects ofcrosstalk can no longer be ignored due to the broadbandtransmitted signal.Then, in this paper, we demonstrate the effect of memorycrosstalk on the Crossover Neural Network Predistorter(CO-NNPD) proposed in [1]. Along, we propose a newcrossover predistortion structure based on this conventionalCO-NNPD which is capable to enhance good performancein MIMO OFDM systems in presence of HPA nonlinearitieswith taken into account the memory effects of crosstalk. TheLevenberg-Marquardt algorithm (LM) is used for neuralnetwork training, which has proven [3] to exhibit a verygood performance with lower computation complexity andfaster convergence than other algorithms used in literature.This paper is supported with simulation results for theAlamouti STBC MIMO OFDM system in terms of Bit ErrorRate (BER) in Rayleigh fading channel

Receiver Technique for Detection and Correction of Nonlinear High Power Amplifier Distortion Errors in OFDM systems

In this paper, we investigate receiver techniques for nonlinear high power amplifier distortion compensation inOrthogonal Frequency Division Multiplexing (OFDM) systems. We introduce a new method for the detection of the nonlinearlydistorted symbols received by the OFDM transmission system receiver. The proposed approach allows the determination ofthe position of the symbol in error and based on the Bussgang theorem application and the fast fourier transform (FFT), wecreate a set of a simultaneous equations which, when solved, return the true symbols before they were distorted. The numericalperformance evaluation shows that the proposed method enables significant performance improvement compared to conventionalreceivers

Iterative receiver cancellation of nonlinear power amplifier distortion in FBMC/OQAM system

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Sensitivity analysis of FBMC signals to Non Linear phase distortion

In this paper, we present a theoretical analysis ofthe impact of High Power Ampli?er (HPA) Non-Linear Distortion(NLD) on the Bit Error Rate (BER) of multicarrier techniques.For the aim of this study, the Saleh?s model was chosen forNL HPA. Two multicarrier schemes are considered: the classicalOrthogonal Frequency Division Multiplexing (OFDM) and theFilter Bank based Multi-Carrier (FBMC). According to theBussgang theorem, the in-band NLD is modeled as a complex gainand an independent additive noise term for both modulations.The BER performance of OFDM and FBMC modulations,transmitting over an Additive Withe Gaussian Noise (AWGN)and Rayleigh channels, is theoretically evaluated and comparedto simulation results. We have established that OFDM and FBMCmodulations show the same performances, in terms of BER, whenjust amplitude distortion is induced by the HPA. However, FBMCsystem is more sensitive to phase distortions when no correctionis adopted at the receiver. This behavior has been explained bythe difference between the probability distribution of the intrinsicinterference present in both OFDM and FBMC modulations

Theoretical analysis of BER performance of nonlinearly amplified FBMC/OQAM and OFDM signals

In this paper, we introduce an analytical study of the impact of high-power amplifier (HPA) nonlinear distortion (NLD) on the bit error rate (BER) of multicarrier techniques. Two schemes of multicarrier modulations are considered in this work: the classical orthogonal frequency division multiplexing (OFDM) and the filter bank-based multicarrier using offset quadrature amplitude modulation (FBMC/OQAM), including different HPA models. According to Bussgang's theorem, the in-band NLD is modeled as a complex gain in addition to an independent noise term for a Gaussian input signal. The BER performance of OFDM and FBMC/OQAM modulations, transmitting over additive white Gaussian noise (AWGN) and Rayleigh fading channels, is theoretically investigated and compared to simulation results. For simple HPA models, such as the soft envelope limiter, it is easy to compute the BER theoretical expression. However, for other HPA models or for real measured HPA, BER derivation is generally intractable. In this paper, we propose a general method based on a polynomial fitting of the HPA characteristics and we give theoretical expressions for the BER for any HPA model. © 2014 Bouhadda et al.; licensee Springer

Theoretical analysis of BER performance of non-linearly ampli?ed FBMC/OQAM and OFDM signals

In this paper, we introduce an analytical study of the impact of high-power amplifier (HPA) nonlinear distortion (NLD) on the bit error rate (BER) of multicarrier techniques. Two schemes of multicarrier modulations are considered in this work: the classical orthogonal frequency division multiplexing (OFDM) and the filter bank-based multicarrier using offset quadrature amplitude modulation (FBMC/OQAM), including different HPA models. According to Bussgang?s theorem, the in-band NLD is modeled as a complex gain in addition to an independent noise term for a Gaussian input signal. The BER performance of OFDM and FBMC/OQAM modulations, transmitting over additive white Gaussian noise (AWGN) and Rayleigh fading channels, is theoretically investigated and compared to simulation results. For simple HPA models, such as the soft envelope limiter, it is easy to compute the BER theoretical expression. However, for other HPA models or for real measured HPA, BER derivation is generally intractable. In this paper, we propose a general method based on a polynomial fitting of the HPA characteristics and we give theoretical expressions for the BER for any HPA model

Adaptive Predistortion techniques for non-linearly ampli?ed FBMC-OQAM signals

The Filter Bank Multicarrier with Offset Quadra-ture Amplitude Modulation (FBMC-OQAM) is emerging as oneof the alternatives to Orthogonal Frequency Division Multi-plexing (OFDM) for next generation broadband wireless accesssystems. In this paper, we focus on the nonlinear distortion effectsin a FBMC-OQAM system when the signal is passed througha nonlinear High Power Ampli?er (HPA) which is modeled asSaleh?s one exhibiting amplitude and phase distortions. First, wedevelop an analysis showing that the FBMC-OQAM signals aremore sensitive to the phase distortion than OFDM signals. Then,we address the problem of the compensation of these distortionsin FBMC-OQAM systems using digital predistortion (DPD) atthe transmitter. Therefore, two DPD schemes are considered inthis investigation and their performance are compared in OFDMand FBMC-OQAM systems