Les applications de variation de vitesse des machines alternatives mettent en oeuvre des réseaux Modulés en Largeur d’Impulsion (MLI). La commande de ces machines nécessite la connaissance de données comme la vitesse ou la position du rotor. La transmission des données par Courant Porteur en Ligne (CPL) sur le réseau d’énergie permet de simplifier l’installation et l’entretien du système, d’augmenter sa fiabilité et de réduire son coût. Les modems CPL actuellement disponibles ne sont pas compatibles avec les applications de variation de vitesse. Le bruit (tension MLI) de type impulsionnel ainsi que l’atténuation du signal de communication à travers les câbles d’énergie sont les deux principaux obstacles au déploiement du CPL sur les réseaux MLI. Le développement d’une solution spécifique est donc nécessaire pour pouvoir utiliser le CPL. A partir du banc d’essai, le moteur, les câbles triphasés de longueurs de 10, 60 et 110 mètres et l’onduleur ont été modélisés et une fonction de transfert du canal est obtenue et validée par des mesures., La tension MLI a été mesurée et caractérisée. À partir de ces données, un calcul du rapport canal à bruit (CNR) a permis d’identifier les fréquences centrales optimales. Deux paires de coupleurs (Rx, Tx) sont réalisées autour de ces fréquences avec une bande passante de 10MHz. Un simulateur de communication intégrant le modèle du canal et du bruit a été développé. Le banc d’essai a été enrichi avec un système de modulation/démodulation QAM complet. Les résultats de simulation, en termes de puissance, débit et TEB, sont ensuite comparés aux résultats obtenus par le banc d’essai. / Pulse Width Modulated (PWM) networks are used in adjustable-speed drive applications. Data like, speed and rotor position, coming from sensors on the motor, are necessary for the control. Other data like, temperature and current value are important for monitoring purposes. Using Power Line Communication (PLC) techniques to transfer data from those sensors to the control has some numerous benefits. The most obvious are, simplified installation and maintenance, increase of reliability and reduction of cost. Unfortunately, PLC modems used in low-voltage sinusoidal network are not compatible with this type of application. In fact, the PLC signal suffers from power cables attenuation. In addition, the PWM voltage can generate high level noise in the bandwidth used by traditional PLC modems. Therefore, a specific PLC solution is needed in this type of applications. To find an optimized solution, the motor, the inverter as well as the cables (10, 60 and 110 meters) are modeled by a chain matrix. The transfer function calculated from the model is verified by measurements. Afterward, the PWM voltage is measured and characterized. Using the transfer function in addition to the PWM measurements, the Channel to Noise Ratio (CNR) is calculated. The CNR provides the best two center frequencies for PLC couplers. For each frequency, a couple of couplers (Tx, Rx) of 10MHz width is made. A communication simulator is made using channel model and noise (PWM) measurements. In addition, the test bench is upgraded with a QAM modem. A wide comparison is made between results (output power, bit rate and BER) obtained from the test bench and from simulations.

In recent years Multiple Input Multiple Output (MIMO) systems have been employed in wireless communication systems to reach the goals of high data rate. A MIMO use multiple antennas at both transmitting and receiving ends. These antennas communicate with each other on the same frequency band and help in linearly increasing the channel capacity. Due to the multi paths wireless channels face the problem of channel fading which cause Inter Symbol Interference (ISI). Each channel path has an independent path delay, independent path loss or path gain and phase shift, cause deformations in a signal and due to this deformation the receiver can detect a wrong or a distorted signal. To remove this fading effect of channel from received signal many Neural Network (NN) based channel equalizers have been proposed in literature. Due to high level non-linearity, NN can be efficient to decode transmitted symbols that are effected by fading channels. The task of channel equalization can also be considered as a classification job. In the data (received symbol sequences) spaces NN can easily make decision regions. Specifically, NN has the universal approximation capability and form decision regions with arbitrarily shaped boundaries. This property supports the NN to be introduced and perform the task of channel equalization and symbol detection. This research project presents the implementation of NN to be use as a channel equalizer for Rayleigh fading channels causing ISI in MIMO systems. Channel equalization has been done using NN as a classification problem. The equalizer is implemented over MIMO system of different forms using Quadrature Amplitude Modulation scheme (4QAM & 16QAM) signals. Levenberg-Marquardt (LM), One Step Secant (OSS), Gradient Descent (GD), Resilient backpropagation (Rprop) and Conjugate Gradient (CG) algorithms are used for the training of NN. The Weights calculated during the training process provides the equalization matrix as an estimate of Channel. The output of the NN provides the estimate of transmitted signals. The equalizer is assessed in terms of Symbol Error Rate (SER) and equalizer efficiency.

The thesis focuses on consideration of possible ways how to realize multi-state modulators for a laboratory instrument. This instrument will illustrate signals, which partake on generation QAM modulation. The design of the laboratory instrument includes theoretic schemata and the execution of a prototype. There are theoretical facts of multi-state signals and multi-state modulations in this thesis. A simple block diagram of the laboratory instrument is made by the theory of creating quadrature amplitude modulation. For each block there are made several schemata, which are compiled to the global scheme. A printed circuit board and the structure items are made by the aid of the global scheme. The next part is devoted to a software facility for a used microprocessor, which ensures the whole function of the laboratory instrument. The final section deals with measuring, which checks the function of the modulator and the right setting coder’s constellation diagrams.

The main aim of this master's thesis was the create function models of wireless network technologies using the modern multitones modulation like is PFDM and FMT. This work is realised in Matlab – Simulink enviroment and models are tested in development kit. Development kit is universal software defined radio developer by Ettus.

Detecting and correcting errors occurring in the transmitted data through a channel is a task of great importance in digital communication. In Error Correction Coding (ECC), some redundant data is added with the original data while transmitting. By exploiting the properties of the redundant data, the errors occurring in the data from the transmission can be detected and corrected. In this thesis, a new coding algorithm named Signal Point Target Code has been studied and various properties of the proposed code have been extended. Signal Point Target Code (SPTC) uses a predefined shape within a given signal constellation to generate a parity symbol. In this thesis, the relation between the employed shape and the performance of the proposed code have been studied and an extension of the SPTC are presented. This research presents simulation results to compare the performances of the proposed codes. The results have been simulated using different programming languages, and a comparison between those programming languages is provided. The performance of the codes are analyzed and possible future research areas have been indicated.

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Neste trabalho, são propostos e analisados algoritmos autodidatas eficientes para a equalização de canais de comunicação, considerando a transmissão de sinais QAM (quadrature amplitude modulation). Suas funções de erro são construídas de forma a fazer com que o erro de estimação seja igual a zero nas coordenadas dos símbolos da constelação. Essa característica os possibilita ter um desempenho similar ao de um algoritmo de equalização supervisionada como o NLMS (normalized least mean-square), independentemente da ordem da constelação QAM. Verifica-se analiticamente que, sob certas condições favoráveis para a equalização, os vetores de coeficientes dos algoritmos propostos e a correspondente solução de Wiener são colineares. Além disso, usando a informação da estimativa do símbolo transmitido e de seus símbolos vizinhos, esquemas de baixo custo computacional são propostos para aumentar a velocidade de convergência dos algoritmos. No caso do algoritmo baseado no critério do módulo constante, evita-se sua divergência através de um mecanismo que descarta estimativas inconsistentes dos símbolos transmitidos. Adicionalmente, apresenta-se uma análise de rastreio (tracking), que permite obter expressões analíticas para o erro quadrático médio em excesso dos algoritmos propostos em ambientes estacionários e não-estacionários. Através dessas expressões, verifica-se que com sobreamostragem, ausência de ruído e ambiente estacionário, os algoritmos propostos podem alcançar a equalização perfeita, independentemente da ordem da constelação QAM. Os algoritmos são estendidos para a adaptação conjunta dos filtros direto e de realimentação do equalizador de decisão realimentada, levando-se em conta um mecanismo que evita soluções degeneradas. Resultados de simulação sugerem que a utilização dos esquemas aqui propostos pode ser vantajosa na recuperação de sinais QAM, fazendo com que seja desnecessário o chaveamento para o algoritmo de decisão direta. / In this work, we propose efficient blind algorithms for equalization of communication channels, considering the transmission of QAM (quadrature amplitude modulation) signals. Their error functions are constructed in order to make the estimation error equal to zero at the coordinates of the constellation symbols. This characteristic enables the proposed algorithms to have a similar performance to that of a supervised equalization algorithm as the NLMS (normalized least mean-square), independently of the QAM order. Under some favorable conditions, we verify analytically that the coefficient vector of the proposed algorithms are collinear with the Wiener solution. Furthermore, using the information of the symbol estimate in conjunction with its neighborhood, we propose schemes of low computational cost in order to improve their convergence rate. The divergence of the constant-modulus based algorithm is avoided by using a mechanism, which disregards nonconsistent estimates of the transmitted symbols. Additionally, we present a tracking analysis in which we obtain analytical expressions for the excess mean-square error in stationary and nonstationary environments. From these expressions, we verify that using a fractionally-spaced equalizer in a noiseless stationary environment, the proposed algorithms can achieve perfect equalization, independently of the QAM order. The algorithms are extended to jointly adapt the feedforward and feedback filters of the decision feedback equalizer, taking into account a mechanism to avoid degenerative solutions. Simulation results suggest that the proposed schemes may be advantageously used to recover QAM signals and make the switching to the decision direct mode unnecessary.

Neste trabalho, são propostos e analisados algoritmos autodidatas eficientes para a equalização de canais de comunicação, considerando a transmissão de sinais QAM (quadrature amplitude modulation). Suas funções de erro são construídas de forma a fazer com que o erro de estimação seja igual a zero nas coordenadas dos símbolos da constelação. Essa característica os possibilita ter um desempenho similar ao de um algoritmo de equalização supervisionada como o NLMS (normalized least mean-square), independentemente da ordem da constelação QAM. Verifica-se analiticamente que, sob certas condições favoráveis para a equalização, os vetores de coeficientes dos algoritmos propostos e a correspondente solução de Wiener são colineares. Além disso, usando a informação da estimativa do símbolo transmitido e de seus símbolos vizinhos, esquemas de baixo custo computacional são propostos para aumentar a velocidade de convergência dos algoritmos. No caso do algoritmo baseado no critério do módulo constante, evita-se sua divergência através de um mecanismo que descarta estimativas inconsistentes dos símbolos transmitidos. Adicionalmente, apresenta-se uma análise de rastreio (tracking), que permite obter expressões analíticas para o erro quadrático médio em excesso dos algoritmos propostos em ambientes estacionários e não-estacionários. Através dessas expressões, verifica-se que com sobreamostragem, ausência de ruído e ambiente estacionário, os algoritmos propostos podem alcançar a equalização perfeita, independentemente da ordem da constelação QAM. Os algoritmos são estendidos para a adaptação conjunta dos filtros direto e de realimentação do equalizador de decisão realimentada, levando-se em conta um mecanismo que evita soluções degeneradas. Resultados de simulação sugerem que a utilização dos esquemas aqui propostos pode ser vantajosa na recuperação de sinais QAM, fazendo com que seja desnecessário o chaveamento para o algoritmo de decisão direta. / In this work, we propose efficient blind algorithms for equalization of communication channels, considering the transmission of QAM (quadrature amplitude modulation) signals. Their error functions are constructed in order to make the estimation error equal to zero at the coordinates of the constellation symbols. This characteristic enables the proposed algorithms to have a similar performance to that of a supervised equalization algorithm as the NLMS (normalized least mean-square), independently of the QAM order. Under some favorable conditions, we verify analytically that the coefficient vector of the proposed algorithms are collinear with the Wiener solution. Furthermore, using the information of the symbol estimate in conjunction with its neighborhood, we propose schemes of low computational cost in order to improve their convergence rate. The divergence of the constant-modulus based algorithm is avoided by using a mechanism, which disregards nonconsistent estimates of the transmitted symbols. Additionally, we present a tracking analysis in which we obtain analytical expressions for the excess mean-square error in stationary and nonstationary environments. From these expressions, we verify that using a fractionally-spaced equalizer in a noiseless stationary environment, the proposed algorithms can achieve perfect equalization, independently of the QAM order. The algorithms are extended to jointly adapt the feedforward and feedback filters of the decision feedback equalizer, taking into account a mechanism to avoid degenerative solutions. Simulation results suggest that the proposed schemes may be advantageously used to recover QAM signals and make the switching to the decision direct mode unnecessary.