PERFORMANCE COMPARISON OF NEW DESIGNS OF CHIEN SEARCH AND SYNDROME BLOCKS FOR BCH AND REED SOLOMON CODES

Error correcting codes constitute one of the core technologies in telecommunications field, especially digital communication applications. The objective of this paper is to compare performance among new designs of chien search block on the one hand and syndrome architectures on the other hand in error correcting codes. All comparison of all designs is made by computing the number of logic, bit error rate values and number of iteration in the case of syndrome architectures Analysis results show that the performances of the new designs based on both second factorization method and Three-Parallel Syndrome architecture are superior to the performances of traditional designs

(In-)validation de modèles de systèmes incertains

The work presented in this dissertation deals with the theoretical analysis of the frequency domain model validation for uncertain systems which considers that the gap between the actual system and the nominal model results not only from disturbing noise but also from model uncertainty. By assuming that both of uncertainty and additive noise are norm bounded we defined the notion of the model-set. Those which we considered are described by a fractional linear representation. The generic question of model validation problem studied in this thesis is as follows: given experimental measurements and a model-set, does a model exist in the model-set which could produce the observed inputs/outputs data? It is simply required to find an element of models-set and an element of unknown of input signal set such that the information observed is produced exactly.The problem of finding such a member of a model-set was formulated according to two strategies. First a noise signal of minimal norm is determined such that the data observed are generated by the model with an uncertainty of norm less than 1. The disadvantage of this method is that the optimization problem posed can be solved by LMI formalism only for special cases of model-set. The second strategy studied is to determine simultaneously the smallest norm of uncertainty and the smallest norm of the noise such that the model obtained generates the data observed. We have make a comparative study of these two problems and we have showed that the solution given with the help of generalized structured singular value not only makes it possible to answer the generic question for a more general class of the models-sets but also to take into account the structured nature of the uncertainty block.The experimental process of 3Tanks as well as an academic example of simulation provided an excellent validation of the studied methods.Le travail de recherche présenté dans ce mémoire porte sur l'analyse théorique de l'approche fréquentielle d'(in-)validation de modèle de systèmes incertains qui consiste à caractériser les écarts objet/modèle par l'introduction non seulement de bruits perturbateurs, mais aussi d'opérateurs d'incertitude dans la relation fonctionnelle associée au modèle choisi. En supposant que les incertitudes et le bruit sont de norme bornée nous avons défini la notion de l'ensemble de modèles. Ceux que nous avons considérés sont formés à partir d'une représentation linéaire fractionnaire. La question générique du problème de validation de modèle de systèmes incertains ainsi étudiée dans cette thèse est la suivante : Etant données des mesures expérimentales et un ensemble de modèles, existe t il un modèle dans l'ensemble de modèles qui pourrait produire les données entrées/sorties observées? Ceci a demandé simplement de trouver un élément de l'ensemble de modèles et un élément de l'ensemble signal d'entrée inconnu tels que les informations observées sont produites exactement. Le problème de trouver un tel membre de l'ensemble de modèles a été formulé selon deux stratégies. La première est de déterminer un signal de bruit de norme minimale tel que les données observées soient générées par le modèle entaché d'une incertitude de norme inférieure à 1. L'inconvénient de cette méthode est que le problème d'optimisation posé ne peut être résolu par le formalisme LMI que pour des cas spéciaux de l'ensemble de modèles. La deuxième stratégie étudiée est de déterminer simultanément la plus petite norme d'incertitude et la plus petite norme du signal de bruit telles que le modèle obtenu génère les données observées. Nous avons mené une étude comparative de ces deux problématiques et nous avons montré que la solution apportée par la valeur singulière structurée généralisée permet non seulement de répondre à la question générique pour une classe plus générale des ensembles de modèles mais aussi de prendre en compte la nature structurée du bloc d'incertitude.Le procédé expérimental de trois cuves ainsi qu'un exemple académique de simulation ont fourni une excellente validation des méthodologies étudiées

(In-)validation de modèles de systèmes incertains

Cette thèse s'intéresse à l'approche fréquentielle d'(in-)validation de modèle qui consiste à caractériser les écarts objet/modèle par l'introduction non seulement de bruits perturbateurs, mais aussi d'opérateurs d'incertitude dans la relation fonctionnelle associée au modèle choisi. En supposant que les incertitudes et le bruit sont de norme bornée nous avons défini la notion de l'ensemble de modèles et la question générique du problème de validation de modèle de systèmes incertains est la suivante : Etant données des mesures expérimentales et un ensemble de modèles, existe t il un modèle dans l'ensemble de modèles qui pourrait produire les données entrées/sorties observées? Ceci a demandé simplement de trouver un élément de l'ensemble de modèles et un élément de l'ensemble signal d'entrée inconnu tels que les informations observées sont produites exactement.Le problème de trouver un tel membre de l'ensemble de modèles a été formulé selon deux stratégies. La première est de déterminer un signal de bruit de norme minimale tel que les données observées soient générées par le modèle entaché d'une incertitude de norme inférieure à 1. L'inconvénient de cette méthode est que le problème d'optimisation posé ne peut être résolu par LMI que pour des cas spéciaux de l'ensemble de modèles. La deuxième stratégie étudiée est de déterminer simultanément la plus petite norme d'incertitude et la plus petite norme du signal de bruit telles que le modèle obtenu génère les données observées. Le procédé expérimental de trois cuves ainsi qu'un exemple académique de simulation ont fourni une excellente validation des méthodes étudiées.This PhD thesis deals with the frequency domain model validation approach for uncertain systems which considers that the gap between the actual system and the nominal model results not only from disturbing noise but also from model uncertainty. By assuming that both of uncertainty and additive noise are norm bounded we defined the notion of the model-set and the model validation problem is as follows: given experimental measurements and a model-set, does a model exist in the model-set which could produce the observed inputs/outputs data? It is simply required to find an element of models-set and an element of unknown of input signal set such that the information observed is produced exactly. The problem of finding such a member of a model-set was formulated according to two strategies. First a noise signal of minimal norm is determined such that the data observed are generated by the model with an uncertainty of norm less than 1. The disadvantage of this method is that the optimization problem can be solved by LMI only for special cases of model-set. The second strategy studied is to determine simultaneously the smallest norm of uncertainty and the smallest norm of the noise such that the model obtained generates the data observed. We have make a comparative study of these two problems and we have showed that the solution given with the help of generalized structured singular value not only makes it possible to answer the generic question for a more general class of the models-sets but also to take into account the structured nature of the uncertainty block. The 3Tanks system and an academic example of simulation provided an excellent validation of the studied methodesORSAY-PARIS 11-BU Sciences (914712101) / SudocSudocFranceF

Bond graph representation of an optimal control problem for output error minimization

International audienceThis paper presents a new procedure based on bond graph formalism for solving an optimal control problem. The proposed procedure concerns the optimal control of linear time invariant MIMO systems where the integral performance index is based on inputs and an error between a specified output and the actual output. The proof uses the Pontryagin Maximum Principle applied to the port-Hamiltonian formulation of the system

Optimal control problem in bond graph formalism

International audienceThis paper presents a new way to derive an optimal control system for a specific optimisation problem, based on bond graph formalism. The procedure proposed concerns the optimal control of linear time invariant MIMO systems and can deal with both cases of the integral performance index, these correspond to dissipative energy minimization and output error minimization. An augmented bond graph model is obtained starting from the bond graph model of the system associated with the optimal control problem. This augmented bond graph, consisting of the original model representation coupled to an optimizing bond graph, supplies, by its bicausal exploitation, the set of differential-algebraic equations that analytically give the solution to the optimal control problem without the need to develop the analytical steps of Pontryagin's method. The proof uses the Pontryagin Maximum Principle applied to the port-Hamiltonian formulation of the system

Représentation bond graph d'un problème de commande optimale

Site de la conférence : http://helios.univ-reims.fr/Labos/LAM/jd-jn-macs07Cet article a pour but de présenter une procédure fondée sur le formalisme bond graph pour résoudre une catégorie des problèmes de commande optimale. Cette procédure permet la construction d'une représentation bond graph qui constitue, grâce à l'exploitation bicausale, un moyen alternatif pour déterminer directement la solution optimale sans passer par les étapes analytiques de la méthode de Pontryagin. Mots-clés-Commande optimale, Principe de maximum de pontryagin, bond graph, bicausalité

Development and Validation of an optimized syndromes block for reed solomon decoder

Reed Solomon decoder plays an indispensable role in many applications involving data transmission, storage applications and Video broadcasting DVB-T and DVB-S2. In this work we propose a new optimized parallel syndrome block [67] for the Reed Solomon RS code (15,11) used in digital Video broadcasting DVB-T. Therefore, this proposed parallel block is compared to the serial syndrome block existing. On the basis of this technique a new architecture based on three syndromes in parallel is developed. This technique reduces both the energy consumption and the number of iterations. The RS code (15, 11) is composed of 255 symbols that are multiples of 3. The symbols are entered in parallel in the syndrome block. These decoding algorithms developed in this work are compared with the existing algorithms, and they are evaluated through a simulation using the hardware description language VHDL, then they are implemented on a Xilinx Spartan type FPGA card using the XILINX software

An Optimal Control Problem: Bond Graph Representation and Solver Implementation

International audienceThe paper deals with an optimal control problem, namely a bond graph approach, from the problem definition up to the simulation stage. The main role of this article is to supply an alternative approach for solving optimal control problems, both at the representation level and the numerical resolution level.The work presented in this paper, although it concerns optimal control, applies this effort at different levels. The framework of this research belongs to a more general task of dimensioning mechatronic systems. The optimal control implementation constitutes one of the phases that has to be overcome, in order to advance in the direction of the virtual prototyping of these systems.The class of the problem concerns linear time invariant single input single output systems, where the performance index corresponds to dissipative energy. The control variable is taken into account as dissipative loss also, using a weighting factor

Procedure for the bond graph construction of an optimal control problem.

International audienceThis paper aims at providing a procedure and the proof of its effective- ness introducing an optimal control formulation into the bond graph language. The class of optimal control problems presented concerns linear time invariant MIMO systems where the integral performance index corresponds to minimising the input and dissipative energy. The procedure enables the formulation to be set up exclusively at a graphical (namely bond graph) level. The proof uses the Pontryagin principle applied to the port-Hamiltonian formulation of the system