Les effets de la foudre sur les réseaux de télécommunications et les moyens de s’en protéger

Cet article présente de façon synthétique les connaissances actuelles sur la foudre, ses effets sur les réseaux de télécommunications et les moyens qui existent pour s’en protéger. Après avoir abordé brièvement les principales grandeurs électriques qui caractérisent la foudre, on s’attarde sur les différents effets que la foudre peut engendrer.En matière de protection des infrastructures contre la foudre, l’article vise à présenter une vue globale des normes internationales en vigueur et relatives à l’analyse du risque et aux méthodes de protection à mettre en place

A time domain model of background noise for inhome PLC networks

International audienceMultiple-Input/Multiple-Output (MIMO) techniques have recently become an important research field for enhancing the performance of in-home Power Line Communication (PLC) systems by exploiting the additional Protective Earth wire. The development of such systems requires an accurate description of the channel noise. In this paper we have presented a model for PLC background noise based on an extensive set of measurements. We have adopted the framework of multivariate time series to model the PLC background noise.This paper employs the Vector Autoregressive (VAR) modeling technique to extract noise model parameters from the measured noise. We have verified the accuracy of the noise model by comparing time and frequency domain correlation of measured and modeled noises

Time-reversal for EMC improvement in powerline communications

National audiencePower Line Communication (PLC) is a technique used to deliver information over the electrical networks. The capacity and performance of PLC has evolved, over the past few decades, from very low bit rate power grid telemetry applications to inhome broadband internet services. However, there are serious electromagnetic compatibility (EMC) issues between PLC systems and radio broadcasters. Due to their dispersive nature, the PLC channels offer a rich scattering medium to a signal. Time-reversal (TR) is a technique which exploits scattering to obtain two major advantages: an improved signal to noise ratio (SNR) at the receiver, and reduced radio pollution to improve the EMC scenario

Power-line communications: smart grid, transmission, and propagation

1 School of Informatics, College of Informatics and Virtual Education, University of Dodoma, P.O. Box 490, Dodoma, Tanzania 2 Electrical Engineering Department, Faculdade de Engenharia, Federal University of Juiz de Fora, Campus Universitario, 36 033 330 Juiz de Fora, MG, Brazil 3Wireless and Power Line Communications Lab, Universita di Udine, 33100 Udine, Italy 4 France Telecom, Orange Labs, 2, Avenue Pierre Marzin, 22 307 Lannion Cedex, Franc

Modélisation des perturbations électromagnétiques générées sur un réseau de télécommunications par une agression de type foudre

Lightning by its direct and indirect effects may engender important damages on a telecommunications network. This thesis approaches the modeling of the coupling of a lightning stroke with a structure composed of a building associated to a wired network. By means of a formalism based on the transmission line theory associated to a topological approach, a study of the efficiency of a lightning protection device, composed of a shielding wire installed in the ground above the underground cable, is made in a exhaustive way by using experimental data obtained by means of triggered lightning. Furthermore, thanks to the antenna theory in the time domain (FDTD), the thesis also approaches the calculation of the currents generated simultaneously on a building and its wired network when the lighting stroke occurs on the considered structure. The practical application aimed by all these works being the improvement of the lightning protection of the radio-sites.LIMOGES-BU Sciences (870852109) / SudocSudocFranceF

Caractérisation des couplages électromagnétiques dans les réseaux filaires cuivre en vue d'optimiser les transmissions à haut débit

La particularité des systèmes xDSL (Digital Subscriber Line) et CPL (Courants Porteurs en ligne) est de réutiliser des supports de transmission existants, à savoir l'infrastructure téléphonique et le réseau électrique domestique. Ces deux techniques présentent ainsi l'avantage d'optimiser l'utilisation de ces media de communication. Néanmoins les supports filaires utilisés n'étaient pas initialement destinés à la transmission d'informations à haut débit et des problèmes de Compatibilité Electromagnétique (CEM) se posent inévitablement. Dans ce contexte, ce travail de thèse étudie les problèmes de CEM dans les réseaux filaires supports des hauts débits, à partir des caractéristiques physiques des supports de transmission. Des solutions innovantes sont proposées pour la réduction de la diaphonie dans les réseaux téléphoniques multifilaires transportant les signaux xDSL; puis pour l'amélioration de la fonction de transfert du réseau électrique domestique, support des CPL.The specificity of xDSL (Digital Subscriber Line) and PLC (Power Line Communications) systems lies in the fact that they reuse the existing networks such as telephonic infrastructure and power line network. These techniques have the significant advantage of optimizing the use of these media of communication. Nevertheless, those last were not initially intended to transmit high bit rate signals and their use at higher frequencies involves some problems of Electromagnetic Compatibility (EMC). This way the main concern of this PhD work consists in studying EMC aspects in wire networks that support high bit rate signals, considering the physical characteristics of the various media of transmission. Some innovative solutions are proposed for reducing crosstalk in multiconductor telephonic networks transmitting xDSL signals and for improving the transfer function of power line networks supporting PLC systems.LIMOGES-BU Sciences (870852109) / SudocSudocFranceF

A cognitive method for ensuring the coexistance between PLC and VDSL2 technologies in home network

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Etude et optimisation des sytèmes à courants porteurs domestiques face aux perturbations du réseau électrique

Avec le développement des techniques d'accès telles que le xDSL ou le FTTH, la plupart des opérateurs de télécommunications proposent de nouveaux services à très haut débit, tels que l'Internet, la téléphonie ou la télévision sur IP.En prolongement du réseau d'accès, l'utilisation de systèmes à courants porteurs domestiques permet d'accéder à l'ensemble de ces services au niveau de chaque prise de l'habitation. Cependant, le réseau électrique n'est pas adapté pour la transmission d'un signal numérique et les autres dispositifs électriques connectés risquent de perturber la communication.Ce travail de thèse consiste à analyser le fonctionnement des systèmes à courants porteurs face à ces perturbations et propose plusieurs solutions d'optimisation complémentaires.D'une part, nous nous sommes intéressés à la détection et la mitigation des perturbations impulsives, en exposant des techniques qui ont permis d'améliorer les performances et la qualité de service des systèmes.D'autre part, nous développons des algorithmes de diminution du bruit introduit par les convertisseurs analogiques/numériques, ce qui permet de résoudre de fortes contraintes d'implémentation.Enfin, l'étude s'attache à définir une meilleure gestion du spectre de puissance, afin d'augmenter les débits et la qualité de service tout en respectant les contraintes de la réglementation.With the emergence of broadband network technologies like ADSL or FTTH, most telecommunication service providers offer new high data rate services, such as broadband Internet, voice over IP and IP television.The use of indoor powerline systems allows the user to have access to each of these services via any socket in the house. However, the electrical network is not designed for the transmission of digital signals. Moreover, other electrical devices may generate some interference degrading the communication link.This Ph. D. analyses the powerline systems performance in the presence of these limitations and suggests several optimization solutions according to different complementary axes.Firstly, we study the detection and mitigation of impulsive noise, in order to improve the system performance in the presence of physical disruption.Secondly, we develop algorithms liable to reduce the analog to digital converter noise which can solve implementation limitations.Finally, the study explores a better power spectrum, management, in order to increase data rates while respecting regulation constraints.RENNES-INSA (352382210) / SudocSudocFranceF

Path Identification in a Power-Line Network Based on Channel Transfer Function Measurements

International audienceThe development of very high data-rate power-line communication (PLC) systems requires an accurate knowledge of the transmission phenomena over the electrical network. In particular, the detection of the multiple propagation paths enables a compact description of the channel models, and gives an indication of the network topology, which may, in turn, be exploited to improve the communication techniques over PLC. In this paper, two high-resolution algorithms for the identification of the propagation paths are studied and adapted to the PLC channel characteristics, namely, the frequency-domain maximum-likelihood (FDML) algorithm and the Matrix Pencil (MP) algorithm. A parametric study is then detailed in order to analyze the performance of both algorithms in terms of resolution, computation time, and residual error. The study demonstrates that the MP algorithm provides a quicker convergence and a lower residual error when compared to the FDML algorithm. Finally, the MP algorithm is validated through its application on experimental network measurements. Results show a good agreement between the measurement and the synthetic channel recomposed from the detected paths