Traitement numérique du signal en modulation multiporteuse appliqué au modem VDSL

Les moderms VDSL (Very high rateDigital Subscriber Line) sont la dernière génération de modems à haut débit (jusqu'à 50 Mb/s) utilisant comme support physique de transmission la ligne téléphonique et succèdent aux modems ADSL (Asymetric Digital Subscriber Line). Ces types de modems utilisent tous deux une modulation multiporteuse : la modulation DMT (Discrete Multi-Tone) pour communiquer entre eux. L'objectif de ce travail est la présentation de la modulation DMT appliquée à la technologie VDSL et l'étude de nouveaux algorithmes de traitement numérique du signal en modulation multiporteuse permettant d'améliorer les performances des modems VDSL en terme de débit ou de complexité algorithmique. Après avoir introduit les dispositifs numériques d'émission et de réception d'un signal DMT utilisé en technologie VDSL, nous listerons les principaux bruits d'un système VDSL en indiquant à chaque fois les méthodes classiques permettant d'annuler ou au moins de limiter leurs impacts sur les performances du mode. On présentera alors la technique dite "Zipper" permettant une très grande flexibilité dans l'allocation des bandes de fréquences affectées aux sens montant et descendant. Lorsque plusieurs lignes téléphoniques sont regroupées dans un même câble, il se crée un bruit provenant des utilisateurs partageant le câble, appelé diaphonie. Ces perturbations étant un des principaux facteurs limitant les performances d'un modem VDSL, la suite de ce travail sera consacrée à la présentation de procédés innovants d'annulation d'écho et de diaphonies permettants d'améliorer de façon significative les performances du modem. Ce travail s'achèvera par l'étude d'une modulation multiporteuse filtrée apelée FMT (Filtered Multi-Tone) dont la particularité est de permettre une meilleure indépendance spectrale entre les porteuses. On s'intéressera à l'optimisation conjointe des filtres d'émission-réception et des coefficients d'égalisation d'un système de communication FMT.GRENOBLE1-BU Sciences (384212103) / SudocSudocFranceF

Learning Methods for RSSI-based Geolocation: A Comparative Study

International audienceIn this paper, we investigate machine learning approaches addressing the problem of geolocation. First, we review some classical learning methods to build a radio map. In particular, these methods are splitted in two categories, which we refer to as likelihood-based methods and fingerprinting methods. Then, we provide a novel geolocation approach in each of these two categories. The first proposed technique relies on a semi-parametric Nadaraya-Watson estimator of the likelihood, followed by a maximum a posteriori (MAP) estimator of the object's position. The second technique consists in learning a proper metric on the dataset, constructed by means of a Gradient boosting regressor: a k-nearest neighbor algorithm is then used to estimate the position. Finally, all the proposed methods are compared on a data set originated from Sigfox network. The experiments show the interest of the proposed methods, both in terms of location estimation performance, and of ability to build radio maps

Optimized MAC algorithms and performance report

This OMEGA deliverable presents a description of medium access control (MAC) layer mechanisms and crosslayer resource allocation algorithms for the band-extended PLC in multi user context

Report on electromagnetic compatibility of power line communications

This OMEGA deliverable presents a study of the EMC issues linked to PLC systems, in the context of a frequency bandwidth extension up to 100 MHz. The current status of EMC regulations for PLC is first recalled. An experimental study is then presented for the assessment of the effect of electromagnetic field radiation from an electrical network, in the 30 ­ 100 MHz band. Recommendations are given for the injected PSD levels to be used for future studies within the OMEGA project. From these results, the capacity of the PLC channel is evaluated in terms of outage probability. This analysis shows that an extended bandwidth up to 100 MHz provides capacities in excess of 1 Gbps, while satisfying the current emission limits. Finally, the concept of cognitive EMC is introduced for the mitigation of EMC issues. We experimentally demonstrate that the FM band can successfully be used for PLC transmission without creating harmful interference to radio services

Electromagnetic compatibility for power line communications. Regulatory issues and countermeasures

International audienceWithin the ICT OMEGA project, a thorough study of the Electro Magnetic Compatibility (EMC) issues linked to Power Line Communications (PLC) has been conducted. In this paper, we present our investigations carried out in the context of a frequency bandwidth extension of PLC systems up to 100 MHz. The current status of EMC regulations for PLC is first recalled. An experimental study is then presented for the assessment of the effect of electromagnetic field radiation from an electrical network, in the 30­100 MHz band. Recommendations are given for the injected PSD levels to be used for future studies within the OMEGA project. From these results, the capacity of the PLC channel is evaluated in terms of outage probability. This analysis shows that an extended bandwidth up to 100 MHz provides capacities in excess of 1 Gbps, while satisfying the current emission limits. Finally, the possible countermeasures for the mitigation of EMC issues are discussed

State of the art, application scenario & specific requirement for PLC

This deliverable provides a state of the art, the application scenarios and the specific requirements for digital communication techniques for power line communications (PLC). The aim is to present a clear position of OMEGA objectives with respect to the existing PLC indoor environment (specifications and technologies). The opportunities for a future HPAV specification or even standard will be discussed, as well as the question of coexistence and interoperability

Performance report of optimized PHY algorithms

This deliverable presents a description of the physical layer algorithms and modulation techniques that have been developed within WP3 for transmission over wide band up to 100 MHz in-home power line communications channels. The performance results show that rates in the order of 1 Gbit/s are achievable, yet assuring the coexistence and/or the compatibility with the existing HomePlug AV technology in the lower band