Démarche de conception d’une plate-forme monopuce de réception de radiodiffusion numérique DRM

The newdrm standard for digital radio broadcast in theam band requires integrated devices for radio receivers at low cost and very low power. A chipset has been developed based on anarm9 dual-core architecture. This paper introduces the application itself, and then presents the development process followed to design such a chip covering the hardware/software partitioning, the architecture definition and all the validation issues. Therf part that partially drives the baseband is also briefly presented. The legal aspects are also investigated. Then as a conclusion, this paper presents the next steps of this development and the methodological gap in the system on chip design process.     

Licence de brevet et partage du risque: Résultats de simulation

Annals of Telecommunications - Le partage du risque est une des raisons les plus souvent avancées pour expliquer les clauses financières des contrats de licence. Pour autant, aucune...     

Quelques résultats théoriques et expérimentaux sur la modulation par déplacement de fréquence à deux états et à phase continue d’indice 0,5 (MSK)

Minimumshift keying modulation seems to be very attractive for digital transmission systems in particular because an only small degradation can be expected on non linear channels. In the first part of this paper, some general features of the signal are recalled. After a theoretical method for the calculation of the bit error rate in presence of inter symbol interference is described; the results are compared with experimental values, obtained with a modulator demodulator build incnet laboratories in Lannion.     

Une caractérisation non gaussienne et à longue mémoire du trafic Internet et de ses anomalies: validation expérimentale et application à la détection d’attaque de DDoS/Non Gaussian Long Memory Model for Internet Traffic: Experimental Validation and Application to DDoS Detection

Being now a mainstream communication, Internet is subject to many kinds of anomalies (failures, flash-crowds, attacks). In order to compare the statistics of normal traffic with traffic with anomalies, we collect both regular and anomalous traffic. The traffic is collected on the Renater network by the Metrosec project and we produce both Denial of Service (DoS) attacks with real attack softwares (TFN2k, TRIN00) aimed at various services (ICMP, SYN, UDP, TCP), and flash-crowd anomalies. We propose a multiresolution, non-Gaussian model with long memory and the corresponding estimators. It models, jointly at all aggregation levels, normal traffic, and also traffic containing anomalies. We show that the model enables to detect the anomalies in the traffic and distinguish between flash-crowd and Dos types of anomaly.     

Étude théorique et expérimentale d’une modulation simplifiée par déplacement de fréquence d’indice 1/2 à phase continue

The minimum shift keying modulation (MSK)to which a lot of recent publications have been done,presents some advantage about linear and non-linear distortions towards common 2 or 4 Phase Shift Keying (PSK)modulations. The simplified MSK modulation described in this paper is obtained by linear filtering of a coherent 2 phase shift keying modulation. Then the demodulator can be implemented with a matched filter followed by a coherent demodulator using only one carrier recovery circuit. In the first part of this paper, the modulator and the demodulator are described. After, some theorical results in the presence of noise and other impairments are given. In CCETT laboratories at Rennes, a modem has been realized at a data rate of 2,048 Mbit/s and performs at 0,8 dB of the theoretical results.     

Retour d’expérience sur différentes applications de réseau actif

Active network technologies, started by D. Tennenhouse’s work atmit in 1995 have led a lot of promises on the evolution of data networks. Active networks aim at integrating new application-level functionalities into active nodes within the network, in a flexible and extensible way. The research works on active networks have raised at the same time as the definition of new open network architectures (e.g., Tina model) and the deployment of intelligent networks merging telecom networks with distributed systems fields. This concept of “programmable networks” led to many technology-oriented projects, but has not identified relevant applications highlighting the benefits of the technology. During the three last years, our laboratory has tackled this gap and prototyped some use cases of open programmable networks. The paper gives an overview of each of these use cases and focuses on the integration with existing network elements both at transfer and management planes. Then it presents some assessments and perspectives. We show that programmable networks are optimizing globally resources to be deployed although they impose an overhead at node level, thanks to efficient integration choices. We present two scenarios of deployment of current programmable network platforms within the same network configuration than a realwan network.     

Compression de données brutes et d’images de radar à synthèse d’ouverture

This paper draws a state of the art of synthetic aperture radar (sar) data compression. Both raw data and synthesized image compression have been investigated. Compression of radar raw signal and sar image are considered separately since those two cases are specific. Also, Radar raw/image compression remains different from optical image compression and has to be considered with specific strategies that are adapted to the context.     

Conception et réalisation d’un simulateur de canal hertzien

The paper presents the design and implementation of a line-of-sight (Los)microwave channel simulator. The basic principle is to reproduce channel transfer functions given by their amplitude and group delay characteristics by driving a linear transversal filter with precomputed data. The transfer functions can be either collected from measurements in the field or derived from any analytical modelling of the Los microwave channel. It is shown that a thirteen tap filter with a 70 MHz period leads to accurate realtime simulations of selective fading in a 50 MHz bandwidth. The control interface, microprocessorbased, allows an efficient and smooth use of the simulator. Finally,hardware problems and technological solutions related to the implementation are presented.     

Étude théorique et expérimentale d’un synchronisateur primaire numérique pour signaux MIC

Bit synchronizers are used in satellite data communications systems to restore the data rate. They provide means to data detection. The paper concerns the theoretical analysis supported by the simulation and the pratical measurements of a digital self bit synchronizer implemented with standart ttl logic. This self bit synchronizer is composed of a non linear element which delivers from the sampled and quantized pcm signal a spectral line at frequency twice the data rate. This spectral line is filtered by a digital phase locked loop and is used to drive a digital matched filter data detector. Theoretical and experimental results show a very small mean acquisition time (about 4 or 5 bit duration) and a degradation lower than 2 dB for snr ranging from +2 dB to +12 dB.     

CRIM: un module de corrélation d’alertes et de réaction aux attaques

With the growing need for protection of informations systems, the intrusion detection approach is interesting but still imperfect. At the moment two main approaches exist: the behaviour based approach and the scenario detection approach. None of those two approaches is fully satisfactory. They often generate two many false positives and the generated alerts are generally too elementary and imprecise to be efficiently processed by a system administrator. An interesting approach consists in developing a cooperation module to analyze and correlate alerts, to generate a more global and synthetic diagnostic, and help the system administrator to choose the best counter-measure given a detected attack. This article presents the work we have achieved in this context to create theRim module (Cooperation and Recognition of Malevolent Intentions).     

Sur les méthodes de calcul de l’exposant linéique de propagation et d’impédance caractéristique des câbles aériens et enterrés

The propagation constant of a line or a cable, and its characteristic impedance represent two parameters which are needed in order to calculate the variation as a function of the time of a current induced by an emp.For the aerial lines expressions which take into account the presence of the soil could be developed but the case of the buried conductors is of a more difficult approach. The aim of this study is to present solutions introduced by different authors and to compare them with a calculation method for the propagation constant using iterations, proposed by the authors. If this value is known it is shown that the characteristic impedance calculation of buried cables can be improved by avoiding the necessity to compute with a reasonable precision the impedance of the ground.     

Présentation de quelques modèles stochastiques de canal MIMO et comparaison expérimentale

Performances ofMimo systems are dependant on the propagation channel properties. These properties must be correctly introduced in theMimo channel propagation models. Several model families exist. We will particularly investigate those relying on the use of second order statistic parameters. No comparison of these models was found in a same propagation environment. As a result, this paper deals with a comparison of six different stochastic models in “indoor” and “outdoor” environments. The principle and the mathematical representation ofMimo systems are introduced. Then, we present the different models considered. The statistical parameters used in the models are computed using an experimental characterization of the two environments. The six models are then compared to measurements using the channel coefficient envelope distribution and the channel capacity. The ability of the models to express the correlation level in the channel is analysed and discussed.     

Amélioration de la sensibilité de détection et de la qualité du radargramme d’un radar pénétrant GPR par une modulation micro-onde

The primary effect of the field continuously capted by aGpr is the production of a class which limits the contrast of the reflections on the targets. The target response becomes illegible sight the influence of certain disturbances which are due to the reflections caused by certain parasitic elements which are randomly distributed in the soil and the dispersion phenomenon. We present in this paper an approach based on a μ-wave modulation which allowed stage this problem. The technique suggested makes it possible to do a classification of capted signals. It will be shown that the frequency of modulation f_m must be higher than a cut-off frequency f_c which depends on the electric parameters of the ground. In a second part of this paper, we show how to improve quality of the radargram of a systemGpr by a simple convolution between the collected signal and a wavelet with a defined parameters.