Architecture d’un réseau actif à base de services Web

This paper presents a novel active architecture for building and deploying network services:aswa, Web Services based Active network Architecture. At the architectural level,aswa defines an active node whose functionalities are divided into the Node Operating System, the Execution Environment, and the Active Applications. At the implementation level,aswa is a Web Services based platform where new components could be added and deployed, in order to dynamically modify network nodes behavior. Applications can be developed with any language and communicate across heterogeneous environments, and across Internet and Intranet structures. At the deployment levelaswa uses an active node approach, and offers a controlled deployment mode. In terms of security, Authentication of deployed code and protection of the nodes is achieved by the use ofhttps and the header extensions of thesoap envelope. Finally to validate this architecture,aswa defines a Firewall as an Active Application to secure the code deployment.     

Synthèse optimale d’un réseau de télécommunication avec contraintes de sécurité

A commonly used method for achieving a prescribed security level in a telecommunication network is to manage extra capacities all over the network. This paper describes a number of computational methods, both exact and approximate, for determining a minimum cost network of extra capacities needed to achieve security under any given trunk dimensioning, routing and grouping policy. From a mathematical point of view, it is shown that the problem reduces to the determination of a minimum cost network subject to a number of non simultaneous multicommodity flow requirements. Since real life instances of such problems commonly result in very large linear programs of many thousands of variables and constraints, the techniques of linear programming would be unacceptably time and space-consuming. Instead, it is shown how the use of Lagrangean relaxation in conjunction with sub-gradient optimization schemes can lead to efficient and easy-to-implement solution methods. The various procedures described in this paper form the heart of a general software product for long and medium term planning applications (Supersec program) which has already been used to investigate the economical implications of security requirements in telecommunication networks.     

Technique de multiplexage pour réseau optique de vidéocommunication

The paper describes the building of the subscriber equipment for a fiber optic local cable network. Three signals are multiplexed on the user access: video, digital audio and anIsdn channel. The multiplexing procedure is matched to a video signal in an analogue format likely to evolve towards the digital format of the future. This procedure is based on the properties of the video signal: the periodicity of a line structure and the availability of a time slot between active sections of the video lines.     

Une plate-forme de validation multi-protocoles et multi-services Résultats d’expérimentation

This article presents the implementation of a validation platform based on formal methods and the experimental results obtained. This platform allows performing conformance and interoperability tests, analysing the specification and constructing a performance model for the services. It covers all stages of the validation which are: formal specification, test architecture definition, test generation and execution for the defined architecture, and performance evaluation. The test methods and architectures used here make it easier to detect and localise errors. The platform has been constructed within the framework of theRnrt (National Telecommunications Research Network) platform project, platonis. This platform is composed of a network integrating the different sites of the project partners. The principal application domains for the platform are telecommunication systems and mobile telephony. In particular, two different cases study are presented that illustrate the platform’s applicability to the test of mobile 3rd generation protocols and services usingWap, gprs andUmts. Nevertheless, the platform is generic and can be used for other types of communication protocols and services.     

Utilisation de la corrélation pondérée dans un processus de détection d’intrusions

Generally, an intruder must perform several actions, organized in an intrusion scenario, to achieve his or her malicious objectives. Actions are modeled by their pre and post conditions, which are a set of logical predicates or negations of predicates. Pre conditions of an action correspond to conditions the system’s state must satisfy to perform the action. Post conditions correspond to the effects of executing the action on the system’s state. When an intruder begins his intrusion, we can deduce, from the alerts generated byidss (Intrusion Detection Systems), several possible scenarios, by correlating attacks, that lead to multiple intrusion objectives. However, with no further analysis, we are not able to decide which are the most plausible ones among the possible scenarios. We propose in this paper to define an order over the possible scenarios by weighting the correlation relations between successive attacks composing the scenarios. These weights reflect to what level executing some actions are necessary to execute some action B. We will see that to be satisfactory, the comparison operator between two scenarios must satisfy some properties.     

Evaluation des performances du réseau en anneau AMBRE pour distribution d’abonnés

ambre is an integrated services digital loop-like network for public local communication. Each communication is a sequence of fixed-length packets separated by fixed-length silences. Performance evaluation is carried through in terms of access-time and transport delays with emphasis on inter packet delay fluctuations.     

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.     

Antennes en réseau à bas niveau de lobes secondaires par commutation de la loi d’alimentation. Optimisation par l’algorithme génétique

The paper presents an approach of synthesis from a new thinned microstrip antennas array with binary feeding law. The operating principle of this type of antennas array consists in establishing a number of elements supplied at the center of the array as well as the feeding of the extreme elements. The problem of synthesis with constraints is dealt with only by the research of the binary feeding law of the array eccentric elements, thus allowing to reduce to the maximum the sidelobes level. To solve this type of problem, the genetic algorithm is proposed.     

Analyseur scalaire de réseau millimétrique couvrant de 16 à 250 GHz

The growing needs to cover the millimeter range have hitherto been restrained by the heaviness and cost of the necessary devices. The problem of available sources is a difficult one : some (Gunn diodes) are small and workable, but very narrowly tunable ; others (bwo tubes) are quite widely tunable, but cumbersome and relying on high-voltage power supplies. The very high frequency range (over 100 GHz) requires klystrons (whose lifetime is short) or carcinotrons (which are powerful, but correspond to a huge investment in terms of money and space). We present here a recently marketed system based on an original idea. Very convenient, workable and lightweight, it is, up to now, the only device in the world which permits to work in the most extended millimeter range, from 16 to 250 GHz continuously, without a great number of sources or any removable drawers. The dynamic range measured is superior to 70 dB from 16 to 94 GHz, and better than 50 dB up to 170 GHz.     

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.