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.     

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.     

Réalisation d’un opérateur de traitement numérique rapide par une machine à flux de données

The authors describe a fast, parallel and static data flow architecture that is used for Fast Riccati Operator (Fro)design. This operator has a cellular, regular structure easy to integrate, and is intended to resolve with high speed execution the matrix Riccati equation for filtering purpose. To evaluate its performances, two solving algorithms, Lindquist and quasilinéarisation, are represented and simulated by data flow Petri nets, defined for this purpose. Simulation results are compared to real needs in search and tracking situations.     

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.     

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.     

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.     

Étude du comportement d’une boucle de Costas en modulation MAQ 16 en présence d’évanouissements sélectifs

This paper gives the variance of the phase recovered by a conventional quadriphase Costas loop in 16 Qam modulation in the presence of a selective fading, represented as a three rays simplified model. The power spectral density of the phase error is computed using a spectral estimation technique. The phase error variance is evaluated for different values of the fade depth, the location of the maximum attenuation in the frequency band and the delay of the reflected ray. Finally the relation between the performance degradation and phase noise is given, assuming a gaussian p.d.f. of the phase error.     

Méthode originale d’analyse du diagramme de diffraction en puissance d’une cible radar en vue de la reconnaissance des formes

Aircraft modeling is often accomplished by replacing the skin of the aircraft by several conveniently placed scatterers. We show that a Radar Cross Section (rcs)diagram can be described as a sum of bipoint s diagrams and that this decomposition can be greatly simplified. Then we consider the extraction of bipoints parameters from the knowledge of a diagram of radar cross section in the far field. This study exhibits that the bipoint function is a system of Chebyshev polynomials of the first or second kind. After a changement of variables,the bipoint function becomes then a A.M. function. By a Fourier analysis of transformed rcs,we can find the lengths between the points and the amplitudes. This study can be also extended to a multipoint in a line which radiates with spatial directivity.