HISD : un nouveau décodeur MIMO utilisant une approche géométrique pour des transmissions MAQ

Dans de nombreux systèmes de communication, l'opération de décodage se résume à résoudre un problème d'optimisation d'un système combinatoire de la forme y = Hx+b. Dans le cas général, son décodage au sens du maximum de vraisemblance (ML) est un problème connu de type « NP-Complet ». Dans cet article, afin de résoudre ce problème, un nouvel algorithme sous optimal appelé HISD (Hyperplane Intersection and Selection Detector) est proposé. Cet algorithme repose sur une approche géométrique. Comparé aux algorithmes existants, le HISD possède trois caractéristiques très attrayantes pour une implantation dans des systèmes réels. La première concerne ses performances en terme de TEB qui sont proches de celles de l'optimum (ML). Sa complexité en terme de calcul est faible et sa structure est intrinsèquement parallèle ce qui rend d'autant plus aisée son implantation matérielle. Dans cet article, l'algorithme HISD est utilisé pour résoudre de manière efficace le problème du décodage des systèmes de transmissions MIMO (Multiple Input Multiple Output)

On chip interconnects for multiprocessor turbo decoding architectures

International audienc

The Physicist's Guide to the Orchestra

An experimental study of strings, woodwinds (organ pipe, flute, clarinet, saxophone and recorder), and the voice was undertaken to illustrate the basic principles of sound production in music instruments. The setup used is simple and consists of common laboratory equipment. Although the canonical examples (standing wave on a string, in an open and closed pipe) are easily reproduced, they fail to explain the majority of the measurements. The reasons for these deviations are outlined and discussed.Comment: 11 pages, 10 figures (jpg files). Submitted to European Journal of Physic

Low complexity soft demapping for non-binary LDPC codes

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Improving Network-on-Chip-based Turbo Decoder Architectures

In this work novel results concerning Networkon- Chip-based turbo decoder architectures are presented. Stemming from previous publications, this work concentrates first on improving the throughput by exploiting adaptive-bandwidth-reduction techniques. This technique shows in the best case an improvement of more than 60 Mb/s. Moreover, it is known that double-binary turbo decoders require higher area than binary ones. This characteristic has the negative effect of increasing the data width of the network nodes. Thus, the second contribution of this work is to reduce the network complexity to support doublebinary codes, by exploiting bit-level and pseudo-floatingpoint representation of the extrinsic information. These two techniques allow for an area reduction of up to more than the 40 % with a performance degradation of about 0.2 d

Une méthode de calibration simultanée des accéléromètres et des pots vibrants dans le plan transversal

The cross-axis sensitivity of accelerometers that is of the order of a few hundredths of the main axis sensitivity, is a common concern in vibration measurements. Usually the manufacturers do not provide a complete information upon the transverse sensitivity of transducers. The transverse motion of mechanical shakers is subject to the same problem and lack of information. The method that we present here is aimed at calibrating at the same time both defaults relatively to the axial components. By mounting an accelerometer on a shaker so that the main motion is perpendicular to the main sensitivity, its response adds up two products of the same order of magnitude : the main motion x the cross-axis sensitivity and the main sensitivity x the transverse motion. These two quantities are separated when the accelerometer rotates around the main-motion axis. All relative components of transverse motion and cross-axis sensitivity are derived from a combination of orientations of the accelerometer relatively to the main-motion axis. Measurements made with a variety of accelerometers exhibit a good consistency of the results concerning the transverse motion of a given shaker. Conversely, a good reproducibility of results pertaining to the cross-axis sensitivity of accelerometers has been achieved. The range in which that method is easily used with good results is limited in the low-frequency region by the motion of the shaker base and attachment

Application of modal analysis and synthesis of reed and pipe to numerical simulations of a clarinet

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Étude modale d'une clarinette

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Simulation numérique d'une clarinette par projection modale

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