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Concatenation De Codes Et Decodage Iteratif Application Des Turbo Codes Produits Aux Transmissions A Forte Efficacite Spectrale
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Book Synopsis CONCATENATION DE CODES ET DECODAGE ITERATIF APPLICATION DES TURBO-CODES PRODUITS AUX TRANSMISSIONS A FORTE EFFICACITE SPECTRALE by : ANNIE.. PICART
Download or read book CONCATENATION DE CODES ET DECODAGE ITERATIF APPLICATION DES TURBO-CODES PRODUITS AUX TRANSMISSIONS A FORTE EFFICACITE SPECTRALE written by ANNIE.. PICART and published by . This book was released on 1998 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: CETTE THESE S'INSCRIT DANS LE CADRE DES TRANSMISSIONS NUMERIQUES A FORTE EFFICACITE SPECTRALE, PROTEGEES PAR UN TURBO-CODE. LA PREMIERE PARTIE DE CE MEMOIRE PRESENTE DIFFERENTES STRUCTURES DE CODES CONCATENES. LES PROPRIETES INTRINSEQUES DU TURBO-CODE DEPENDENT DU TYPE DE CONCATENATION (PARALLELE OU SERIE), DE LA NATURE DES CODES ELEMENTAIRES (EN BLOCS OU CONVOLUTIFS, RECURSIFS OU NON), DE L'ENTRELACEUR (TAILLE ET LOI D'ENTRELACEMENT). AINSI, UN CODE OBTENU PAR LA CONCATENATION EN PARALLELE DE CODES CONVOLUTIFS RECURSIFS BENEFICIE D'UN GAIN D'ENTRELACEMENT, MAIS SA DISTANCE MINIMALE EST FONCTION DE LA LOI D'ENTRELACEMENT. UN CODE PRODUIT, QUI RESULTE DE LA CONCATENATION EN SERIE DE CODES EN BLOCS, A UNE GRANDE DISTANCE MINIMALE, MAIS NE BENEFICIE PAS DE GAIN D'ENTRELACEMENT. LA SECONDE PARTIE EST CONSACREE AUX TURBO-CODES PRODUITS QUE L'ON ASSOCIE AUX MODULATIONS MAQ16 ET MAQ64, SELON UNE APPROCHE CLASSIQUE, PUIS DANS UN CODAGE MULTINIVEAU AVEC UN PARTITIONNEMENT SELON UNGERBOECK. L'APPROCHE CLASSIQUE S'EST REVELEE LA PLUS PERFORMANTE. LES GAINS DE CODAGE SONT DE L'ORDRE DE 6 A 7DB, POUR DES EFFICACITES SPECTRALES DE 2 A 6 BIT/HZ/S. CES PERFORMANCES SURPASSENT CELLES DES MODULATIONS CODEES EN TREILLIS ET SONT EQUIVALENTES A CELLES DES TURBO-CODES CONVOLUTIFS POUR DES RENDEMENTS SUPERIEURS A 0,6. POUR CES EFFICACITES SPECTRALES, LES PERFORMANCES DES TURBO-CODES PRODUITS SE SITUENT EN MOYENNE A 3DB DE LA LIMITE DE SHANNON.
Book Synopsis Turbo Code Applications by : Keattisak Sripimanwat
Download or read book Turbo Code Applications written by Keattisak Sripimanwat and published by Springer Science & Business Media. This book was released on 2006-02-23 with total page 393 pages. Available in PDF, EPUB and Kindle. Book excerpt: Turbo Code Applications: a journey from a paper to realization presents c- temporary applications of turbo codes in thirteen technical chapters. Each chapter focuses on a particular communication technology utilizing turbo codes, and they are written by experts who have been working in related th areas from around the world. This book is published to celebrate the 10 year anniversary of turbo codes invention by Claude Berrou Alain Glavieux and Punya Thitimajshima (1993-2003). As known for more than a decade, turbo code is the astonishing error control coding scheme which its perf- mance closes to the Shannon’s limit. It has been honored consequently as one of the seventeen great innovations during the ?rst ?fty years of information theory foundation. With the amazing performance compared to that of other existing codes, turbo codes have been adopted into many communication s- tems and incorporated with various modern industrial standards. Numerous research works have been reported from universities and advance companies worldwide. Evidently, it has successfully revolutionized the digital commu- cations. Turbo code and its successors have been applied in most communications startingfromthegroundorterrestrialsystemsofdatastorage,ADSLmodem, and ?ber optic communications. Subsequently, it moves up to the air channel applications by employing to wireless communication systems, and then ?ies up to the space by using in digital video broadcasting and satellite com- nications. Undoubtedly, with the excellent error correction potential, it has been selected to support data transmission in space exploring system as well.
Download or read book Conference Record written by and published by . This book was released on 1999 with total page 582 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis LES TURBO-CODES ET LEUR APPLICATION AUX TRANSMISSIONS A FORTE EFFICACITE SPECTRALE by : STEPHANE.. LE GOFF
Download or read book LES TURBO-CODES ET LEUR APPLICATION AUX TRANSMISSIONS A FORTE EFFICACITE SPECTRALE written by STEPHANE.. LE GOFF and published by . This book was released on 1995 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: INVENTES RECEMMENT, LES TURBO-CODES CONSTITUENT UNE NOUVELLE FAMILLE DE CODES CORRECTEURS D'ERREURS BINAIRES, OBTENUE EN CONCATENANT EN PARALLELE DEUX CODES CONVOLUTIFS SYSTEMATIQUES ET RECURSIFS, ET EN UTILISANT UN PROCEDE INEDIT DE DECODAGE AVEC CONTRE-REACTION. DURANT CETTE THESE, NOUS AVONS EFFECTUE UNE ETUDE APPROFONDIE DES TURBO-CODES, PRINCIPALEMENT EN VUE DE LEUR INSERTION A L'INTERIEUR DE SYSTEMES PERMETTANT D'ATTEINDRE DE FORTES EFFICACITES SPECTRALES (JUSQU'A 7 BIT/S/HZ). POUR CELA, LES PERFORMANCES DES TURBO-CODES DE RENDEMENTS ELEVES (COMPRIS ENTRE 1/2 ET 7/8) ONT TOUT D'ABORD ETE ETUDIEES. LES RESULTATS OBTENUS A L'AIDE DE SIMULATIONS ONT PERMIS DE METTRE EN EVIDENCE LE HAUT POUVOIR DE CORRECTION DES TURBO-CODES, CECI QUELS QUE SOIENT LES RENDEMENTS ET LES CANAUX DE TRANSMISSION CONSIDERES (CANAL GAUSSIEN OU DE RAYLEIGH SANS MEMOIRE). ENSUITE, UNE EVALUATION DE LA COMPLEXITE DU CODEUR ET DU DECODEUR A ETE EFFECTUEE, DONT LES CONCLUSIONS SONT TRES FAVORABLES VIS-A-VIS DES SYSTEMES CONCURRENTS. TOUT CECI A CONDUIT A LA DEFINITION D'UN NOUVEAU SYSTEME DE TRANSMISSION PERMETTANT D'ATTEINDRE DE FORTES EFFICACITES SPECTRALES (COMPRISES ENTRE 2 ET 7 BIT/S/HZ), ET OBTENU EN ASSOCIANT UN TURBO-CODE A UNE MODULATION A GRAND NOMBRE D'ETATS (MDP8, MAQ16, MAQ32, ETC). ELABORE SUIVANT UNE APPROCHE PRAGMATIQUE, CE SYSTEME EST NON SEULEMENT RELATIVEMENT SIMPLE A METTRE EN UVRE, MAIS EGALEMENT TOUT A FAIT APTE A FONCTIONNER A DES DEBITS ELEVES. DE PLUS, NOUS MONTRONS QU'IL PERMET D'OBTENIR DES GAINS DE CODAGE IMPORTANTS PAR RAPPORT A DES MODULATION CODEES EN TREILLIS DE FORTE COMPLEXITE (TREILLIS A 64 ETATS). AINSI, GRACE A SES PERFORMANCES ET A SA RELATIVE SIMPLICITE, LE SYSTEME PROPOSE CONSTITUE UNE EXCELLENTE ALTERNATIVE AUX MODULATIONS CODEES, ET POURRAIT DEVENIR DANS LES ANNEES A VENIR UN STANDARD DANS LE DOMAINE DES COMMUNICATIONS NUMERIQUES
Book Synopsis Turbo Coding, Turbo Equalisation and Space-Time Coding by : Lajos Hanzo
Download or read book Turbo Coding, Turbo Equalisation and Space-Time Coding written by Lajos Hanzo and published by John Wiley & Sons. This book was released on 2011-05-03 with total page 839 pages. Available in PDF, EPUB and Kindle. Book excerpt: Covering the full range of channel codes from the most conventional through to the most advanced, the second edition of Turbo Coding, Turbo Equalisation and Space-Time Coding is a self-contained reference on channel coding for wireless channels. The book commences with a historical perspective on the topic, which leads to two basic component codes, convolutional and block codes. It then moves on to turbo codes which exploit iterative decoding by using algorithms, such as the Maximum-A-Posteriori (MAP), Log-MAP and Soft Output Viterbi Algorithm (SOVA), comparing their performance. It also compares Trellis Coded Modulation (TCM), Turbo Trellis Coded Modulation (TTCM), Bit-Interleaved Coded Modulation (BICM) and Iterative BICM (BICM-ID) under various channel conditions. The horizon of the content is then extended to incorporate topics which have found their way into diverse standard systems. These include space-time block and trellis codes, as well as other Multiple-Input Multiple-Output (MIMO) schemes and near-instantaneously Adaptive Quadrature Amplitude Modulation (AQAM). The book also elaborates on turbo equalisation by providing a detailed portrayal of recent advances in partial response modulation schemes using diverse channel codes. A radically new aspect for this second edition is the discussion of multi-level coding and sphere-packing schemes, Extrinsic Information Transfer (EXIT) charts, as well as an introduction to the family of Generalized Low Density Parity Check codes. This new edition includes recent advances in near-capacity turbo-transceivers as well as new sections on multi-level coding schemes and of Generalized Low Density Parity Check codes Comparatively studies diverse channel coded and turbo detected systems to give all-inclusive information for researchers, engineers and students Details EXIT-chart based irregular transceiver designs Uses rich performance comparisons as well as diverse near-capacity design examples
Book Synopsis Turbo-like Codes by : Aliazam Abbasfar
Download or read book Turbo-like Codes written by Aliazam Abbasfar and published by Springer Science & Business Media. This book was released on 2007-09-09 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book introduces turbo error correcting concept in a simple language, including a general theory and the algorithms for decoding turbo-like code. It presents a unified framework for the design and analysis of turbo codes and LDPC codes and their decoding algorithms. A major focus is on high speed turbo decoding, which targets applications with data rates of several hundred million bits per second (Mbps).
Book Synopsis Turbo Coding for Satellite and Wireless Communications by : M. Reza Soleymani
Download or read book Turbo Coding for Satellite and Wireless Communications written by M. Reza Soleymani and published by Springer Science & Business Media. This book was released on 2006-04-18 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt: 6. 5 137 7 Performance of BTCs and 139 their Applications 7. 1 Introduction 139 7. 2 Some Results from the Literatures 139 7. 3 Applications of Block Turbo Codes. 142 7. 3. 1 Broadband Wireless Access Standard 144 7. 3. 2 Advanced Hardware Architectures (AHA) 145 7. 3. 3 COMTECH EF DATA 147 7. 3. 4 Turbo Concept 149 7. 3. 5 Paradise Data Com 150 Summary 7. 4 151 8 Implementation Issues 153 8. 1 Fixed-point Implementation of Turbo Decoder 153 8. 1. 1 Input Data Quantization for DVB-RCS Turbo Codes 155 8. 1. 2 Input Data Quantization for BTC 157 8. 2 The Effect of Correction Term in Max-Log-MAP Algorithm 159 8. 3 Effect of Channel Impairment on Turbo Codes 163 8. 3. 1 System Model for the Investigation of Channel Impairments 163 8. 3. 2 Channel SNR Mismatch 164 8. 3. 2. 1 Simulation Results 165 8. 3. 3 Carrier Phase Recovery 170 8. 3. 3. 1 The Effect of Phase Offset on the Performance of RM Turbo Codes 170 8. 3. 3. 2 The Effect of Preamble Size on the Performance of RM Turbo Codes 170 8. 3. 3. 3 Simulation Results 170 8. 4 Hardware Implementation of Turbo Codes 171 8. 5 Summary 175 9 177 Low Density Parity Check Codes 9. 1 Gallager Codes: Regular Binary LDPC Codes 177 9. 2 Random Block Codes 178 9. 2. 1 Generator Matrix 179 9. 2.
Book Synopsis Codes and turbo codes by : Claude Berrou
Download or read book Codes and turbo codes written by Claude Berrou and published by Springer Science & Business Media. This book was released on 2011-01-27 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is devoted to one of the essential functions of modern telecommunications systems: channel coding or error correction coding. Its main topic is iteratively decoded algebraic codes, convolutional codes and concatenated codes.
Book Synopsis Turbo Codes by : Alexandre Giulietti
Download or read book Turbo Codes written by Alexandre Giulietti and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 158 pages. Available in PDF, EPUB and Kindle. Book excerpt: PREFACE The increasing demand on high data rate and quality of service in wireless communication has to cope with limited bandwidth and energy resources. More than 50 years ago, Shannon has paved the way to optimal usage of bandwidth and energy resources by bounding the spectral efficiency vs. signal to noise ratio trade-off. However, as any information theorist, Shannon told us what is the best we can do but not how to do it [1]. In this view, turbo codes are like a dream come true: they allow approaching the theoretical Shannon capacity limit very closely. However, for the designer who wants to implement these codes, at first sight they appear to be a nightmare. We came a huge step closer in striving the theoretical limit, but see the historical axiom repeated on a different scale: we know we can achieve excellent performance with turbo codes, but not how to realize this in real devices.
Book Synopsis Turbo Coding, Turbo Equalisation and Space-Time Coding for Transmission over Fading Channels by : Lajos L. Hanzo
Download or read book Turbo Coding, Turbo Equalisation and Space-Time Coding for Transmission over Fading Channels written by Lajos L. Hanzo and published by Wiley-IEEE Press. This book was released on 2002-09-09 with total page 766 pages. Available in PDF, EPUB and Kindle. Book excerpt: Turbo coding has opened an exciting new chapter in the design of iterative detection assisted communication systems. Similar dramatic advances have been achieved with the advent of space time coding, when communicating over dispersive fading wireless channels. By assuming no prior knowledge in the field of channel coding, the authors provide a self-contained reference on these stimulating hot topics, concluding at an advanced level. This essential volume is divided into five key parts: 1. Convolutional and Block Coding Introduces the family of convolutional codes, hard and soft-decision Viterbi algorithms and the most prominent classes of block codes, namely Reed-Solomon (RS) and Bose-Chaudhuri-Hocquenghem (BCH) codes, as well as their algebraic and trellis-decoding. 2. Turbo Convolutional and Turbo Block Coding Introduces turbo convolutional codes and details the Maximum A-Posteriori (MAP), Log-MAP and Max-Log-MAP as well as the Soft Output Viterbi Algorithm (SOVA). Investigates the effects of the various turbo codec parameters. Studies the super-trellis structure of turbo codes and characterises turbo BCH codes. Portrays Redundant Residue Number System (RRNS) based codes and their turbo decoding. 3. Coded Modulation: TCM, TTCM, BICM, BICM-ID Studies Trellis Coded Modulation (TCM), Turbo Trellis Coded Modulation (TTCM), Bit-Interleaved Coded Modulation (BICM), Iterative BICM (BICM-ID) and compares them under various channel conditions. 4. Space-Time Block and Space-Time Trellis Coding Introduces space-time codes and studies their performance using numerous channel codecs providing guidelines for system designers. Studies Multiple-Input Multiple-Output (MIMO) based schemes and the concept of near-instantaneously Adaptive Quadrature Amplitude Modulation (AQAM) combined with near-instantaneously adaptive turbo channel coding. 5. Turbo Equalisation Covers the principle in detail, provides theoretical performance bounds for turbo equalisers and includes a study of various turbo equaliser arrangements. Also addresses the problem of reduced implementation complexity and covers turbo equalised space-time trellis codes. If you are looking for a comprehensive treatment covering both classic channel coding techniques and recent advances in this field, then this is the book for you. Researchers, practising engineers and advanced students will all find it both informative and stimulating.
Download or read book Turbo Coding written by Chris Heegard and published by Springer. This book was released on 2013-02-02 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt: When the 50th anniversary of the birth of Information Theory was celebrated at the 1998 IEEE International Symposium on Informa tion Theory in Boston, there was a great deal of reflection on the the year 1993 as a critical year. As the years pass and more perspec tive is gained, it is a fairly safe bet that we will view 1993 as the year when the "early years" of error control coding came to an end. This was the year in which Berrou, Glavieux and Thitimajshima pre sented "Near Shannon Limit Error-Correcting Coding and Decoding: Turbo Codes" at the International Conference on Communications in Geneva. In their presentation, Berrou et al. claimed that a combi nation of parallel concatenation and iterative decoding can provide reliable communications at a signal to noise ratio that is within a few tenths of a dB of the Shannon limit. Nearly fifty years of striving to achieve the promise of Shannon's noisy channel coding theorem had come to an end. The implications of this result were immediately apparent to all -coding gains on the order of 10 dB could be used to dramatically extend the range of communication receivers, increase data rates and services, or substantially reduce transmitter power levels. The 1993 ICC paper set in motion several research efforts that have permanently changed the way we look at error control coding.
Book Synopsis CONCEPTION ET PERFORMANCES D'UN CIRCUIT INTEGRE TURBO DECODEUR DE CODES PRODUITS by : OLIVIER.. RAOUL
Download or read book CONCEPTION ET PERFORMANCES D'UN CIRCUIT INTEGRE TURBO DECODEUR DE CODES PRODUITS written by OLIVIER.. RAOUL and published by . This book was released on 1997 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt: LES TURBO CODES CONVOLUTIFS, INVENTES EN 1992 A L'ENSTBR PAR C. BERROU ET AL., SONT DES CODES CORRECTEURS D'ERREURS DONT LE POUVOIR DE CORRECTION AVOISINE LA LIMITE THEORIQUE DE SHANNON. LEURS EXCELLENTES PERFORMANCES ET LA FAIBLE COMPLEXITE DES DECODEURS CORRESPONDANTS ONT INCITE R. PYNDIAH ET AL. A TRANSPOSER LES CONCEPTS NOVATEURS DU TURBO DECODAGE DES CODES CONVOLUTIFS A DE PUISSANTS CODES EN BLOCS CONCATENES, LES CODES PRODUITS. EN 1994 A L'ENSTBR, R. PYNDIAH A PROPOSE UN ALGORITHME DE TURBO DECODAGE DES CODES PRODUITS DONT LES PERFORMANCES EN TERME DE TAUX D'ERREURS BINAIRES SE SONT AVEREES COMPARABLES A CELLE DES TURBO CODES CONVOLUTIFS, VOIRE MEILLEURES POUR LES RENDEMENTS DE CODAGE ELEVES (>0,7). CETTE THESE TRAITE DE L'INTEGRATION SUR SILICIUM DE CET ALGORITHME DE TURBO DECODAGE DES CODES PRODUITS. NOUS PROPOSONS DEUX ARCHITECTURES POUR IMPLANTER LE CIRCUIT. LA PREMIERE EST UNE STRUCTURE MODULAIRE DANS LAQUELLE LES DONNEES SONT TRAITEES SEQUENTIELLEMENT. LA SECONDE S'APPARENTE A UNE MACHINE DITE DE VON NEUMANN ET PERMET DE TRAITER LES DONNEES SEQUENTIELLEMENT OU PAR BLOCS. LES AVANTAGES ET INCONVENIENTS DE CHAQUE SOLUTION - EN TERMES DE DEBIT, DE LATENCE ET DE TAILLE DES MEMOIRES UTILISEES - SONT DISCUTES DANS L'ETUDE. NOUS ABORDONS ENSUITE LA CONCEPTION DE L'UNITE DE DECODAGE POUR DES CODES PRODUITS CONSTRUITS A PARTIR DE CODES BCH. LES SURFACES DE SILICIUM OBTENUES, BIEN QUE RELATIVEMENT IMPORTANTES, PERMETTENT DE CONCLURE A L'INTEGRABILITE DE L'ALGORITHME. NOUS PROPOSONS ALORS DIFFERENTES SOLUTIONS POUR REDUIRE DE PRES DE 60% LA SURFACE DE L'UNITE DE DECODAGE SANS DEGRADER SIGNIFICATIVEMENT LES PERFORMANCES DU CIRCUIT. CES RESULTATS, CONCRETISES PAR LA REALISATION D'UN PREMIER PROTOTYPE DE TURBO DECODEUR SUR CIRCUIT FPGA XILINX, FONT DES TURBO CODES EN BLOCS UNE ALTERNATIVE SEDUISANTE AUX SOLUTIONS RETENUES JUSQU'ALORS POUR LES TRANSMISSIONS NUMERIQUES NECESSITANT UNE FORTE EFFICACITE SPECTRALE ET UN TRES FAIBLE TAUX D'ERREURS.
Book Synopsis Trellis and Turbo Coding by : Christian B. Schlegel
Download or read book Trellis and Turbo Coding written by Christian B. Schlegel and published by John Wiley & Sons. This book was released on 2004-09-07 with total page 403 pages. Available in PDF, EPUB and Kindle. Book excerpt: Trellis and turbo coding are used to compress and clean communications signals to allow greater bandwidth and clarity Presents the basics, theory, and applications of these techniques with a focus on potential standard state-of-the art methods in the future Provides a classic basis for anyone who works in the area of digital communications A Wiley-IEEE Press Publication
Download or read book Turbo Codes written by Branka Vucetic and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 330 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book grew out of our research, industry consulting and con tinuing education courses. Turbo coding initially seemed to belong to a restricted research area, while now has become a part of the mainstream telecommu nication theory and practice. The turbo decoding principles have found widespread applications not only in error control, but in de tection, interference suppression and equalization. Intended for use by advanced students and professional engi neers, involved in coding and telecommunication research, the book includes both basic and advanced material. The chapters are se quenced so that the knowledge is acquired in a logical and progres sive way. The algorithm descriptions and analysis are supported by examples throughout the book. Performance evaluations of the presented algorithms are carried out both analytically and by sim ulations. Basic material included in the book has been taught to students and practicing professionals over the last four years in the form of senior undergraduate or graduate courses, lecture series and short continuing education courses.
Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781720380955 Total Pages :32 pages Book Rating :4.3/5 (89 download)
Book Synopsis An Interactive Concatenated Turbo Coding System by : National Aeronautics and Space Administration (NASA)
Download or read book An Interactive Concatenated Turbo Coding System written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-05-29 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper presents a concatenated turbo coding system in which a Reed-Solomon outer code is concatenated with a binary turbo inner code. In the proposed system, the outer code decoder and the inner turbo code decoder interact to achieve both good bit error and frame error performances. The outer code decoder helps the inner turbo code decoder to terminate its decoding iteration while the inner turbo code decoder provides soft-output information to the outer code decoder to carry out a reliability-based soft- decision decoding. In the case that the outer code decoding fails, the outer code decoder instructs the inner code decoder to continue its decoding iterations until the outer code decoding is successful or a preset maximum number of decoding iterations is reached. This interaction between outer and inner code decoders reduces decoding delay. Also presented in the paper are an effective criterion for stopping the iteration process of the inner code decoder and a new reliability-based decoding algorithm for nonbinary codes.Liu, Ye and Tang, Heng and Lin, Shu and Fossorier, MarcGoddard Space Flight CenterCONCATENATED CODES; BINARY CODES; ALGORITHMS; DECODING; REED-SOLOMON CODES; ITERATION; STOPPING; BIT ERROR RATE; RELIABILITY
Book Synopsis Codes et turbocodes by : Claude Berrou
Download or read book Codes et turbocodes written by Claude Berrou and published by Springer Science & Business Media. This book was released on 2007-03-13 with total page 408 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cet ouvrage est consacré à l'une des fonctions essentielles des systèmes de télécommunications modernes : le codage de canal ou codage correcteur d'erreurs. À la croisée de la théorie de l'information, des mathématiques et de l'électronique, le codage de canal a connu de nombreux développements depuis les travaux fondateurs de Claude Shannon. Du simple code de Hamming (1950) aux récents turbocodes (1993) en passant par les codes LDPC (1962), le codage de canal a considérablement évolué et a intégré des concepts de plus en plus sophistiqués, en particulier le traitement probabiliste de l'information. Codes algébriques, codes convolutifs et codes concaténés décodés itérativement font la matière principale de l'ouvrage qui comporte également une présentation des modulations numériques, auxquelles le codage de canal est intimement associé pour former le cœur de la couche physique des systèmes de télécommunications. Les aspects théoriques les plus importants sont présentés, la construction des codes est détaillée et justifiée. Les algorithmes de décodage sont développés et, dans la mesure du possible, accompagnés de résultats de simulation, caractéristiques de leur pouvoir de correction et de leurs applications. Les auteurs sont des enseignants-chercheurs reconnus pour leur expertise dans le domaine des algorithmes de codage et de décodage ainsi que des circuits électroniques associés. Codes et Turbocodes a été pensé pour être à la fois un ouvrage de découverte du domaine, une source précieuse d'informations sur les nombreuses techniques imaginées depuis le milieu du vingtième siècle, et une ouverture vers des problèmes non encore complètement résolus.
Book Synopsis Contributions au codage d'erreur by : Andrzej Michal Kabat
Download or read book Contributions au codage d'erreur written by Andrzej Michal Kabat and published by . This book was released on 2009 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt: Les codes de la famille des turbocodes associés à un décodage itératif sont maintenant largement envisagés dans les nouveaux standards. Cependant, il existe toujours beaucoup d'applications où des codes longs à fort pouvoir de correction comme le code Reed-Solomon RS(255,239) sont utilisés, et où un décodeur à décision ferme est utilisé. Dans la première partie de cette thèse, le décodage pondéré de codes longs linéaires en blocs est étudié. Nous nous focalisons sur les algorithmes de décodage de type liste que nous nommons « TERIS ». Les algorithmes de cette famille génèrent des mots de code compétitifs en ré-encodant le message reçu dont les bits ont préalablement été rangés selon l'ordre croissant de leur fiabilité et modifiés par l'ajout de vecteurs de test (TEP). L'état de l'art permet d'identifier deux points cruciaux dans ce type d'algorithmes : la génération des vecteurs de test et les critères d'optimalité capables de diminuer la complexité de décodage en éliminant les TEP peu fiables ou en arrêtant la procédure de décodage. Dans cette thèse nous proposons deux méthodes efficaces de génération des TEP. La première (ALMLT) produit des TEP selon leur efficacité décroissante. L'efficacité d'un TEP est liée à la probabilité d'occurrence du motif d'erreur associé et est déterminée en utilisant la moyenne statistique des fiabilités des bits (ordonnés par fiabilité décroissante). La seconde est une méthode itérative fondée sur la résonance stochastique, où les fiabilités des bits sont modifiées par un coefficient multiplicateur à chaque itération. Nous proposons aussi trois nouvelles conditions d'optimalité qui ont rendu possible les simulations jusqu'à des taux d'erreur trame de l'ordre de 10-6. Dans la deuxième partie de cette thèse, nous nous focalisons sur les communications coopératives sans fil utilisant des relais, où l'implémentation d'un codage réseau comme celui utilisé pour les réseaux fixes ne pourrait pas être envisagée. La transmission sur le canal mobile est en effet perturbée par des erreurs et l'utilisation de codes à fort pouvoir de correction semble pouvoir offrir une solution pratique à ce problème. Nous proposons un nouveau schéma de codage distribué mettant en œuvre un code produit. L'encodage des colonnes est réalisé au niveau de chaque source indépendamment. L'encodage des lignes est quant à lui réalisé au niveau du relais. Un décodage classique itératif des turbo codes en blocs peut être alors effectué au niveau du récepteur, sur la concaténation des mots de code provenant des sources et du relais. Cette solution ouvre un vaste champ d'applications et des perspectives d'études intéressantes.
