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Estimation Et Egalisation Aveugles De Canal Pour Les Communications Mobiles
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Book Synopsis Estimation et égalisation aveugles de canal pour les communications mobiles by : Jaouhar Ayadi
Download or read book Estimation et égalisation aveugles de canal pour les communications mobiles written by Jaouhar Ayadi and published by . This book was released on 1999 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt: NOUS TRAITONS LE PROBLEME DE L'ESTIMATION ET DE L'EGALISATION AVEUGLES DE CANAL DANS LE CONTEXTE DES COMMUNICATIONS MOBILES. LES METHODES D'IDENTIFICATION QUE NOUS DEVELOPPONS UTILISENT UN MODELE MULTI-CANAL POUR DECRIRE LE CANAL DE TRANSMISSION ENTRE L'EMETTEUR ET LE RECEPTEUR. NOUS COMMENCONS PAR LA DESCRIPTION DES SOUS-ESPACES SIGNAL ET BRUIT CORRESPONDANT A L'ESTIMATION DES PARAMETRES DU CANAL, ET NOUS DISCUTONS DES DIFFERENTES PARAMETRISATIONS DU SOUS-ESPACE BRUIT AINSI QUE LEUR RELATION AVEC L'ENGENDREMENT DE CE DERNIER. NOUS PRESENTONS, ENSUITE, DES METHODES D'ESTIMATION DETERMINISTES QUI INCLUENT LES APPROCHES D'AJUSTEMENT DE SOUS-ESPACES POUR LESQUELLES NOUS PROPOSONS DES TECHNIQUES ALTERNATIVES QUI EVITENT LA DECOMPOSITION PROPRE DE LA MATRICE DE COVARIANCE. UNE AUTRE CLASSE INTERESSANTE DE METHODES DETERMINISTES EST CELLE QUI EST BASEE SUR LE CRITERE DE MAXIMUM DE VRAISEMBLANCE. NOUS PROPOSONS DEUX ALGORITHMES POUR OPTIMISER CE CRITERE. LE PREMIER ALGORITHME PERMET DE DEBRUITER LE CRITERE CONSIDERE ET PAR CONSEQUENT D'OBTENIR DES ESTIMEES SANS BIAIS DU CANAL. POUR CE QUI EST DU DEUXIEME ALGORITHME, IL SE BASE SUR UNE REFORMULATION DE LA FONCTION DE COUT CONSIDEREE COMME UN CRITERE QUADRATIQUE PONDERE DE FACON A CE QUE SON GRADIENT CORRESPONDE EXACTEMENT AU GRADIENT DU CRITERE DE MAXIMUM DE VRAISEMBLANCE. ASYMPTOTIQUEMENT, CES DEUX ALGORITHMES SONT GLOBALEMENT CONVERGENTS ET LEUR CONVERGENCE NECESSITE QUELQUES ITERATIONS. LA PERFORMANCE DU DEUXIEME ALGORITHME RESTE ETROITEMENT PROCHE DE LA BORNE DE CRAMER-RAO. NOUS EXPLOITONS, ENSUITE, LA CONNAISSANCE A PRIORI DES FILTRES DE TRANSMISSION/RECEPTION. NOUS ETENDONS LES METHODES AVEUGLES POUR INCORPORER CETTE CONNAISSANCE ET NOUS CALCULONS LES BORNES DE CRAMER-RAO CORRESPONDANT A CE CAS. NOUS CONSTATONS QUE LES METHODES ETENDUES ABOUTISSENT A DES PERFORMANCES MEILLEURES. EN EFFET, LES BORNES DE PERFORMANCE SONT BEAUCOUP PLUS BASSES QUE CELLES CORRESPONDANT AU CAS PUREMENT AVEUGLE, LES CRITERES A OPTIMISER SONT MIEUX CONDITIONNES ET DES CANAUX QUI NE SONT PAS IDENTIFIABLES PAR DES METHODES AVEUGLES PEUVENT ETRE IDENTIFIES GRACE A L'EXPLOITATION DE CETTE CONNAISSANCE. NOUS PROPOSONS DEUX PROCEDURES ALTERNATIVES POUR PRESERVER LA ROBUSTESSE DES METHODES D'ESTIMATION AVEUGLE EN ABSENCE DE CONNAISSANCE PRECISE SUR LA LONGUEUR DU CANAL. EN FAIT, LA PREMIERE APPROCHE PEUT ETRE VUE COMME UN MECANISME DE DETECTION IMPLICITE DE L'ORDRE DU CANAL, PAR CONTRE LA SECONDE APPROCHE DETECTE CET ORDRE DE FACON EXPLICITE. NOUS DEVELOPPONS UNE METHODE D'AJUSTEMENT DE SOUS-ESPACE POUR IDENTIFIER LE CANAL LORSQUE LE BRUIT ADDITIF N'EST PLUS SUPPOSE BLANC MAIS UNIQUEMENT STATIONNAIRE DE COULEUR INCONNUE. LA METHODE PROPOSEE EXPLOITE UNE STRUCTURE DE DEPLACEMENT DE LA MATRICE DE COVARIANCE DU SIGNAL RECU DANS LAQUELLE LA CONTRIBUTION DU BRUIT DISPARAIT. NOUS ETENDONS, ENSUITE, LA METHODE PROPOSEE POUR EXPLOITER LA CONNAISSANCE A PRIORI DES FILTRES DE TRANSMISSION/RECEPTION AFIN D'AMELIORER SA PERFORMANCE. NOUS PROPOSONS AUSSI UNE METHODE D'ESTIMATION DE CANAL BASEE SUR LE CRITERE D'EGALISATION AVEUGLE DE FORCAGE A ZERO MINIMISANT L'ERREUR QUADRATIQUE MOYENNE. NOUS AVONS PROUVE, DANS CE CONTEXTE, L'EQUIVALENCE ENTRE PLUSIEURS CRITERES D'EGALISATION DANS LE CAS SANS BRUIT ET SOUS LA CONTRAINTE D'ABSENCE DU BIAIS. PAR CONSEQUENT, NOUS AVONS DEDUIT QU'UNE ETAPE DE DEBRUITAGE DE LA MATRICE DE COVARIANCE DU SIGNAL RECU EST NECESSAIRE AVANT SON UTILISATION DANS LA METHODE D'ESTIMATION AVEUGLE. L'AVANTAGE PRINCIPAL DE CETTE METHODE EST QU'ELLE EVITE LA DECOMPOSITION PROPRE DE LA MATRICE DE COVARIANCE TOUT EN ABOUTISSANT A DES PERFORMANCES OPTIMALES PAR RAPPORT A LA BORNE DE CRAMER-RAO.
Book Synopsis IDENTIFICATION DE CANAL ET EGALISATION AVEUGLES ET SEMI-AVEUGLES POUR LES COMMUNICATIONS MOBILES by : Élisabeth de Carvalho
Download or read book IDENTIFICATION DE CANAL ET EGALISATION AVEUGLES ET SEMI-AVEUGLES POUR LES COMMUNICATIONS MOBILES written by Élisabeth de Carvalho and published by . This book was released on 1999 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt: LA PLUPART DES STANDARDS DE COMMUNICATIONS MOBILES ACTUELS INCLUENT UNE SEQUENCE D'APPRENTISSAGE POUR ESTIMER LE CANAL. LES TECHNIQUES AVEUGLES PEUVENT ESTIMER LE CANAL SANS SYMBOLES D'APPRENTISSAGE, PERMETTANT AINSI D'AUGMENTER LE DEBIT UTILE, MAIS MANQUENT DE ROBUSTESSE. LE BUT DE L'EGALISATION SEMI-AVEUGLE EST D'EXPLOITER L'INFORMATION AVEUGLE ET L'INFORMATION PROVENANT DES SYMBOLES CONNUS. LES TECHNIQUES SEMI-AVEUGLES ROBUSTIFIENT LE PROBLEME AVEUGLE ET PERMETTENT D'ESTIMER DES REPONSES IMPULSIONNELLES PLUS LONGUES QUE POSSIBLE EN APPRENTISSAGE. POUR UNE QUALITE D'ESTIMATION DONNEE, ELLES PERMETTENT L'UTILISATION DE SEQUENCES D'APPRENTISSAGE PLUS COURTES. DE PLUS, ELLES OFFRENT DE MEILLEURES PERFORMANCES D'ESTIMATION QUE LES METHODES AVEUGLES ET D'APPRENTISSAGE. NOUS PRESENTONS LES CONDITIONS D'IDENTIFIABILITE POUR L'ESTIMATION DE MULTICANAUX SEMI-AVEUGLE ET DES BORNES DE PERFORMANCE PERMETTANT UNE COMPARAISON DES TECHNIQUES SEMI-AVEUGLES AVEC LES TECHNIQUES AVEUGLES ET D'APPRENTISSAGE. UNE ETUDE DE PERFORMANCE SOUS CONTRAINTES EST DONNEE POUR CARACTERISER L'ESTIMATION AVEUGLE. LES METHODES SEMI-AVEUGLES PROPOSEES SONT BASEES SUR LE PRINCIPE DE MAXIMUM DE VRAISEMBLANCE (MV) QUI OFFRE LA POSSIBILITE D'INCORPORER LA CONNAISSANCE DE SYMBOLES D'ENTREE. POUR DES SYMBOLES CONNUS GROUPES, DES CRITERES SOUS-OPTIMAUX APPARAISSENT COMME LA COMBINAISON LINEAIRE D'UN CRITERE D'APPRENTISSAGE ET DU CRITERE MV AVEUGLE. AFIN DE CONSTRUIRE DES CRITERES SEMI-AVEUGLES PERFORMANTS, NOUS NOUS CONCENTRONS AUSSI SUR L'ETUDE DES METHODES MV AVEUGLES. ENFIN, NOUS PROPOSONS DES METHODES COMBINANT UN CERTAIN CRITERE AVEUGLE ET UN CRITERE D'APPRENTISSAGE. DES STRUCTURES D'EGALISEURS EN MODE PAQUET SONT EGALEMENT ETUDIEES ET EN PARTICULIER LA STRUCTURE D'UN ANNULATEUR D'INTERFERENCES ENTRE SYMBOLES AVEC UNE IMPLEMENTATION BASEE SUR DES DECISIONS DOUCES. ENFIN, DES BORNES DE PERFORMANCE DE RECEPTEURS BASES SUR DES MODELES DE CANAUX D'ORDRE REDUIT SONT DONNEES.
Book Synopsis Optimisation d'un précodeur MIMO-OFDM dans le contexte de l'estimation aveugle et semi-aveugle du canal de communication by : Tarek Chehade
Download or read book Optimisation d'un précodeur MIMO-OFDM dans le contexte de l'estimation aveugle et semi-aveugle du canal de communication written by Tarek Chehade and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: L'estimation de canal joue un rôle important dans les communications mobiles sans fil et en particulier dans les systèmes multi-antennes MIMO. Contrairement aux techniques classiques d'estimation de canal basées sur des séquences d'apprentissage ou des symboles pilotes, les techniques aveugles ne nécessitent aucune insertion de symboles d'apprentissage et permettent d'augmenter le débit utile. Les principales difficultés des techniques aveugles résident dans l'ambiguïté présente sur les estimées. Les techniques d'estimation semi-aveugles, basées sur les mêmes méthodes que l'estimation aveugle, sont plus robustes. Elles exploitent l'information aveugle ainsi que l'information provenant d'un nombre réduit de symboles d'apprentissage. Cette estimation du canal de communication est très utile dans les systèmes MIMO et permet de précoder le signal MIMO-OFDM en lui appliquant un pré-mélange permettant d'améliorer les performances. De nombreux types de précodeurs existent et leurs performances varient en fonction des critères d'optimisation retenus (Water-Filling, MMSE, Equal Error, max-SNR, max-d min ...), mais aussi avec la qualité de l'estimation du canal de communication. Nous étudions dans cette thèse l'impact de l'utilisation de l'information du canal (CSI) provenant des méthodes d'estimation aveugle et semi-aveugle, dans l'application des précodeurs linéaires MIMO. Nous présentons également une étude statistique de l'erreur d'estimation provenant de ces méthodes. L'optimisation de ces précodeurs nous mène par la suite à exploiter un autre procédé permettant l'amélioration des performances : les codes correcteurs d'erreur. Nous nous intéressons particulièrement aux codes LDPC non-binaires et leur association avec les précodeurs linéaires MIMO. Nous montrons qu'une adaptation est possible et s'avère bénéfique dans certains cas. L'optimisation de cette association nous a permis de proposer un nouveau précodeur basé sur la maximisation de l'information mutuelle, robuste et plus performant.
Download or read book Annales des télécommunications written by and published by . This book was released on 1998 with total page 540 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Harmonies of Political Economy by : Frédéric Bastiat
Download or read book Harmonies of Political Economy written by Frédéric Bastiat and published by Jazzybee Verlag. This book was released on 2017 with total page 770 pages. Available in PDF, EPUB and Kindle. Book excerpt: Keine Angaben
Book Synopsis Dictionary of Building and Civil Engineering by : Don Montague
Download or read book Dictionary of Building and Civil Engineering written by Don Montague and published by Taylor & Francis. This book was released on 1996 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dual-language dictionary lists over 20,000 specialist terms in both French and English, covering architecture, building, engineering and property terms. It meets the needs of all building professionals working on projects overseas. It has been comprehensively researched and compiled to provide an invaluable reference source in an increasingly European marketplace.
Book Synopsis Signal Processing for Wireless Communication Systems by : H. Vincent Poor
Download or read book Signal Processing for Wireless Communication Systems written by H. Vincent Poor and published by Springer Science & Business Media. This book was released on 2006-01-19 with total page 299 pages. Available in PDF, EPUB and Kindle. Book excerpt: Signal Processing for Wireless Communication Systems brings together in one place important contributions and up-to-date research results in this fast moving area. The Contributors to this work were selected from leading researchers and practitioners in this field. The book's 18 chapters are divided into three areas: systems, Networks, and Implementation Issues; Channel Estimation and Equalization; and Multiuser Detection. The Work, originally published as Volume 30, Numbers 1-3 of the Journal of VLSI Signal Processing Systems for Signal, Image, and Video Technology, will be valuable to anyone working or researching in the field of wireless communication systems. It serves as an excellent reference, providing insight into some of the most challenging issues being examined today.
Book Synopsis Quantum Communications and Cryptography by : Alexander V. Sergienko
Download or read book Quantum Communications and Cryptography written by Alexander V. Sergienko and published by CRC Press. This book was released on 2018-10-03 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt: All current methods of secure communication such as public-key cryptography can eventually be broken by faster computing. At the interface of physics and computer science lies a powerful solution for secure communications: quantum cryptography. Because eavesdropping changes the physical nature of the information, users in a quantum exchange can easily detect eavesdroppers. This allows for totally secure random key distribution, a central requirement for use of the one-time pad. Since the one-time pad is theoretically proven to be undecipherable, quantum cryptography is the key to perfect secrecy. Quantum Communications and Cryptography is the first comprehensive review of the past, present, and potential developments in this dynamic field. Leading expert contributors from around the world discuss the scientific foundations, experimental and theoretical developments, and cutting-edge technical and engineering advances in quantum communications and cryptography. The book describes the engineering principles and practical implementations in a real-world metropolitan network as well as physical principles and experimental results of such technologies as entanglement swapping and quantum teleportation. It also offers the first detailed treatment of quantum information processing with continuous variables. Technologies include both free-space and fiber-based communications systems along with the necessary protocols and information processing approaches. Bridging the gap between physics and engineering, Quantum Communications and Cryptography supplies a springboard for further developments and breakthroughs in this rapidly growing area.
Book Synopsis A German-English Dictionary for Chemists by : Austin M 1876-1956 Patterson
Download or read book A German-English Dictionary for Chemists written by Austin M 1876-1956 Patterson and published by Scholar Select. This book was released on 2015-08-08 with total page 340 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work has been selected by scholars as being culturally important, and is part of the knowledge base of civilization as we know it. This work was reproduced from the original artifact, and remains as true to the original work as possible. Therefore, you will see the original copyright references, library stamps (as most of these works have been housed in our most important libraries around the world), and other notations in the work. This work is in the public domain in the United States of America, and possibly other nations. Within the United States, you may freely copy and distribute this work, as no entity (individual or corporate) has a copyright on the body of the work.As a reproduction of a historical artifact, this work may contain missing or blurred pages, poor pictures, errant marks, etc. Scholars believe, and we concur, that this work is important enough to be preserved, reproduced, and made generally available to the public. We appreciate your support of the preservation process, and thank you for being an important part of keeping this knowledge alive and relevant.
Book Synopsis A New Pocket Dictionary of the French and English Languages in Two Parts by : Thomas Nugent
Download or read book A New Pocket Dictionary of the French and English Languages in Two Parts written by Thomas Nugent and published by . This book was released on 1770 with total page 476 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Classical and Modern Direction-of-Arrival Estimation by : T. Engin Tuncer
Download or read book Classical and Modern Direction-of-Arrival Estimation written by T. Engin Tuncer and published by Academic Press. This book was released on 2009-07-10 with total page 451 pages. Available in PDF, EPUB and Kindle. Book excerpt: Classical and Modern Direction of Arrival Estimation contains both theory and practice of direction finding by the leading researchers in the field. This unique blend of techniques used in commercial DF systems and state-of-the art super-resolution methods is a valuable source of information for both practicing engineers and researchers. Key topics covered are: - Classical methods of direction finding - Practical DF methods used in commercial systems - Calibration in antenna arrays - Array mapping, fast algorithms and wideband processing - Spatial time-frequency distributions for DOA estimation - DOA estimation in threshold region - Higher order statistics for DOA estimation - Localization in sensor networks and direct position estimation - Brings together in one book classical and modern DOA techniques, showing the connections between them - Contains contributions from the leading people in the field - Gives a concise and easy- to- read introduction to the classical techniques - Evaluates the strengths and weaknesses of key super-resolution techniques - Includes applications to sensor networks
Book Synopsis Wireless Communications by : H. Vincent Poor
Download or read book Wireless Communications written by H. Vincent Poor and published by Prentice Hall. This book was released on 1998 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A complete guide to the state-of-the-art in signal processing for wireless communications. Complete coverage is given of data compression, channel coding, modulator/demodulator design, receiver and transmitter design, and antenna design.
Book Synopsis Building Wireless Community Networks by : Rob Flickenger
Download or read book Building Wireless Community Networks written by Rob Flickenger and published by "O'Reilly Media, Inc.". This book was released on 2003 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: Building Wireless Community Networks is about getting people online using wireless network technology. The 802.11b standard (also known as WiFi) makes it possible to network towns, schools, neighborhoods, small business, and almost any kind of organization. All that's required is a willingness to cooperate and share resources. The first edition of this book helped thousands of people engage in community networking activities. At the time, it was impossible to predict how quickly and thoroughly WiFi would penetrate the marketplace. Today, with WiFi-enabled computers almost as common as Ethernet, it makes even more sense to take the next step and network your community using nothing but freely available radio spectrum. This book has showed many people how to make their network available, even from the park bench, how to extend high-speed Internet access into the many areas not served by DSL and cable providers, and how to build working communities and a shared though intangible network. All that's required to create an access point for high-speed Internet connection is a gateway or base station. Once that is set up, any computer with a wireless card can log onto the network and share its resources. Rob Flickenger built such a network in northern California, and continues to participate in network-building efforts. His nuts-and-bolts guide covers: Selecting the appropriate equipment Finding antenna sites, and building and installing antennas Protecting your network from inappropriate access New network monitoring tools and techniques (new) Regulations affecting wireless deployment (new) IP network administration, including DNS and IP Tunneling (new) His expertise, as well as his sense of humor and enthusiasm for the topic, makes Building Wireless Community Networks a very useful and readable book for anyone interested in wireless connectivity.
Download or read book Wireless Hacks written by Rob Flickenger and published by "O'Reilly Media, Inc.". This book was released on 2003 with total page 310 pages. Available in PDF, EPUB and Kindle. Book excerpt: Continuing with the successful Hack Series, this title provides real-world working examples of how to make useful things happen with wireless equipment.
Author :John Henry Lorentz Publisher :Historical Dictionaries of Asia, Oceania, and the Middle East ISBN 13 : Total Pages :570 pages Book Rating :4.F/5 ( download)
Book Synopsis Historical Dictionary of Iran by : John Henry Lorentz
Download or read book Historical Dictionary of Iran written by John Henry Lorentz and published by Historical Dictionaries of Asia, Oceania, and the Middle East. This book was released on 2007 with total page 570 pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides an overview of specific events, movements, people, political and social groups, places, trends, and chronology. Allows for considerable exploration of a number of historical and contemporary topics and issues. The modern period, defined as 1800-present, is covered extensively.
Book Synopsis Philostratus by : Philostratus (the Athenian)
Download or read book Philostratus written by Philostratus (the Athenian) and published by . This book was released on 1912 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Scientific Canadian Mechanics' Magazine and Patent Office Record by : Canada. Patent Office
Download or read book Scientific Canadian Mechanics' Magazine and Patent Office Record written by Canada. Patent Office and published by . This book was released on 1966-03 with total page 1070 pages. Available in PDF, EPUB and Kindle. Book excerpt:
