Global ETD Search

1	Conception et réalisation d'un système de Télécommunications MIMO avec Formation Numérique de Faisceaux en réception ; Calibrage aveugle du Démodulateur triphasé Zéro-IF et comparaison au démodulateur classique à 2 voies I et Q. Mabrouk, Kais 12 December 2008 (has links) (PDF) Dans le cadre de ce travail de recherche, nous nous somme intéressés à un système de télécommunication MIMO (Multiple Input Multiple Output) à multiplexage spatial utilisant des récepteurs Zero-IF et la technique de formation numérique de faisceaux (FF). Le domaine d'application de ces travaux de recherches peuvent être aussi bien les applications fixes (exp: WiFi, IEEE) que les applications mobiles (exp: LTE, 3GPP).<br /> La première partie de ce travail est consacrée à une étude comparative entre les différents types de démodulateurs cinq-port et triphasés. Cette étude a permis de mettre en évidence l'aspect tridimensionnel des démodulateurs cinq-port et triphasés, de gagner 20dB en termes de réjection des produits d'intermodulation des signaux adjacents et de trouver une nouvelle méthode de calibrage aveugle du récepteur.<br /> La seconde partie de la thèse se concentre sur le prototypage d'un système MIMO. Cette phase nous a permis d'exposer les difficultés de mise en place de ce genre de système et de souligner les nouvelles problématiques qui n'apparaissait pas auparavant dans les systèmes mono- transcepteur. Aussi, un algorithme de Formation de Faisceau a été développé dans cette partie. Ce FF numérique a permis non seulement d'accroître la capacité mais aussi la qualité de liaison en considérant le système MIMO comme N système SIMO en parallèle. Comparativement à la technique ZF(Zero Forcing), nous démontrons que le FF permet d'obtenir une meilleure qualité de signaux pour des faibles valeurs de rapport signal à bruit. [SPI] Engineering Sciences Mimo Cinq-port Five-port Digital beamforming Antenna array Zero-if Receiver Calibration Smart antenna Lte 3gpp Blocker Interference 3d Foramtion de faisceau Reseau d antennes
2	Systemanalyse und Entwicklung Six-Port basierter Funkempfängerarchitekturen unter Berücksichtigung analoger Störeffekte Mailand, Marko 09 January 2008 (has links) (PDF) Due to the increasing demand of broadband capability and reconfigurability for mobile applications, there is an enormous interest to develop appropriate analog receiver front-ends. In this respect, one promising candidate group is the Six-Port-based direct conversion receiver. The presented work focuses on the investigation of Six-Port-based mobile receiver front-ends with their specific systematical signal processing. Thereby, issues of spurious interfering signals which are generated within the down conversion process of such receivers are of special interest. Based on a comprehensive description of the analog signal processing within additive frequency conversion, a reason could be identified why existing Six-Port receivers have not found any practical application in mobile communication yet – the dynamic DC-offset. With this insight compensation techniques were developed to overcome the negative influences of the dynamic DC-offset. Furthermore, this work presents novel Six-Port-based receiver architectures which, on the one hand, keep the advantages of additive mixing systems like: low power consumption, broadband capability and simplicity of implementation especially for mm-wave transmissions. On the other hand, these novel architectures comprise compensation techniques such that systematically generated spurious signals are inherently compensated in the analog part of the receiver. Moreover, the influence of impairments of phase and amplitude within the IQ-branches of a receiver was investigated. The resulting, unwanted IQ-imbalance was shown to be a mixing method (multiplicative or additive) independent spurious effect. It is suggested to compensate for IQ-imbalance in the digital part of the receiver system. This can be realized with the use of adaptive algorithms. The comparison with conventional analog receiver architectures (especially homodyne receivers) with respect to the reception of today’s and future digitally modulated transmission signals indicate the proposed Six-Port-based receiver architectures to be suitable candidates to fulfill the difficult tasks of modern mobile communication. Empfänger Six-Port Five-Port Hochfrequenz Hochfrequenzselbstmishcungsprodukt IQ-Imbalance blinde Signalseparation Seven-Port N-Port Architektur Funk Mobilfunk Front-End Software Defined Radio UWB Ultra Wideband Empfängerarchitektur Störef Receiver Six-Port Five-Port Seven-Port N-Port radio frequency spurious effect analog front-end architecture receiver architecture blind source separation IQ-imbalance radio transmission software defined radio UWB Ultra Wideband mobile com ddc:620 rvk:ZN 6560
3	Systemanalyse und Entwicklung Six-Port basierter Funkempfängerarchitekturen unter Berücksichtigung analoger Störeffekte Mailand, Marko 22 October 2007 (has links) Due to the increasing demand of broadband capability and reconfigurability for mobile applications, there is an enormous interest to develop appropriate analog receiver front-ends. In this respect, one promising candidate group is the Six-Port-based direct conversion receiver. The presented work focuses on the investigation of Six-Port-based mobile receiver front-ends with their specific systematical signal processing. Thereby, issues of spurious interfering signals which are generated within the down conversion process of such receivers are of special interest. Based on a comprehensive description of the analog signal processing within additive frequency conversion, a reason could be identified why existing Six-Port receivers have not found any practical application in mobile communication yet – the dynamic DC-offset. With this insight compensation techniques were developed to overcome the negative influences of the dynamic DC-offset. Furthermore, this work presents novel Six-Port-based receiver architectures which, on the one hand, keep the advantages of additive mixing systems like: low power consumption, broadband capability and simplicity of implementation especially for mm-wave transmissions. On the other hand, these novel architectures comprise compensation techniques such that systematically generated spurious signals are inherently compensated in the analog part of the receiver. Moreover, the influence of impairments of phase and amplitude within the IQ-branches of a receiver was investigated. The resulting, unwanted IQ-imbalance was shown to be a mixing method (multiplicative or additive) independent spurious effect. It is suggested to compensate for IQ-imbalance in the digital part of the receiver system. This can be realized with the use of adaptive algorithms. The comparison with conventional analog receiver architectures (especially homodyne receivers) with respect to the reception of today’s and future digitally modulated transmission signals indicate the proposed Six-Port-based receiver architectures to be suitable candidates to fulfill the difficult tasks of modern mobile communication. info:eu-repo/classification/ddc/620 ddc:620
4	VCO Banda Larga Integrado para Receptor a Cinco Portas Brito Filho, Francisco de Assis 03 September 2009 (has links) Made available in DSpace on 2014-12-17T14:55:40Z (GMT). No. of bitstreams: 1 FranciscoAB.pdf: 846082 bytes, checksum: d9718796dd9ac807f8f053e7d371d2bb (MD5) Previous issue date: 2009-09-03 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / This work presents an wideband ring VCO for cognitive radio five-port based receivers. A three-stage differential topology using transmission gate was adopted in order to maintain wide and linear tuning range and a low phase-noise. Monte-Carlo analysis were performed for phase-shift response of individual stages, which is an important figure of merit in five-port works. It was observed a fairly linear correlation between control voltage and oscillation frequency in the range between 200 MHz and 1800 MHz. The VCO was preliminarily designed for IBM 130nm CMOS technology / Este trabalho apresenta um VCO anel banda-larga para ser utilizado em receptores para R?dio Cognitivo baseados no correlator a cinco portas. Uma arquitetura diferencial de tr?s est?gios com porta de transmiss?o ? utilizada como forma de manter uma sintonia linear em larga faixa de frequ?ncias, bem como, um baixo ru?do de fase. An?lises de Monte-Carlo foram feita para avaliar as varia??es de fase em cada est?gio, o que constitui uma figura de m?rito importante em receptores baseados no correlator de cinco portas. Observou-se correspond?ncia razoavelmente linear entre tens?o de controle e freq??ncia de oscila??o na faixa compreendida entre 200 MHz e 1800 MHz. O VCO foi preliminarmente projetado para tecnologia CMOS IBM de 130 nan?metros R?dio cognitivo R?dio definido por software Cinco portas Receptores RF Receptores banda-larga Osciladores banda-larga VCO Anel Cognitive radio Software defined radio Five-Port RF Receivers Wide-Band Receivers Wide-Band Oscillators Ring VCO CNPQ::ENGENHARIAS::ENGENHARIA ELETRICA

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