Systèmes hertziens à forte efficacité spectrale pour les communications mobiles multi-antennes et multi-porteuses de 4° génération

Abstract : The present work proposes solutions with high spectral efficiency for multi-antenna and multi-carrier mobile communications, optimized for the down link of wireless systems. This study arises in a competing context for the access to wireless high data rates, and contributes to the joint effort within the European projects on 4G (4th generation) systems. The first part of the document presents the framework, identifying the physical, technological and financial constrains, as well as the requirements of 4G systems in terms of services, data-rate and mobility. Specifically, a reasonable complexity at the mobile receiver is necessary in the down link to respect cost and consumption. In a practical framework, the wideband and mobile MIMO propagation channel is described. The correlations in space/time/frequency induce the design of the proposed digital communication system. The second part of the document is dedicated to a cohesive study of multi-carrier, multi-user and multi-antenna systems, in order to explore several options taking advantage of the channel properties. First, the wideband multi-user access relies on the combination of OFDM and CDMA, so as to discuss the diversity/orthogonality compromise related to the chip-mapping and detection algorithms considered. Next, to exploit the antenna array, diversity and multiplexing gains offered by the MIMO channel depending on the context, multi-antenna techniques are classified, and a strategy that preserves a low detection complexity is proposed.We detail the most appropriate systems in a mobile downlink context, that do not require channel knowledge at the transmitter side. Finally, the entire MIMO-OFDM-CDMA communication chain is presented insisting on the flexibility of the adopted linear algorithms. The third part of the document optimizes the previous combinations in realistic environments, and proposes innovative techniques for coding and estimating in space/time/frequency. First, pragmatism implies the exploitation of diversity to ensure robustness, simple detection and compatibility with a wide range of terminals. We favor a spatial coding of rate 1, and propose to manage multiple paths using the additional antennas. We optimize the coding, chip-mapping, detection and reliability propagation. Compared to previous methods like OSTBC or CDD, gains are illustrated in terms of performance, power distribution, capability of adaptation and robustness. . .Next, moderating complexity and spatial orthogonality restrictions, we propose new solutions in more favorable contexts. Even with a simple linear MMSE detection, these techniques are promising in high data-rate mobile transmissions as soon as the number of antennas increases. Finally, we introduce proper MIMO channel estimation schemes, using scattered pilots and iterative methods with decoded data, in order to fulfil a wide range of compromises on diverse receivers. The various results obtained exhibit the relevance of the developed solutions.
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https://tel.archives-ouvertes.fr/tel-00694774
Contributor : Fabrice Portier <>
Submitted on : Sunday, May 6, 2012 - 4:49:10 PM
Last modification on : Friday, November 16, 2018 - 1:29:49 AM
Long-term archiving on : Thursday, December 15, 2016 - 4:46:22 AM

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  • HAL Id : tel-00694774, version 1

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Fabrice Portier. Systèmes hertziens à forte efficacité spectrale pour les communications mobiles multi-antennes et multi-porteuses de 4° génération. Traitement du signal et de l'image [eess.SP]. INSA de Rennes, 2007. Français. ⟨tel-00694774⟩

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