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Theses Year : 2010

Space-Time Block Codes Construction for MIMO Multiple-Access Channels

Codage Espace Temps pour les canaux MIMO à accès multiple

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Abstract

Extensive research has been carried out these last few years on the single-user MIMO Space-Time block code (STBC) design using advanced algebraic tools, namely cyclic division algebra. Families of single-user codes have been carefully constructed to achieve the diversity-multiplexing tradeoff (DMT) of the MIMO channel. Motivated by the promising results obtained in the single-user scenario, the aim of this thesis is to construct new families of multi-user STBCs. Multi-user MIMO (MU-MIMO) channels have recently attracted considerable attention because of its essential practical implication in today's and future communication systems, i.e., IEEE 802.11n, 3GPP Long Term Evolution Advanced (LTE-A), IEEE 802.16m, etc. The current study focuses on the uplink multiuser MIMO channel, equivalently, the MIMO multiple-access channel (MAC). In a MIMO-MAC, multiple users equipped with multiple transmit antennas communicate with one multiple-antenna receiver. A coherent communication system is considered, where the receiver has a perfect channel state information (CSI) while the transmitters do not have any CSI, but are aware of the channel statistics. The construction of the proposed multiple-access codes is based on an in-depth understanding of the information theoretic aspects of the MAC that give insight on the behavior of the channel. In order to simplify the problem, a MAC with single-antenna at the transmitters and an arbitrary number of antennas at the receiver is first considered. Next, the general MIMO-MAC with multiple-antenna at both the transmitters and the receiver is investigated. Throughout this thesis, all the presented results deal with multiple-access systems under the assumption of synchronized users which may not be practical for several reasons: the users do not necessarily share the same timing reference, they access the channel randomly, they have different geometrical locations, etc. As a practical application, the effect of asynchronism on the multiple-access code performance is studied in the single-antenna scenario. The proposed code turns out to be delay tolerant, i.e., does not lose its performance gain due to asynchronism. Finally, the multiple-access relay channel (MARC) is considered, where one or more relays help the users communicate with the destination while the cooperation between the users is not allowed. Relaying techniques exploit the spatial diversity in a wireless network and, thus, significantly improve the performance of the system. The multi-access amplify-and-forward (MAF) strategy, characterized by its low relaying complexity and its linear nature, is considered. The MAF relay channel is shown to be equivalent to a virtual MIMO-MAC for which, the code constructed for the MIMO-MAC can be applied in a distributed way.
Multiples travaux de recherche on été munis ces dernières années pour construire des codes espace-temps optimaux pour les communications sans fil de point a point (monoutilisateur). Plusieurs familles de codes, dont la construction utilise des outils algébriques avances et qui atteignent le dmt ont été proposées dans la littérature. Ce compromis a été développe par zheng et tse pour capturer les avantages duels d'un canal a évanouissement pour les snr élèves: l'augmentation du débit (augmentation du gain de multiplexage) et l'augmentation de la fiabilité (augmentation du gain de diversité). Motivés par les résultats promettant obtenus dans le cas des canaux mono-utilisateur, notre but dans cette thèse est de proposer des nouvelles constructions de codes espace temps pour les canaux à accès multiple (i.e., multi-utilisateur) en se basant sur une profonde compréhension de ce dernier du point de vue de la théorie de l'information. Nous considérons dans une première partie le cas mono antenne pour lequel nous proposons une nouvelle construction de code qui offre un gain significative et dont les performances sont conservées dans le cas synchrone et asynchrone. Motive par le gain de performance important obtenu dans le cas momo antenne et arme par la compréhension des aspects théoriques du canal a accès multiple, nous avons propose un nouveau code dont les performances sont meilleures comparées aux codes existants. Ce code est ensuite utilise pour construire un nouveau code distribue pour le canal à accès multiple avec relais.
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Dates and versions

pastel-00006005 , version 1 (09-07-2010)

Identifiers

  • HAL Id : pastel-00006005 , version 1

Cite

Maya Badr. Codage Espace Temps pour les canaux MIMO à accès multiple. domain_other. Télécom ParisTech, 2010. Français. ⟨NNT : ⟩. ⟨pastel-00006005⟩
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