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Codage Espace Temps pour les canaux MIMO à accès multiple

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.
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https://pastel.archives-ouvertes.fr/pastel-00006005
Contributor : Ecole Télécom Paristech <>
Submitted on : Friday, July 9, 2010 - 8:00:00 AM
Last modification on : Friday, July 31, 2020 - 10:44:07 AM
Long-term archiving on: : Thursday, March 30, 2017 - 5:56:31 AM

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

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