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Optimisation d'un précodeur MIMO-OFDM dans le contexte de l'estimation aveugle et semi-aveugle du canal de communication

Abstract : Channel estimation plays an important role in wireless mobile communications, especially in MIMO systems. Unlike conventional channel estimation techniques based on training sequences or pilot symbols, blind techniques does not require the insertion of training symbols and allow higher throughput. The main problems of the blind lies in the ambiguity over the estimated channel. Based on the same methods as the blind estimation, the semi-blind estimation techniques are more robust. They exploit the blind information along with information provided by a small number of training symbols. The channel estimation is useful in MIMO systems and allows the precoding of the MIMO-OFDM signal by applying a pre-mixture in order to improve performance. Many types of precoders exist and their performance varies depending not only on the optimization criteria (Water-Filling, MMSE, Equal Error, max-SNR, max-d min ...), but also on the estimated channel. In this thesis we study the impact of using the channel information (CSI) from the blind and semi-blind estimation techniques to apply MIMO linear precoders. We also present a statistical study of the estimation error of these methods. The optimization of these precoders leads eventually to use another process allowing more performance improvement: the error correcting codes. We are particularly interested in non-binary LDPC codes and their association with linear MIMO precoders. We show that a matching is possible, and is beneficial in some cases. The optimization of this combination has allowed us to propose a new robust and more efficient precoder based on the maximization of mutual information.
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https://tel.archives-ouvertes.fr/tel-02005696
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Submitted on : Monday, February 4, 2019 - 11:24:37 AM
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Tarek Chehade. Optimisation d'un précodeur MIMO-OFDM dans le contexte de l'estimation aveugle et semi-aveugle du canal de communication. Autre. Université de Bretagne occidentale - Brest, 2015. Français. ⟨NNT : 2015BRES0077⟩. ⟨tel-02005696⟩

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