Schémas pratiques pour la diffusion (sécurisée) sur les canaux sans fils

Abstract : In this thesis, we aim to study broadcast channels with practical transmission constraints. First, we study the impact of finite input alphabet constraint on the achievable rates for the Gaussian broadcast channel with two users. We consider two models of broadcast channels, when there is in addition of a common message for two users, (i) a private message for one of them without secrecy constraint (ii) a confidential message for one of them which should be totally hidden from the other user. We present several broadcast strategies distinguished by their complexity of implementation. More precisely, we study achievable rate regions using time sharing, superposition modulation and superposition coding. For superposition modulation and superposition coding strategies, maximal achievable rate regions are obtained by maximizing over both symbol positions in the constellation and the joint probability distribution. We study the tradeoff between the complexity of implementation of the transmission strategies and their efficiency in terms of gains in achievable rates. We study also the impact of the secrecy constraint on communication by comparing the achievable rates with and without this constraint. Finally, we study the system performance using HARQ schemes for the block-fading wiretap channel when the transmitter has no instantaneous channel state information but knows channel statistics. We consider an adaptive-rate scheme for the secure communication by using multilevel feedback channels to change sub-codeword lengths at each retransmission, in order to maximize the secrecy throughput under outage probabilities constraints.
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Submitted on : Monday, September 1, 2014 - 11:02:08 AM
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Zeina Mheich. Schémas pratiques pour la diffusion (sécurisée) sur les canaux sans fils. Autre [cond-mat.other]. Université Paris Sud - Paris XI, 2014. Français. ⟨NNT : 2014PA112095⟩. ⟨tel-01059512⟩



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