Speaker: 
Xuan-Thang Vu
Date: 
Tue, 01/14/2014 -
14:30 to 16:30
Lieu: 
Supelec, amphi F.3.05
Résumé/Abstract: 
In this thesis, we aim to design high performance receivers and analyze its performance for network-coded cooperative networks in practical scenarios. Firstly, we propose two Iterative Network/Channel Decoding (INCD) algorithms for the Multiple-Access Relay Channel (MARC) with two notable relaying schemes named Decode-and-Forward (DF) and Demodulate-and-Forward (DMF). The INCD algorithm operates based on turbo-like decoding methods and reduces the impact of the error propagation problem with the aid of a channel-aware receiver design. Both perfect Channel State Information (CSI) and imperfect CSI at the receiver side are investigated. We propose a practical method that forwards the quantized version of the relay decoding errors to the destination. It is shown that the proposed algorithms achieve full diversity gain and significantly outperforms solutions which do not take care of error propagation. We also show that the number of pilot symbols affects only the coding gain but has a negligible impact on the diversity order, while the quantization level affects both the diversity and coding gain. Secondly, we propose a Near Optimal Joint Network/Channel Decoding (NOJNCD) algorithm for the MARC that allows to analyze the system Bit Error Rate (BER). The NOJNCD algorithm performs network decoding and channel decoding in one decoding step of the super code, which comprises of all trellis states of individual code at the sources via NC. Furthermore, NC combined with Relay Selection (RS) is considered and the achievable diversity order is studied with the aid of outage analysis. We analytically show that Single Relay Selection (SRS) always achieves a diversity order two and Multiple Relay Selection (MRS) can achieve full diversity gain only when the number of selected relays exceeds the number of the sources. Last but not least, we propose a so-called partial relaying protocol to improve the spectral efficiency for channel coding assisted relay networks. Closed-form expression of the BER and the system diversity order are computed for partial relaying. We show, by analysis and simulations, that with a proper Convolutional Code (CC), partial relaying can achieve full diversity gain and same coding gain as the classical (full) relaying protocol in finite signal-to-noise ratio region while it obtains a better spectrum usage. Moreover, we propose a new protocol based on partial relaying in opportunistic relaying cooperative networks and show that this protocol significantly outperforms the NC-based cooperation in some circumstances.
Membres du jury
Charly Poulliat, INP - ENSEEIHT, France Rapporteur
Erdal Arikan, Bilkent University, Turkey Rapporteur
Pierre Duhamel, LSS-CNRS, France Examinateur
Bernard Fleury, Aalborg University, Denmark Examinateur
Luc Vandendopre, UCL, Belge Examinateur
Marco Di Renzo, LSS-CNRS, France Directeur de thèse
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