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Techniques de synchronisation aveugles pour les systèmes codés

Abstract : The past few years have seen an increasing demand for efficient and reliable digital communication systems. In order to protect the transmitted data from noise, error correcting codes should be used in the transmission scheme. LDPC (Low Density Parity Check) codes, product codes and turbocodes have proven their efficiency in detecting and correcting errors, even at low SNR (Signal to Noise Ratio). However, a degradation in the performance of these codes is expected in the case of a bad synchronization. Therefore, the use of efficient synchronization methods is essential to keep the system in a good working order. Conventional synchronization techniques involve the insertion of pilot bits in the transmitted sequence of data. The detection of these bits at the reception enables us to carry out synchronization. However, applying these methods decreases the spectral efficiency of the transmission especially when error correcting codes of small sizes are used in the system. For that reason, we are interested in this thesis by the design of novel methods of blind synchronization, which are able to synchronize even on low SNR. We consider in this thesis the problem of frame synchronization, CFO (Carrier Frequency Offset) estimation and phase estimation. We propose powerful synchronization techniques that involve the calculation and the minimization of functions of the LLR (Log-Likelihood Ratio) of the syndrome calculated from the parity check matrix of the error correcting code. Simulation results have shown that the proposed techniques are very powerful and their performance clearly exceeds those of several existing methods.
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Contributor : Rodrigue Imad <>
Submitted on : Wednesday, December 2, 2009 - 10:44:56 AM
Last modification on : Wednesday, January 6, 2021 - 3:36:45 PM
Long-term archiving on: : Thursday, September 23, 2010 - 11:12:04 AM


  • HAL Id : tel-00428895, version 2


Rodrigue Imad. Techniques de synchronisation aveugles pour les systèmes codés. Traitement du signal et de l'image [eess.SP]. Ecole Nationale Supérieure des Télécommunications de Bretagne - ENSTB, 2009. Français. ⟨tel-00428895v2⟩



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