Code-aided synchronization for digital burst communications

by Herzet, Cédric

Abstract (Summary)
This thesis deals with the synchronization of digital communication systems. Synchronization (from the Greek syn (together) and chronos (time)) denotes the task of making two systems running at the same time. In communication systems, the synchronization of the transmitter and the receiver requires to accurately estimate a number of parameters such as the carrier frequency and phase offsets, the timing epoch... In the early days of digital communications, synchronizers used to operate in either data-aided (DA) or non-data-aided (NDA) modes. However, with the recent advent of powerful coding techniques, these conventional synchronization modes have been shown to be unable to properly synchronize state-of-the-art receivers. In this context, we investigate in this thesis a new family of synchronizers referred to as code-aided (CA) synchronizers. The idea behind CA synchronization is to take benefit from the structure of the code used to protect the data to improve the estimation quality achieved by the synchronizers. In a first part of the thesis, we address the issue of turbo synchronization, i.e., the iterative synchronization of continuous parameters. In particular, we derive several mathematical frameworks enabling a systematic derivation of turbo synchronizers and a deeper understanding of their behavior. In a second part, we focus on the so-called CA hypothesis testing problem. More particularly, we derive optimal solutions to deal with this problem and propose efficient implementations of the proposed algorithms. Finally, in a last part of this thesis, we derive theoretical lower bounds on the performance of turbo synchronizers.
Bibliographical Information:


School:Université catholique de Louvain

School Location:Belgium

Source Type:Master's Thesis

Keywords:factor graph em algorithm synchronization sp digital communications signal processing timing recovery turbo code phase


Date of Publication:04/21/2006

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