Nonlinear Digital Encoders for Data Communications E-Book

Calin Vladeanu

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch

Seitenzahl: 179

Veröffentlichungsjahr: 2014

Beschreibung

This book presents digital encoders for data communications. After an introduction on data communications and different sequences, the authors present the frey encoder as a digital filter followed by the trellis-coded and parallel turbo trellis-coded modulation schemes using nonlinear digital encoders. The book contains many numerical examples that complete the description of the analyzed schemes. Also, some performance simulation results are provided. Appendixes include demonstrations for the mathematical apparatus used throughout the book and some Matlab/Simulink source files used to run the simulations. Therefore, students can easily understand the concepts presented in the book and to simulate the schemes.

Leseprobe

Table of Contents

Preface

Introduction

Chapter 1: Applications of Nonlinear Digital Encoders

1.1. Secure communications using nonlinear digital encoders

1.2. Chaotic spreading sequences for direct-sequence code division multiple access

1.3. Sequence synchronization in discrete-time nonlinear systems

Chapter 2: Presentation of the Frey Nonlinear Encoder as a Digital Filter

2.1. The mathematical analysis of the Frey encoder

2.2. The definitions and properties of the unsigned and 2’s complement signed sample operators

2.3. The properties of the LCIRC nonlinear function used in the Frey encoder scheme

2.4. The simulation of the Frey sequence generator block in Simulink: some practical considerations

Chapter 3: Trellis-Coded Modulation Schemes Using Nonlinear Digital Encoders

3.1. The presentation of the Frey nonlinear encoder as a convolutional encoder

3.2. Frey encoder trellis design optimization methods for pulse amplitude – trellis-coded modulation (TCM) schemes

3.3. Optimum nonlinear encoders for phase shift keying – TCM schemes

3.4. Optimum nonlinear encoders for quadrature amplitude modulation – TCM schemes

3.5. Performance analysis of TCM data communications using modified nonlinear digital encoders: simulation results

Chapter 4: Parallel Turbo Trellis-Coded Modulation Schemes Using Nonlinear Digital Encoders

4.1. Recursive convolutional-left circulate (RC-LCIRC) encoder in a turbo trellis-coded modulation (TTCM) scheme

4.2. New recursive and systematic convolutional nonlinear encoders for parallel TTCM schemes

4.3. Punctured TTCM transmissions using recursive systematic convolutional nonlinear encoders

4.4. Extrinsic information transfer (EXIT) charts analysis for TTCM schemes using nonlinear RSC encoders

4.5. Performance analysis of TTCM data communications using nonlinear digital encoders: simulation results

Appendix: Demonstrations for the Properties of the Unsigned and Signed Finite Precision Operators

A1.1. The demonstration of theorem 2.2

A1.2. The general expression of the addition operation in the 2N-set

A1.3. The subtraction as the inverse of addition in the 2N-set

Bibliography

Index

First published 2014 in Great Britain and the United States by ISTE Ltd and John Wiley & Sons, Inc.

Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act 1988, this publication may only be reproduced, stored or transmitted, in any form or by any means, with the prior permission in writing of the publishers, or in the case of reprographic reproduction in accordance with the terms and licenses issued by the CLA. Enquiries concerning reproduction outside these terms should be sent to the publishers at the undermentioned address:

ISTE Ltd27-37 St George’s RoadLondon SW19 4EUUK

www.iste.co.uk

John Wiley & Sons, Inc.111 River StreetHoboken, NJ 07030USA

www.wiley.com

© ISTE Ltd 2014

The rights of Călin Vlădeanu and Safwan El Assad to be identified as the authors of this work have been asserted by them in accordance with the Copyright, Designs and Patents Act 1988.

Library of Congress Control Number: 2013956557

British Library Cataloguing-in-Publication DataA CIP record for this book is available from the British LibraryISSN 2051-2481 (Print)ISSN 2051-249X (Online)ISBN 978-1-84821-649-5

Preface

Several applications using nonlinear dynamical systems have been developed over the last few decades. Among these, the field of telecommunications has clearly benefited from these nonlinear blocks. Hence, the nonlinear blocks have proved to be suitable for implementing several telecommunications techniques, such as encryption, spectrum spreading and channel coding.

In this book, we present novel solutions for channel coding using nonlinear sequence generators. To the best of our knowledge, there are only a few works that attempt to propose the use of nonlinear functions for channel coding in telecommunications systems. In this context, this book aims to demonstrate that nonlinear encoders can be designed to provide good performances and to encourage researchers to investigate these approaches further.

This book contains many numerical examples that complete the description of the analyzed schemes. Also, some performance simulation results are provided. Some sections include presentations of the mathematical apparatus used throughout the book and some Matlab/Simulink scripts and schemes used to run the simulations.

We recommend this book to students, especially for Master’s and PhD students who will easily understand the concepts presented in this book and can design and test these schemes by simulations.

We also consider that this book may be used by telecommunications engineers to complete their grounding in the field of signal processing for telecommunications, especially on non-conventional and nonlinear coded modulation techniques.

Călin VLĂDEANUSafwan EL ASSADJanuary 2014

Introduction

During the last few decades, several chaotic sequence generators have been investigated for secure and efficient digital communication systems. Because of their generators’ sensitive dependence on the initial state, these sequences present pseudo-random properties and offer an enhanced security.

As is well known, chaotic sequence generators are nonlinear dynamical systems and their finite precision or quantized approximations affect the chaotic regimes. Hence, this problem can be overcome by developing digital generators. In [FRE 93], Frey proposed a chaotic digital infinite impulse response (IIR) filter for a secure communications system. The Frey filter contains a nonlinear function called the left-circulate (LCIRC) function, which provides the chaotic properties of the filter. The LCIRC function performs a bit left circulation over the N bits representation word. In the same paper, Frey showed that this nonlinear recursive filter possesses quasi-chaotic properties, both for autonomous and non-autonomous modes. In [WER 98], Werter improved this encoder in order to increase the randomness between the output sequence samples. The performances of a pulse amplitude modulation (PAM) communication system using the Frey encoder, with additive white Gaussian noise (AWGN), were analyzed in [AIS 96]. A modified state feedback decoder was proposed in [AIS 96] and performs better than the Frey inverse filter decoder, in terms of bit error rate (BER) at a high signal-to-noise ratio (SNR).