LDPC Coded Modulations

by Franceschini, Michele; Ferrari, Gianluigi; Raheli, Riccardo

• ISBN13: 9783540694557
• ISBN10: 3540694552
• Format: Hardcover
• Copyright: 2009-05-01
• Publisher: Springer Verlag

Summary

This book focuses on the analysis and design of low-density parity-check (LDPC) coded modulations, which are becoming part of several current and future communication systems, such as high-throughput terrestrial and satellite wireless networks. In this book, a two-sided perspective on the design of LDPC coded systems is proposed, encompassing both code/modulation optimization (transmitter side) and detection algorithm design (receiver side). After introducing key concepts on error control coding, in particular LDPC coding, and detection techniques, the book presents several relevant applications. More precisely, by using advanced performance evaluation techniques, such as extrinsic information transfer charts, the optimization of coded modulation schemes are considered for (i) memoryless channels, (ii) dispersive and partial response channels, and (iii) concatenated systems including differential encoding. This book is designed to be used by graduate students working in the field of communication theory, with particular emphasis on LDPC coded communication schemes, and industry experts working on related fields.

Table of Contents

Preface	p. 1
Preliminary Concepts	p. 3
Introduction	p. 3
Modeling a Communication System	p. 3
Modulation	p. 6
Error Correcting Codes	p. 7
Block Codes	p. 7
Stream Codes	p. 9
Information Theory Basics	p. 10
The Following chapters	p. 17
Trellis-based Detection Techniques	p. 19
Introduction	p. 19
Hard-Output and Soft-Output Detection	p. 19
The Viterbi Algorithm	p. 21
The Forward-Backward Algorithm	p. 25
Optimal Detection Strategies for Channels with Memory	p. 30
Detection of Encoded Data	p. 32
Joint Detection and Decoding	p. 32
Separate Detection and Decoding	p. 33
Iterative Detection and Decoding	p. 33
Turbo Detection	p. 35
Concluding Remarks	p. 36
Low-Density Parity-Check Codes	p. 37
Introduction	p. 37
Description of LDPC Codes	p. 37
Statistical Description of LDPC Codes	p. 40
Decoding Algorithms for LDPC Codes	p. 42
Sum-Product Algorithm	p. 42
Min-Sum Algorithm	p. 49
Alternative Decoding Algorithms	p. 53
Practical LDPC Code Design from Statistical Description	p. 53
Encoding Techniques for LDPC Codes	p. 56
Encoding by Matrix Multiplication	p. 56
Recursive Encoding and Structured Codes	p. 58
Concluding Remarks	p. 59
Performance Analysis Techniques	p. 61
Introduction	p. 61
Monte Carlo System Simulation	p. 62
Density Evolution	p. 68
EXIT Charts	p. 71
EXIT Curves and EXIT Charts	p. 72
SISO Detectors and EXIT Charts	p. 73
EXIT Charts for LDPC Codes	p. 78
Concluding Remarks	p. 81
LDPC Coded Modulations: Analysis and Design	p. 83
Introduction	p. 83
LDPC Coded Modulation Schemes: Basics	p. 85
A Graph-Based Detection/Decoding Approach	p. 85
A "Turbo" Detection/Decoding Approach	p. 86
Communication System Model	p. 87
EXIT Chart-Based Performance Analysis	p. 90
The First Iterations	p. 91
The Asymptotic Convergence Region	p. 92
Upper and Lower Bounds on the BER	p. 93
MI-Based Lower Bounds on the BER	p. 93
MI-Based Upper Bound on the BER	p. 94
Code Design for LDPC Coded Modulations	p. 95
The Need for Optimization	p. 96
Optimizing the EXIT Charts	p. 97
Code Design for Fast Decoding Convergence	p. 101
Code Design for a Target BER	p. 110
Target BER-Based LDPC Code Design for BEC	p. 112
Code Design for Dispersive and Partial Response Channels	p. 120
System Structure and Analysis	p. 120
Theoretical Considerations	p. 121
An ISI Channel SISO Property	p. 124
LDPC Codes Designed for ISI Channels	p. 124
Comments	p. 126
Concluding Remarks	p. 127
Memoryless Channels and LDPC Codes	p. 129
Introduction	p. 129
Performance of LDPC Codes on Binary-Input Memoryless Channels	p. 130
The Start Point in EXIT Charts	p. 131
Numerical Evidence	p. 132
Implications	p. 136
Multilevel Code Design	p. 137
Multilevel Scheme Overview	p. 138
Code Selection with the MI Rule	p. 140
Concluding Remarks	p. 144
LDPC Codes and Differential Modulations	p. 147
Introduction	p. 147
Serial Concatenation of LDPC Codes with PSK and DE-PSK	p. 148
Optimized LDPC Codes for PSK	p. 152
LDPC Codes for DE-QAM	p. 157
LDPC Codes for DE-PSK with Noncoherent Detection	p. 159
Detection by Multiple Trellises	p. 160
Time-Invariant Parameters	p. 161
Time-Varying Parameters	p. 163
LDPC Coded Schemes with Detection by Multiple Trellises	p. 170
Phase-Uncertain Channels	p. 170
Flat Fading Channels	p. 172
Concluding Remarks	p. 178
Final Remarks	p. 179
List of Acronyms	p. 193
Index	p. 195
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