Low-density Parity-check Codes with Reduced Decoding Complexity

Low-density Parity-check Codes with Reduced Decoding Complexity

Author: Benjamin Smith

Publisher:

Published: 2007

Total Pages: 156

ISBN-13: 9780494273289

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This thesis presents new methods to design low-density parity-check (LDPC) codes with reduced decoding complexity. An accurate measure of iterative decoding complexity is introduced. In conjunction with extrinsic information transfer (EXIT) chart analysis, an efficient optimization program is developed, for which the complexity measure is the objective function, and its utility is demonstrated by designing LDPC codes with reduced decoding complexity. For long block lengths, codes designed by these methods match the performance of threshold-optimized codes, but reduce the decoding complexity by approximately one-third. The performance of LDPC codes is investigated when the decoder is constrained to perform a sub-optimal decoding algorithm. Due to their practical relevance, the focus is on the design of LDPC codes for quantized min-sum decoders. For such a decoder, codes designed for the sum-product algorithm are sub-optimal, and an alternative design strategy is proposed, resulting in gains of more than 0.5 dB.


Low Density Parity Check Code for Next Generation Communication System

Low Density Parity Check Code for Next Generation Communication System

Author: Mayank Ardeshana

Publisher: LAP Lambert Academic Publishing

Published: 2011-12

Total Pages: 72

ISBN-13: 9783845420417

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Channel coding provides the means of patterning signals so as to reduce their energy or bandwidth consumption for a given error performance. LDPC codes have been shown to have good error correcting performance which enables efficient and reliable communication. LDPC codes have linear decoding complexity but performance approaching close to shannon capacity with iterative probabilistic decoding algorithm. In this dissertation, the performance of different error correcting code such as convolution, Reed Solomon(RS), hamming, block code are evaluated based on different parameters like code rate, bit error rate (BER), Eb/No, complexity, coding gain and compare with LDPC code. In general, message passing algorithm and the sum-product algorithm are used to decode the message. We showed that logarithmic sum-product algorithm with long block length code reduces multiplication to addition by introducing logarithmic likelihood ratio so that it achieves the highest BER performance among all the decoding algorithms. The astonishing performance combined with proposed modified MS decoding algorithm make these codes very attractive for the next generations digital broadcasting system (ABS - S).


Error-Correction Coding and Decoding

Error-Correction Coding and Decoding

Author: Martin Tomlinson

Publisher: Springer

Published: 2017-02-21

Total Pages: 527

ISBN-13: 3319511033

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This book discusses both the theory and practical applications of self-correcting data, commonly known as error-correcting codes. The applications included demonstrate the importance of these codes in a wide range of everyday technologies, from smartphones to secure communications and transactions. Written in a readily understandable style, the book presents the authors’ twenty-five years of research organized into five parts: Part I is concerned with the theoretical performance attainable by using error correcting codes to achieve communications efficiency in digital communications systems. Part II explores the construction of error-correcting codes and explains the different families of codes and how they are designed. Techniques are described for producing the very best codes. Part III addresses the analysis of low-density parity-check (LDPC) codes, primarily to calculate their stopping sets and low-weight codeword spectrum which determines the performance of th ese codes. Part IV deals with decoders designed to realize optimum performance. Part V describes applications which include combined error correction and detection, public key cryptography using Goppa codes, correcting errors in passwords and watermarking. This book is a valuable resource for anyone interested in error-correcting codes and their applications, ranging from non-experts to professionals at the forefront of research in their field. This book is open access under a CC BY 4.0 license.


Codes and turbo codes

Codes and turbo codes

Author: Claude Berrou

Publisher: Springer Science & Business Media

Published: 2011-01-27

Total Pages: 400

ISBN-13: 2817800397

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This book is devoted to one of the essential functions of modern telecommunications systems: channel coding or error correction coding. Its main topic is iteratively decoded algebraic codes, convolutional codes and concatenated codes.


A Study of Low Density Parity-Check Codes Using Systematic Repeat-Accumulate Codes

A Study of Low Density Parity-Check Codes Using Systematic Repeat-Accumulate Codes

Author:

Publisher:

Published: 2015

Total Pages: 82

ISBN-13:

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Low Density Parity-Check, or LDPC, codes have been a popular error correction choice in the recent years. Its use of soft-decision decoding through a message-passing algorithm and its channel-capacity approaching performance has made LDPC codes a strong alternative to that of Turbo codes. However, its disadvantages, such as encoding complexity, discourages designers from implementing these codes. This thesis will present a type of error correction code which can be considered as a subset of LDPC codes. These codes are called Repeat-Accumulate codes and are named such because of their encoder structure. These codes is seen as a type of LDPC codes that has a simple encoding method similar to Turbo codes. What makes these codes special is that they can have a simple encoding process and work well with a soft-decision decoder. At the same time, RA codes have been proven to be codes that will work well at short to medium lengths if they are systematic. Therefore, this thesis will argue that LDPC codes can avoid some of its encoding disadvantage by becoming LDPC codes with systematic RA codes. This thesis will also show in detail how RA codes are good LDPC codes by comparing its bit error performance against other LDPC simulation results tested at short to medium code lengths and with different LDPC parity-check matrix constructions. With an RA parity-check matrix describing our LDPC code, we will see how changing the interleaver structure from a random construction to that of a structured can lead to improved performance. Therefore, this thesis will experiment using three different types of interleavers which still maintain the simplicity of encoding complexity of the encoder but at the same time show potential improvement of bit error performance compared to what has been previously seen with regular LDPC codes.


Performance Analysis and Optimization of Reduced Complexity Low Density Parity Check Decoding Algorithms

Performance Analysis and Optimization of Reduced Complexity Low Density Parity Check Decoding Algorithms

Author: Jeff Castura

Publisher:

Published: 2000

Total Pages: 0

ISBN-13:

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Reduced complexity decoding algorithms for Low Density Parity Check codes are presented. The performance of these algorithms is optimized using the concept of density evolution and they are shown to perform well in practical decoding situations. The codes are examined from a performance vs. complexity point of view. It is shown that there is an optimal complexity for practical decoders beyond which performance will suffer. The idea of practical decoding is used to develop the sum-transform-sum algorithm, which is very well suited for a fixed-point hardware implementation. The performance of this algorithm approaches that of the sum-product algorithm, but is much less complex.