Efficient Analysis, Design and Decoding of Low-density Parity-check Codes [microform] - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Efficient Analysis, Design and Decoding of Low-density Parity-check Codes [microform] write by Masoud Ardakani. This book was released on 2004. Efficient Analysis, Design and Decoding of Low-density Parity-check Codes [microform] available in PDF, EPUB and Kindle. This dissertation presents new methods for the analysis, design and decoding of low-density parity-check (LDPC) codes. We start by studying the simplest class of decoders: the binary message-passing (BMP) decoders. We show that the optimum BMP decoder must satisfy certain symmetry and isotropy conditions, and prove that Gallager's Algorithm B is the optimum BMP algorithm. We use a generalization of extrinsic information transfer (EXIT) charts to formulate a linear program that leads to the design of highly efficient irregular LDPC codes for the BMP decoder. We extend this approach to the design of irregular LDPC codes for the additive white Gaussian noise channel. We introduce a "semi-Gaussian" approximation that very accurately predicts the behaviour of the decoder and permits code design over a wider range of rates and code parameters than in previous approaches. We then study the EXIT chart properties of the highest rate LDPC code which guarantees a certain convergence behaviour. We also introduce and analyze gear-shift decoding in which the decoder is permitted to select the decoding rule from among a predefined set. We show that this flexibility can give rise to significant reductions in decoding complexity. Finally, we show that binary LDPC codes can be combined with quadrature amplitude modulation to achieve near-capacity performance in a multitone system over frequency selective Gaussian channels.
Low-density Parity-check Codes with Reduced Decoding Complexity
Low-density Parity-check Codes with Reduced Decoding Complexity - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Low-density Parity-check Codes with Reduced Decoding Complexity write by Benjamin Smith. This book was released on 2007. Low-density Parity-check Codes with Reduced Decoding Complexity available in PDF, EPUB and Kindle. 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 Codes for Gilbert-Elliott and Markov-modulated Channels [microform]
Low-density Parity-check Codes for Gilbert-Elliott and Markov-modulated Channels [microform] - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Low-density Parity-check Codes for Gilbert-Elliott and Markov-modulated Channels [microform] write by Andrew William Eckford. This book was released on 2004. Low-density Parity-check Codes for Gilbert-Elliott and Markov-modulated Channels [microform] available in PDF, EPUB and Kindle. The problem of low-density parity-check (LDPC) decoding in channels with memory has been attracting increasing attention in the literature. In this thesis, we use LDPC codes in an estimation-decoding scheme for the Gilbert-Elliott (GE) channel and more general Markov-modulated channels. The major accomplishments of this thesis include both analysis and design components. To analyze our estimation-decoding scheme, we derive density evolution for the GE channel, which has previously been used largely in memoryless channels. Furthermore, we develop techniques that use density evolution results to more efficiently characterize the space of Markov-modulated parameters. We begin by applying a characterization to the GE channel, following which we generalize this characterization into a partial ordering of Markov-modulated channels in terms of probability of symbol error. We also consider the design problem of developing LDPC degree sequences that are optimized for the GE channel. We obtain a novel design tool that approximates density evolution for our estimation-decoding algorithm, and present degree sequences that represent the best known codes in the GE channel. We also present a method of generalizing this tool to Markov-modulated channels, and give some of the first optimized degree sequences ever obtained for these channels.
Efficient Design and Decoding of the Rate-compatible Low-density Parity-check Codes
Efficient Design and Decoding of the Rate-compatible Low-density Parity-check Codes - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Efficient Design and Decoding of the Rate-compatible Low-density Parity-check Codes write by . This book was released on . Efficient Design and Decoding of the Rate-compatible Low-density Parity-check Codes available in PDF, EPUB and Kindle. HKUST Call Number: Thesis ECED 2009 WuXX.
Efficient Encoding and Decoding of Low Density Parity Check Codes
Efficient Encoding and Decoding of Low Density Parity Check Codes - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Efficient Encoding and Decoding of Low Density Parity Check Codes write by Hemanth Reddy Chintalapani. This book was released on 2006. Efficient Encoding and Decoding of Low Density Parity Check Codes available in PDF, EPUB and Kindle.
