Density Evolution Analysis of Generalized Low-density Parity-check Codes under a Posteriori Probability Decoder

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Main Authors: Chang, Dongxu, Peng, Qingqing, Ma, Zhiming, Wang, Guanghui, Yin, Dawei
Format: Preprint
Published: 2024
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author Chang, Dongxu
Peng, Qingqing
Ma, Zhiming
Wang, Guanghui
Yin, Dawei
author_facet Chang, Dongxu
Peng, Qingqing
Ma, Zhiming
Wang, Guanghui
Yin, Dawei
contents In this study, the performance of generalized low-density parity-check (GLDPC) codes under the a posteriori probability (APP) decoder is analyzed. We explore the concentration, symmetry, and monotonicity properties of GLDPC codes under the APP decoder, extending the applicability of density evolution to GLDPC codes. On the binary memoryless symmetric channels, using the BEC and BI-AWGN channels as two examples, we demonstrate that with an appropriate proportion of generalized constraint (GC) nodes, GLDPC codes can reduce the original gap to capacity compared to their original LDPC counterparts. Additionally, on the BI-AWGN channel, we apply and improve the Gaussian approximation algorithm in the density evolution of GLDPC codes. By adopting Gaussian mixture distributions to approximate the message distributions from variable nodes and Gaussian distributions for those from constraint nodes, the precision of the channel parameter threshold can be significantly enhanced while maintaining a low computational complexity similar to that of Gaussian approximations. Furthermore, we identify a class of subcodes that can greatly simplify the performance analysis and practical decoding of GLDPC codes, which we refer to as message-invariant subcodes. Using the aforementioned techniques, our simulation experiments provide empirical evidence that GLDPC codes, when decoded with the APP decoder and equipped with the right fraction of GC nodes, can achieve substantial performance improvements compared to low-density parity-check (LDPC) codes.
format Preprint
id arxiv_https___arxiv_org_abs_2404_01136
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Density Evolution Analysis of Generalized Low-density Parity-check Codes under a Posteriori Probability Decoder
Chang, Dongxu
Peng, Qingqing
Ma, Zhiming
Wang, Guanghui
Yin, Dawei
Information Theory
In this study, the performance of generalized low-density parity-check (GLDPC) codes under the a posteriori probability (APP) decoder is analyzed. We explore the concentration, symmetry, and monotonicity properties of GLDPC codes under the APP decoder, extending the applicability of density evolution to GLDPC codes. On the binary memoryless symmetric channels, using the BEC and BI-AWGN channels as two examples, we demonstrate that with an appropriate proportion of generalized constraint (GC) nodes, GLDPC codes can reduce the original gap to capacity compared to their original LDPC counterparts. Additionally, on the BI-AWGN channel, we apply and improve the Gaussian approximation algorithm in the density evolution of GLDPC codes. By adopting Gaussian mixture distributions to approximate the message distributions from variable nodes and Gaussian distributions for those from constraint nodes, the precision of the channel parameter threshold can be significantly enhanced while maintaining a low computational complexity similar to that of Gaussian approximations. Furthermore, we identify a class of subcodes that can greatly simplify the performance analysis and practical decoding of GLDPC codes, which we refer to as message-invariant subcodes. Using the aforementioned techniques, our simulation experiments provide empirical evidence that GLDPC codes, when decoded with the APP decoder and equipped with the right fraction of GC nodes, can achieve substantial performance improvements compared to low-density parity-check (LDPC) codes.
title Density Evolution Analysis of Generalized Low-density Parity-check Codes under a Posteriori Probability Decoder
topic Information Theory
url https://arxiv.org/abs/2404.01136