2016/05/16 by Sachini Jayasooriya, Jayasooriya, Sachini, Mahyar Shirvanimoghaddam +7
Computer Science · Engineering · #Advanced MIMO Systems Optimization #Advanced Wireless Communication Techniques #Error Correcting Code Techniques #FOS: Computer and information sciences #Information Theory (cs.IT)
paper · pdf · doi:10.48550/arxiv.1605.04665
openalex publication_date 2016/05/16 · openalex created_date 2022/10/04 · openalex updated_date 2026/07/28
This paper considers density evolution for lowdensity parity-check (LDPC) and\nmulti-edge type low-density parity-check (MET-LDPC) codes over the binary input\nadditive white Gaussian noise channel. We first analyze three singleparameter\nGaussian approximations for density evolution and discuss their accuracy under\nseveral conditions, namely at low rates, with punctured and degree-one variable\nnodes. We observe that the assumption of symmetric Gaussian distribution for\nthe density-evolution messages is not accurate in the early decoding\niterations, particularly at low rates and with punctured variable nodes. Thus\nsingle-parameter Gaussian approximation methods produce very poor results in\nthese cases. Based on these observations, we then introduce a new density\nevolution approximation algorithm for LDPC and MET-LDPC codes. Our method is a\ncombination of full density evolution and a single-parameter Gaussian\napproximation, where we assume a symmetric Gaussian distribution only after\ndensity-evolution messages closely follow a symmetric Gaussian distribution.\nOur method significantly improves the accuracy of the code threshold\nestimation. Additionally, the proposed method significantly reduces the\ncomputational time of evaluating the code threshold compared to full density\nevolution thereby making it more suitable for code design.\n