Author: Li, Yidong
Title: Modified noisy gradient descent bit-flipping decoding algorithms for LDPC codes
Advisors: Lau, Francis (EIE)
Degree: M.Sc.
Year: 2022
Subject: Coding theory
Error-correcting codes (Information theory)
Hong Kong Polytechnic University -- Dissertations
Department: Department of Electronic and Information Engineering
Pages: xxvii, 68 pages : color illustrations
Language: English
Abstract: A few modified Noisy Gradient Descent Bit Flipping (NGDBF) algorithms have been proposed for decoding Low-Density Parity-Check (LDPC) codes on the additive white Gaussian noise (AWGN) channel, which are categorized as NGDBF+. A new idea is introduced to generate the perturbation signals by using a transformation method to process the received messages. It means that random number generators (RNG) are no longer needed for NGDBF+ to generate perturbation signal, which can reduce the complexity of the whole system to some degree. Another innovation of this algorithm is that it combines the advantages of both GDBF and NGDBF algorithms. The GDBF algorithm is used in the first few iterations, and the NGDBF algorithm is used in the remaining iterations. By using the GDBF algorithm to speed up convergence, the error correction performance and convergence speed of the NGDBF+ algorithm can be improved. Another innovation of this algorithm is that the flip state of the bits in the current iteration will be recorded to adjust the threshold in the next iteration. This threshold will make it difficult for most flipped bits to be flipped in the next iteration. Hence, it can reduce oscillation to some degree and it can reduce the threshold sensitivity of this algorithm. Moreover, a new idea is proposed to re-use the flip state to eliminate the delay caused by the global operation. Therefore, the throughput can be further increased. In general, compared with NGDBF algorithm, NGDBF+ algorithm can achieve 0.15dB error correction performance improvement and nearly 30% increase in convergence speed. Furthermore, this is a hardware-friendly design. The hardware architecture details are presented for implementing the NGDBF+ algorithm. Complexity analysis is also included.
Rights: All rights reserved
Access: restricted access

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