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IEEE Vehicular Technology Conference

A Perturbation Method for Decoding of LDPC Aided by CRC

Chunlei Lin, Dongliang Xiao, Hongbing Cheng, Meng Ma, Bingli Jiao

Published Sep 1, 2006• 2 citations
Publisher

Abstract

In this paper, we propose a new decoding method for LDPC aided by CRC and perturbation for improving FER performance. The CRC is used to check the decoding error of BP algorithm. Once an error is found, the perturbation method will be used to start re-decoding processing. Simulation results show that this method performs within about 1.2 dB of the sphere-packing bound for codeword length of several hundred bits.

DOI
10.1109/vtcf.2006.323

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In this paper, we propose a new decoding method for LDPC aided by CRC and perturbation for improving FER performance. The CRC is used to check the decoding error of BP algorithm. Once an error is found, the perturbation method will be used to start re-decoding processing. Simulation results show that this method performs within about 1.2 dB of the sphere-packing bound for codeword length of several hundred bits.
In this paper, a novel decoding algorithm using perturbation techniques for LDPC concatenated with CRC (LDPC-CRC) is proposed. The CRC is used to check the residual error of the BP algorithm, while a new parameter is introduced to LDPC decoding to describe the reliability of each bit in the iterative decoding algorithm. Upon an error is detected, re-decoding process with perturbation method will be aroused. Simulation results show that this method lowers the error floor for codeword length of several hundred bits effectively.
In this paper, a fresh belief propagation (BP) decoding algorithm is proposed. The proposed decoding algorithm with improved perturbation method is designed for short length low density parity-check (LDPC) codes aided by cyclic redundancy check (CRC). In the proposed algorithm corresponding to path size L, L decoding paths are considered concurrently. Then, a single codeword is selected according to the checking results of CRC. Simulation results show that the modified CRC-aided decoding scheme can enhance the error-correcting performance of short LDPC codes effectively.
In modern communication systems, the concatenation of a low-density parity-check (LDPC) code with a cyclic redundancy check (CRC) code is commonly used for error correction. In this paper, we propose a low-complexity two-stage scheme for decoding these codes using their concatenation structures. In the first stage, the traditional belief propagation (BP)-based iterative algorithm with a relative small maximum number of iterations is performed for decoding the LDPC code. If an LDPC codeword is obtained in this stage, the decoding process terminates. Otherwise, the second stage of the decoding process is performed, in which the guessing random additive noise decoding (GRAND) algorithm is applied to the CRC code. A list of information sequences satisfying the CRC check is obtained, each of which is then encoded to an LDPC codeword. The most likely codeword among them is the output of the decoding approach. The simulation results indicate that the proposed two-stage decoding approach can outperform the traditional BP-based iterative algorithm with a large maximum number of iterations. Moreover, the average complexity of the proposed approach is relatively low.
Irregular Low-Density Parity-Check (LDPC) codes generally achieve better performance than regular LDPC codes at low E b /N 0 values. They have, however, higher error floors than regular LDPC codes. With respect to the construction of the irregular LDPC code, it can achieve the trade-off between the performance degradation of low E b /N 0 region and lowering error floor. It is known that a decoding algorithm can achieve very good performance if it combines the Ordered Statistic Decoding (OSD) algorithm and the Log Likelihood Ratio-Belief Propagation (LLR-BP) decoding algorithm. Unfortunately, all the codewords obtained by the OSD algorithm satisfy the parity check equation of the LDPC code. While we can not use the parity check equation of the LDPC code to stop the decoding process, the wrong codeword that satisfies the parity check equation raises the error floor. Once a codeword that satisfies the parity check equation is generated by the LLR-BP decoding algorithm, we regard that codeword as the final estimate and halt decoding; the OSD algorithm is not performed. In this paper, we propose a new encoding/decoding scheme to lower the error floor created by irregular LDPC codes. The proposed encoding scheme encodes information bits by Cyclic Redundancy Check (CRC) and LDPC code. The proposed decoding scheme, which consists of the LLR-BP decoding, CRC check, and OSD decoding, detects errors in the codewords obtained by the LLR-BP decoding algorithm and the OSD decoding algorithm using the parity check equations of LDPC codes and CRC. Computer simulations show that the proposed encoding/decoding scheme can lower the error floor of irregular LDPC codes.
In this paper, we focus on how to further improve the performance of short block-length low-density parity-check (LDPC) codes, especially the short LDPC codes in 5th generation (5G) New Radio (NR) systems. We propose an enhanced adaptive belief propagation (ABP) decoding algorithm with the assistance of partial cyclic redundancy check (CRC) bits. Meanwhile, the error detection ability can still be guaranteed by the remaining CRC bits and adaptive decoder parameters. Moreover, the proposed partial CRC-aided ABP (CA-ABP) decoding can be combined with the conventional BP decoding to further improve the performance. Simulation results show that compared with the BP decoding our proposed decoding method achieves an improvement in the error-correction performance.
The dynamic perturbation (DP) decoding algorithm of Cyclic Redundancy Check (CRC) concatenated polar codes over Additive White Gaussian Noise (AWGN) channel is proposed. CRC concatenated polar codes append the CRC bits at the end of information bits and then feeds the resulting vector as input to the polar encoder. This paper improves the CRC-aided decoding method of polar codes based on perturbation, and proposes a dynamic perturbation decoding method for Polar-CRC concatenation code by controlling the interference noise dynamically. The proposed dynamic perturbation decoding is better than the original method with successive cancellation (SC) decoding.