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HIGH-PERFORMANCE SIMPLE-ENCODING GENERATOR-BASED SYSTEMATIC IRREGULAR ldpc codeS AND RESULTED PRODUCT codeS

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Journal of Electronics(China) 2007年第5期24卷 613-621页

作者： Yang Fengfan Ye Ming Luo Lin Dept of Electronic Engineering Nanjing University of Aeronautics ＆ Astronautics Nanjing 210016 China Dept of Radio Engineering Southeast University Nanjing 210096 China

Low-Density Parity-Check (ldpc) code is one of the most exciting topics among the coding theory *** is of great importance in both theory and practical communications over noisy *** most advantage of ldpc codes is their relatively lower decoding complexity compared with turbo codes,while the disadvantage is its higher encoding *** this paper,a new ap- proach is first proposed to construct high performance irregular systematic ldpc codes based on sparse generator matrix,which can significantly reduce the encoding complexity under the same de- coding complexity as that of regular or irregular ldpc codes defined by traditional sparse parity-check ***,the proposed generator-based systematic irregular ldpc codes are adopted as con- stituent block codes in rows and columns to design a new kind of product codes family,which also can be interpreted as irregular ldpc codes characterized by graph and thus decoded ***, the performance of the generator-based ldpc codes and the resultant product codes is investigated over an Additive White Gaussian Noise (AWGN) and also compared with the conventional ldpc codes under the same conditions of decoding complexity and channel noise.

关键词： ldpc code Iterative decoding Parity-check Generator matrix Product code Graph Kronecker product

An Iterative Decoding Scheme for Davey-MacKay Construction

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China Communications 2018年第6期15卷 187-195页

作者： Yuan Liu Weigang Chen School of Microelectronics Tianjin UniveristyTianjin 300072China

In the Davey-MacKay(DM) construction,the inner decoder treats unknown transmitted bits as random independent substitution errors. It limits the synchronization capability of the inner decoder, and thus weakens the error-correcting capability of the DM *** order to improve the performance of the DM construction, an iterative decoding scheme is proposed, which iteratively utilizes the more accurate estimates of transmitted codewords. In the proposed scheme, the estimated average bit error rates and the estimated low-density parity-check(ldpc) codewords from the outer decoder are fed back into the inner decoder to update the synchronization process. Simulation results show that the proposed iterative decoding scheme significantly outperforms the traditional DM construction.

关键词： Davey-MacKay construction iterative decoding ldpc code synchronization error

Regular Quasi Cyclic Low Density Parity Check codes with Girth 8 from Elementary Number Theory

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China Communications 2012年第4期9卷 80-88页

作者： He Guofeng Li Xiangxue Li Qiang Zhou Zhiheng Zheng Dong School of Electronic Information and Electrical Engineering Shanghai Jiao Tong University Shanghai 200240 P. R. China Hangzhou Key Lab of E-business and Information Security Hangzhou Normal University Hangzhou 310036 P. R. China Department of Computer Science and Technology East China Normal University Shanghai 200241 P. R. China

This paper is concerned with (3,n) and (4,n) regular quasi-cyclic Low Density Parity Check (ldpc) code constructions from elementary number *** the column weight,we determine the shift values of the circulant permutation matrices via arithmetic *** proposed constructions of quasi-cyclic ldpc codes achieve the following main advantages simultaneously:1) our methods are constructive in the sense that we avoid any searching process;2) our methods ensure no four or six cycles in the bipartite graphs corresponding to the ldpc codes;3) our methods are direct constructions of quasi-cyclic ldpc codes which do not use any other quasi-cyclic ldpc codes of small length like component codes or any other algorithms/cyclic codes like building block;4)the computations of the parameters involved are based on elementary number theory,thus very simple and *** results show that the constructed regular codes of high rates perform almost 1.25 dB above Shannon limit and have no error floor down to the bit-error rate of 10-6.

关键词： quasi-cyclic ldpc code error floor Shannon limit number theory

ldpc Decoding for Signal Dependent Visible Light Communication Channels

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ZTE Communications 2016年第2期14卷 41-46页

作者： YUAN Ming SHA Xiaoshi LIANG Xiao JIANG Ming WANG Jiaheng ZHAO Chunming National Mobile Communications Research Laboratory Southeast University

Avalanche photodiodes （APD） are widely employed in visible light communication （VLC） systems. The general signal dependent Gaussian channel is investigated. Experiment results reveal that symbols on different constellation points under official illuminance inevitably suffer from different levels of noise due to the multiplication process of APDs. In such a case, conventional log likely-hood ratio （LLR） calculation for signal independent channels may cause performance loss. The optimal LLR calculation for decoder is then derived because of the existence of non-ignorable APD shot noise. To find the decoding thresholds of the optimal and suboptimal detection schemes, the extrinsic information transfer （EXIT） chat is further analyzed. Finally a modified minimum sum algorithm is suggested with reduced complexity and acceptable performance loss. Numerical simulations show that, with a reg- ular （3, 6） low-density parity check （ldpc） code of block length 20,000, 0.7 dB gain is achieved with our proposed scheme over the ldpc decoder designed for signal independent noise. It is also found that the coding performance is improved for a larger modulation depth.

关键词： VLC APD shot noise ldpc code

Channel Coding Based on Power Line Communication

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Journal of Information Hiding and Privacy Protection 2021年第3期3卷 101-107页

作者： Xiaojun Chen Yunxiao Zu School of Electronic Engineering Beijing University of Posts and TelecommunicationsBeijing100876China

This paper focuses on the forward error correction(FEC),the basic parameters determination of the RS convolution code,Turbo code and the ldpc code,and the corresponding encoding and decoding algorithm in power line communication(PLC)*** experiment which is designed for narrow-band power line communication system based on OFDM is *** coding using RS convolution code,Turbo code and ldpc code are compared,and further it is determined that which encoding method is more suitable for power line communication in China.

关键词： OFDM communication RS convolution code Turbo code ldpc code channel coding

An FPGA-based ldpc decoder with optimized scale factor of NMS decoding algorithm

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Journal of Measurement Science and Instrumentation 2022年第4期13卷 398-406页

作者： LI Jinming ZHAGN Pingping WANG Lanzhu WANG Guodong School of Instruments and Electronics North University of ChinaTaiyuan 030051China

Considering that the hardware implementation of the normalized minimum sum(NMS)decoding algorithm for low-density parity-check(ldpc)code is difficult due to the uncertainty of scale factor,an NMS decoding algorithm with variable scale factor is proposed for the near-earth space ldpc codes(8177,7154)in the consultative committee for space data systems(CCSDS)*** shift characteristics of field programmable gate array(FPGA)is used to optimize the quantization data of check nodes,and finally the function of ldpc decoder is *** simulation and experimental results show that the designed FPGA-based ldpc decoder adopts the scaling factor in the NMS decoding algorithm to improve the decoding performance,simplify the hardware structure,accelerate the convergence speed and improve the error correction ability.

关键词： ldpc code NMS decoding algorithm variable scale factor quantization

基于Polar code的可见光通信信道编码研究

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基于Polar Code的可见光通信信道编码研究

作者：姚春梅山东大学

学位级别：硕士

在现代信息社会,无线通信技术发展迅猛,信息交互和传输更是日益繁多。然而,频谱资源逐渐受限,引起了频谱拥塞的问题。可见光通信正是由于丰富的频谱资源而受到广泛关注。另外,Polar code是在理论上唯一能够达到香农极限的信道编码技术,... 详细信息

在现代信息社会,无线通信技术发展迅猛,信息交互和传输更是日益繁多。然而,频谱资源逐渐受限,引起了频谱拥塞的问题。可见光通信正是由于丰富的频谱资源而受到广泛关注。另外,Polar code是在理论上唯一能够达到香农极限的信道编码技术,并且能有效降低传输误码率。因此,本文结合Polar code的优势,主要研究基于Polar code的可见光通信信道编码技术。本文充分调研了可见光通信的研究背景以及国内外关于信道编码技术的研究现状,详细介绍了可见光通信系统组成和调制技术,并具体介绍了五种主要的信道编码技术,包括线性分组码、卷积码、Turbo code、ldpc code和Polar code,并分别介绍了各自的发展历程和编译码过程。本文针对Polar code的编译码过程进行了深入研究,不仅将Polar code应用到VLC系统中,还创新地提出了一种应用于VLC系统的改进型Polar code编码方案。该方案主要针对传统编码结构中与或运算的较高复杂度进行了改进,在发射端将待发送的信号按照每个信道传输2个比特信息的方式,进行Polar code原始核心编码原理的迭代过程,再通过两两与或运算获得与传统编码一致的输出信号,从而形成Polar code的编码输出信号,再进行相应的信号传输。本文针对提出的新型方案进行了系统仿真和分析验证。首先,对比了 ldpc code和Polar code在AWGN信道下的误码率性能,还分析了Polar code在可见光通信信道中不同参数下的误码率性能,运用Polar code信道编码技术能够提高通信系统的传输准确率,改善了系统性能。然后,分析了运算复杂度的性能,仿真验证了改进型Polar code编码方案能够使计算量实现2的指数型降低,极大地降低了运算复杂度,提高了系统性能。

关键词：可见光通信 Polar code 信道极化 ldpc code 运算复杂度

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ldpc码编译码算法的研究

LDPC码编译码算法的研究

作者：谢东觉南京大学

学位级别：硕士

In 1962, Gallager invented an error correcting code, Low Density Parity Check code. This kind of code decodes effectively and maintains a linear relationship between decode complexity and code length when code length is long, because of sparseness of the check-up matrix. ldpc codes performance close to Shannon limit, so it becomes hot spot in channel coding field. Researchers proposed various methods to reduce high encoding complexity of ldpc codes, which makes ldpc code practical use possible. In this thesis firstly introduce the development history of channel encoding, then introduce the principles of ldpc code, including the structure of check-up matrix, coding algorithm and decoding algorithm, at last research the ldpc codes of IEEE802.16e.In this thesis, ldpc decoding algorithms are researched. On BP algorithms, BP, LLR BP, UMP BP-Based, Normalized BP and Offset BP algorithm are studied and simulated. An improved BP algorithm was proposed, using multiplicative factor to compensate the correlation between message nodes, which compensates the shortcomings of ldpc codes with short cycles. On bit-flipping algorithm, the criteria for bit flipping in IMWBF algorithm and RRWBF algorithm are summarized, and a multi-bit flipping algorithm is proposed on considering the reliability ratio and absolute value of symbol. In this algorithm, multi-bit are flipping per iteration, making decoding faster, gaining lower BER with the same iterations. ldpc codes of IEEE802.16e are also researched in this thesis. The check matrix of ldpc codes have quasi-cyclic structure, and use the quasi-diagonal sub-matrix to iterative encoding. ldpc code with 1/2 code rate is simulated using the improved BP and BF decoding algorithm. The result shows that improved BP algorithm is better than LLR BP algorithm and the BF algorithm. On the same code rate condition, the code with longer length has better performance, and on the same code length condition, the code with bigger code rate has

关键词： ldpc code BP decoding Bit-flipping decoding IEEE 802.16e