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A Novel Construction Approach of Irregular LDPC codes Based on QC Structure and Zigzag Pattern

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Chinese Journal of Electronics 2015年第4期24卷 783-789页

作者： LEI Jing YAO Chunguang CHEN Bin WEN Lei LIU Wei College of Electronic Science and Engineering National University of Defense Technology

This paper presents a novel construction method of irregular Low-density parity-check(ldpc)codes based on Quasi-cyclic(QC) structure and zigzag pattern. By using the proposed method, a class of irregular and highly structured LDPC codes can be designed with the advantages of low storage requirement and linear time encoding complexity. The constructed codes are called Irregular repeat-accumulate like(IRA-like) codes since their parity-check matrices are similar with those of IRA codes,which all contain a sparse zigzag pattern submatrix. The left part of the parity-check matrix of IRA-like codes is a kind of circulant permutation matrix. A best-effort analyzing method for optimizing the cycle structure of IRAlike codes is presented. We further details the proper constraints for avoiding short cycles and low-weight codewords. Simulation results show that the proposed IRA-like codes have low encoding complexity, good iterative decoding performance and flexible choice of code parameters.

关键词： LDPC codes QC structure Zigzag pattern IRA-like codes

Bilayer expurgated LDPC codes with uncoded relaying

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Digital Communications and Networks 2017年第3期3卷 176-179页

作者： Md. Noor-A-Rahim Nan Zhang Sk. Md. Rabiul Islam Y.L. Guan Centre for Infocomm Technology (INFINITUS) Nanyang Technological University Singapore Institute for TelecommunicationsResearch University of South Australia Adelaide Australia Dept.of Eleetronics and Communication Engineering Khulna University of Engineering & Technology Bangladesh

Bilayer low-density parity-check (ldpc) codes are an effective coding technique for decode-and-forward relaying, where the relay forwards extra parity bits to help the destination to decode the source bits correctly. In the existing bilayer coding scheme, these parity bits are protected by an error correcting code and assumed reliably available at the receiver. We propose an uncoded relaying scheme, where the extra parity bits are forwarded to the destination without any protection. Through density evolution analysis and simulation results, we show that our proposed scheme achieves better performance in terms of bit erasure probability than the existing relaying scheme. In addition, our proposed scheme results in lower complexity at the relay.

关键词： Bilayer codes LDPC codes Density evolution Decode-and-forward relaying

Two constructions of LDPC codes based on pseudo-symplectic geometry over finite fields

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The Journal of China Universities of Posts and Telecommunications 2018年第2期25卷 49-59页

作者： Wang Xiuli Hao Yakun College of Science Civil Aviation University of China

F（2v＋ 1） q Based on the pseudo-symplectic space over q of characteristics 2, combining the definition of low density parity check （ldpc） codes with the knowledge of graph theory, two kinds of LDPC codes with larger girth are constructed. By the knowledge of bipartite graph and the girth properties of LDPC codes, both the girth of the code C（m1 ,2v ＋ 1 ,q） and the code C（m2 ,2v ＋ 1 ,q） are computed are 8. The girth is larger, the performance of LDPC codes is better. Finally, according to the properties of the check matrix and the linear relation between the column vectors of the check matrix, both the minimum distances of the two codes are obtained are 2q ＋ 2.

关键词： LDPC codes pseudo-symplectic geometry minimum distance girth

Probability stopping criterion for analog decoding of LDPC codes

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The Journal of China Universities of Posts and Telecommunications 2017年第1期24卷 35-39页

作者： Zheng Hao Zhang Shuyi Li Lintao Gao Yuan Shao Liwei School of Information and Electronics Beijing Institute of TechnologyBeijing 100081China School of Telecommunication Engineering Beijing University of Posts and TelecommunicationsBeijing 100876China Research Institute of Beijing Institute of Technology in Zhongshan Zhongshan 528400China

To detect uncorrectable frames and terminate the decoding procedure early, a probability stopping criterion for iterative analog decoding of low density parity check （ldpc） codes is proposed in this paper. By using probabilities of satisfied checks to detect uncorrectable frames and terminate decoding, the proposed criterion could be applied to analog decoders without much structure modifications. Simulation results show that the proposed criterion can reduce the average number of iterations and achieve a better balance in bit error ratio （BER） performance and decoding complexity than other stopping criteria using extrinsic information.

关键词： LDPC codes analog decoding early stopping probability stopping criterion

Lowering the Error Floor of ADMM Penalized Decoder for LDPC codes

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China Communications 2016年第8期13卷 127-135页

作者： Jiao Xiaopeng Mu Jianjun School of Computer Science and Technology Xidian University Xi'an 710071 Shaanxi Province China Key Laboratory of Information Coding and Transmission Southwest Jiaotong University Chengdu 610031 China

Decoding by alternating direction method of multipliers(ADMM) is a promising linear programming decoder for low-density parity-check(ldpc) codes. In this paper, we propose a two-step scheme to lower the error floor of LDPC codes with ADMM penalized decoder.For the undetected errors that cannot be avoided at the decoder side, we modify the code structure slightly to eliminate low-weight code words. For the detected errors induced by small error-prone structures, we propose a post-processing method for the ADMM penalized decoder. Simulation results show that the error floor can be reduced significantly over three illustrated LDPC codes by the proposed two-step scheme.

关键词： LDPC codes linear programming decoding alternating direction method of multipliers(ADMM) error floor

Cross-layer design of LT codes and LDPC codes for satellite multimedia broadcast/multicast services

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Chinese Journal of Aeronautics 2013年第5期26卷 1269-1275页

作者： Wang Zhenbang Wang Zhenyong Gu Xuemai Guo Qing School of Electronics and Information Engineering Harbin Institute of Technology

According to large coverage of satellites, there are various channel states in a satellite broadcasting network. In order to introduce an efficient rateless transmission method to satellite multimedia broadcasting/multicast services with finite-length packets, a cross-layer packet transmission method is proposed with Luby transform （LT） codes for efficiency in the network layer and low density parity check （ldpc） codes for reliability in the physical layer jointly. The codewords generated from an LT encoder are divided into finite-length packets, which are encoded by an ldpc encoder subsequently. Based on noise and fading effects of satellite channels, the LT packets received from an ldpc decoder either have no error or are marked as erased, which can be mod- eled as a binary erasure channels （BECs）. By theoretical analysis on LT parameters and ldpc parameters, the relationships between ldpc code rates in the physical layer and LT codes word lengths in the network layer are investigated. With tradeoffs between the LT codes word lengths and the ldpc code rates, optimized cross-layer solutions are achieved with a binary search algorithm. Verified by simulations, the proposed solution for cross-layer parameters design can provide the best transmission mode according to satellite states, so as to improve throughput performance for satellite multimedia transmission.

关键词： Broadcast/multicast Cross-layer LDPC codes LT codes Satellite multimedia

基于相对残余度的ldpc码置信传播译码调度算法(英文)

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China Communications 2011年第5期8卷 47-53页

作者：黄捷张立军 School of Electronics and Information Engineering Beijing Jiaotong University

Two Relative-Residual-based Dynamic Schedules(RRDS) for Belief Propagation(BP) decoding of Low-Density Parity-Check(ldpc) codes are proposed,in which the Variable code-RRDS(VN-RRDS) is a greediness-reduced version of the Check code-RRDS(CN-RRDS).The RRDS only processes the variable(or check) node,which has the maximum relative residual among all the variable(or check) nodes in each decoding iteration,thus keeping less greediness and decreased complexity in comparison with the edge-based Variable-to-Check Residual Belief Propagation(VC-RBP) algorithm.Moreover,VN-RRDS propagates first the message which has the largest residual based on all check equations.For different types of LDPC codes,simulation results show that the convergence rate of RRDS is higher than that of VC-RBP while keeping very low computational complexity.Furthermore,VN-RRDS achieves faster convergence as well as better performance than CN-RRDS.

关键词： LDPC codes dynamic schedule relative-residual greediness BP

Performance evaluation of multicast relay network using ldpc and convolutional channel codes along-with XOR network coding

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The Journal of China Universities of Posts and Telecommunications 2012年第4期19卷 122-128页

作者： Tariq Aziz Nasir Saleem Muhammad Iqba School of Information and Communication Beijing University of Posts and Telecommunications

In this paper, we have compared the performance of joint network channel coding （JNCC） for multicast relay network using low density parity check （ldpc） codes and Convolutional codes as channel codes while exclusive or （XOR） network coding used at the intermediate relay nodes. Multicast relay transmission is a type of transmission scheme in which two fixed relay nodes contribute in the second hop of end-to-end transmission between base transceiver station （BTS） and a pair of mobile stations. We have considered one way and two way multicast scenarios to evaluate the bit error rate （BER） and throughput performance. It has been shown that when using XOR network coding at the intermediate relay nodes, the same transmission becomes possible in less time slots hence throughput performance can be improved. Moreover we have also discussed two possible scenarios in the proposed system model, in which both diversity and multiplexing gain has been considered. It is worth notifying that BER and throughput achieved for LDPC codes is better than Convolutional codes for all the schemes discussed.

关键词： cooperative relaying network coding multicast relay networks LDPC codes convolutional codes

Near-Optimum Results on Improved Belief Propagation-Based Decoding of LDPC codes

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Near-Optimum Results on Improved Belief Propagation-Based De...