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IEEE International Conference on Signal Processing, Communications and Computing (ICSPCC)

作者： Li, Dong Wu, Yanbo Zhu, Min Chinese Acad Sci Inst Acoust Beijing 100190 Peoples R China Univ Chinese Acad Sci Beijing 100190 Peoples R China Chinese Acad Sci State Key Lab Acoust Beijing 100190 Peoples R China Beijing Engn Technol Res Ctr Ocean Acoust Equipme Beijing 100190 Peoples R China

ISBN: (纸本)9781538631423

Concatenated code based on nonbinary ldpc code and Hadamard code is used for noncoherent underwater acoustic communication system. 32-ary (620, 320) regular ldpc code and irregular ldpc code is constructed by quasi-cyclic extension method and Progressive edge-growth (PEG) algorithm, respectively. Under non-Gaussian noise model, Gaussian mixture model (GMM) is used to fit the noise, and the parameters in GMM is estimated by Expectation Maximization (EM) algorithm, the probability density of noise is further estimated. In Rayleigh fading channel, posterior probabilities of Hadamard code-words are calculated based on GMM, and nonbinary ldpc code is further decoded by Belief Propagation (BP) algorithm based on Tanner graph. It is verified by simulation that concatenated irregular ldpc code and Hadamard code has a 0.4 dB benefit than concatenated regular ldpc code and Hadamard code under white Gaussian noise;under Gaussian mixture noise, the EM algorithm based on GMM can exactly estimate the probability density of noise and improve the error correcting performance of concatenated code, the performance gap is 0.1 dB compared to results in known probability density condition. Noise samples were acquired by experiments carried out in deep sea and shallow lake. Under actual noise, the advantages of concatenated code based on GMM in practical application is verified.

关键词： Noncoherent underwater acoustic communication nonbinary ldpc code Gaussian mixture model EM algorithm

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nonbinary ldpc code for Noncoherent Underwater Acoustic Communication and Its Experiment Results

Nonbinary LDPC Code for Noncoherent Underwater Acoustic Comm...

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MTS/IEEE Oceans Conference

作者： Wu, Yanbo Zhu, Min Zhu, Weiqing Xing, Zeping Xu, Lijun Yang, Bo Chinese Acad Sci Inst Acoust Lab Ocean Acoust Technol Beijing 100190 Peoples R China

ISBN: (纸本)9780933957404

Noncoherent underwater acoustic communication channel in adverse condition is modeled as phase-random Rayleigh fading channel. Concatenated code based on nonbinary ldpc code and constant weight code is proposed in noncoherent communication and iteratively decoded in probability domain. Without information of channel amplitude or phase, statistic parameters of signal and noise bins were estimated based on moment estimation method, posterior probabilities of constant weight code-words were further calculated, and nonbinary ldpc code was decoded with nonbinary sum-product algorithm. It is verified by simulation that the proposed concatenated code has a 3 dB SNR benefit than non-iterative concatenated code. Underwater communication experiments were carried out in both deep ocean ( vertical communication, 5 km) and shallow lake ( horizontal communication, near 3 km, delay spread larger than 50 ms), signal frequency band was 6 similar to 10 kHz, and data transmission rate was 357 bps. It is shown that the proposed scheme can correctly transmit in both experiments with a signal noise ratio of 2 dB. The performance of proposed algorithm was verified by experiment.

关键词： Noncoherent underwater acoustic communication Rayleigh fading channel nonbinary ldpc code Hadamard code

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nonbinary ldpc codes on Cages: Structural Property and code Optimization

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IEEE TRANSACTIONS ON COMMUNICATIONS 2015年第2期63卷 364-375页

作者： Chen, Chao Bai, Baoming Shi, Guangming Wang, Xiaotian Jiao, Xiaopeng Xidian Univ Sch Elect Engn Xian 710071 Peoples R China Xidian Univ Sch Telecommun Engn State Key Lab Integrated Serv Networks Xian 710071 Peoples R China Xidian Univ Sch Comp Sci & Technol Xian 710071 Peoples R China

A (v, g)-cage is a (not necessarily unique) smallest v-regular graph of girth g. On such a graph, a nonbinary (2, v)-regular low-density parity-check (ldpc) code can be defined such that the Tanner graph has girth 2g and the code length achieves the minimum possible. In this paper, we focus on two aspects of this class of codes, structural property and code optimization. We find that, in addition to those found previously, many cages can be used to construct structured ldpc codes. We show that all cages with even girth can be structured as protograph-based codes, many of which have block-circulant Tanner graphs. We also find that four cages with odd girth can be structured as protograph-based codes with block-circulant Tanner graphs. For code optimization, we develop an ontology-based approach. All possible inter-connected cycle patterns that lead to low symbol-weight codewords are identified to put together the ontology. By doing so, it becomes handleable to estimate and optimize distance spectrum of equivalent binary image codes. We further analyze some known codes from the Consultative Committee for Space Data Systems recommendation and design several new codes. Numerical results show that these codes have reasonably good minimum bit distance and perform well under iterative decoding.

关键词： nonbinary ldpc code cage protograph-based code CCSDS recommendation minimum distance

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A Fully Parallel nonbinary ldpc Decoder With Fine-Grained Dynamic Clock Gating

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IEEE JOURNAL OF SOLID-STATE CIRCUITS 2015年第2期50卷 464-475页

作者： Park, Youn Sung Tao, Yaoyu Zhang, Zhengya Univ Michigan Dept Elect Engn & Comp Sci Ann Arbor MI 48109 USA

nonbinary ldpc (NB-ldpc) codes, defined over Galois field, offer better coding gain and a lower error floor than binary ldpc codes. However, the complex decoding and large memory requirement have prevented any practical chip implementations. We present a 1.22 Gb/s fully parallel decoder of a GF(64) (160, 80) regular-(2, 4) NB-ldpc code in 65 nm CMOS. The reduced number of edges in NB-ldpc code's factor graph permits a low wiring overhead in the fully parallel architecture. The throughput is further improved by a one-step look-ahead check node design that increases the clock frequency to 700 MHz, and the interleaving of variable node and check node operations that shortens one decoding iteration to 47 clock cycles. We allow each processing node to detect its own convergence and apply dynamic clock gating to save power. When all processing nodes have been clock gated, the decoder terminates and continues with the next input to increase the throughput to 1.22 Gb/s. The dynamic clock gating and decoder termination improve the energy efficiency to 3.03 nJ/b, or 259 pJ/b/iteration, at 1.0 V and 700 MHz. Voltage scaling to 675 mV improves the energy efficiency to 89 pJ/b/iteration for a throughput of 698 Mb/s at 400 MHz.

关键词： Dynamic clock gating ldpc code ldpc decoder architecture nonbinary ldpc code

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Joint sparse graph over GF(q) for code division multiple access systems

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IET COMMUNICATIONS 2015年第5期9卷 707-718页

作者： Wen, Lei Su, Man Univ Surrey Ctr Commun Syst Res Guildford GU2 7XH Surrey England Natl Univ Def Technol Coll Elect Sci & Engn Guangzhou 410073 Guangdong Peoples R China

Low-density signature code division multiple access (LDS-CDMA) and low-density parity-check (ldpc) code can both be represented by a single sparse graph. In this study, the authors propose a joint sparse graph (JSG) over GF(q) which combines LDS-CDMA and non-binary ldpc codes, namely JSG-CDMA. On the JSG, multiple accessing and channel coding are well-linked together, in addition, joint detection and decoding are performed by message passing algorithm. Two schedules for message updating on the JSG, that is, flooding and serial schedules, are, respectively, presented. To predict the convergence behaviour of the joint detection and decoding, they depict the iterative structure of the JSG-CDMA receiver and analyse its extrinsic information transfer chart. Key factors of JSG-CDMA include message passing schedule, maximum iteration number and Galois field order. Simulation results show that JSG-CDMA performs much better than conventional CDMA, in addition, compared with LDS-CDMA and turbo structured LDS-CDMA, at a bit error rate of 3 x 10(-4), JSG-CDMA brings about 1.9 and 1.1 dB gain, respectively.

关键词： code division multiple access parity check codes channel coding graph theory message passing radio receivers Galois fields turbo codes error statistics iterative decoding joint sparse graph low density signature code division multiple access low density parity check code nonbinary ldpc code channel coding message passing algorithm message updating iterative structure JSG-CDMA receiver turbo structured LDS-CDMA bit error rate GF decoding Galois field order

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A coding technique for Q-frequency S-user gaussian channel

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JOURNAL OF COMMUNICATIONS TECHNOLOGY AND ELECTRONICS 2014年第12期59卷 1483-1488页

作者： Frolov, A. A. Zyablov, V. V. Russian Acad Sci Inst Informat Transmiss Problems Moscow Russia

The paper addresses the problem of constructing an asynchronous multiple access system for a multiuser Q-frequency channel with additive white gaussian noise (AWGN). To solve the problem we propose a coding scheme for the channel. The major component of the scheme is non-binary low-density parity-check (ldpc) code. To increase the transmission rate we introduce the embedded modulation. The efficiency of the resulting multiple-access system is shown by simulations.

关键词： multiple access asynchronous nonbinary ldpc code embedded modulation

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Simple nonbinary Coding Strategy for Very Noisy Relay Channels

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IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES 2012年第12期E95A卷 2122-2129页

作者： Suthisopapan, Puripong Kasai, Kenta Meesomboon, Anupap Imtawil, Virasit Sakaniwa, Kohichi Khon Kaen Univ Dept Elect Engn Khon Kaen 40002 Thailand Tokyo Inst Technol Dept Commun & Integrated Syst Tokyo 1528552 Japan

From an information-theoretic point of view, it is well known that the capacity of relay channels comprising of three terminals is much greater than that of two terminal direct channels especially for low SNR region. Previously invented relay coding strategies have not been designed to achieve this relaying gain occurring in the low SNR region. In this paper, we propose a new simple coding strategy for a relay channel with low SNR or, equivalently, for a very noisy relay channel. The multiplicative repetition is utilized to design this simple coding strategy. We claim that the proposed strategy is simple since the destination and the relay can decode with almost the same computational complexity by sharing the same structure of decoder. An appropriate static power allocation which yields the maximum throughput close to the optimal one in low SNRs is also suggested. Under practical constraints such as equal time-sharing etc., the asymptotic performance of this simple strategy is within 0.5 dB from the achievable rate of a relay channel. Furthermore, the performance at few thousand bits enjoys a relaying gain by approximately 1 dB.

关键词： nonbinary ldpc code multiplicative repetition decode-and-forward half duplex relaying relay channel very noisy relay channel

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Efficient Stopping Criterion for Hybrid Weighted Symbol-Flipping Decoding of nonbinary ldpc codes

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IEEE COMMUNICATIONS LETTERS 2011年第3期15卷 337-339页

作者： Liu, Bing Dou, Gaoqi Tao, Wei Gao, Jun Naval Univ Engn Dept Commun Engn Elect Coll Engn Wuhan 430033 Peoples R China Naval Acad Armament Beijing 100073 Peoples R China

A two-stage hybrid iterative decoding algorithm with an efficient stopping criterion for nonbinary low-density parity-check (ldpc) codes is proposed, which combines weighted symbol-flipping (WSF) algorithm and fast Fourier transform q-ary sum-product algorithm (FFT-QSPA). The first WSF decoding would be stopped in advance by analyzing the trend of the number of unsatisfied checks. If the first stage decoding is stopped or failed, the second powerful FFT-QSPA is activated. The proposed decoding with the efficient stopping achieves error performance as good as that of FFT-QSPA with a low complexity, and converges faster than hybrid WSF (HWSF) algorithm.

关键词： nonbinary ldpc code weighted symbol-flipping (WSF) algorithm hybrid iterative decoding stopping criterion finite field

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Joint nonbinary low-density parity-check codes and modulation diversity over fading channels

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JOURNAL OF APPLIED REMOTE SENSING 2010年第1期4卷 041780-041780页

作者： Shi, Zhiping Li, Tiffany Jing Zhang, Zhongpei Univ Elect Sci & Technol China Natl Key Lab Commun Chengdu 610054 Peoples R China Lehigh Univ Dept Elect & Comp Engn Bethlehem PA 18015 USA

A joint exploitation of coding and diversity techniques to achieve efficient, reliable wireless transmission is considered. The system comprises a powerful non-binary low-density parity-check (ldpc) code that will be soft-decoded to supply strong error protection, a quadratic amplitude modulator (QAM) that directly takes in the non-binary ldpc symbols and a modulation diversity operator that will provide power-and bandwidth-efficient diversity gain. By relaxing the rate of the modulation diversity rotation matrices to below 1, we show that a better rate allocation can be arranged between the ldpc codes and the modulation diversity, which brings significant performance gain over previous systems. To facilitate the design and evaluation of the relaxed modulation diversity rotation matrices, based on a set of criteria, three practical design methods are given and their point pairwise error rate are analyzed. With EXIT chart, we investigate the convergence between demodulator and decoder. A rate matching method is presented based on EXIT analysis. Through analysis and simulations, we show that our strategies are very effective in combating random fading and strong noise on fading channels.

关键词： nonbinary ldpc code modulation diversity rotation matrix iterative decoding performance analysis

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Design of q-ary Irregular Repeat-Accumulate codes

Design of <i>q</i>-ary Irregular Repeat-Accumulate Codes

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23rd International Conference on Advanced Information Networking and Applications Workshops

作者： Lin, Wei Bai, Baoming Li, Ying Ma, Xiao Xidian Univ State Key Lab ISN Xian Peoples R China Sun Yat Sen Univ Sci Informat Sci & Technol Guangzhou Peoples R China

ISBN: (纸本)9781424440009

This paper is concerned with the construction of a class of nonbinary irregular repeat accumulate (IRA) codes. Since they are defined on the finite field GF(q) (q>2), we will refer to the constructed codes as q-ary IRA (QIRA) codes. While preserving the excellent error correcting capability of q-ary ldpc codes, QIRA codes can be efficiently encoded like conventional binary IRA codes. By adopting the progressive edge growth (PEG) algorithm to construct the parity check matrices, we can achieve the increased girth of their factor graphs and improved decoding performance. Simulation results show that, using the sum-product algorithm on GF(q), QIRA codes outperform binary ldpc codes and Turbo codes in terms of bit error ratio and frame error ratio on AWGN channels. Especially, they could achieve excellent error performance when combined with high order modulations. Feasibility study indicates, with the use of the extended min-sum (EMS) decoding algorithm, QIRA codes are competitive candidates for practical applications.

关键词： repeat accumulate code nonbinary ldpc code progressive edge growth EMS algorithm

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