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Performance and Complexity Trade-Off between Short-Length Regular and Irregular LDPC

Journal of Computer and Communications 2024年第9期12卷 208-215页

作者： Ziyuan Peng Ruizhe Yang School of Information Science and Technology Beijing University of Technology Beijing China

In this paper, both the high-complexity near-ML list decoding and the low-complexity belief propagation decoding are tested for some well-known regular and irregular LDPC codes. The complexity and performance trade-off is shown clearly and demonstrated with the paradigm of hybrid decoding. For regular LDPC code, the SNR-threshold performance and error-floor performance could be improved to the optimal level of ML decoding if the decoding complexity is progressively increased, usually corresponding to the near-ML decoding with progressively increased size of list. For irregular LDPC code, the SNR-threshold performance and error-floor performance could only be improved to a bottle-neck even with unlimited decoding complexity. However, with the technique of CRC-aided hybrid decoding, the ML performance could be greatly improved and approached with reasonable complexity thanks to the improved code-weight distribution from the concatenation of CRC and irregular LDPC code. Finally, CRC-aided 5GNR-LDPC code is evaluated and the capacity-approaching capability is shown.

关键词： Regular LDPC Irregular LDPC Near-ML Decoding List Decoding belief propagation algorithm Sum-Product algorithm CRC-Aided Hybrid Decoding

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Feedback in a hierarchical model of object recognition in cortex

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BMC Neuroscience 2009年第1期10卷 1-2页

作者： Salvador Dura Thomas Wennekers Sue Denham Centre for Theoretical and Computational Neuroscience University of Plymouth Plymouth PL4 8AA UK

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Hybrid DFSF-BP Equalization for ATSC DTV Receivers

Hybrid DFSF-BP Equalization for ATSC DTV Receivers

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IEEE International Symposium on Circuits and Systems

作者： Yanjie Peng Andrew G. Klein Xinming Huang Department of Electrical and Computer Engineering Worcester Polytechnic Institute Worcester MA 01609 USA

ISBN: (纸本)9781479934331

Severe intersymbol interference (ISI) is one of the main obstacles for reliable signal reception in ATSC DTV systems. Decision feedback equalizers (DFEs) are commonly used to suppress the ISI. However, DFEs may suffer from error propagation due to incorrect symbol decisions from the symbol slicer. This phenomenon deteriorates the performance even more when the post-cursor ISI is strong. In order to reduce error propagation, we present a novel hybrid equalization scheme for ATSC channels. The proposed scheme consists of an adaptive decision feedback sparsening filter (DFSF), and an iterative maximum a posteriori (MAP) equalizer based on the belief propagation (BP) algorithm. In the first stage, instead of removing all the ISI from post cursors, the DFSF employs a modified feedback filter which leaves the strongest post-cursor ISI taps uncorrected. As a result, a long ISI channel is equalized to a sparse channel having only a small number of nonzero taps. In the second stage, a belief propagation algorithm is applied to mitigate the residual ISI. Since the channel is typically time-varying and suffers from Doppler fading, the DFSF is adapted using the least mean square (LMS) algorithm, such that the amplitude and the locations of the nonzero taps of the equalized sparse channel appear to be fixed. As such, the channel appears to be static during the second stage of equalization which consists of the BP detector. Simulation results demonstrate that the proposed scheme outperforms the traditional DFE in symbol error rate, under both static channels and dynamic ATSC channels.

关键词： ATSC DTV belief propagation algorithm channel sparsening intersymbol interference intersymbolic interference belief propagation Equalization Error propagation sparse channel decision feedback equalisers WATER FAUCETS feedback filter signal reception Bit error rate Digital television

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Performance Comparison of Hybrid Partial Response Detectors over Frequency-Selective Fading Channels

Performance Comparison of Hybrid Partial Response Detectors ...

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IEEE International Symposium on Circuits and Systems

作者： Yanjie Peng Xinming Huang Department of Electrical and Computer Engineering Worcester Polytechnic Institute Worcester MA 01609 USA

ISBN: (纸本)9781479934331

Frequency-selective fading channels are encountered in many modern wireless communication systems. In order to combat the intersymbol interference (ISI) introduced by such fading, equalization is required for reliable symbol detection. The maximum-likelihood sequence detector is the optimal equalization scheme;however its implementation complexity increases exponentially with the channel length and thus can be prohibitively high. In this paper, we compare the performance of two practically implementable suboptimal symbol detectors, including the partial response maximum-likelihood (PRML) detector and the partial response belief propagation (PRBP) detector, under frequency-selective fading channels. Both detectors employ a hybrid two-stage scheme, and allow a tradeoff between performance and complexity. The first stage is a partial response equalizer implemented as a linear filter which transforms the original channel impulse response to a target impulse response with reduced ISI. The residual ISI is then cancelled in the second stage using a more sophisticated nonlinear detector. In simulations, we consider a slow fading environment and use the ITU-R 3G channel models. From the numerical results, it is shown that in frequency-selective fading wireless channels, the PRBP detector provides superior performance over both the traditional minimum mean squared error linear equalizer and the PRML detector. Due to the effect of colored noise, the PRML detector in fading wireless channels is not as effective as it is in magnetic recording applications.

关键词： belief propagation algorithm partial response equalization maximum-likelihood sequence estimation frequency-selective fading Partial Remission maximum likelihood sequence estimation Frequency-selective fading channels detector selective fading belief propagation Partial Response Maximum Likelihood IMPULSE RESPONSE non-linear detection channel impulse response

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Hybrid Decoding algorithm for LDPC Codes with Circles

Hybrid Decoding Algorithm for LDPC Codes with Circles

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The 2011 International Conference on Advanced Materials and Information Technology Processing(AMITP 2011)

作者： Lishuang Hu Mingshan Liu Yuan Zhou Yang Sun State Key Laboratory of Automobile Dynamic Simulation School of Communication EngineeringJilin University

ISBN: (纸本)9783037851579

At present, Low-Density Parity-Check(LDPC) codes widely used in many fields of communications have the best performance of all the Error Correcting Codes(ECC). This paper mainly studies the decoding algorithms of LDPC. It proposes an improved algorithm which is named Check-Variable nodes Hybrid(CVH) algorithm on the basis of the existing algorithms. The CVH algorithm can reduce the computational complexity during the check-node update while overcome with the correlation between the variable-node news in a code with circles. As well as, comparing with the original algorithms the performance of the new one saves 0.1 and 0.3 d B than Log-likelihood Ratios(LLR) belief propagation(BP) and BP- based algorithms under Additive White Gaussian Noise(AWGN) channel when the Bit Error Rate(BER) falls to 410-through the simulation. This point shows that this algorithm can increase the decoding performance and reduce the error rate effectively.

关键词： LDPC codes with circles belief propagation algorithm CVH algorithm Correction coefficient

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A Modified Offset Min-Sum Decoding algorithm for LDPC Codes

A Modified Offset Min-Sum Decoding Algorithm for LDPC Codes

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2010 3rd IEEE International Conference on Computer Science and Information Technology—ICCSIT 2010

作者： Meng Xu National ASIC system engineering research center Southeast University Nanjing,China Jianhui Wu,Meng Zhang National ASIC system engineering research center Southeast University Nanjing,China

In this paper a modified Offset Min-Sum decoding algorithm for Low-Density Parity Check Codes is *** this modified algorithm,the offset factor in the original Offset Min-Sum algorithm is adjusted iteratively with the assistance of the check-node computation outputs of the Normalized MinSum *** a result,the offset factor in our modified algorithm can be calculated adaptively and more efficiently according to the previous decoding procedure,which can minimize the decoding degradation compared with the belief propagation decoding *** simulation results show that,compared with the original Offset Min-Sum decoding algorithm,our modified algorithm can achieve noticeable performance improvement with minor extra hardware *** example,when BER is 10 5,our algorithm can achieve 0.1dB and 0.2dB decoding gain over Offset MinSum algorithm for regular and irregular LDPC codes respectively.

关键词： belief propagation algorithm LDPC codes Normalized and Offset Min-Sum algorithm

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Iterative Soft-Decision Decoding of Binary Cyclic Codes Based on Extended Parity-Check Transformation algorithm

Iterative Soft-Decision Decoding of Binary Cyclic Codes Base...

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IEEE Canadian Conference on Electrical and Computer Engineering

作者： Oluwaseyi Babalola Jaco Versfeld Department of Electrical and Electronics Engineering Stellenbosch University Stellenbosch 7600 South Africa

ISBN: (纸本)9781538624111

In this paper, an iterative soft-decision (SD) decoding algorithm for cyclic codes based on extended parity-check equations is developed. The algorithm does not necessarily utilize the algebraic properties of the code, but operates on transforming the systematic parity-check matrix using the soft reliability information matrix obtained from the received vector. Results show a significant performance gain when compared with the hard decision Berlekamp-Massey (B-M) and belief propagation (BP) algorithms, but present a similar bit error rate (BER) performance when compared to the adaptive belief propagation (ABP) algorithm. An important feature of the decoder is that it functions within a practical decoding time complexity, and can be generally implemented for the class of linear block codes.

关键词： Soft-decision decoding Cyclic codes Extended parity-check equations Berlekamp-Massey algorithm belief propagation algorithm Adaptive belief propagation algorithm

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OPTIMAL DESIGN AND APPLICATIONS OF GENERALIZED FOUNTAIN CODES

OPTIMAL DESIGN AND APPLICATIONS OF GENERALIZED FOUNTAIN CODE...

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2010 2nd IEEE International Conference on Network Infrasturcture & Digital Content(2010年第二届IEEE网络基础设施与数字内容国际会议 IC-NIDC 2010)

作者： Yuwen Liu Xuehong Lin Baoyu Tian Beijing University of Posts and Telecommunications Beijing China

Fountain codes have been suggested as an efficient solution for multimedia communications over erasure packet network. Therefore, the unequal error protection (UEP) fountain codes schemes are needed for the multimedia data of different importance. This paper proposed a novel technique to optimize the degree distribution of the generalized fountain codes that can provide strong UEP property. We further verify our work with simulations. Simulation results show that the proposed fountain codes have a better decoding performance than the fountain codes without optimization.

关键词： fountain codes unequal error protection decodable set belief propagation algorithm

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Underwater Target Threat Assessment Method Based on Bayesian Network

Underwater Target Threat Assessment Method Based on Bayesian...

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第40届中国控制会议

作者： Danyi Li Meiqin Liu Senlin Zhang State Key Laboratory of Industry Control Technology Zhejiang University College of Electrical Engineering Zhejiang University

Underwater targets are used more and more frequently in modern ocean *** is important to assess the threat from an enemy target after it is detected immediately,in order to prepare quick counterattack and *** paper proposes a method for underwater target threat assessment based on Bayesian *** threat model uses a hierarchy view for threat *** factors are divided into three parts:environment,target space and target *** part contains several detailed factors,which are arranged based on their causal *** factors are applied into the Bayesian Network and the probability of threat is calculated through Bayesian ***,a simulation is conducted and the method can effectively assess the target *** model has a relatively good performance and can generate the assessment with low time cost.

关键词： Underwater target threat assessment situation awareness Bayesian Network belief propagation algorithm

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