检索结果-内蒙古大学图书馆

Graph-based iterative decoding algorithms for parity-concatenated trellis codes

IEEE TRANSACTIONS ON INFORMATION THEORY 2001年第3期47卷 1062-1074页

作者： Wang, Q Wei, L Australian Natl Univ FEIT Dept Engn Canberra ACT 0200 Australia

In this paper, we construct parity-concatenated trellis codes in which a trellis code is used as the inner code and a simple parity-check code is used as the outer code. From the Tanner-Wiberg-Loeliger (TWL) graph representation, several iterative decoding algorithms can be derived. However, since the graph of the parity-concatenated code contains many short cycles, the conventional min-sum and sum-product algorithms cannot achieve near-optimal decoding. After some simple modifications, we obtain near-optimal iterative decoders. The modifications include either a) introducing a normalization operation in the min-sum and sum-product algorithms or b) cutting the short cycles which arise in the iterative Viterbi algorithm (IVA), After modification, all three algorithms can achieve near-optimal performance, but the IVA has the least average complexity. We also show that asymptotically maximum-likelihood (ML) decoding and a posteriori probability (APP) decoding can be achieved using iterative decoders with only two iterations, Unfortunately, this asymptotic behavior is only exhibited when the bit-energy-to-noise ratio is above the cutoff rate. Simulation results show that with trellis shaping, iterative decoding can perform within 1.2 dB of the Shannon limit at a bit error rate (BER) of 4 x 10(-5) for a block size of 20 000 symbols. For a block size of 200 symbols, iterative decoding can perform within 2.1 dB of the Shannon limit.

关键词： concatenated codes iterative decoding algorithms trellis-coded modulation (TCM) Tanner-Wiberg-Loeliger (TWL) graph Viterbi algorithm (VA)

来源：评论

学校读者我要写书评

暂无评论

On implementation of min-sum algorithm and its modifications for decoding low-density parity-check (LDPC) codes

引用

IEEE TRANSACTIONS ON COMMUNICATIONS 2005年第4期53卷 549-554页

作者： Zhao, JG Zarkeshvari, F Banihashemi, AH Carleton Univ BCWS Ottawa ON K1S 5B6 Canada Carleton Univ Dept Syst & Comp Engn Ottawa ON K1S 5B6 Canada

The effects of clipping and quantization on the performance of the min-sum algorithm for the decoding of low-density parity-check (LDPC) codes at short and intermediate block lengths are studied. It is shown that in many cases, only four quantization bits suffice to obtain close to ideal performance over a wide range of signal-to-noise ratios. Moreover, we propose modifications to the min-sum algorithm that improve the performance by a few tenths of a decibel with just a small increase in decoding complexity. A quantized version of these modified algorithms is also studied. It is shown that, when optimized, modified quantized min-sum algorithms perform very close to, and in some cases even slightly outperform, the ideal belief-propagation algorithm at observed error rates.

关键词： clipping iterative decoding algorithms low-density parity-check (LDPC) codes max-product algorithm max-sum algorithm min-sum algorithm modified min-sum algorithms quantization

来源：评论

学校读者我要写书评

暂无评论

Soft-bit decoding of regular low-density parity-check codes

引用

IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS II-EXPRESS BRIEFS 2005年第10期52卷 646-650页

作者： Howard, SL Gaudet, VC Schlegel, C Univ Alberta Dept Elect & Comp Engn HCDC Lab Edmonton AB T6G 2V4 Canada

A novel representation, using soft-bit messages, of the belief propagation (BP) decoding algorithm for low-density parity-check codes is derived as an alternative to the log-likelihood-ratio (LLR)-based BP and min-sum decoding algorithms. A simple approximation is also presented. Simulation results demonstrate the functionality of the soft-bit decoding algorithm. Floating-point soft-bit and LLR BP decoding show equivalent performance;the approximation incurs 0.5-dB loss, comparable to min-sum performance loss over BE Fixed-point results show similar performance to LLR BP decoding;the approximation converges to floating-point results with one less bit of precision.

关键词： belief propagation (BP) iterative decoding algorithms low-density parity-check (LDPC) codes soft output decoding

来源：评论

学校读者我要写书评

暂无评论

Research of an Improved BP decoding Algorithm

Research of an Improved BP Decoding Algorithm

引用

1st International Symposium on Information Engineering and Electronic Commerce

作者： Wu, Guoqiang Sun, Zhaowei Harbin Inst Technol Res Ctr Satellite Technol Harbin 150006 Peoples R China

ISBN: (纸本)9780769536866

That the computation load is big is a shortcoming of traditional BP decoding algorithm. According to this shortcoming we give an improved BP decoding algorithm. The decoding algorithm in the iterative decoding process, only need to update the possibility of a wrong bit of information without having to update the information whose reliability is very high, raises the decoding efficiency and reduces decoding time delay. The simulation result shows: the calculation load of improved BP decoding algorithms descends distinctively with the increasing iteration numbers;Along with the times increasing of LDPC code iterations upper limit, coding performance can be obviously improved.

关键词： LDPC Code BP decoding arithmetic AWGN channel Decoder iterative decoding algorithms

来源：评论

学校读者我要写书评

暂无评论

On the Use of Extrinsic Probabilities in the Computation of Non-Bayesian Cramer-Rao Bounds for Coded Linearly Modulated Signals

引用

IEEE TRANSACTIONS ON SIGNAL PROCESSING 2018年第8期66卷 2128-2140页

作者： Noels, Nele Moeneclaey, Marc Univ Ghent B-9000 Ghent Belgium

This contribution considers the non-Bayesian Cramer-Rao bound (CRB) related to parameter estimation from a linearly modulated signal observed in additive white Gaussian noise. We compare the exact CRB expression for coded modulation with two ad hoc CRB (ACRB) expressions;the first ACRB is obtained by substituting in the exact CRB expression for un-coded modulation the a priori symbol probabilities by the extrinsic symbol probabilities;the second ACRB, which has received some attention in recent scientific publications, additionally assumes that the real and imaginary parts of the symbols are independent. Our exposition focuses on the particular case of phase shift estimation. By means of examples we show that although for some coded modulation schemes the exact and ACRBs yield virtually the same numerical result, for other coded modulation schemes the ACRBs differ considerably among themselves and from the exact CRB. We provide some explanations for this behavior. We also argue that both ACRBs are expected to virtually coincide with the exact CRB in the case of bit-interleaved coded modulation combined with a rectangular constellations with independent in-phase and quadrature mapping and a binary code for which the factor graph does not contain short cycles.

关键词： Parameter estimation Cramer-Rao bounds channel codes iterative decoding algorithms approximation error

来源：评论

学校读者我要写书评

暂无评论

FPGA implementation of low complexity LDPC iterative decoder

引用

INTERNATIONAL JOURNAL OF ELECTRONICS 2016年第7期103卷 1112-1126页

作者： Verma, Shivani Sharma, Sanjay Thapar Univ Elect & Commun Engn Dept Patiala 147004 Punjab India

Low-density parity-check (LDPC) codes, proposed by Gallager, emerged as a class of codes which can yield very good performance on the additive white Gaussian noise channel as well as on the binary symmetric channel. LDPC codes have gained lots of importance due to their capacity achieving property and excellent performance in the noisy channel. Belief propagation (BP) algorithm and its approximations, most notably min-sum, are popular iterative decoding algorithms used for LDPC and turbo codes. The trade-off between the hardware complexity and the decoding throughput is a critical factor in the implementation of the practical decoder. This article presents introduction to LDPC codes and its various decoding algorithms followed by realisation of LDPC decoder by using simplified message passing algorithm and partially parallel decoder architecture. Simplified message passing algorithm has been proposed for trade-off between low decoding complexity and decoder performance. It greatly reduces the routing and check node complexity of the decoder. Partially parallel decoder architecture possesses high speed and reduced complexity. The improved design of the decoder possesses a maximum symbol throughput of 92.95Mbps and a maximum of 18 decoding iterations. The article presents implementation of 9216 bits, rate-1/2, (3, 6) LDPC decoder on Xilinx XC3D3400A device from Spartan-3A DSP family.

关键词： check-node unit LDPC SMPA parity-check matrix iterative decoding algorithms

来源：评论

学校读者我要写书评

暂无评论

Rate-adaptive codes for distributed source coding

引用

SIGNAL PROCESSING 2006年第11期86卷 3123-3130页

作者： Varodayan, David Aaron, Anne Girod, Bernd Stanford Univ Dept Elect Engn Informat Syst Lab Stanford CA 94305 USA

Source coding with correlated decoder side information is considered. We impose the practical constraint that the encoder be unaware of even the statistical dependencies between source and side information. Two classes of rate-adaptive distributed source codes, both based on low-density parity-check (LDPC) codes, are developed and their design is studied. Specific realizations are shown to be better than alternatives of linear encoding and decoding complexity. The proposed rate-adaptive LDPC accumulate (LDPCA) codes and sum LDPC accumulate (SLDPCA) codes (of length 6336 bits) perform within 10% and 5% of the Slepian-Wolf bound in the moderate and high rate regimes, respectively. (c) 2006 Elsevier B.V. All rights reserved.

关键词： distributed source coding Slepian-Wolf theorem side information LDPC codes iterative decoding algorithms

来源：评论

学校读者我要写书评

暂无评论

Design of A High-speed Parallel LDPC Encoder

引用

JOURNAL OF COMPUTERS 2013年第8期8卷 1995-2002页

作者： Wu, Guoqiang Tan, Shujun Zhang, Jianwei Dalian Univ Technol State Key Lab Struct Anal Ind Equipment Dalian 116024 Peoples R China Dalian Univ Technol Sch Aeronaut & Astronaut Dalian 116024 Peoples R China Dalian Univ Technol Sch Elect Sci & Technol Dalian 116024 Peoples R China

In this paper, the traditional BP decoding algorithm of LDPC code is investigated in detail. The large computation load is a shortcoming of traditional BP decoding algorithm, and an improved BP decoding algorithm is then proposed to deal with the problem. In the iterative decoding process, the wrong bit information only needs to be updated for the decoding algorithm, which consequently improves the efficiency and reduces time-delay of decoding. According to the improved BP decoding algorithm, the high-speed parallel encoder is designed, which can be used in various distributed sensor network applications. Furthermore, the error correction performance of this high speed parallel encoder in the Gaussian channel is studied. The simulation is provided to illustrate that the improved high speed parallel encoder has lower computational complexity and higher decoding speed based on the premise of a little decoding performance loss.

关键词： LDPC Code BP decoding arithmetic AWGN channel high-speed Parallel decoder iterative decoding algorithms

来源：评论

学校读者我要写书评

暂无评论

Density Evolution Analysis of Node-Based Verification-Based algorithms in Compressed Sensing

引用

IEEE TRANSACTIONS ON INFORMATION THEORY 2012年第10期58卷 6616-6645页

作者： Eftekhari, Yaser Heidarzadeh, Anoosheh Banihashemi, Amir H. Lambadaris, Ioannis Carleton Univ Dept Syst & Comp Engn Ottawa ON K1S 5B6 Canada

In this paper, we present a new approach for the analysis of iterative node-based verification-based (NB-VB) recovery algorithms in the context of compressed sensing. These algorithms are particularly interesting due to their low complexity (linear in the signal dimension n). The asymptotic analysis predicts the fraction of unverified signal elements at each iteration l in the asymptotic regime where n -> l. The analysis is similar in nature to the well-known density evolution technique commonly used to analyze iterative decoding algorithms. To perform the analysis, a message-passing interpretation of NB-VB algorithms is provided. This interpretation lacks the extrinsic nature of standard message-passing algorithms to which density evolution is usually applied. This requires a number of nontrivial modifications in the analysis. The analysis tracks the average performance of the recovery algorithms over the ensembles of input signals and sensing matrices as a function of l. Concentration results are devised to demonstrate that the performance of the recovery algorithms applied to any choice of the input signal over any realization of the sensing matrix follows the deterministic results of the analysis closely. Simulation results are also provided which demonstrate that the proposed asymptotic analysis matches the performance of recovery algorithms for large but finite values of n. Compared to the existing technique for the analysis of NB-VB algorithms, which is based on numerically solving a large system of coupled differential equations, the proposed method is more accurate and simpler to implement.

关键词： Asymptotic analysis channel coding compressed sensing density evolution iterative decoding algorithms iterative recovery algorithms low-complexity compressed sensing low-density parity-check (LDPC) codes message-passing algorithms sparse graphs sparse sensing matrix success threshold verification-based recovery algorithms

来源：评论

学校读者我要写书评

暂无评论

Density Evolution Analysis of Node-Based Verification-Based algorithms in Compressed Sensing

Density Evolution Analysis of Node-Based Verification-Based ...

引用

IEEE International Symposium on Information Theory (ISIT)

作者： Eftekhari, Yaser Heidarzadeh, Anoosheh Banihashemi, Amir H. Lambadaris, Ioannis Carleton Univ Dept Syst & Comp Engn Ottawa ON K1S 5B6 Canada

ISBN: (纸本)9781457705953

In this paper, we present a new approach for the analysis of iterative node-based verification-based (NB-VB) recovery algorithms in the context of compressive sensing. These algorithms are particularly interesting due to their low complexity (linear in the signal dimension n). The asymptotic analysis predicts the fraction of unverified signal elements at each iteration l in the asymptotic regime where n -> infinity. The analysis is similar in nature to the well-known density evolution technique commonly used to analyze iterative decoding algorithms. To perform the analysis, a message-passing interpretation of NB-VB algorithms is provided. This interpretation lacks the extrinsic nature of standard message-passing algorithms to which density evolution is usually applied. This requires a number of non-trivial modifications in the analysis. The analysis tracks the average performance of the recovery algorithms over the ensembles of input signals and sensing matrices as a function of l. Concentration results are devised to demonstrate that the performance of the recovery algorithms applied to any choice of the input signal over any realization of the sensing matrix follows the deterministic results of the analysis closely. Simulation results are also provided which demonstrate that the proposed asymptotic analysis matches the performance of recovery algorithms for large but finite values of n. Compared to the existing technique for the analysis of NB-VB algorithms, which is based on numerically solving a large system of coupled differential equations, the proposed method is much simpler and more accurate.

关键词： Algorithm design and analysis Compressed sensing decoding Differential equations Niobium Sensors Simulation asymptotic analysis compressed sensing coupled differential equations data compression density evolution analysis differential equations input signals iterative NB-VB recovery algorithms iterative decoding iterative decoding algorithms iterative methods iterative node-based verification-based recovery algorithms matrix algebra message passing message-passing interpretation nontrivial modifications sensing matrices signal reconstruction

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：