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Checking chase Termination: Cyclicity Analysis and Rewriting Techniques

IEEE TRANSACTIONS ON KNOWLEDGE AND DATA ENGINEERING 2015年第3期27卷 621-635页

作者： Greco, Sergio Spezzano, Francesca Trubitsyna, Irina Univ Calabria DIMES Arcavacada Rende Cosenza Italy

The aim of this paper is to present more general criteria and techniques for chase termination. We first present extensions of the well-known stratification criterion and introduce a new criterion, called local stratification, which generalizes both super-weak acyclicity and stratification-based criteria (including the class of constraints which are inductively restricted). Next, the paper presents a rewriting algorithm transforming the original set of constraints Sigma into an "equivalent" set Sigma(alpha) and verifying the structural properties for chase termination on Sigma(alpha). The rewriting of constraints allows us to recognize larger classes of constraints for which chase termination is guaranteed. In particular, we show that if Sigma satisfies chase termination conditions T, then the rewritten set Sigma(alpha) satisfies T as well, but the vice versa is not true, that is there are significant classes of constraints for which Sigma(alpha) satisfies T and Sigma does not. A more general rewriting algorithm producing as output an equivalent set of dependencies and a Boolean value stating whether a sort of cyclicity has been detected is also proposed. The new rewriting technique and the checking of acyclicity allow us to introduce the class of acyclic constraints, which generalizes local stratification and guarantees that all chase sequences are finite with a length polynomial in the size of the input database.

关键词： Data exchange data integration chase algorithm chase termination

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Windowed Fast chase Detection for Long Intersymbol Interference Channels

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FREQUENZ 2010年第7-8期64卷 134-139页

作者： Li Hui Shen Yuehong Xu Kun PLA Univ Sci & Technol Dept Wireless Commun Inst Commun Engn Nanjing 210007 Peoples R China

The design of receiver based on maximum likelihood sequence detection(MLSD) is too complicated for long intersymbol interference (ISI) channels. To solve the problem, Nammi has published a two-stage list-based data detection algorithm named WCE [1] in 2009, well known for its significantly low complexity and a bit error rate (BER) performance approaching MLSD. To further reduce the calculation complexity of the WOE algorithm, the paper modifies the decision rule, proposes to arrange candidate test sequences according to Gray coding during the WOE operation, and deduces the corresponding iteration expression of the windowed fast chase detection algorithm. Complexity analysis and simulation results validate that our detector constructed by adopting the two improvements mentioned above, can ensure BER performance nearly the same as WOE approaching MLSD, meanwhile the total calculation complexity can be less than 20 percent of WOE, especially under low signal-to-noise ratio (SNR) circumstances.

关键词： Intersymbol interference(ISI) Equalization Maximum likelihood sequence detection(MLSD) chase algorithm Gray coding Minimum Euclidean distance

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An efficient chase decoder for turbo product codes

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IEEE TRANSACTIONS ON COMMUNICATIONS 2004年第6期52卷 896-898页

作者： Argon, C McLaughlin, SW Georgia Inst Technol Sch Elect & Comp Engn Atlanta GA 30332 USA

In this letter, we propose an efficient decoding algorithm for turbo product codes as introduced by Pyndiah. The proposed decoder has no performance degradation and reduces the complexity of the original decoder by an order of magnitude. We concentrate on extended Bose-Chaudhuri-Hocquengem codes as the constituent row and column codes because of their already low implementation complexity. For these component codes, we observe that the weight and reliability factors can be fixed, and that there is no need for normalization. Furthermore, as opposed to previous efficient decoders, the newly proposed decoder naturally scales with a test-pattern parameter p that can change as a function of iteration number, i.e., the efficient chase algorithm presented here uses conventionally ordered test patterns, and the syndromes, even parities, and extrinsic metrics are obtained with a minimum number of operations.

关键词： block turbo code chase algorithm error-correction coding iterative decoding turbo code turbo product code (TPC)

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Stochastic chase Decoding of Reed-Solomon Codes

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IEEE COMMUNICATIONS LETTERS 2010年第9期14卷 863-865页

作者： Leroux, Camille Hemati, Saied Mannor, Shie Gross, Warren J. McGill Univ Dept Elect & Comp Engn Montreal PQ H3A 2A7 Canada Technion Israel Inst Technol Dept Elect Engn IL-32000 Haifa Israel

In this letter, we propose a probabilistic approach to the generation of test patterns in the chase algorithm (CA) denoted as the Stochastic chase algorithm (SCA). We compare the performance of SCA with the regular CA for different Reed-Solomon codes. Simulation results show that the probabilistic nature of the SCA helps in providing a more efficient test pattern generation. SCA avoids the use of least reliable bits selection and reduces the number of candidate codewords up to 60% for the same decoding performance.

关键词： Stochastic decoding chase algorithm soft decision decoding Reed-Solomon codes

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On Combining chase-2 and Sum-Product algorithms for LDPC Codes

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ETRI JOURNAL 2012年第4期34卷 629-632页

作者： Tong, Sheng Zheng, Huijuan Xidian Univ State Key Lab ISN Xian Peoples R China Xian Univ Posts & Telecommun Dept Telecommun Xian Peoples R China

This letter investigates the combination of the chase-2 and sum-product (SP) algorithms for low-density parity-check (LDPC) codes. A simple modification of the tanh rule for check node update is given, which incorporates test error patterns (TEPs) used in the chase algorithm into SP decoding of LDPC codes. Moreover a simple yet effective approach is proposed to construct TEPs for dealing with decoding failures with low-weight syndromes. Simulation results show that the proposed algorithm is effective in improving both the waterfall and error floor performance of LDPC codes.

关键词： LDPC codes chase algorithm sum-product (SP) algorithm

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A novel chase based multiuser detector for MIMO-CDMA systems

A novel Chase based multiuser detector for MIMO-CDMA systems

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66th IEEE Vehicular Technology Conference

作者： Liu, Feng Soleymani, M. Reza Concordia Univ Dept Elect & Comp Engn Montreal PQ H3G 1M8 Canada

ISBN: (纸本)9781424402632

This paper proposes a new chase based multiuser detection scheme for MIMO-CDMA systems. The proposed approach provides performance gain by concentrating on improving the detection accuracy of the weakest symbol. Compared to the layered space-time multiuser detector (LAST-MUD), the proposed scheme can achieve substantial performance improvement, especially, when the number of transmit antennas is equal to the number of receive antennas. The comparison between our scheme and another chase based scheme, the B-chase detector, which was originally proposed for improving the performance of the vertical Bell Laboratories layered space-time (V-BLAST) system, is also presented. The problem existing in the B-chase detector is the criterion for selecting the weakest symbol. In our scheme, a more reasonable selection criterion is proposed. We show that the proposed scheme has less complexity than the B-chase detector but with the tendency of achieving better performance at high SNR.

关键词： code division multiple access (CDMA) multiuser detection multiple-input multiple-output (MIMO) systems chase algorithm

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A chase based multistage parallel interference cancellation scheme for asynchronous fading channels

A chase based multistage parallel interference cancellation ...

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20th Annual Canadian Conference on Electrical and Computer Engineering

作者： Feng, Liu Soleymani, M. Reza Concordia Univ Dept Elect & Comp Engn Wireless & Satellite Communicat Lab Montreal PQ H3G 1M8 Canada

ISBN: (纸本)9781424410200

A key issue in a multistage parallel interference cancellation (PIC) scheme is to improve the hard decision accuracy after matched filters (MFs). For achieving this purpose, one category of PIC schemes keeps the hard decision values after MFs intact and focuses on choosing the suitable weight for each user in current stage so that the hard decision accuracy is improved as much as possible in the next stage. Another category of PIC focuses on optimizing the hard decision values in current stage. Rather than directly using the hard decision values after MFs to do the interference cancellation, this approach reviews the possible hard decision combinations and selects the one minimizing a cost function as the final hard decision result to do the interference cancellation. In [7], a new PIC scheme using the normalized least-mean-square (NLMS) at the earlier stages and chase in the later stages for synchronous Rayleigh fading channels is proposed. In this paper, the proposed technique is applied to asynchronous Rayleigh fading channels. Simulation shows that the proposed scheme can achieve a better performance than multistage NLMS-PIC but with complexity reduction.

关键词： code division multiple access (CDMA) multiuser detection parallel interference cancellation chase algorithm

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chase based multiuser detection for MIMO-CDMA systems

Chase based multiuser detection for MIMO-CDMA systems

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20th Annual Canadian Conference on Electrical and Computer Engineering

作者： Feng, Liu Soleymani, M. Reza Concordia Univ Dept Elect & Comp Engn Wireless & Satellite Commun Lab Montreal PQ H3G 1M8 Canada

ISBN: (纸本)9781424410200

In multiuser MIMO-CDMA systems, the layered space-time multiuser detector (LAST-MUD) can achieve high data rate and reliable communication by combining time-domain technique and space-domain technique. At the receiver side of LAST-MUD, the mathematical expression of the signals passing through the space-code matched filters is similar to the received signals of the V-BLAST system. This similarity makes it possible to apply some advance detection schemes originally used in single user V-BLAST system to multiuser MIMO-CDMA system. Recently, the B-chase and L-chase detectors have been developed to improve V-BLAST system performance. In this paper, we investigate the use of these two chase based schemes to MIMO-CDMA system. The simulation results show that the performance of the L-chase detector is worse than LAST-MUD due to the error in noise estimation, while the B-chase detector can achieve a better performance than LAST-MUD.

关键词： code division multiple access (CDMA) multiuser detection multiple-input multiple-output channel V-BLAST chase algorithm

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Sampling-Based Soft Equalization for Coherent Optical Channels

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JOURNAL OF LIGHTWAVE TECHNOLOGY 2009年第16期27卷 3599-3606页

作者： Ding, Zizhe Wang, Xiaodong Zhang, Xian-Da China Mobile Commun Corp Dept Management Informat Syst Beijing 100032 Peoples R China Columbia Univ Dept Elect Engn New York NY 10027 USA Tsinghua Univ Automat Dept Beijing 100084 Peoples R China

In this paper, we propose low-complexity, high-performance soft-equalization techniques for mitigating polarization mode dispersion (PMD) and chromatic dispersion ( CD) in fiber optic communication systems employing multilevel modulation and coherent detection. Using deterministic sampling and tree search, the two proposed algorithms offer near-optimal performance at a much lower complexity than the maximum-likelihood sequence detection (MLSD). Moreover, the a posteriori symbol probabilities at the output can be employed effectively as a soft-input-soft-output demodulator in a turbo-type receiver in a channel-coded system to successively improve the receiver performance. Computer simulation results are provided to demonstrate the effectiveness of the proposed equalizers in high-speed fiber optic channels.

关键词： chase algorithm chromatic dispersion (CD) coherent detection fiber optic communications polarization mode dispersion (PMD) soft equalization tree-search

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Efficient Decoding of Block Turbo Codes

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JOURNAL OF COMMUNICATIONS AND NETWORKS 2018年第4期20卷 345-353页

作者： Son, Jaeyong Kong, Jun Jin Yang, Kyeongcheol Samsung Elect Co Ltd Memory Business Controller Dev Team Suwon South Korea Pohang Univ Sci & Technol POSTECH Dept Elect Engn Pohang South Korea

Block turbo codes (BTCs) under iterative decoding are product codes showing excellent performance with reasonable complexity, whose component codes are conventionally decoded in two stages. The chase algorithm is employed in the first stage to make a list of candidate codewords from the received vector, while the extrinsic information for iterative decoding is generated in the second stage. In this paper, we propose an efficient decoding algorithm for BTCs. The proposed algorithm can avoid a number of unnecessary hard-decision decoding operations by imposing two conditions on the chase algorithm. Also, it simply computes the extrinsic information for the decision codeword. Numerical results demonstrate that the proposed algorithm has not only much lower computational complexity, but also a little better performance than the conventional decoding scheme based on the chase algorithm. Furthermore, it can provide a trade-off between the performance and the computational complexity of BTCs by properly selecting a decoding parameter.

关键词： Algebraic code block turbo codes (BTCs) chase algorithm efficient decoding product codes

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