• ETRI Journal
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• v.25 no.1
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• pp.1-8
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• 2003

This paper introduces an efficient iterative decoding method for high-dimensional block turbo codes. To improve the decoding performance, we modified the soft decision Viterbi decoding algorithm, which is a trellis-based method. The iteration number can be significantly reduced in the soft output decoding process by applying multiple usage of extrinsic reliability information from all available axes and appropriately normalizing them. Our simulation results reveal that the proposed decoding process needs only about 30% of the iterations required to obtain the same performance with the conventional method at a bit error rate range of $10^{-5}\;to\;10^{-6}$.

• Proceedings of the IEEK Conference
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• 2000.06c
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• pp.133-136
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• 2000

A RVLC(Reversible Variable Length Code) with an efficient table memory is proposed in this paper. In the conventional decoding methods, the weight of symbols and code values are used for the decoding table. These methods can be applied for Huffman decoding. In VLC decoding, many studies have been done for memory efficiency and decoding speed. We propose an improved table construction method for general VLC and RVLC decoding, which uses the transition number of bits within a symbol with an enhanced weight decomposition. In this method, tile table for RVLC decoding can be implemented with a smaller memory

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.11
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• pp.21-28
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• 1993

Decoding algorithm of noncyclic Reed-Solomon codes consists of four steps which are to compute syndromes, to find error-location polynomial, to decide error-location, and to solve error-values. There is a decoding method by which the computation of both error-location polynomial and error-evaluator polynimial can be avoided in conventional decoding methods using Euclid algorithm. The disadvantage of this method is that the same amount of computation is needed that is equivalent to solve the avoided polynomial. This paper considers the division method on polynomial on GF(2$^{m}$) systematically. And proposes a novel method to find error correcting polynomial by simple mathematical expression without the same amount of computation to find the two avoided polynomial. Especially. proposes the method which the amount of computation to find F (x) from the division M(x) by x, (x-1),....(x--${\alpha}^{n-2}$) respectively can be avoided. By applying the simple expression to decoding procedure on RS codes, propses a new decoding algorithm, and to show the validity of presented method, computer simulation is performed.

• Journal of the Korea Society for Simulation
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• v.14 no.4
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• pp.87-93
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• 2005

In this paper we propose a new iterative decoding method of turbo code which computes the log-likelihood ratios at each MAP (maximum a posteriori) decoder in parallel in each iteration step and combines them with proper weights to produce better decisions. Our results indicate that the proposed decoding method is particularly useful for systems with limited number of iterations and low code rates.

• Journal of Korea Multimedia Society
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• v.2 no.3
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• pp.289-296
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• 1999

In this paper, an improved fractal color image decoding method using the data dependence parts and the vector distortion measure is proposed. The vector distortion measure exploits the correlation between different color components. The pixel in RGB color space can be considered as a 30dimensional vector with elements of RGB components. The root mean square error(rms) in RGB color for similarity measure of two blocks R and R' was used. We assume that various parameter necessary in image decoding are stored in the transform table. If the parameter is referenced in decoding image, then decoding is performed by the recursive decoding method. If the parameter is not referenced in decoding image, then the parameters recognize as the data dependence parts and store its in the memory. Non-referenced parts can be decoded only one time, because its domain informations exist in the decoded parts by the recursive decoding method. Non-referenced parts are defined the data dependence parts. Image decoding method using data dependence classifies referenced parts and non-referenced parts using information of transform table. And the proposed method can be decoded only one time for R region decoding speed than Zhang & Po's method, since it is decreased the computational numbers by execution iterated contractive transformations for the referenced range only.

• The KIPS Transactions:PartC
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• v.10C no.1
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• pp.27-32
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• 2003

An efficient soft-decision decoding algorithm for binary block codes it proposed. The proposed soft-decision decoding algorithm is implemented by a series of hard-decision decoding process. By the hard-decision decoding result, the candidate codewords are efficiently searched for A new decoding method, which prevents the missing of the candidate codeword, is proposed. Also, the method fir reducing complexity is developed. This method removes the practical complexity increase caused by the improved algorithm. There facts are confirmed by the simulation results for binary (63, 36) BCH code.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.12
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• pp.1401-1412
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• 1992

On band limited channel like satellite communication and voice communication. TCM(Trellis Coded Modulation) is a communication method that has coding gain which combines modulation with channel coding without bandwidth expansion. In this paper, we apply PAM, PSK, QAM to TCM, and propose the extended path back method decoding algorithm which improved drawback of viterbi decoding algorithm and apply to TCM this decoding algorithm. Using Monte Carlo simulation, we analyze performance of each modulation technique and efficiency of decoding algorithm.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.3
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• pp.16-33
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• 1993

New decoding algorithm of double-error-correction Reed-Solmon codes over GF(2$^{8}$) for optical compact disks is proposed and decoding algorithm of RS codes with triple-error-correcting capability is presented in this paper. First of all. efficient algorithms for estimating the number of errors in the received code words are presented. The most complex circuits in the RS decoder are parts for soving the error-location numbers from error-location polynomial, so the complexity of those circuits has a great influence on overall decoder complexity. One of the most known algorithm for searching the error-location number is Chien's method, in which all the elements of GF(2$^{m}$) are substituted into the error-location polynomial and the error-location number can be found as the elements satisfying the error-location polynomial. But Chien's scheme needs another 1 frame delay in the decoder, which reduces decoding speed as well as require more stroage circuits for the received ocode symbols. The ther is Polkinghorn method, in which the roots can be resolved directly by solving the error-location polynomial. Bur this method needs additional ROM (readonly memory) for storing tthe roots of the all possible coefficients of error-location polynomial or much more complex cicuit. Simple, efficient, and high speed method for solving the error-location number and decoding algorithm of double-error correction RS codes which reudce considerably the complexity of decoder are proposed by using Hilbert theorems in this paper. And the performance of the proposed decoding algorithm is compared with that of conventional decoding algorithms. As a result of comparison, the proposed decoding algorithm is superior to the conventional decoding algorithm with respect to decoding delay and decoder complexity. And decoding algorithm of RS codes with triple-error-correcting capability is presented, which is suitable for error-correction in digital audio tape, also.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.12A
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• pp.1960-1965
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• 1999

In this paper, we propose a new method of erased concatenated code with RS-convolutional code. In the method, we make use of erasure for undecoded information when we have some errors in RS decoding. For decoding with erasure, the method is processed inner decoding and outer decoding again. After the erasure decoding, if the decoding result is better than the previous one, then we use this result. If not, use the previous one. In this paper, we use concatenated RS(63,31)-convolutional(4.1/2) code. Simulation result is compared with calculation result for performance analysis. According to the result, the proposed method has better performance than the others without erasure such that 2dB when 0.5$\leq\rho\leq$1 and 4dB when $\rho\leq$0.3.

• Journal of Broadcast Engineering
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• v.16 no.4
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• pp.635-646
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• 2011

In distributed video coding, low complexity encoder can be realized by shifting encoder-side complex processes to decoder-side. However, not only motion estimation/compensation processes but also complex LDPC decoding process are imposed to the Wyner-Ziv decoder, therefore decoder-side complexity has been one important issue to improve. LDPC decoding process consists of numerous iterative decoding processes, therefore complexity increases as the number of iteration increases. This iterative LDPC decoding process accounts for more than 60% of whole WZ decoding complexity, therefore it can be said to be a main target for complexity reduction. Previously, HDA (Hard Decision Aided) method is introduced for fast LDPC decoding process. For currently received parity bits, HDA method certainly reduces the complexity of decoding process, however, LDPC decoding process is still performed even with insufficient amount of parity request which cannot lead to successful LDPC decoding. Therefore, we can further reduce complexity by avoiding the decoding process for insufficient parity bits. In this paper, therefore, a parity request estimation method is proposed using bit plane-wise correlation and temporal correlation. Joint usage of HDA method and the proposed method achieves about 72% of complexity reduction in LDPC decoding process, while rate distortion performance is degraded only by -0.0275 dB in BDPSNR.