• Proceedings of the IEEK Conference
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• 2004.06a
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• pp.39-42
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• 2004

Turbo codes, proposed by Berrou, that increase the interleaver size and the number of iteration have better than conventional convolutional codes, in case of BER performance. However, because turbo codes has been required much decoding delay to increase iteration number, it demands unnecessary iterative decoding. Therefore, in this paper, we propose iterative decoding stop criterion that uses the variance of absolute value of LLR. This algorithm can be reduced average iterative decoding number and had lossless performance of BER, because of decreasing unnecessary iterative decoding.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 1998.10a
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• pp.421-431
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• 1998

Error control performance of the (16, 7) minimum-bandwidth binary error cotrol line code (MB-ECLC) according to decoding algorithms is analyzed and compared in this paper. As a result , when retransmission is not allowed or meaningless. to reduce performance degradation ad computational burden. the modified soft decision decoding algorithm using the structure of (16,7) MB-ELEC is proposed. The error cotnrol capability of this modified algorithm is far better than that of a hard decision decoding algorithm, and almost same as that of a full soft decision decoding algorithm. In additino, the number of comparisons for the modified algorithm is decreased more than 5 times as compared with a full soft decision decoding algorithm.

• Journal of IKEEE
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• v.11 no.4
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• pp.198-204
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• 2007

For parallel and serially concatenated trellis coded modulation (TCM), improved iterative decoding schemes with a simple mechanism are proposed and their performances are compared with those of conventional decoding schemes. Simulation results have shown that the proposed schemes have provided a considerable decoding gain in additive white Gaussian noise (AWGN) channels and Rayleigh fading channels, even if they can be implemented by a simple modification of conventional decoding algorithms.

• ETRI Journal
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• v.34 no.5
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• pp.719-726
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• 2012

Messages are generally selected with the same probability in the encoding scheme of rateless codes for equal error protection. In addition, a belief propagation (BP) decoding scheme is generally used because of the low computational complexity. However, the probability of recovering a new message by BP decoding is reduced if both the recovered and unrecovered messages are selected uniformly. Thus, more codeword symbols than expected are required for the perfect recovery of message symbols. Therefore, a new encoding scheme with a nonuniform selection of messages is proposed in this paper. In addition, a BP-Gaussian elimination hybrid decoding scheme that complements the drawback of the BP decoding scheme is proposed. The performances of the proposed schemes are analyzed and compared with those of the conventional schemes.

• 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.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.12A
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• pp.1145-1151
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• 2010

Hochwald et al. introduced unitary space-time codes for quasi-static Rayleigh fading channels which allows for noncoherent decoding when the channel response is not known at the receiver. However, when reliable information on the channel response is available, coherent decoding is preferable for improved performance. Here, we study the relationship between the performance criteria on the diversity and coding advantages provided by unitary space-time codes with noncoherent and coherent decoding. We show that when a unitary space-time code achieves full spatial diversity with noncoherent decoding, full spatial diversity is also guaranteed with coherent decoding.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.8
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• pp.3749-3768
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• 2018

As one of the most potential types of low-density parity-check (LDPC) codes, CPM-QC-LDPC code has considerable advantages but there still exist some limitations in practical application, for example, the existing decoding algorithm has a low convergence rate and a high decoding complexity. According to the structural property of this code, we propose a new method based on a CPM-RID decoding algorithm that decodes block-by-block with weights, which are obtained by neural network training. From the simulation results, we can conclude that our proposed method not only improves the bit error rate and frame error rate performance but also increases the convergence rate, when compared with the original CPM-RID decoding algorithm and scaled MSA algorithm.

• 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.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.6C
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• pp.450-456
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• 2005

In this paper, we propose a high-speed turbo decoding algorithm and present results of its implementation. The latency caused by (de)interleaving and iterative decoding in conventional MAP turbo decoder can be dramatically reduced with the proposed scheme. The main cause of the time reduction is to use radix-4, center to top, and parallel decoding algorithm. The reduced latency makes it possible to use turbo decoder as a FEC scheme in the real-time wireless communication services. However the proposed scheme costs slight degradation in BER performance because the effective interleaver size in radix-4 is reduced to an half of that in conventional method. To ensure the time reduction, we implemented the proposed scheme on a FPGA chip and compared with conventional one in terms of decoding speed. The decoding speed of the proposed scheme is faster than conventional one at least by 5 times for a single iteration of turbo decoding.

• ETRI Journal
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• v.37 no.4
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• pp.736-742
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• 2015

A serial concatenated decoding algorithm with dynamic threshold is proposed for low-density parity-check codes with short and medium code lengths. The proposed approach uses a dynamic threshold to select a decoding result from belief propagation decoding and order statistic decoding, which improves the performance of the decoder at a negligible cost. Simulation results show that, under a high SNR region, the proposed concatenated decoder performs better than a serial concatenated decoder without threshold with an Eb/N0 gain of above 0.1 dB.