• ETRI Journal
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• v.34 no.4
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• pp.637-640
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• 2012

The Davey-MacKay construction is a promising concatenated coding scheme involving an outer $2^k$-ary code and an inner code of rate k/n, for insertion-deletion-substitution channels. Recently, a lookup table (LUT)-based inner decoder for this coding scheme was proposed to reduce the computational complexity of the inner decoder, albeit at the expense of a slight degradation in word error rate (WER) performance. In this letter, we show that negligible deterioration in WER performance can be achieved with an LUT as small as $7{\cdot}2^{k+n-1}$, but no smaller, when the probability of receiving less than n-1 or greater than n+1 bits corresponding to one outer code symbol is at least an order of magnitude smaller than the WER when no LUT is used.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.10
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• pp.858-866
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• 2013

In the DVB-S2, which is the technical specification of the second generation digital video broadcasting via satellite, APSK modulation scheme along with LDPC coding schemes are defined. APSK is a multi-lelvel PSK modulation scheme and decoding of LDPC coded signal requires soft decision information. Therefore, the APSK demodulator at the receiver should have capability of estimating soft information. In this paper, we introduce a method to estimate soft information by using simple distance estimation, and show that this method overestimates the soft information. Subsequently, this overestimated soft information leads to performance degradation. In order to overcome this problem, we propose a scaling method to improve the performance at the receiver In addition, we show that the proposed scaling scheme enables us to estimate the soft information with linear order complexity and produce the performance close to the maximum likelihood detection.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.10
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• pp.1075-1085
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• 2008

Recently, it is studied actively that DVB-S2 for mobility standard(DVB-S2M) is combined with DVB-H, DVB-T and conventional DVB-S2 standard for continuous satellite broadcasting and internet service. Especially, overcoming deep fading by tunnel is main subject. For overcoming deep fading, DVB-S2M proposed cross layer system is consist of upper layer and physical layer. Thus, this paper proposed optimal upper layer coding system fixing the physical layer coding under the simulation results by coding methods, train speed, data rate, interleaver size and IP packet size.

• Journal of electromagnetic engineering and science
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• v.6 no.4
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• pp.244-252
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• 2006

A block Jacket transform and. its block inverse Jacket transformn have recently been reported in the paper 'Fast block inverse Jacket transform'. But the multiplication of the block Jacket transform and the corresponding block inverse Jacket transform is not equal to the identity transform, which does not conform to the mathematical rule. In this paper, new binary block Jacket transforms and the corresponding binary block inverse Jacket transforms of orders $N=2^k,\;3^k\;and\;5^k$ for integer values k are proposed and the mathematical proofs are also presented. With the aid of the Kronecker product of the lower order Jacket matrix and the identity matrix, the fast algorithms for realizing these transforms are obtained. Due to the simple inverse, fast algorithm and prime based $P^k$ order of proposed binary block inverse Jacket transform, it can be applied in communications such as space time block code design, signal processing, LDPC coding and information theory. Application of circular permutation matrix(CPM) binary low density quasi block Jacket matrix is also introduced in this paper which is useful in coding theory.

• The Journal of the Korea institute of electronic communication sciences
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• v.3 no.3
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• pp.170-176
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• 2008

According to the development of Internet, DWDM system needs to improve the performance for long distance transmission international optical signals. For higher the transmission capacity, we have to raise the transmission speed and increase a number of channels. To make qualifications, there are a lot of technologies such as line coding, modulation, precious fiber, broadband amplification, dispersion and forward error correction. Especially, FEC has been considered as a progressive technology for long distance transmission to carry out high speed and large capacity traffic. This paper introduced the progress of each new generation of FEC and the way to employ by current system analyzed the coding gain.

• ETRI Journal
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• v.31 no.5
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• pp.489-499
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• 2009

This paper focuses on assessment and design of transmission systems for distribution of digital signals over standard Category-7A copper cables at speeds beyond 10 Gbps. The main contribution of this paper is on the technical feasibility and system design for data rates of 40 Gbps and 100 Gbps over copper. Based on capacity analysis and rate optimization algorithms, system parameters are obtained and the design implementation trade-offs are discussed. Our simulation results confirm that with the aid of a decision-feedback equalizer and powerful coding techniques, namely, TCM or LDPC code, 40 Gbps transmission is feasible over 50 m of CAT-7A copper cable. These results also indicate that 100 Gbps transmission can be achieved over 15 m cables.

• 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.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2008.11a
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• pp.81-84
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• 2008

최근 센서네트워크와 같은 에너지 제한 환경을 위한 경량화 부호화 기술의 필요성이 대두됨에 따라 분산 소스 부호화 기술(Distributed Source Coding)의 응용기술로 비디오 부호화 복잡도의 대부분을 차지하는 움직임 예측/보상과정을 부호화기가 아닌 복호화기에서 수행하는 분산 비디오 부호화 기술(Distributed Video Coding)에 대한 연구가 활발히 이루어져 왔다. 이에 가장 대표적인 기술인 Wyner-Ziv 코딩 기술은 채널 코드를 이용하여 원본 프레임과 이에 대한 복호화기의 예측영상인 보조정보 사이의 잡음을 제거하여 영상을 복원한다. 일반적으로 보조정보는 원본영상에 유사한 키 프레임간의 프레임 보간을 통하여 생성되며 채널 코드는 Shannon limit에 근접한 성능을 보이는 Turbo 코드나 LDPC 코드가 사용된다. 이와 같은 채널 코드의 복호화는 채널 잡음 모델에 기반하여 수행되어지며 Wyner-Ziv 코딩 기술에서는 이 채널 잡음 모델을 '상관 잡음 모델' (Correlation Noise Modeling)이라 하고 일반적으로 Laplacian이나 Gaussian으로 모델화 한다. 하지만 복호화기에는 원본 영상에 대한 정보가 없기 때문에 정확한 상관 잡음 모델을 알 수 없으며 잡음 모델에 대한 예측의 부정확성은 잡음 제거를 위한 패리티 비트의 증가를 야기해 부호화 기술의 압축 성능 저하를 가져온다. 이에 본 논문은 원본 프레임과 보조정보 사이의 잡음을 정확하게 예측하여 잡음을 정정할 수 있는 향상된 상관 잡음 모델을 제안한다. 제안 방법은 잘못된 잡음 예측에 의해 Laplacian 계수가 너무 커지는 것을 방지하면서 영상내의 잡음의 유무에 별다른 영향을 받지 않는 새로운 문턱값을 사용한다. 다양한 영상에 대한 제안 방법의 실험 결과는 평균적으로 약 0.35dB에 해당하는 율-왜곡 성능 향상을 보여주었다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.11C
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• pp.889-895
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• 2010

MIMO system generally requires more than one antenna at the communication device. However, many wireless devices are limited by size, cost or hardware complexity to one antenna. To overcome such restrictions, we used a new technique, called cooperative communication. We propose a new cooperative transmission strategy system using cross-layer coding method base on H-ARQ for optimal communication. Proposed cooperative H-ARQ system that can improve the above problems and can get the better performance. In proposed cooperative system with H-ARQ method, if the received signal from source node is satisfied by the destination preferentially, the destination transmit ACK message to both relay node and source node, and then recovers the received signal. In addition, if ARQ message indicates NACK message, relay node operates selective retransmission. Based on the simulation results in aspect to BER performance and throughput, the proposed method which combined cooperative system with H-ARQ based on cross-layer coding can improve spectral efficiency reliability of system compared with that of general one by one system.

• Journal of Broadcast Engineering
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• v.16 no.6
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• pp.1026-1035
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• 2011

This paper presents generalization and application for the conventional SISO decoding algorithm of Block Turbo Codes. R. M. Pyndiah suggested an iterative SISO decoding algorithm for Product Codes, two-dimensionally combined linear block codes, on AWGN channel. It wascalled Block Turbo Codes. Based on decision of Chase algorithm which is SIHO decoding method, SISO decoder for BTC computes soft decision information and transfers the information to next decoder for iterative decoding. Block Turbo Codes show Shannon limit approaching performance with a little iteration at high code rate on AWGN channel. In this paper we generalize the conventional decoding algorithm of Block Turbo Codes, under BPSK modulation and AWGN channel transmission assumption, to the LLR value based algorithm and suggest an application example such as concatenated structure of LDPC codes and Block Turbo Codes.