• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.2C
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• pp.123-129
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• 2006

In this paper, we concentrate on reducing the complexity for efficient encoder. We design structural LDPC code using circulant matrix and permutation matrix and eIRA code. It is possible to design low complex encoder by using shift register and differential encoder and interleaver than general LDPC encoder that use matrix multiplication operation. The code designed by this structure shows similar performance as random code. And the proposed codes can considerably reduce a number of XOR gates.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.3A
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• pp.151-156
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• 2012

In this paper, design of quasi-cyclic(QC) low-density parity-check codes is proposed to have full diversity for space-time bit-interleaved coded modulation(ST-BICM) systems. Necessary and sufficient conditions that the proposed scheme has full diversity are proved as the condition that submatrices corresponding to the system part of codewords are invertible. And new construction method of binary invertible matrices for QC LDPC codes in ST-BICM systems are also proposed and modification for parity-check matrices are also explained.

• The KIPS Transactions:PartC
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• v.13C no.3 s.106
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• pp.317-322
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• 2006

This paper presents an efficient user-cooperation protocol associated with cyclic coding for WSNs (Wireless Sensor Networks) using LEACH(Low-Energy Adaptive Clustering Hierarchy). Since the proposed user-cooperation requires no CSI(Channel State Information) at both transmitter and receiver, and encoding and decoding of cyclic codes are simple, the processing complexity of sensor nodes is significantly reduced. Simulation results reveal such a combination can save the network energy up to 10dB over single-hop transmission at BER of $10^{-4}$.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.2C
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• pp.155-160
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• 2008

In this letter, we propose a new design of recursive systematic convolutional (RSC) codes based on the distance spectrum properties which can maximize the performance. Good constituent RSC codes of code rate 1/2 are searched by computer and presented in a table. Their performances are shown by computer simulation. New designed codes shows faster convergences according to iterative decoding and good performances.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.1
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• pp.117-124
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• 2012

In this paper, we propose a simple H parity check matrix from the CPM(circulant permutation matrix), which can easily avoid the cycle-4, and approach to flexible code rates and lengths. As a result, the operations of the submatrices will become the multiplications between several CPMs, the calculations of the LDPC(low density parity check) encoding could be simplest. Also we consider the fast encoding problem for LDPC codes. The proposed constructions could lead to fast encoding based on the simplest matrices operations for both regular and irregular LDPC codes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.12
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• pp.1745-1747
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• 2016

In this paper, we propose a construction method of irregular quasi-cyclic low-density parity-check codes based on perfect difference families with various block sizes. The proposed codes have advantages in that they support various values with respect to code rate, length, and degree distribution. Also, this construction enables very short lengths which are usually difficult to be achieved by a random construction. We verify via simulations the error-correcting performance of the proposed codes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.2B
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• pp.325-333
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• 2010

Most communication systems including Wibro use quasi-cyclic LDPC codes composed of circulants. However, it is very difficult to design quasi-cyclic(QC) LDPC codes with optimal degree distribution satisfying conditions on layered decoding and girth due to the restriction of the size of its base matrix. In this paper, we propose a good solution by introducing superposition matrices to QC LDPC codes. We derive the conditions on checking girth of QC LDPC codes with superposition matrices, and propose new decoder to support layered decoding both for original QC LDPC codes and their modifications with superposition matrices. Simulation results show considerable improvements to convergence speed and error-correcting performance of proposed scheme which adopts QC LDPC codes with superposition matrices.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.4
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• pp.403-408
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• 2014

In this paper, we consider the encoding scheme of low density codes. In particular, we propose the fast encoding algorithm of the low density codes using circulant permutation matrices, The fast encoding algorithm is similar to the fast Hadamard transform, and the results show that the proposed scheme is a simple and fast encoding algorithm of the low density codes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.1C
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• pp.15-20
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• 2009

For perpendicular magnetic recording (PMR) channels, noise-predictive maximum likelihood (NPML) detection method has been used. But, it is hard to expect improving the performance when the bit density is increased. Hence, we exploit the coding methods which has good performance. In this paper, we show the performance of the recursive systematic convolutional (RSC) codes with turbo-equalization method with different channel bit densities. The noise model is 80% jitter noise and 20% AWGN.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.04a
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• pp.631-634
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• 2010

기존의 Quasi-Cyclic LDPC 부호는 하나의 기본행렬의 순환행렬을 부행렬로 사용하여 패리티 검사 행렬을 만든다. 본 논문에서는 무게가 서로 다른 두 개의 기본 행렬의 순환행렬들과 영행렬을 부행렬로 사용하고, 이 세 개의 부행렬들을 주어진 조건하에서 무작위로 조합하여 패리티 검사 행렬을 만드는 방법을 제안한다. 제안된 LDPC 부호는 girth가 6이상인 Irregular LDPC 부호이다.