• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 I
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• pp.89-92
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• 2003

A geometrically uniform code in AWGN channel has strong symmetry properties such as a) the distance profiles form codewords On C to all other codewords are all the same, and b) all Voronoi regions of codewords in C have the same shape. Such properties make the word error probability of geometrically uniform codes be transparent to the transmitted codeword. In this paper, we extend the geometrically uniform codes in AWGN channel to the geometrical uniform codes in fading channel with multiple transmit antennas.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(1)
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• pp.273-276
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• 2001

In this thesis we propose symbol-based decoding for turbo codes which is used SOVA as a decoding algorithm. The proposed turbo codes that is interleaved on symbol-by-symbol basis and inputted as n-bit symbols to the decoder. This method makes that the stages of the original trellis are merged together and the trellis depth is reduced by 1/n. We research turbo codes with symbol size n=2 in this paper and its performance.

• Journal of Communications and Networks
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• 제15권1호
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• pp.71-76
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• 2013

A new class of quantum low-density parity-check (LDPC) codes whose parity-check matrices are dual-containing matrices constructed based on lines of Euclidean geometries (EGs) is presented. The parity-check matrices of our quantum codes contain one and only one 4-cycle in every two rows and have better distance properties. However, the classical parity-check matrix constructed from EGs does not satisfy the condition of dual-containing. In some parameter conditions, parts of the rows in the matrix maybe have not any nonzero element in common. Notably, we propose four families of fascinating structure according to changes in all the parameters, and the parity-check matrices are adopted to satisfy the requirement of dual-containing. Series of matrix properties are proved. Construction methods of the parity-check matrices with dual-containing property are given. The simulation results show that the quantum LDPC codes constructed by this method perform very well over the depolarizing channel when decoded with iterative decoding based on the sum-product algorithm. Also, the quantum codes constructed in this paper outperform other quantum codes based on EGs.

• Journal of Communications and Networks
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• 제10권1호
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• pp.5-9
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• 2008

Researchers have investigated many upper bound techniques applicable to error probabilities on the maximum likelihood (ML) decoding performance of turbo-like codes and low density parity check (LDPC) codes in recent years for a long codeword block size. This is because it is trivial for a short codeword block size. Previous research efforts, such as the simple bound technique [20] recently proposed, developed upper bounds for LDPC codes and turbo-like codes using ensemble codes or the uniformly interleaved assumption. This assumption bounds the performance averaged over all ensemble codes or all interleavers. Another previous research effort [21] obtained the upper bound of turbo-like code with a particular interleaver using a truncated union bound which requires information of the minimum Hamming distance and the number of codewords with the minimum Hamming distance. However, it gives the reliable bound only in the region of the error floor where the minimum Hamming distance is dominant, i.e., in the region of high signal-to-noise ratios. Therefore, currently an upper bound on ML decoding performance for turbo-like code with a particular interleaver and LDPC code with a particular parity check matrix cannot be calculated because of heavy complexity so that only average bounds for ensemble codes can be obtained using a uniform interleaver assumption. In this paper, we propose a new bound technique on ML decoding performance for turbo-like code with a particular interleaver and LDPC code with a particular parity check matrix using ML estimated weight distributions and we also show that the practical iterative decoding performance is approximately suboptimal in ML sense because the simulation performance of iterative decoding is worse than the proposed upper bound and no wonder, even worse than ML decoding performance. In order to show this point, we compare the simulation results with the proposed upper bound and previous bounds. The proposed bound technique is based on the simple bound with an approximate weight distribution including several exact smallest distance terms, not with the ensemble distribution or the uniform interleaver assumption. This technique also shows a tighter upper bound than any other previous bound techniques for turbo-like code with a particular interleaver and LDPC code with a particular parity check matrix.

• 한국통신학회논문지
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• 제36권6A호
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• pp.577-586
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• 2011

현대 디지털 통신 시스템에서는 여러 가지 열화 조건을 극복하기 위하여 거의 모든 시스템에서 오류정정 부호를 사용하며, 최근에는 반복적인 복호 기법으로 우수한 복호 성능 도출이 가능한 터보부호나 저밀도 패리티 검사부호 등을 사용하는 시스템이 늘고 있는 추세이다. 특히 반복적인 복호 방법으로 성능을 향상 시키는 부호를 다중안테나 시스템에서 사용하기 위해서는 수신단에서 송선 신호를 검출할 때 연판정된 채널 이득값의 계산이 필수적으로 요구된다. 본 논문에서는 반복 복호 기법을 사용하는 다중안테나 시스템에서 효과적으로 연판정 값을 검출하는 방법에 대해 살펴보고, 여러 가지 MIMO 검출 방법에 대하여 그 유도 과정을 제시한다. 또한, 유도된 연판정 검출 방법에 대한 시뮬레이션 결과를 제시하여, 제안된 방식이 적은 복잡도로 우수한 성능을 얻을 수 있음을 보인다.

• 대한전자공학회논문지
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• 제12권1호
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• pp.7-11
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• 1975

12-Tuple DS (digit sequence) (또는 coordinate sequence)의 여러 가지 성질에 관하여 논하였으며 그것을 통일적으로 표시하기 위한 31종의 PDS(prime digit sequence)를 제안하여 이에 단순히 회전변환만을 실시함으로써 실제의 부호를 표시하는 348종의 DS를 얻을 수 있고 또 이것들에 대한번호교환 즉 순열(permutation)과 부호의 초기조건을 고려하면 단위거리 12진 부호의 총수는 120,576종이며 이 중의 임의의 부호를 지정하든지 기술하든지 할 수 있도록 하였다. 그리고 대칭부호(반대부호), Lippel 부호등 특수한 부호를 위한 DS들의 특성과 그것들이 회로화에 대하여도 언급하였다. Investigations on sole characteristics of unit-distance duo-decimal codes are carried out, and 31kinds of Prime Digit Sequence (PDS) are proposed in order to express various digit sequences. From these PDS, by means of the rotational conversion, 348 digit sequences which express the practical GC are obtained, and, ism these digit sequences, it is found that there are 120576 unit distance codes by the permutation of the coordinate number and the initial condition of the codes. Some special codes such as reflected or symmetrical codes and Lippel codes, and their application to the practical GC counter are also studied.

• Journal of information and communication convergence engineering
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• 제4권4호
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• pp.136-140
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• 2006

In this paper, we consider the detection of orthogonal space-time block codes (OSTBCs) without channel state information (CSI) at the receiver. Based on the conventional blind cyclic decoder, we propose an enhanced blind cyclic decoder which has higher system performance than the conventional one. Furthermore, the proposed decoder offers low complexity since it does not require the computation of singular value decomposition.

• 대한수학회보
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• 제55권6호
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• pp.1627-1638
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• 2018

In this paper, we study an special type of cyclic codes called skew cyclic codes over the ring ${\mathbb{F}}_p+v{\mathbb{F}}_p+v^2{\mathbb{F}}_p$, where p is a prime number. This set of codes are the result of module (or ring) structure of the skew polynomial ring (${\mathbb{F}}_p+v{\mathbb{F}}_p+v^2{\mathbb{F}}_p$)[$x;{\theta}$] where $v^3=1$ and ${\theta}$ is an ${\mathbb{F}}_p$-automorphism such that ${\theta}(v)=v^2$. We show that when n is even, these codes are either principal or generated by two elements. The generator and parity check matrix are proposed. Some examples of linear codes with optimum Hamming distance are also provided.

• 전자공학회논문지B
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• 제31B권4호
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• pp.106-114
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• 1994

A new merging technique is adopted for combining rectangular parallelepipes produced by 2-D rectangular code into more intuitive 30D volume elements. Rectangular parallelepiped codes (RP codes) can be used in volume-based representation of a three-dimensional object. We proposed more regularity-conserving 2-D rectangular coding scheme to merge rectangular cells represented by RP codes in three-dimensional space. After being constructed from modified 2-D rectangular code, 3-D RP codes are merged in the two orthogonal directions using new merging algorithm. The shape of merged 3-D object reconstructed by proposed algorithm is shown to be much closer to the original object shape than that of conventional RP codes. The storage requirement of merged object can be also reduced.

• 한국통신학회논문지
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• 제40권3호
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• pp.491-496
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• 2015

본 논문에서는 Griesmer 한계식을 만족하는 [$2^k-1$, k, $2^{k-1}$] 심플렉스(simplex) 부호와 [$2^k-1+k$, k, $2^{k-1}+1$] 부호를 소개한다. 또한 두 부호의 부분접속수(locality)에 대해 유도하고 그 값들을 비교한다. [$2^k-1+k$, k, $2^{k-1}+1$] 부호는 주어진 부호차원과 최소거리에 대해 최적의 부호길이를 가질 뿐만 아니라 좋은 부분접속수 특성을 가진다. 그러므로 이 부호는 다양한 분산 저장 시스템에 널리 사용될 수 있을 것으로 기대된다.