• 시스템엔지니어링학술지
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• 제17권2호
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• pp.69-81
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• 2021

The human performance issues and increased automation issues in advanced Small Modular Reactors (SMRs) are critical to numerous stakeholders in the nuclear industry, due to the undesirable implications targeting the Man Machine Interface Systems (MMIS) complexity of (Generation IV) SMRs. It is imperative that the design of future SMRs must address these problems. Nowadays, Multi Agent Systems (MAS) are used in the industrial sector to solve multiple complex problems; therefore incorporating this technology in the proposed innovative SMR (I-SMR) design will contribute greatly in the decision making process during plant operations, also reduce the number MCR operating crew and human errors. However, it is speculated that an increased level of complexity will be introduced. Prior to achieving the objectives of this research, the tools used to analyze the system for complexity reduction, are the McCabe's Cyclomatic complexity metric and the Henry-Kafura Information Flow metric. In this research, the systems engineering approach is used to guide the engineering process of complexity reduction concept of the system in its entirety.

• The Journal of the Acoustical Society of Korea
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• 제17권3E호
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• pp.53-57
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• 1998

Spectral information at a speech coder should be quantized with sufficient accuracy to keep perceptually transparent output speech. Spectral information at a low bit rate speech coder is usually transformed into corresponding line spectrum pair parameters and is often quantized with a vector quantization algorithm. As the vector quantization algorithm generally has high complexity in the optimal code vector searching routine, the complexity reduction in that routine is investigated using the ordering property of the line spectrum pair. When the proposed complexity reduction algorithm is applied to the well-known split vector quantization algorithm, the 46% complexity reduction is achieved in the distortion measure compu-tation.

• 한국통신학회논문지
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• 제34권8A호
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• pp.583-591
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• 2009

높은 PAPR을 갖는 직교 주파수 분할 다중 접속 신호는 비선형 왜곡을 발생시키거나, 송신기의 전력 증폭기의 효율을 나쁘게 한다. 그래서 비선형 왜곡을 줄이기 위한 상호 변조 왜곡 저감 기법이 제안되었다. IMD 저감 기법은 비선형 왜곡에 대하여 PAPR 저감 기법보다 비트 오차율 작게 한다. 하지만 IMD 저감 기법의 결정 기준은 주파수 영역에서 이루어지기 때문에 송신기에 FFT가 추가되어 시스템 복잡도가 증가하고, IMD 연산의 복잡한 계산 과정과, 이에 따른 처리시간이 증가하는 문제가 있다. 그러므로 본 논문에서는 이러한 기존의 IMD 저감 기법의 복잡도와 계산량 저감하기 위한 새로운 방식의 IMD 저감 방식을 제안한다. 또한 본 논문에서는 제안된 방식을 PTS 방식의 OFDM 통신 시스템에 적용하여 기존의 기법과 복잡도와 계산량을 비교한다. 제안된 기법은 PAPR처럼 시간영역에서 IMD의 전력량을 계산하므로 송신기에서 시스템의 복잡도와 계산량을 크게 줄일 수 있다. 또한 새로운 기법은 기존 방식과 BER 성능 면에서 차이를 보이지 않는다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권6호
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• pp.2554-2580
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• 2018

Lenstra-Lenstra-$Lov{\acute{a}}sz$ (LLL) is an effective receiving algorithm for Multiple-Input-Multiple-Output (MIMO) systems, which is believed can achieve full diversity in MIMO detection of fading channels. However, the LLL algorithm features polynomial complexity and shows poor performance in terms of convergence. The reduction of algorithmic complexity and the acceleration of convergence are key problems in optimizing the LLL algorithm. In this paper, a variant of the LLL algorithm, the Hybrid-Fix-and-Round LLL algorithm, which combines both fix and round measurements in the size reduction procedure, is proposed. By utilizing fix operation, the algorithmic procedure is altered and the size reduction procedure is skipped by the hybrid algorithm with significantly higher probability. As a consequence, the simulation results reveal that the Hybrid-Fix-and-Round-LLL algorithm carries a faster rate of convergence compared to the original LLL algorithm, and its algorithmic complexity is at most one order lower than original LLL algorithm in real field. Comparing to other families of LLL algorithm, Hybrid-Fix-and-Round-LLL algorithm can make a better compromise in performance and algorithmic complexity.

• 대한전자공학회논문지TC
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• 제46권5호
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• pp.88-94
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• 2009

본 논문에서는 다중 안테나 시스템에서 신호 수신을 위한 lattice reduction (LR) 기반 복호기의 복잡도를 줄이기 위한 방법을 제안한다. ML (Maximum Likelihood) 방식이 복호 성능은 우수하지만 안테나와 성상 점의 개수에 따라 지수적으로 복잡도가 증가하는데 반해 LR 기반의 복호기는 상대적으로 적은 복잡도로 동일한 다이버시티 성능을 보이는 것으로 알려져 있다. 그러나 LR 과정도 채널 행렬의 열 벡터 교환 과정을 포함한 반복 연산에 의해서 복잡도가 높고 하드웨어 구현이 어려운 점이 있다. LR 과정은 채널 행렬이 주어지는 경우 유일하게 결정되기 때문에 이 과정을 offline으로 미리 수행하여 Look-Up Table(LUT)에 저장하는 방식으로 계산량을 줄일 수 있다. 본 논문에서는 LR 기반 수신기에서 LUT 를 효율적으로 구성하는 방법을 제시하고 성능을 비교한다. 제안된 방식을 적용할 경우 기존의 LR 방식에 비하여 적은 연산량으로 유사한 수신 성능을 보임을 모의실험을 통하여 보인다.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제20권2호
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• pp.107-121
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• 2016

We analyze the complexity of the LLL algorithm, invented by Lenstra, Lenstra, and $Lov{\acute{a}}sz$ as a a well-known lattice reduction (LR) algorithm which is previously known as having the complexity of $O(N^4{\log}B)$ multiplications (or, $O(N^5({\log}B)^2)$ bit operations) for a lattice basis matrix $H({\in}{\mathbb{R}}^{M{\times}N})$ where B is the maximum value among the squared norm of columns of H. This implies that the complexity of the lattice reduction algorithm depends only on the matrix size and the lattice basis norm. However, the matrix structures (i.e., the correlation among the columns) of a given lattice matrix, which is usually measured by its condition number or determinant, can affect the computational complexity of the LR algorithm. In this paper, to see how the matrix structures can affect the LLL algorithm's complexity, we derive a more tight upper bound on the complexity of LLL algorithm in terms of the condition number and determinant of a given lattice matrix. We also analyze the complexities of the LLL updating/downdating schemes using the proposed upper bound.

• 전자공학회논문지B
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• 제33B권3호
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• pp.126-132
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• 1996

In this paper, the complexity reduction method for QCELP speech coder (IS-96) without any perfomrance degradation is proposed for the vecoder of CDMA digital cellular system. The energy terms in pitch parameter search and codebook search routines that require large computations are calculated recursively by utilizing the overlapped structure of code vectors in adaptive codebook and excitation codebook. The additional complexity reduction in the codebook search routine can be achieved by using a simple form in calculation of the energy term when the initial codebook value is zero. In the case of lower transmission rates such as 4,2,1 kbps, the complexity reduction by recursive calulations of energy term is increased.

• ETRI Journal
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• 제34권1호
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• pp.110-113
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• 2012

We propose a very-low-complexity lattice-reduction (LR) algorithm for multi-input multi-output detection in time-varying channels. The proposed scheme reduces the complexity by performing LR in a block-wise manner. The proposed scheme takes advantage of the temporal correlation of the channel matrices in a block and its impact on the lattice transformation matrices during the LR process. From this, the proposed scheme can skip a number of redundant LR processes for consecutive channel matrices and performs a single LR in a block. As the Doppler frequency decreases, the complexity reduction efficiency becomes more significant.

• 한국전자파학회논문지
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• 제15권9호
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• pp.863-871
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• 2004

본 논문에서는 정합 필터 출력을 이용하여 연산 복잡도가 감소된 DS/CDMA DMB 하향 링크 시스템에서의 부분 공간 채널 추정 기법을 제안한다. 연산 복잡도 감소 효과는 채널 벡터의 길이가 짧고 시스템의 부하가 적절할 때 매우 크게 나타난다. 이전에 제안된 부분 공간 채널 추정 알고리즘은 화산 이득이 큰 시스템에서 막대한 연산 복잡도 문제를 겪게 된다. 제안된 알고리즘에 약간의 성능 손실이 발생하지만 데이터 행렬의 길이가 길어지게 되면 그 영향은 미미해진다. 시뮬레이션과 분석적인 MSE 성능의 유도를 통해 성능을 평가한다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -3
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• pp.2035-2038
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• 2002

The necessity of the filter coefficients compensation for the LTJ adaptive filter was explained generally and easily by analyzing it with respect to the time-varying transform domain adaptive filter. And also the reduction method of computational complexity for filter coefficients compensation was proposed and its effectiveness was verified through experiments using artificial and real speech signals. The proposed adaptive filter reduces the computational complexity for filter coefficients compensation by 95%, and when the filter is applied to the acoustic echo canceller with 1000 taps, the total complexity is reduced by 82%