• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.8
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• pp.868-876
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• 2016

MUSIC (multiple signal classification) algorithm is a representative algorithm estimating the angle of arrival using the eigenvalues and eigenvectors. Generally, the eigenvalues and eigenvectors are obtained through the eigen-analysis, but this analysis requires high computational complexity and late convergence time. For this reason, it is almost impossible to construct the real-time system with low-cost using this approach. Even though QR iteration is considered as the eigen-analysis approach to improve these problems, this is inappropriate to apply to the MUSIC algorithm. In this paper, we analyze the problems of conventional method based on the eigenvalues for convergence decision and propose the improved decision algorithm using the eigenvectors.

• Proceedings of the Acoustical Society of Korea Conference
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• 1991.06a
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• pp.38-41
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• 1991

RLS algorithms are required for applications to adaptive line enhancers, adaptive equalizers for voiceband telephone and HF modems, and wide-badn digital spectrum mobile raio in which their convergence time and tracking speed are significant. The fast QR RLS algorithm satisfies above the requirements. Its computational complexity is linearly proportional to the tap number of a filter, N and its performance remains numerically stable. From the result of simumulation, the fast QR RLS algorithm represented Cioffi is better than gradient based algorithm in its initial performance when being applied to an adaptive line enhancer for cancelling noise.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.10
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• pp.75-82
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• 2008

In this paper, we propose an efficient symbol detection algorithm for multiple-input multiple-output spatial multiplexing (MIMO-SM) systems and present its design and implementation results. By enhancing the performance of the first detected symbol which causes error propagation, the proposed algorithm achieves a considerable performance gain as compared to the conventional sorted QR decomposition (SQRD) based detection and the ordered successive detection (OSD) algorithms. The bit error rate (BER) performance of the proposed detection algorithm is evaluated by the simulation. In case of 16QAM MIMO-SM system with 4 transmit and 4 receive ($4{\times}4$) antennas, at $BER=10^{-3}$ the proposed algorithm obtains the gai improvement of about 2.5-13.5 dB over the conventional algorithms. The proposed detection algorithm was designed in a hardware description language (HDL) and synthesized to gate-level circuits using 0.18um 1.8V CMOS standard cell library. The results show that the proposed algorithm can be implemented without increasing the hardware costs significantly.

• Proceedings of the IEEK Conference
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• 2002.06a
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• pp.25-28
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• 2002

본 논문에서는 W-CDMA(Wide-Code Division Mul-tiple Access)용 Systolic 어레이 구조를 잣는 상향링크 빔형성기법에 대한 성능 분석을 하였다. 적응 어레이 안테나와 Systolic 구조의 MVDR(Minimum Variance Distortionless Response) 알고리즘을 사용하여 구해진 가중치 벡터를 이용하여 원하는 사용자의 방향으로 빔을 형성하고 원하지 않는 사용자의 방향으로는 null을 형성하는 공간필터를 적용하여 W-CDMA 상향링크에서 다중 경로 페이딩과 다중 접속 간섭의 증가에 따른 수신 성능을 분석하였다. 그리고, 안테나 시스템에서 사용되는 가중벡터를 갱신하기 위해 Systolic 구조의 MVDR과 역방향 파일럿 채널을 이용하는 QR-RLS(QR-Recursive Least Squares) 알고리즘을 적용하였다. 본 논문에서는 빔 형성기에 사용하기 위한 역행렬의 계산과 정에 Systolic 어레이 구조를 적용하여 병렬적인 고속처리가 가능한 방법과 효율적인 계산과정을 위해 MVDR 과 QR-RLS 알고리즘을 적용한 공간 필터링의 성능을 소개한다.

• Journal of IKEEE
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• v.18 no.1
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• pp.165-171
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• 2014

This paper presents a low complexity QR decomposition (QRD) architecture for MIMO detector. In the proposed approach, various CORDIC-based QRD algorithms are efficiently combined together to reduce the computational complexity of the QRD hardware. Based on the computational complexity analysis on various QRD algorithms, a low complexity approach is selected at each stage of QRD process. The proposed QRD architecture can be applied to any arbitrary dimension of channel matrix, and the complexity reduction grows with the increasing matrix dimension. Our QR decomposition hardware was implemented using Samsung $0.13{\mu}m$ technology. The numerical results show that the proposed architecture achieves 47% increase in the QAR (QRD Rate/Gate count) with 28.1% power savings over the conventional Householder CORDIC-based architecture for the $4{\times}4$ matrix decomposition.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06c
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• pp.400-402
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• 2012

본 논문은 모바일 단말기에 장착된 센서를 이용한 QR코드 기반의 인터랙티브한 모바일 증강현실 시스템을 제안한다. QR코드는 많은 양의 정보를 담을 수 있는 2차원 바코드이다. 본 논문에서 활용한 QR코드는 QR코드 메타데이터와 콘텐츠 상세 메타데이터로 구성된다. 메타 데이터를 사용함으로써 기존의 프로그램을 수정하지 않고 사용자가 쉽게 콘텐츠를 작성할 수 있다. 또한 상세 메타데이터를 이용해 마커위에 증강하고자 하는 모델의 정보를 데이터 서버로부터 획득한다. 기존의 증강현실시스템은 영상처리 기반의 카메라 자세 추정을 사용한다. 하지만 모바일 단말기에서는 낮은 사양의 컴퓨팅 파워와 많은 양의 알고리즘 계산으로인해 실시간 카메라 자세 추정이 힘들다. 따라서 본 논문에서는 모바일 단말기에 장착된 센서를 사용하여 카메라의 포즈를 계산 하여 증강현실을 구현한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.27 no.1
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• pp.103-108
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• 2023

We study the problem of selecting a subset of sensor nodes in sensor networks in order to maximize the performance of parameter estimation. To achieve a low-complexity sensor selection algorithm, we propose a greedy iterative algorithm that allows us to select one sensor node at a time so as to maximize the log-determinant of the inverse of the estimation error covariance matrix without resort to direct minimization of the estimation error. We apply QR factorization to the observation matrix in the log-determinant to derive an analytic selection rule which enables a fast selection of the next node at each iteration. We conduct the extensive experiments to show that the proposed algorithm offers a competitive performance in terms of estimation performance and complexity as compared with previous sensor selection techniques and provides a practical solution to the selection problem for various network applications.

• Journal of Korea Society of Industrial Information Systems
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• v.25 no.3
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• pp.21-30
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• 2020

With the widespread of smartphones, the Quick response (QR) code became one of the most popular codes. In this paper, a new type of QR code is proposed to increase the storage capacities and also to contain private information by changing the colors and the shape of patterns in the codes. Then, for a variety of applications of the printed QR codes, this paper proposes an efficient authentic certification system, which is built on an conventional CNN (Convolutional neural network) architecture - VGGNet and classifies authentic or counterfeit with smartphones, easily. For authentic codes, the proposed system extracts the embedded private information. Through practical experiments with a printed QR code, it is shown that the proposed system can classify authentic or counterfeit code, perfectly, and also, are useful for extracting private information.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.3
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• pp.1-7
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• 2008

This paper proposes a new QRD-LS adaptive algorithm with computational complexity of O(N). The main idea of proposed algorithm(D-QR-RLS) is based on the fact that the computation for the unit vector of is made from the process during Givens Rotation. The performance of the algorithm is evaluated through computer simulation of FIR system identification problem. As verified by simulation results, this algorithm exhibits a good performance. And, we can see the proposed algorithm converges to optimal coefficient vector theoretically.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.1
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• pp.46-56
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• 2017

Recently, the spread of IoT technology has been spreading, and it has been applied to all industrial fields such as home / home appliance / medical care. Due to the low specification, low power consumption characteristic and communication data characteristic of IoT, implementation of existing algorithm is difficult thing. From this reason, we have proposed for the first time that encryption and decryption can be proceeded by introducing a kind of variable length bit XOR operation method which changes a variable the bit length value by using carry up and carry down method. We confirmed the practicality of encrypting short message data frequently processed by IoT device / QR code / RFID / NFC without changing the size of data before and after encryption.