Advanced technologies for LTE advanced

Shin, Oh-Soon,Elayoubi, Salah Eddine,Jeong, Yeon Kyoon,Shin, Yoan Springer (Biomed Central Ltd.) 2013 EURASIP journal on wireless communications and net Vol.2013 No.-

무선인지 시스템에서 협력 스펙트럼 센싱 성능 향상을 위한 경판정 결합 기법

신오순(Oh-Soon Shin),신요안(Yoan Shin) 한국통신학회 2009 韓國通信學會論文誌 Vol.34 No.2A

무선인지 기술은 비어있는 스펙트럼을 검출하고 이를 사용하여 통신하는 기술로서 주파수 부족 현상을 해소하기 위한 방안으로 활발히 연구가 이루어지고 있다. 무선인지 기술을 도입하기 위해 핵심적인 요소는 부사용자가 주사용자의 통신을 방해하지 않으면서 주파수 사용의 효율성을 최대화하는 것이다. 이를 위해서는 주사용자의 스펙트럼 점유 여부를 정확하게 판단하는 센싱 기술이 필요하다. 각각의 부사용자가 독립적으로 센싱을 수행하는 개별 센싱 기술은 음영지역, 잠복 터미널 문제 등이 있어서 최근 여러 부사용자가 협력하여 센싱을 수행하는 협력 스펙트럼 센싱 기술이 주목받고 있다. 본 논문은 협력 스펙트럼 센싱에 있어서 각 부사용자가 개별적으로 센싱한 결과의 경판정 값을 취합하여 이를 효과적으로 결합하는 방법을 제안한다. 제안한 방법은 과거의 협력 센싱 결과를 이용하여 각 부사용자의 개별 센싱 결과에 신뢰도를 나타내는 가중치를 부여하여 결합함으로써 협력 센싱 성능을 향상시킨다. 다양한 환경에서 제안한 방법의 검출 성능을 평가하여 기존의 가중치 없는 경판정 결합 방법과 비교한 결과를 제시한다. Cognitive radio is considered as a promising solution to scarce spectrum problem. The primary object of cognitive radio is to increase spectral efficiency, while causing limited interference to primary users who are using the spectrum. Hence, an essential part of cognitive radio systems is spectrum sensing which determines whether a particular spectrum is occupied or not by a primary user at a particular time. However, sensing decision of each individual secondary user alone may not be reliable enough due to shadowing and multipath fading of wireless channels. The so called hidden terminal problem makes the problem even worse, possibly yielding undesired interference to the primary users. Recently, cooperative spectrum sensing is emerging as a remedy to these problems of individual sensing. Cooperative sensing allows a group of secondary users to share local sensing information to extract a global decision with high fidelity. In this paper, we investigate a cooperative spectrum sensing algorithm based on hard decisions of local sensing outcomes. Specifically, we propose an effective scheme for combining local decisions by introducing weighting factors that reflect reliability of the corresponding secondary user. Through computer simulations, the performance of the proposed combining scheme is compared with that of the conventional scheme without weighting factors in various environments.

OFDM 시스템을 위한 효율적인 디지털 구현 알고리즘

신요안,김만제 崇實大學校 生産技術硏究所 1997 論文集 Vol.27 No.1

본 논문에서는 IFFT(inverse fast Fourier transform)와 FFT(fast Fourier transform)를 이용하여 변조 및 복조를 수행하는 OFDM(orthogonal frequency division multiplexing)시스템에서 BPSK(binary phase shift keying)변조방식을 사용할 경우데 대하여 OFDM과 동일한 비트오율(bit error ratio)성능을 갖고, 계산량과 대역폭을 줄이는 IFFT/FFT 기반의 새로운 디지털 구현 알고리듬과 제안된 알고리듬에 적용되는 등화기 구조를 제안한다. 제안된 방법의 성능은 저속 시변 주파수 선택적 페이딩(slowly time-varing frequency selective fading)및 부가성 백색 Gaussian 잡음 (additive white Gaussian noise) 채널 하에서 안테나 diversity 와 각각의 branch에 등화기를 이용하여 MRC(maximal ratio combiner)로 수신했을 경우에 대하여 모의 실험을 통해 확인하였다.

점진 형성형 고차 신경회로망을 이용한 수동 해저 소나 신호의 분류

신요안 崇實大學校 生産技術硏究所 1995 論文集 Vol.25 No.1

In this paper, an incrementally constructive higher-order feedforward neural network algorithm called the ridge polynomial network, is exploited for the classification of passive oceanic sonar signals from natural sources. For the experiments, Gabor wavelet coefficients and other time and frequency information are used for the input features, and some multi-layered perceptron based algorithms are also used for the comparison as classifiers. The performance of the classifiers is measured in terms of classification accuracy in the case of zero rejection and computational complexity for the training of neural networks. The simulation results show that all the neural networks used exhibit good classification performance for a moderate-size test data set,however,the ridge polynomial network's incrementally constructive learning algorithm requires much less computational complexity.

Performance of TTCM Multicode-CDMA Systems over Nonlinear Multipath Fading Channel

Younsik KIM,Yoan Shin 대한전자공학회 2005 ITC-CSCC :International Technical Conference on Ci Vol.2005 No.2

멀티코드 CDMA 방식을 이용한 전력성 통신 시스템

나성주,신요안 崇實大學校 1999 論文集 Vol.29 No.1

전력선은 백색 가우시안 배경 잡음뿐 아니라 임펄스 잡음, 고조파 잡음 등의 비 가우시안 잡음들로 인해 통신 채널로서 열악한 전송 특성을 나타낸다. 또한 좁은 가용 대역폭으로 인해, 광대역 특성이 요구되는 DS-CDMA 방식과 같은 대역 확산 시스템의 적용에 한계가 있다. 본 연구에서는 차세대 고속 이동 통신을 위한 다원접속/변조방식인 멀티코드 (multi-code) CDMA 방식과 이에 길쌈 부호와 인터리빙 등의 부호화 기능을 더한 시스템을 전력선 통신 시스템에 적용하고, 모의실험을 통해 전력선 채널의 비 가우시안 잡음의 영향을 매우 효과적으로 보상할 수 있음을 확인하였다.

Adaptive SLM Scheme Based on Peak Observation for PAPR Reduction of OFDM Signals

Suckchel Yang,Yoan Shin 대한전자공학회 2006 ITC-CSCC :International Technical Conference on Ci Vol.2006 No.2

A Self-Supervised Method Based on Noise2Noise Model for SAR Image Despeckling

Chushi Yu,Yoan Shin 한국통신학회 2021 한국통신학회 학술대회논문집 Vol.2021 No.6

Synthetic aperture radar (SAR) imaging plays an important role in recent earth observation research, which is a form of radar imaging technology that collects information with a high spatial resolution even in adverse weather and lighting conditions. Different from optical images, SAR images are contaminated by speckle noises and the presence of speckle noises in SAR images makes it difficult to understand and be widely applied. A self-supervised speckle denoising model is proposed in this paper based on the Noise2Noise model. The experimental results show that the proposed method can preserve details and reduce smoothing not only in speckle noise multiplicative domain but also additive domain. The tentative study demonstrates the potential of SAR images despeckling without clean data.

Effect of Spectrum Sensing Reliability on the Capacity of Multiuser Uplink Cognitive Radio Systems

Junsu Kim,Yoan Shin,Tae Won Ban,Schober, R. IEEE 2011 IEEE Transactions on Vehicular Technology VT Vol.60 No.9

<P>In this paper, we investigate the performance of opportunistic scheduling in uplink cognitive radio (CR) systems by taking into account the CR users' spectrum sensing reliability. In uplink CR systems, each secondary transmitter (CR user) has a spectrum sensing responsibility to protect the primary system, and the secondary receiver (base station) schedules the transmission opportunities for the CR users. We propose novel optimal and suboptimal scheduling schemes by simultaneously taking into account the spectrum sensing reliability and the data channel quality. Analytical performance results for the proposed suboptimal scheduling schemes show that the spectrum sensing reliability should be considered for scheduling to maximize the capacity of the secondary system. Moreover, we also analyze the achievable multiuser diversity (MUD) gain of one of the proposed suboptimal scheduling schemes, which is based on the linear combination of the sensing channel and the data channel qualities. We show that the MUD gain of uplink CR systems grows significantly slower than that of conventional multiuser systems, particularly if the quality of the sensing channel is poor. Analytical and simulation results confirm that the proposed optimal and suboptimal scheduling schemes taking into account the spectrum sensing reliability and the data channel quality yield significant performance gains compared with conventional opportunistic scheduling.</P>

Maximum Signal-to-Interference Ratio for Receivers Communicating with Multiple Transmission Sources

KIM, Jaewon,SHIN, Yoan,SUNG, Wonjin The Institute of Electronics, Information and Comm 2009 IEICE transactions on fundamentals of electronics, Vol.92 No.2

<P>In this letter, we present an exact analytic expression for the maximum signal-to-interference ratio (SIR) for receivers communicating with multiple transmitting nodes over a general time-varying channel, where one of the nodes is chosen as a desired signal source based on the instantaneous channel condition and the other nodes act as interference sources. As an illustrative example, the maximum SIR distribution of a mobile receiver surrounded by three base stations (BS) is determined in a closed-form formula for Rayleigh fading channels, and its accuracy is confirmed using simulation results.</P>