• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.11C
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• pp.1518-1526
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• 2004

In this paper, an algorithm using wavelet transform for detecting a cut that is a radical scene transition point, and fade and dissolve that are gradual scene transition points is proposed. The conventional methods using wavelet transform for this purpose is using features in both spatial and frequency domain. But in the proposed algorithm, the color space of an input image is converted to YUV and then luminance component Y is transformed in frequency domain using 2-level lifting. Then, the histogram of only low frequency subband that may contain some spatial domain features is compared with the previous one. Edges obtained from other higher bands can be divided into global, semi-global and local regions and the histogram of each edge region is compared. The experimental results show the performance improvement of about 17% in recall and 18% in precision and also show a good performance in fade and dissolve detection.

• Proceedings of the KIEE Conference
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• 1999.07g
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• pp.3218-3220
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• 1999

본 논문에서는 Local Multipoint Distribution Service(LMDS) 시스템을 위한 결정궤솬 적응 등화기를 웨이블릿 변환영역 적응 알고리즘을 이용하여 설계하였다. 아울러, 제시된 결정 궤환 등화기를 16-QAM/QPSK 변조 방식을 이용한 Rummler 채널 모델을 사용하여 성능을 검증하였다. LMDS 채널 및 시스템 특성에 적합한 수치적 복잡성과 수렴 속도를 얻을 수 있었다.

• The Journal of the Acoustical Society of Korea
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• v.12 no.1E
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• pp.5-11
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• 1993

본 논문에서는 페이딩 채널에서 백색 가우시안 잡음과 임펄스성 잡음이 부가된 디지털 신호를 복원하기 위하여 적응 LMS알고리즘과 RLS 알고리즘을 사용하여 TDL 등화기, 결정 궤환 등화기, 그리고 격자 등화기의 성능을 평가하고 비교하였다. 오차 성능 분석 결과, 페이딩이 존재하고 임펄스성과 가우스성 잡음이 존재하는 채널에서 10-3BER을 얻기 위해서, 격자 등화기는 LMS이 등화기보다 3.0dB, RLS TDL 등화기보다 3.9dB의 신호대 잡음비(SNR)여유를, 그리고 LMS DFE 등화기보다 0.5dB, RLS DFE등화기보다 -0.5dB의 SNR 여유를 갖음을 확인하였다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1997.11a
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• pp.15-18
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• 1997

OFDM(Orthogonal Frequency Division Multiplexing) 시스템은 여러 개의 부채널을 사용함으로써 다중 경로에 강한 성능을 보인다. 하지만 인접 심볼 사이에 보호구간 사용으로 인하여 전송 효율상의 손실을 보게 된다. 본 논문에서는 BER 성능이 유지될 수 있는 상태에서 보호구간을 줄일 수 있는 방안을 제안하고자 한다. 제안된 방법은 일반적으로 사용되는 주파수 영역의 등화와 병행하여 시간 영역 등화기를 사용하여 전송 효율을 향상시킨다. 시간 영역 등화기로는 신경망 결정 궤환 등화기를 적용하여 BER 성능이 유지될 수 있는 상태에서 보호구간을 최고 30%를 줄일 수 있음과 동시에 충분한 보호구간을 사용하는 경우에도 시간 영역 등화기를 사용하지 않는 경우보다 나은 BER 성능을 나타냄을 보인다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.7A
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• pp.755-761
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• 2007

In this paper the uplink single carrier scheme is proposed for wireless Internet application and its performance is evaluated in terms of PAPR (peak to average power ratio) and ABR (achievable bit rate) compared with the uplink OFDM scheme. There exist constraints regarding the signal amplification because the non-linear amplifier should be exploited instead of the linear amplifier due to its high cost of linear amplifier and power inefficiency at the WiBro terminal. Therefore characteristics in the uplink scheme design are discussed in order to maximize ABR and relieve the requirements for the amplifier specifications.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.9
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• pp.2094-2100
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• 2014

The performance of underwater acoustic communication system is sensitive to the inter-symbol interference due to delay spread develop of multipath signal propagation. Thus, it is necessary technique of equalizer and channel code to eliminate inter-symbol interference. In this paper, underwater acoustic communication system were analyzed by experiment using these techniques on the Kyeong-chun lake, Munkyeong City. Based on the results of experiment, we confirmed that the performance of the proposed iterative BCJR equalization method is improved by increasing the number of iterations.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.1
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• pp.123-132
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• 1999

In this paper, a quadratic sigmoid neural equalizer(QSNE) is proposed to improve the performance of conventional neural equalizer in terms of bit error probability by using a quadratic sigmoid function as the activation function of neural networks. Conventional neural equalizers which have been used to compensate for nonlinear distortions adopt the sigmoid function. In the case of sigmoid neural equalizer, each neuron has one linear decision boundary. So many neurons are required when the neural equalizer has to separate complicated structure. But in case of the proposed QSNF and quadratic sigmoid neural decision feedback equalizer(QSNDFE), each neuron separates decision region with two parallel lines. Therefore, QSNE and QSNDFE have better performance and simpler structure than the conventional neural equalizers in terms of bit error probability. When the proposed QSNDFE is applied to communication systems and digital magnetic recording systems, it is an improvement of approximately 1.5dB~8.3dB in signal to moise ratio(SNR) over the conventional decision feedback equalizer(DEF) and neural decision feedback equalizer(NDFE). As intersymbol interference(ISI) and nonlinear distortions become severer, QSNDFE shows astounding SNR shows astounding SNR performance gain over the conventional equalizers in the same bit error probability.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2013.11a
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• pp.105-107
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• 2013

단일 반송파 시스템은 다중경로를 가지는 무선채널을 통과할 때 심볼 간 간섭(Inter-symbol Interference, ISI)에 의한 영향을 크게 받으며 이를 보상하기 위한 등화방식은 그동안 많이 연구되어왔다. 본 논문에서는 단일 반송파 시스템에서 심볼 간 간섭의 영향을 보상하기 위해서 잡음 예측기와 결합된 이중 피드백 구조의 등화 방식을 제안한다. 또한, 제안된 등화 방식이 기존 반복 결정 궤환 등화기에 비해 향상된 성능을 가지는 것을 이론적 분석과 모의실험을 통해서 분석한다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.1
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• pp.38-46
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• 2012

In this paper, we propose a decision feedback equalizer based on LDPC(Low Density Parity Check) code for the fast processing and performance improvement in OFDM system. LDPC code has good error correcting capability and its performance approaches the Shannon capacity limit. However, it has longer parity check matrix and needs more iteration numbers. In our proposed system, MSE(Mean Square Error) of signal between decision device and decoder is fed back to equalizer. This proposed system can improve BER performance because it corrects estimated channel response more accurately. In addition, the proposed system can reduce complexity because it has a lower number of iterations than system without feedback at the same performance. Simulation results evaluate and show the performance of OFDM system with the CFO and phase noise in multipath channel.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.5
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• pp.2390-2395
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• 2011

For intersymbol interference (ISI) compensation from communication channels with multi-path fading and impulsive noise, a decision feedback equalizer algorithm that minimizes Euclidean distance of error probability is proposed. The Euclidean distance of error probability is defined as the quadratic distance between the probability error signal and Dirac-delta function. By minimizing the distance with respect to equalizer weight based on decision feedback structures, the proposed decision feedback algorithm has shown to have significant effect of residual ISI cancellation on severe multipath channels as well as robustness against impulsive noise.