• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.6B
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• pp.767-775
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• 2001

본 논문에서는 비터비 검출기의 복잡도와 전력소모를 감소시킬 수 있는 폴딩 비터비 검출기를 제안하였다. 제안된 폴딩 비터비 검출기는 상태 천이도가 대칭적인 것을 이용하여 상태는 서로 반전된 값을 갖는 것끼리 묶어지며, 확률거리의 경우 서로 부호가 반대인 값끼리 묶여진다. 제안된 폴딩 비터비 검출기를 EPRML 읽기 채널에 적용할 경우 확률거리 계산에 필요한 두 개의 가산기를 하나의 가감산기로 대체하여 기존의 GVA 알고리즘에 비해 하드웨어 복잡도를 37.4% 감소시킬 수 있었다. 또한 불필요한 전력소모의 원인이 되는 글리치 발생을 신호 재배치와 병렬 구조와 같은 상위 수준의 저전력 기법을 적용하여 억제한 결과 12.7%의 전력소모 감소를 나타내었다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1997.11a
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• pp.9-13
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• 1997

본 논문에서는 two-ray 시간선택성 레일레이 페이딩 채널상에서 DPSK 신호를 차동검출 (differential detection)할 때 심볼에러율을 분석한다. 현재까지 수행된 많은 연구는 주파수 선택성 페이딩 채널 및 단일 경로 시간선택성 페이딩 채널을 대상으로 하였고, 다경로 시간선택성 페이딩 채널을 대상으로 한 예는 극히 드물다. 또한 다경로 시간선택성 페이딩 채널을 가장 간단히 모델링 할 수 있는 two-ray 페이딩 채널에 대한 연구도 지금까지 수행된 예가 극히 적다. 본 논문에서는 심볼열의 형태에 따라 수신신호들간의 관계를 세가지 그룹으로 나눈 후 각각의 경우에 대하여 위상 옵셋값을 계산하는 방식을 취하였다. 이와 같이 계산된 위상옵셋과 신호대 잡음비를 인자로 하여 차동검출된 신호가 가지는 위상의 확률밀도 함수를 계산하고 이 함수를 이용하여 심볼에러율을 계산하였다. 결과로부터 two-ray 페이딩 채널의 특성을 결정짓는 지연시간과 지연신호의 전력이 증가함에 따라 위상 옵셋값 및 에러율이 모두 증가하는 것을 확인하였다.

• Journal of Broadcast Engineering
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• v.19 no.6
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• pp.967-970
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• 2014

An efficient peak detection algorithm in magnitude spectrum is proposed to distinguish the M-frequency shift keying(FSK) signals from other digitally modulated signal. In addition, recognition of the modulation order estimation of FSK signals is also studied based on the fact that the magnitude spectrum of FSK signals reveals the number of peaks equal to the modulation order. When no a priori information about the signals, we utilize the histogram of the magnitude spectrum to determine the threshold which is important factor in peak detection algorithm. The simulation results show high probability of classification under 500 symbols and signal-to-noise ratio(SNR) higher than 4dB.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.8 s.338
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• pp.33-40
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• 2005

This paper presents a structure of the searcher using a diversity in array antenna systems operating in the cdma2000 1x signal environments. The new technique exploits the fact that the In-phase and quadrature components of interferers can respectively be viewed as an independent gaussian noise at each antnna element in most practical cdma signal environments. The proposed PN acquisition scheme is a singles-dwell PN acquisition system consisting of two stages, that is, the searching stage and the verification stage. The searching stage independently correlates the receiver multiple signals with PN generator of each antenna element for obtaining the synchronous energy at the entire region. Then, the searching results of each antenna element are non-coherently combinind. The verification stage compares the searching energy with the optimal threshold, which is predesigned in the lock detector, and decides whether the acquisition is successful or fail. In this paper, we analyzed the effect of tile diversity order to determine the mean acquisition time. In general, it is known that the mean acquisition time significantly decrease as the number of antenna elements increases. But, as the diversity order goes up, the enhancement of the performance is saturated. Therefore, to decrease the mean acquisition time of the searcher, we must design the optimal array antenna systems by considering the operating SNR range of the receiver, the probability of detection $P_D$ and that of false alarm $P_{FA}$ . The Performance of the proposed PN acquisition scheme is analyzed in frequency selective Rayleigh fading channels. In this paper, the effect of the number of antenna elements on PN acquisition scheme is shown according to the probability of detection $P_D$ and that of false alarm $P_{FA}$.

• Proceedings of the Korea Information Processing Society Conference
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• 2016.04a
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• pp.887-889
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• 2016

본 연구는 전도성 섬유를 양말에 부착하여 발바닥에서 심전도(ECG, Electrocardiogram) 신호를 검출하였다. 발바닥에서 측정한 심전도 신호와 손목에서 측정한 심전도 신호에 Pan-Tompkins algorithm을 적용하였고 R-R interval을 검출하였다. 이후 발바닥과 손목에서 측정된 심전도의 유의성을 검출하기 위해 비모수 검정법인 Spearman검정을 사용하여 상관분석을 수행하였다. 상관분석 결과, 유의확률 p=0.00에서 correlation coefficient=0.901로 두 데이터는 강한 양의 선형 관계에 있는 것으로 나타났다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.2
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• pp.55-61
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• 2007

In this paper, we represent the maximum detection probability formulas of symbol synchronization timing at each received delay signal in multipath channel delay profile in the multiplied correlation and difference type correlated symbol synchronization timing detection method. The computer simulation results show that the correlation symbol timing detection method have maximum detection probability at the lead of received delay signal of highest amplitude, but the difference type of correlation symbol timing detection method always have maximum detection probability at the lead of first received delay signal in the multipath channel models. Using this results, we show the BER characteristics difference between the IEEE802.11a OFDM signals which is obtained in case of the symbol synchronization timing is taken at zero error(perfect) timing position and at -1 sample error symbol timing position from perfect timing position in the multipath channel models regardless the length of channel delay spread.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.6
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• pp.87-92
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• 2013

This paper focuses on analyzing the effects of primary user (PU) signal arrival on the local spectrum sensing performance. The probability for signal arrival at a sample in the sensing time is uniformly distributed in the sensing time. We first analyze the main factor that causes the degradation in the detection results in the conventional energy detection (CED) under the uniformly random arrival of the PU-signal. Thus we propose an approach in order to enhance the detection performance, in which an estimator which detects the arrival of the PU signal cooperates with a composite energy detection. The mathematical analysis and numerical simulation has validated the outperformance of the proposed approach compared to the CED.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.49 no.1
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• pp.97-103
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• 2012

In this paper, we propose a novel voice activity detection (VAD) algorithm to effectively distinguish speech from nonspeech in various noisy environments. Global speech absence probability (GSAP) derived from likelihood ratio (LR) based on the statistical model is widely used as the feature parameter for VAD. However, the feature parameter based on conventional GSAP is not sufficient to distinguish speech from noise at low SNRs (signal-to-noise ratios). The presented VAD algorithm utilizes GSAP based on Teager energy (TE) as the feature parameter to provide the improved performance of decision for speech segments in noisy environment. Performances of the proposed VAD algorithm are evaluated by objective test under various environments and better results compared with the conventional methods are obtained.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.8 no.3
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• pp.145-150
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• 2014

In this paper, we propose a novel scheme to improve the performance of a voice activity detection(VAD) which is based on the deep belief networks(DBN) with the likelihood ratio(LR). The proposed algorithm applies the DBN learning method which is trained in order to minimize the probability of detection error instead of the conventional decision rule using geometric mean. Experimental results show that the proposed algorithm yields better results compared to the conventional VAD algorithm in various noise environments.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.7 no.6
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• pp.101-109
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• 2008

In this paper, we introduce clustering scheme to calculate probability of detection which is practically required for conventional weighted-collaborative sensing technique. We also propose an improved weighted-collaborative spectrum sensing scheme using new weight generation algorithm to achieve better performance in Cognitive Radio systems. We calculate Pd in each cluster which is a CR users group with similar channel situation. New weight factor is generated using square sum of all cluster's Pds. Simulations under slow fading show that we can get better total detection probability and lower false alarm rate when PU (Primary User) suddenly terminates their transmission.