• Journal of Advanced Navigation Technology
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• v.6 no.1
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• pp.17-26
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• 2002

In this paper, we have analyzed the BER (Bit Error Rate) performance of multi-user detectors employing SIC(Successive Interference Cancellation) and PIC (Parallel Interference Cancellation) which are the representative schemes in the subtractive interference cancellation. We have considered the MUD structure employing HIC (Hybrid Interference Cancellation) which combines SIC with PIC scheme, and then analyzed the BER performance. We have evaluated the BER performance of SIC and HIC schemes which execute the soft decision to generate the tentative data bit for the purpose of the interference cancellation in MAI and noise environments. Through the numerical analysis and computer simulation, it is shown that HIC can remove the effect of MAI more efficiently than the others, that improve the BER performance and increase the capacity of DS-CDMA systems regardless of the power control conditions. The reason is that the SIC scheme in front of HIC can solve the near-far problem caused by the imperfect power control and PIC scheme in the rear of it can improve the performance much more.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.12
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• pp.45-51
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• 2011

This paper presents a wideband low-noise amplifier (LNA) covering 800MHz~5.8GHz for various wireless communication standards by utilizing in a 0.13um CMOS technology. Particularly, the LNA consists of two stages to improve the low-noise characteristics, that is, a cascode input stage and an output buffer with noise cancellation technique. Also, a feedback resistor is exploited to help achieve wideband impedance matching and wide bandwidth. Measure results demonstrate the bandwidth of 811MHz~5.8GHz, the maximum gain of 11.7dB within the bandwidth, the noise figure of 2.58~5.11dB. The chip occupies the area of $0.7{\times}0.9mm^2$, including pads. DC measurements reveal the power consumption of 12mW from a single 1.2V supply.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.1183-1186
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• 1998

Adaptive nois canceller can extract the noiseremoved spech in noisy speech signal by adapting the filter-coefficients to the background noise environment. A kind of LMS algorithm is one of the most popular adaptive algorithm for noise cancellation due to low complexity, good numerical property and the merit of easy implementation. However there is the matter of increasing misadjustment at voiced speech signal. Therefore the demanded speech signal may be extracted. In this paper, we propose a fast and noise robust wavelet packet adaptive noise canceller with NLMS-SUM method LMS combined algorithm. That is, we decompose the frequency of noisy speech signal at the base of the proposed analysis tree structure. NLMS algorithm in low frequency band can efficiently dliminate the effect of the low frequency noise and SUM method LMS algorithm at each high frequency band can remove the high frequency nosie. The proposed wavelet packet adaptive noise canceller is enhanced the more in SNR and according to Itakura-Satio(IS) distance, it is closer to the clean speech signal than any other previous adaptive noise canceller.

• Journal of KSNVE
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• v.11 no.3
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• pp.422-427
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• 2001

In this paper is presented passive-active noise control in a duct using a ring-type smart foam. The ring-type smart foam is comprised of a PVDF film embedded in elastic noise control foam of lining shape. The embeddedPVDF element acts as an actuator to reduce noise at lower frequencies and the foam absorbs noise at higher frequencies. By implementing an adaptive filtered-x LMS algorithm, experiments are performed to reduce both tonal and broadband noise in a duct with one end closed and the other end open.

• The Journal of the Acoustical Society of Korea
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• v.19 no.8
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• pp.26-34
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• 2000

This paper presents a new adaptive impulse noise cancelling technique based on the adaptive nonlinear suppressing function. The proposed "adaptive threshold algorithm (ATA)" is controlled by the normalized power prior input data term, and this adaptive threshold makes the cancelling system highly robust against additive impulse noise. For the performance evaluation, we have tested the proposed algorithm with the observed signals simulated in various impulsive noise environments and real EMG signals. As a result the proposed algorithm shows superior performance of 51.7% to the available techniques in the points of SNR and MSE.

• Journal of KSNVE
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• v.2 no.2
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• pp.107-116
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• 1992

An adaptive signal processing technique is implemented for the active noise cancellation of the plane acoustic wave propagating in a duct. To avoid the instability caused by the acoustic feedback from the control speaker to the detect microphone, an off-line modeling of the acoustic feedback plant is done using the FIR filter. Auxiliary path required for the filtered-x LMS algorithm is modeled as well. Before going into the experiments, a simulation is carried out under the same conditions with experiments. The simulation shows that the longer the length of the adaptive filter is, the better the results are achieved. Experiments have been carried out at lower audio frequency range (50 - 400Hz), and the results are in good agreements with those of simulation study. As a results of this adaptive noise control, around 50dB is reduced for a pure tone noise, and for a bandlimited noise with the bandwidth of 316Hz, a maximum of 30dB noise reduction is attained.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.1
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• pp.83-90
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• 2019

LED lighting is spreading on the strength of LED lighting, and various government policies are being implemented. VLC research which is a wireless communication technology using lighting has been actively conducted, and it has been proven through many studies that a general LED light source such as a high-speed data transmitter can be used. But from now on, one of the main problems is the noise from side lights, which can be compared to the noise of radio broadcasts. So in this paper, we proposed a noise canceling model to remove the interference of ambient light by using an optical filter for a detachable VLC channel. In order to verify the proposed model, various high brightness RGB LED modules were used for comparative analysis. In addition, the applicability was verified through experiments using High Luminance LED lighting which is applied in real life.

• Proceedings of the KSPS conference
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• 2003.10a
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• pp.105-108
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• 2003

본 논문은 잡음 환경에서의 음성인식을 위하여 음성에 부가된 잡음을 제거하는 방법으로 프레임 단위로 웨이브렛 변환 영역의 표준편차를 활용하여 시간 적응적 임계값을 사용하는 새로운 방법을 제안한다. 웨이브렛 변환영역의 cD1과 cA3의 표준편차 값을 이용하여 임계값을 설정함으로써 음성의 변화에 적응할 수 있도록 하였다. 또한 묵음구간의 잔여 잡음을 제거하기 위한 방법을 제안하였다. 실험을 통하여 제안한 방법이 기존의 웨이브렛 변환과 웨이브렛 패킷 변환을 이용한 잡음제거 방법보다 SNR(Signal to Noise Ratio)과 MSE(Mean Squared Error) 측면에서 향상됨을 확인할 수 있었다.

• The Journal of the Acoustical Society of Korea
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• v.15 no.1E
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• pp.84-88
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• 1996

In this paper, we propose a novel adaptive digital filter for tonal noise cancellation, with a frequency tracking capability. The proposed algorithm not only estimates the magnitude and phase of the tonal disturbance but also tracks its frequency, which changes in quasi-static manner. The algorithm uses the steepest descent method and the instantaneous frequency approach for the phase/magnitude estimation and frequency tracking, respectively. A number of computer simulations have been carried out in order to demonstrate the feasibility of the proposed ANC algorithm under various conditions.

• The Journal of the Acoustical Society of Korea
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• v.15 no.3E
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• pp.45-59
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• 1996

Generalized iterative methods for reducing noise in contaminated chaotic signals are proposed. These methods minimize a cost function composed of two parts : one containing information that represents how close enhanced signals are to the observed signal and another composed of constraints that fit the dynamics of the system. The convergence conditions and the error systems of the proposed are investigated. As one aspect of noise reduction, the suppression or cancellation of a chaotic interference signal is discussed.