• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.11
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• pp.955-966
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• 2013

We propose two feedback interference cancellers(FICs) to improve the performance of the equalization digital on-channel repeater(EDOCR) with the FIC for the ATSC DTV broadcasting system. The FIC estimates the feedback channel between Tx. and Rx. antennas of the repeater by cross-correlating the reference signal and the feedback signal. Since there is a DC pilot which ruins the white property of the ATSC DTV signals, the FIC cannot estimate the feedback channel accurately. To solve the problem, the structural method which uses an additional DC pilot free reference for feedback channel estimation and the algorithmic method based on the digital signal processing which whitens the ATSC DTV signals and performs the feedback cancellation in the whitened signal domain. Simulation results show that the proposed two FICs show better feedback cancellation performance than the conventional FIC.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.6 no.3
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• pp.55-67
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• 1995

The error rate equations of MPSK and DS/MPSK radio signals transmitted through the m-distributed fading channel in Gaussian noise and tone interference environments have been derived. Using the derived equations, the error rate performance is evaluated and shown as functions of carrier-to-noise ratio, carrier-to-interference ratio, processing gain, fading index and the number of diversity branches. The derivation has been done for two cases. The first case assumes that only the signal is undergoing the influence of fading, and the second case assumes that both signal and interference are undergoing the influence of fading simultaneously. From the obtained results, we have known that the error performance of MPSK signal is improved by using diversity technique and direct sequence spread spectrum technique even in a fading environment. Also comparing the error rate performance of two cases, the latter is worse than the former.

• Journal of Sensor Science and Technology
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• v.32 no.6
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• pp.340-351
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• 2023

Wearable sensors designed for strain, pressure, and temperature measurements are essential for monitoring human movements, health status, physiological data, and responses to external stimuli. Notably, recent research has led to the development of high-performance wearable sensors using innovative materials and device structures that exhibit ultra-high sensitivity compared with their commercial counterparts. However, the quest for accurate sensing has identified a critical challenge. Specifically, the mechanical flexibility of the substrates in wearable sensors can introduce interference signals, particularly when subjected to varying external stimuli and environmental conditions, potentially resulting in signal crosstalk and compromised data fidelity. Consequently, the pursuit of non-interference sensing technology is pivotal for enabling independent measurements of concurrent input signals related to strain, pressure, and temperature, ensuring precise signal acquisition. In this comprehensive review, we present an overview of the recent advances in noninterference sensing strategies. We explore various fabrication methods for sensing strain, pressure, and temperature, emphasizing the use of hybrid composite materials with distinct mechanical properties. This review contributes to the understanding of critical developments in wearable sensor technology that are vital for their ongoing application and evolution in numerous fields.

• Journal of Industrial Technology
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• v.24 no.A
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• pp.127-131
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• 2004

In this paper, we proposed an optical balance using a Michelson Interferometer structure. The frequency of the interference signal is changed nonlinearly related with a weight to be measured, and this frequency change is processed by a processor to give a measured weight. Several measurements were performed and the good results were obtained with the fluctuation of about 1g.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.6 no.4
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• pp.262-266
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• 2013

In OFDM system, cyclic prefix (CP) is used to eliminate the inersymbol interference that is caused by the channel dispersion. However, a long CP reduces the data transmission rate. An alternative to a logn CP is the a time domain channel shortening filter at the receiver that shortens the effective channel, thus a short CP is used in spite of a long channel impulse response. In the paper, we compare a various channel shortening techniques; minimum shortened signal to noise ratio (MSSNR), minimum interblock interference (min-IBI), and minimum ISI (min-ISI).

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.37 no.2
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• pp.60-67
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• 2000

When the eigenvalues of the input covariance matrix of an array system spread by orders of magnitude, conventional adaptive arrays can't remove all the interference signals effectively In this paper, an Applebaum array adopting an adaptive gain controller (AGC) in the feedback loop of the array is proposed When eigenvalue spreaded interferences are incident to an array, a high power interference is removed easily in several iterations while a relative low power interference which is a cause of eigenvalue spread is still remained In the array output After some initial iterations, the proposed array increases the correlation between the low power interference and the array output by amplifying the output signal of the array As a result, the weights vector adapts to the direction of the low power interference as well as that of the high power interference Computer simulation results show that the proposed array gives high output signal to interference plus noise ratio (SINR) and a fast convergence speed.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.2
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• pp.99-104
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• 2015

This paper proposes the RMMA (Region based Multiple Modulus Algorithm) algorithm that is possible to improving the performance of MMA adaptive equalization algorithm in order to the reduction of intersymbol interference occurs at the communication channel. In RMMA algorithm, the output constellation of equalizer are divided by 4 different regions in order to get the error signal for adapting the channel characteristic, and the small error signal is obtained by mapping each region to 4-QAM signal. The conversion effect of constant modulus from nonconstant modulus signal was obtained. In this paper, the adaptive equalization performance of proposed RMMA were evaluated comared to the present MMA. As a result of computer simulation, the convergence speed and residual quantity were improved in residual isi and MD. Especially the superiorities of robustness was confirm in SER performance compared to present MMA.

• Journal of Communications and Networks
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• v.16 no.3
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• pp.280-292
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• 2014

This article presents a novel cooperative spectrum sharing (CSS) scheme. The primary transmitter transmits a complex Quadrature amplitude modulation (QAM) signal in the first phase, and CSS occurs in the second phase. The secondary transmitter with the largest forwarding channel gain among the nodes that successfully decode the primary signal in the first phase is selected for CSS. This selected node employs a pulse-amplitude modulation (PAM) signal for primary information message (IM) instead of the QAM signal, and it employs a modified PAM signal for the secondary IM. The proposed modified PAM signal depends on the amplitude of the primary PAM signal. This method results in no mutual interference and negligible primary interference constraint and allows a higher degree of exploitation of spatial diversity, thus enabling increase in secondary power to improve primary transmission. The outage performance is enhanced in both the primary and secondary systems. The critical region, in which the primary outage performance is enhanced with the proposed CSS scheme, can be adjusted and widened by varying either the modulation cooperation sharing factor or the number of secondary transmitters.

• Korean Journal of Materials Research
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• v.17 no.5
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• pp.239-243
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• 2007

The evaluation and comparison have been made for the EMI noise which was included in the signal from the sensors in the acoustic emission testing for the bottom plate of ground tank at full. The EMI signal has been classified into two types. One is the signal with very short AE count, and this signal possibly can be filtered by front end filter setting of the channel count with low level of 4 and high level of $10^8$. The other EMI signal occurred from CH 1, CH 3 and CH 10, and had high and constant duration with high energy and count (maximun duration > $10^5\;{\mu}s$), and has characteristic gradient of accumulation amplitude distribution. This signal should be removed in the AE signal evaluation by filtering, because this may affect to the total gradient.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1206-1210
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• 2005

This paper presents performance improvement in optical CDMA system under the presence of beat noise using a cancellation technique. Optical fibers and atmospheric optical communications have been proposed the connection between base stations and central station. The optical signal beat noise is due to interference between lightwave, many optical waves are simultaneously incident on each receiver photodiode. Since the photodiode acts as a square-law detector, beat noise can occur in the receiver. While A two-stage cancellation technique is analyzed and verified via simulation employed here because of its system simplicity. By using the random ingredients of all user signals are estimated, the beat noise is rebuilt and removed from the intended signal. In addition to cancellation technique cancel the inherent multiuser interference (MUI) in CDMA system and nonlinear distortion (NLD) in optical system. It is performed at the receiver of the central station where the random ingredients of all user signals are estimated and the MUI and the NLD are rebuilt and removed from the received signal. The validity of the cancellation technique is theoretically analyzed and shown by numerical results. The increasing of capacity in two stage cancellation are obtained.