• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.549-551
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• 2002

A Wireless Local Area Network (WLAN) is a flexible data communication system implemented as an extension to, or as an alternative for, a wired LAN with in a building or campus. However, communications in an indoor environment present problems not encountered in outdoor wireless communication systems. Since cellular type systems are interference limited, the indoor environment is more hostile than the outdoor environment due to the lower propagation constant. In this paper, the equation for the signal to interference ratio in a multistory building will be derived. Knowing the S/I ratio, the floor frequency reuse can be determined. Finally, the simulation in this research is designed to study the performance (BER) of WLAN system in the multistory environment by applying the 8-PSK Trellis Coded modulation technique. The procedure allows a quick evaluation of BER in Wireless LAN system due to the co-channel interference.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.6 no.2
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• pp.159-164
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• 2005

When an optical pulse propagates through the atmospheric channel, the atmospheric turbulence attenuates and spreads this pulse. This attenuation and broadening of pulse are occurred by the fluctuation in the arrival time of pulse at the optical receiver. This pulse broadening induces the intersymbol interference (ISI) between the adjacent pulses. finally, the adjacent pulses are overlapped and the bit rate and the repeaterless transmission length are limited by the ISI. In digital communication system, therefore, the pulse broadening is more important factor than the attenuation. In this paper, thus, we find the ISI in the atmospheric turbulence as the function of the structure constant for the refractive index fluctuation that presents the strength of turbulence using the temporal momentum function and present it by numerical analysis.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.6 no.3
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• pp.24-35
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• 1995

In this paper, we study the Spectrum Use Measure(SUM) model for quantifying the extent of spectrum use by existing radio communication systems. This model calculates the interference level between transmitters and receivers by applying the EMC analysis technique of interference prediction process such as antenna radiation pattern model and propagation model which are well known. While several previous works have described the spectrum resources by constructing the interference contours around existing radio systems, the SUM technique is developed for quantifying and portraying the spectrum resources used by radio communication systems in a geographic area. Computer simula- tion results are illustrated to verify the calculations for the Spectrum Use Bandwidth(SUB) and Spectrum Use Factor (SUF) performed by the SUM model and find the usefulness of the SUM model.

• Journal of Advanced Navigation Technology
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• v.20 no.1
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• pp.45-52
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• 2016

In this paper, the method of interference analysis and its simulation have been suggested for the frequency sharing between aeronautical radio navigation systems and Link-16 platforms. In order to get the criteria for interoperability, the algorithm of interference analysis and protection ratio are derived to assure frequency sharing. Also the receiving power of wireless system has been illustrated with the help of radio propagation model of ITU-R Rec. P.1546 in VHF-UHF band. Finally the required receiving power or separation distance between DME/TACAN beacons and Link-16 ground station terminals has been considered based on system link budget in terms of evaluating interoperability as well as actual applications. As a result, if the suggested interference analysis and test set-up are applied to the field trial, it will lead to easy means to make a decision on interoperability over the existing incumbent systems.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.6
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• pp.41-49
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• 2017

Theoretical modelling and computational results for frequency coordination are presented over mobile base station and fixed wireless systems in urban or sub-urban area. Computational results with key parameters needed for interference analysis are performed and discussed in terms of system characteristics, propagation model, protection ratio, frequency dependent rejection, and discrimination angle with signal-interference plane. Based upon minimum coupling loss methodology, calculated interference powers of victim receiver for assumed system parameters are compared with maximum allowable interference power derived from protection ratio as functions of discrimination angle and distance including height-gain model in urban or sub-urban area. The proposed method is applicable for technical analysis on co-existence or interoperability for the various wireless systems, mandatory for frequency coordination or reallocation process.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.6A
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• pp.476-483
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• 2009

Recently much attention has been devoted to femtocell's potential to improve indoor cellular coverage and high speed wireless communications. Femtocell based commercial services have been already launched in some countries and standardization activities are actively on-going, there has been concern however over potential issues of interference between femtocells and the micro/macro networks. With universal frequency reuse, the ensuing cross-tier interference causes unacceptable data rate and outage probability, so an analysis of effect of interference in femtocell embedded networks would be necessary for a stable system design. This paper investigates the effect of interference on system performances of femtocell embedded hierarchical cell structure (HCS) networks considering the characteristics of propagation environments. Various channel parameters are specially considered for indoor environments where most of femtocells are deployed to investigate the effect of interference of femtocell embedded RCS networks. System capacity and coverage are provided with variant distance between macrocell and femtocell, location of the user in femtocell coverage, and characteristic of building structures.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.12
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• pp.1211-1221
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• 2012

This paper describes separation distance to protect radiocommunication services from the interference of inductive systems using frequencies below 30 MHz for the co-existence between radiocommunication services and inductive systems. For the analysis, the interference scenario model is proposed between inductive system and radiocommunication services. Then the calculation method of protection distance is suggested by comparing the radiation power of inductive system with the allowable interference level of victim services, radiocommunication services, according to the applied propagation model. Also, the protection distance for protecting radiocommunication services in the 30 MHz below is calculated through the interference analysis from RFID(Radio Frequency IDentification) and PDP(Plasma Display Panel) TV based on the suggested method. The proposed calculation method was adopted as ITU-R recommendation in related with resolution 63 at ITU-R SG(Study Group) 1 meeting in June, 2012. It will be available to use for the protection of radiocommunication services from the interference of wireless power transfer system and power line telecommunication system.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.561-563
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• 2004

In this paper, distortion of waveform in AC-PDP module has been studied. The propagation losses and interference due to coupling between the electrodes can be considered as the causes for waveform distortion. The distorted waveform has been obtained from the calculated propagation losses. The coupling between the electrodes has been measured using a proper experimental setup. This distorted waveform could account for underfiring problem in AC PDP module.

• Journal of Sensor Science and Technology
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• v.23 no.1
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• pp.1-6
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• 2014

In many medical image devices, dc noise often prevents normal diagnosis. In wireless capsule endoscopy systems, multipath fading through indoor wireless links induces inter-symbol interference (ISI) and indoor electric devices generate impulsive noise in the received signal. Moreover, dc noise, ISI, and impulsive noise are also found in optical fiber communication that can be used in remote medical diagnosis. In this paper, a blind signal processing method based on the biased probability density functions of constant modulus error that is robust to those problems that can cause error propagation in decision feedback (DF) methods is presented. Based on this property of robustness to error propagation, a DF version of the method is proposed. In the simulation for the impulse response of optical fiber channels having slowly varying dc noise and impulsive noise, the proposed DF method yields a performance enhancement of approximately 10 dB in mean squared error over its linear counterpart.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1998.10a
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• pp.474-478
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• 1998

A new approach for the decision feedback equalizer(DFE) based on the back-propagation neural networks is described. We propose the method of optimal structure for back-propagation neural networks model. In order to construct an the optimal structure, we first prescribe the bounds of learning procedure, and the, we employ the method of incrementing the number of input neuron by utilizing the derivative of the error with respect to an hidden neuron weights. The structure is applied to the problem of adaptive equalization in the presence of inter symbol interference(ISI), additive white Gaussian noise. From the simulation results, it is observed that the performance of the propose neural networks based decision feedback equalizer outperforms the other two in terms of bit-error rate(BER) and attainable MSE level over a signal ratio and channel nonlinearities.