• Journal of Communications and Networks
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• v.15 no.5
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• pp.486-495
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• 2013

In this article, we suggest a two-dimensional genetic algorithm (GA) method that applies a cognitive radio (CR) decision engine which determines the optimal transmission parameters for multicarrier communication systems. Because a CR is capable of sensing the previous environmental communication information, CR decision engine plays the role of optimizing the individual transmission parameters. In order to obtain the allowable transmission power of multicarrier based CR system demands interference analysis a priori, for the sake of efficient optimization, a two-dimensionalGA structure is proposed in this paper which enhances the computational complexity. Combined with the fitness objective evaluation standard, we focus on two multi-objective optimization methods: The conventional GA applied with the multi-objective fitness approach and the non-dominated sorting GA with Pareto-optimal sorting fronts. After comparing the convergence performance of these algorithms, the transmission power of each subcarrier is proposed as non-interference emission with its optimal values in multicarrier based CR system.

• Journal of electromagnetic engineering and science
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• v.9 no.4
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• pp.202-210
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• 2009

In this paper, we have analyzed the effect of interference between ultra-wideband(UWB) and intelligent transport systems(ITS). The maximum possible UWB emission power and minimum possible distance between UWB devices and ITS are found. In order to analyze the interference, we employ the Monte-Carlo(MC) method. We consider six situations, which are indoor office line-of-sight(LOS), indoor office non-line-of-sight(NLOS), indoor residential LOS, indoor residential NLOS, outdoor rural LOS, and outdoor rural NLOS environments. From the simulation results, it is confirmed that coexistence between UWB and ITS devices can be realized in accordance with the emission mask of 19.3 dB for indoor application or 19.3 dB for an image system. And in the outdoors, coexistence between UWB and ITS devices can be realized if the emission mask is at least 1.6 dB for vehicles' radar systems.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.9
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• pp.746-751
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• 1998

There are several methods capable of determining he magnitude of optical anisotropy, such as spectrometric ellipsometry and polarized light reflectometry. The interference method is estimated to be no influence of surface scattering. The magnitude of anisotropy is a-As/sub 40/Ge/sub 10/S/sub 35/Se/sub 15/ thin film is analyzed by the reflection interference analysis method based on the difference depending on a phase of s- and p-polarized light. The theoretically analyzed value is compared with the result obtained by the measured technique.

• Journal of Communications and Networks
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• v.8 no.3
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• pp.323-329
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• 2006

For orthogonal frequency division multiplexing (OFDM), the discrete Fourier transform (DFT)-based processing at the receiver has been perceived equivalent to the matched filter (MF)-based processing. In this paper, we revisit the equivalence and mathematically show that when the guard interval is insufficient, the well-known DFT-based processing inherently causes more intersymbol and interchannel interference (ISI/ICI) than the MF-based processing. Then, with the adverse increase of interference, analytical expressions for the link performance are derived in terms of bit error rate (BER). Numerical results from computer simulation and analysis are presented to justify our claims.

• The Journal of the Korea Contents Association
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• v.5 no.6
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• pp.129-137
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• 2005

A performance analysis of LEO Satellite Communication Service is being made in a variety of ways. In this paper we examined the variation of interference caused by the distribution of terminals within a cell and the maximum number of users according to the average distance between terminals, which had not been considered in former researches. Also we examined the interference made by sopt beam isolation value of some antennas(tapered-apertured antenna, gaussian antenna) which are used on LEO Satellite Communication Service Assigning this interference to the bandwidth of channels in LEO Satellite Communication Service, and with principal parameters(bandwidth, number of carrier) we made a performance analysis. And comparing tapered-apertured antenna with gaussian antenna we will find out which one is more effective and more suitable for interference.

• Journal of the Korean Institute of Gas
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• v.12 no.4
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• pp.8-13
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• 2008

The stray current interference problem could induce the corrosion of near-by structure and rail itself. Many efforts has been concentrated on the reduction of the interference. In this work the influences of separation distance, soil resistivity, pipe coating resistance, leak resistance of rail were studied using the numerical analysis methods. These analysis could be used to estimate the sensitivity of each variables in the study of the mitigation method and their numerical analysis.

• Journal of IKEEE
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• v.7 no.2 s.13
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• pp.281-287
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• 2003

This paper proposed an improvement scheme for effective usage of radio-frequency management system(RFMS), which has been operated to facilitate national spectrum management and monitoring in Korea. Based on the wave propagation models, interference analysis algorithms, and sharing criteria recommended by ITU-R, we derived criteria for the automated selection of the channel interference analysis algorithms and sharing conditions adequate to the environment to be analysed. Then using the obtained criteria, computer and program has been made and shown to select the most appropriate propagation models, interference analysis algorithms, and sharing criteria from the ones provided in RFMS, with the illustrative example.

• ETRI Journal
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• v.33 no.2
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• pp.279-282
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• 2011

Coexistence analysis is extremely important in examining the possibility for spectrum sharing between orthogonal frequency-division multiplexing (OFDM)-based international mobile telecommunications (IMT)-Advanced and other wireless services. In this letter, a new closed form method is derived based on power spectral density analysis in order to analyze the coexistence of OFDM-based IMT-Advanced systems and broadcasting frequency modulation (FM) systems. The proposed method evaluates more exact interference power of IMT-Advanced systems in FM broadcasting systems than the advanced minimum coupling loss (A-MCL) method. Numerical results show that the interference power is 1.3 dB and 3 dB less than that obtained using the A-MCL method at cochannel and adjacent channel, respectively. This reduces the minimum separation distance between the two systems, which eventually saves spectrum resources.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.6
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• pp.647-656
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• 2008

In this paper, we present interference power distribution results when radio frequency identification(RFID) and ubiquitous sensor network(USN) systems share the $908.5{\sim}914MHz$ frequency bands. Average interference powers are obtained by simulation and statistical analysis, respectively. Simulation results are then verified by statistical analysis. According to the number of interferers and the diameter of the protection area, the cumulative density functions(CDFs) of interference power are simulated under the various conditions. From the simulation results, the probability that both USN and RFID systems meet the required maximal interference power levels is 95 % on condition that there are 1 low revered RFID reader and several USN nodes and that the minimum distance between a RFID reader and an USN node is greater than 1 m. Our results can be used as an basic research for coexistence analysis of RFID and USN systems in the $908.5{\sim}914MHz$ frequency bands.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.6 no.3
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• pp.122-137
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• 2007

In this paper, compatibility between different radio services or systems is analyzed when they are in adjacent band or co-channel. The first step of the compatibility analysis is establishing an interference scenario. And an interference pobability from an interfering transmitter to a victim receiver is calculated by means of Monte-Carlo simulation techniques. Then the calculated result is compared with the predefined interference criteria, maximum permissible interference probability and we can determine compatibility in accordance with the active interferer density, channel bandwidth, cell radius, distance between interfering transmitter and victim receiver, and duty cycle. It is assumed that Propagation modes are the free space model and extened Hata model.