• Electronics and Telecommunications Trends
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• v.10 no.1 s.35
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• pp.85-90
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• 1995

급증하는 이동통신에 대한 수요를 충족시키기 위하여 선진 각국은 가입자 수용한계에 직면한 아날로그 방식에서 보다 수용용량이 큰 디지털 이동통신 시스템 개발에 주력하고 있다. 본 고에서는 디지털 이동통신의 제외국 표준화 및 기술동향에 대하여 살펴보고 국내 동향과 문제점 및 대책방안을 결론으로 제시하고자 한다.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.11a
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• pp.467-467
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• 2004

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.07a
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• pp.454-454
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• 2004

• Information and Communications Magazine
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• v.26 no.7
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• pp.10-16
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• 2009

본고에서는 무선 통신 망에서 게임 이론이 적용된 주요 물리 계층 설계 기술을 소개한다. 셀룰러 망과 ad-hoc 망에서 일반적으로 적용할 수 있는 비협력 게임 이론 모형을 제시하고 서로 다른 목적을 위해 제안된 게임 전략과 유틸리티 함수를 소개함으로써 게임 이론으로 다양한 분산 알고리즘을 도출할 수 있음을 보인다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.2C
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• pp.123-130
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• 2002

To cope with the Internet host mobility in a cellular network environment, we propose an adaptive mobility management scheme that can compensate drawbacks of Mobile IP. We also propose protocol that supports the proposed scheme. Our proposed scheme determines foreign agent care-of addresses adaptively according to user mobility. Consequently, it is different from other proposals for micro mobility, which statically assign the gateway in the domain as a foreign agent. Using such a scheme, it is possible to effectively meet the users demands for different service qualities in the various environments considered in the cellular network and to reduce signaling overhead due to frequent handovers occurred in Mobile IP. The performance of the proposed scheme is examined by simulation. The results of simulation show that the proposed scheme can provide relatively stable points of attachment to the mobile node.

• Journal of Korea Multimedia Society
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• v.13 no.9
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• pp.1329-1336
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• 2010

Cellular Automata is a discrete dynamical system which natural phenomena may be specified completely in terms of local relation, can increase and decrease the difference of luminance locally according to transition rule by keeping the characteristic of target image. In this paper, we propose a noise reduction method by keeping the characteristic using transition rule of Cellular Automata, also we propose methods of effective transition rule, the selection of parameters, the selection of number of neighborhood pixels. For uniform distribution noise, Gaussian noise, impulse noise, we do an experiment on adaptive state using different mathematical operations and compare its results. It was confirmed that the proposed transition rule is based on fast convergence speed and has stabile results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.11C
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• pp.1108-1115
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• 2005

In this paper, we propose a practical iterative channel estimation and decoding method for an LDPC-coded frequency hopping OFDMA system in the uplink of a packet-based cellular system. In the method, the channel gain and noise variance are iteratively estimated with both pilot symbols and LDPC decoder outputs to provide more reliable decoding metrics in intercell interference (ICI) environments. In addition, the channel correlation coefficient is also estimated to select proper filter coefficients according to the channel variation rate. Through simulations under the various channel conditions and different receiver configurations, it is shown that the proposed iterative receiver improves the performance without boosting the pilot power and mitigates the adverse effects of the non-uniform ICI.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.9A
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• pp.781-787
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• 2005

In this paper, an estimation method of intercell carrier frequency-offset(CFO) in orthogonal frequency division multiplexing(OFDM)-based cellular systems is proposed for a user's equipment(UE), especially at the cell boundary, in downlink channels. Also, after deriving an estimation method of intercell CFO from the signals received by adjacent base stations(BSs), we propose a cell-searching method using the estimated CFOs. It is shown by computer simulation that the proposed methods can uniquely estimate the intercell CFOs and identify the target BS with a high detection probability.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.3
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• pp.36-40
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• 2011

OFDM technology is already commonplace in the current mobile communication system environment. However, inter-cell interference causes many problems in the cellular system as seen from the problem caused by the surge in the use of smart phones. In this paper, we will research how user distribution influences a performance of a conventional proposed algorithm in the certain cell area and confirm it through computer simulations. As a result, we proved that there is an appropriate user distribution in the cell. In addition, it has an effect on the performance of inter-cell interference coordination.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.10
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• pp.1194-1199
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• 2010

In this paper, for a relay-based cellular network, a interference avoidance beamforming technique is proposed to enhance direct link capacity while minimizing loss in the capacity of concurrent relaying link. A direct link is transmitted by beamforming at the transmitter, and the relaying link with the least interference to the direct link is scheduled to transmit data by a collision avoidance scheduling algorithm. Simulation results show that the proposed IA beamforming provides a considerable direct link capacity enhancement while minimizing relaying link capacity loss by effectively mitigating inference between concurrent direct and relaying links only with limited feedback.