• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.2
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• pp.115-121
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• 2013

LED-ID (Light Emitting Diode-Identification) network is envisioned to be the next generation indoor wireless communication medium by which simultaneously high speed data transmission, identification, and illumination are possible. In spite of being extremely promising, it suffers from much impairment. Signals having different propagation paths can suffer from delays, and phase shifts which will eventually result interference. The probability of interference is also increased when communication links are established between a tag and several readers. Therefore it is necessary to reduce the interference in LED-ID network to ensure quality of service. It is possible to avoid interference by knowing the information about readers prior to assign the available spectrum. In this paper, we have proposed dynamic spectrum decision using cognitive radio concept. The simulation results justify that the proposed scheme is better than the conventional scheme.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.1
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• pp.41-48
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• 2004

In this paper, we analyzed channel performance of PPM modulated UWB communication system in indoor radio fading environment that consider amplitude characteristic of channel. Fading channel considered various channel environments by fading index m utilizing Nakagami-m distribution model with data through an UBW radio signal experiment that announced in existing. Also, we improved performance of system that it is decreased in fading environment employing convolution encoding techniques.

• Proceedings of the IEEK Conference
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• 2000.07a
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• pp.144-147
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• 2000

In this paper, we propose two receiver structures of the impulse radio (IR) system to improve its performance in multipath environments. Recently, the impulse radio system has drawn much attention for future high-speed wire-less communication services. The conventional IR receiver directly correlates received signals with the ideal reference waveform, which results in performance degradation in multipath environments. The Key idea of the proposed receiver structures is to reflect the multipath Characteristics into the IR receiver. One is to deconvolve the received waveform with estimates of the multipath gains to obtain the transmitted waveform while the other is to modify the reference waveform of the correlator according to the estimates of the multipath gains. We examine the performance of the proposed schemes for the statistical indoor wireless communication channel model using computer simulation.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.4
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• pp.1502-1519
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• 2020

Recently, new devices have been developed for the Internet of Things concept. The devices commonly use RF (Radio Frequency) based wireless communication. With the increase in the number of devices, the space allocated for the radio frequency band in wireless communication fills rapidly. Visible Light Communication (VLC) is an alternative, secure and economical communication technology that uses light instead of radio frequencies. While Web of Things (WoT) is the adaptation of the experience and knowledge acquired from the web into the internet of things ecosystems. By combining these two technologies, the development of the Visible Light Communication for Web of Things (VLC4WoT) system, which can use VLC and WoT technologies, has been our motivation. In our study, microcontroller control circuit was created for VLC4WoT system. Control of the circuits over the internet was performed. VLC based receiver and transmitter units have been developed for wireless communication. Web based interface was created for control. The test apparatus consisting of four objects with four outputs and a transfer unit was carried out. In this test, communication was achieved successfully. It was presented in the study that VLC can be used in the web of things architecture. In the future, it is envisaged to use this system as a safe and economical system in indoor environments.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.2
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• pp.19-24
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• 2010

This paper analyzes potential interference effect of DTV service on Radio Microphone in adjacent channel. For analysis, we assume that DTV operates on CH 51(692 MHz ~ 698 MHz) and radio microphone operates on CH 52 (698 MHz ~ 704 MHz) according to the Korea Communications Commission policy. Minimum Coupling Loss(MCL) method is used to determine the required protection distance and Monte Carlo method is used to determine guard band to meet interference probability of 0 % below. In conclusions, protection distance of 1.71 km and guard band of 2.4 MHz are required for indoor and protection distance of 18.86 km and guard band of 5.7 MHz are required for outdoor.

• Journal of Convergence Society for SMB
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• v.4 no.4
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• pp.37-42
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• 2014

In this paper, we analyzed the main factors that affect the performance in Visible Light Communication (VLC) system. Generally, published papers of VLC system have been studies to focus on increased data rates, transmission distance and modulation scheme. Therefore, in order to analyze detailed environment for VLC system, we was performed to analyze the performance of a major impact on the VLC system according to communication distance and the angle of incidence. The computer simulation results show that the performance attenuation was confirmed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.128-131
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• 2003

본 논문에서는 채널의 진폭 특성만을 고려한 실내 무선 페이딩 환경에서 PPM 변조된 UWB 통신 시스템의 채널 성능을 분석하였다. 페이딩 채널은 기존에 발표되었던 UWB 전파 실험을 통한 데이터를 바탕으로 Nakagami-m분포 모델을 이용하여 페이딩 지수 m에 따른 다양한 채널 환경을 고려하였다. 또한, 채널 성능을 평가하기 위해 신호대 잡음비, 페이딩 지수 m, 그리고 시스템 성능 파라미터인 펄스반복개수(Ns)를 이용하여 다양한 페이딩 환경에서의 UWB 시스템 성능을 분석하였다.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.449-450
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• 2011

본 논문에서는 실제 옥내 전력선 통신 네트워크를 기반으로 다중 사용자 환경에서의 outage probability의 변화를 확인하였다. 2명의 사용자를 가정하고 시뮬레이션을 통하여 outage probability의 변화를 확인해 본 결과 거리에 따라 최대 70% outage 확률의 변화를 확인하였다. 또한 수신부의 위치에 따라서 outage 확률이 4% 이상 차이가 난다는 것을 확인하였다.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.711-711
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• 2006

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.11a
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• pp.177-181
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• 2002

본 논문에서는 FCC에서 제정한 허용 주파수 3.1-10.6GHz 대역 내에서 사용 가능한 모노펄스를 이용하여 PPM 변조된 TH IR 시스템 시뮬레이터를 설계하고 시뮬레이터를 이용하여 모노사이클 펄스 특성 및 시스템 성능을 분석하였다. 또한, 제안한 파라미터를 이용하여 다원접속 간섭 환경에서 IR 시스템의 오율 성능을 분석하였다.