• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.2
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• pp.3-9
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• 2016

In this paper, we propose a Radio over Fiber system for small cell applications and for mobile fronthaul networks supporting cloud-radio access networks(RAN). We built a system with a downlink employing orthogonal frequency division multiplexing (OFDM) techniques and an uplink using single carrier-frequency multiple access(SC-FDMA). System parameters are evaluated for various subcarrier modulations and the results of link performance measurements are analyzed.

• Journal of Electrical Engineering and information Science
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• v.2 no.3
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• pp.95-98
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• 1997

A nonlinear optical-microwave interaction is carried out in an uniplanar CPW-to-Slotline ring resonator on the semi-insulating GaAs substrate, in which a Schottky photodetector is monolithically integrated as a coupling gap. When the capacitive reactance of the detetor is modulated, the parametric amplification effect of the mixer occurs. In this device structure, the parametric amplification gain of 20 dB without the applied bias in RF signal is obtained. This microwave optoelectronic mixer can be used in the fiber-optic communication link.

• ETRI Journal
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• v.37 no.6
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• pp.1120-1128
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• 2015

We propose a pseudo optical N-level pulse-amplitude modulation (PO PAM-N) signal using a few externally-modulated lasers (EMLs) operating at different wavelengths, which is suitable for upgrading the transmission speed over an optical link of < 10 km single-mode fiber with low-cost components. To compare a PO PAM-N signal with that of a standard optical PAM-N signal, we perform experiments for evaluating the performance of a 51.56-Gb/s PO PAM-4 signal and standard 51.56-Gb/s optical PAM-4 signal. The receiver sensitivity (at $BER=10^{-5}$) of the PO PAM-4 signal is 1.5 dB better than the receiver sensitivity of a standard optical PAM-4 signal. We also investigate the feasibility of PO PAM-N (N = 4, 8, and 16) signals operating at 103.12 Gb/s, considering relative intensity noise, timing jitter, extinction ratio (ER) of EMLs, and dispersion. From the results, a PO PAM-8 signal performs better than PO PAM-4 and PO PAM-16 signals at 103.12 Gb/s. Finally, we suggest a timing control method to suppress the effect of dispersion in a PO PAM-N signal. We show that the tolerance to dispersion of a 103.12-Gb/s PO PAM-8 signal can be improved to ${\pm}40ps/nm$ by applying a proposed scheme.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.12
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• pp.94-105
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• 2003

OBS(Optical Burst Switching) networks which decouple the burst from its header has characteristic one-way reservation. Therefore, the fault of a fiber link may lead to the magnitude of burst loss. Since sending a header packet and using an offset time before the transmission of the corresponding burst. In this paper, we analysis a offset time based on the burst loss rate resulting from only link failure and by applying the restoration schemes in an optical burst switching networks. The simulation results in terms of the effect of a offset time is evaluated in our network model to verify that comparing the numerical analysis with simulation result. Finally, and through these results, We propose the new restoration scheme based on offset time considered Quality of Service.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.10
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• pp.2687-2702
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• 1996

It is desirable that the implementation of next generation information infrastructure is the Integrated Network combining the satellite and the terrestrial network. The application of the ATM network being the dominant infrastrure of terrestrial network to the satellite network is being studied variously. Considering these concepts, this paper analyzes due to ATM transport via satellite, evaluates the degradation of QoS and proposes reliable method of ATM cell transport via satellite. Because ATM is investigated with the optical fiber which is almost error free characteristics, the practical application of ATM transport via satellite essentially need the channel coding(FEC:Forward Error Correction) to enhance BER performance. But using the FEC coding, satellite link has burst error characteristics which evoke severe performance degradation fo ATM QoS. Therefore in satellite link, we analyze burst error characteristics using experimental results of computer simulation. Then to compensate these characteristics, based on this analysis and HEC dual mode algorithm we propose various interleaver structures(Block interleaver, Intra interlever, and Inter-Intra interleaver) to improve cell transmission QoS. We execute performance evaluations of iterleaver structures by computer simulation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.5
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• pp.714-724
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• 2022

The spread of mobile devices comes to increase explosive data traffic and then results in various types of service demands. In order to satisfy the increment of traffic and the requirements for various services, optical internet technologies that transmit several Tbps through only a single optical fiber have been actively studied. Because of the large bandwidth, an optical link can accommodate a large number of service types. Therefore, new technologies are required to guarantee the survivability of optical internet and handle the requirements of each service. So, in this article, a new scheme based on GMPLS technologies is proposed to deal with the various service demands and survivability issues in IP over WDM networks.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.7A
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• pp.535-541
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• 2005

This paper proposes a hybrid optical lines composed of single-mode fiber(SMF) and multi-mode fiber(MMF) for gigabit-capable Passive Optical Network(GPON) using a WDM method with a single light source per each channel, and reports the results of transmission performance the proposed lines. The transmission link uses a direct modulated DFB-LD for high speed downstreams at the optical line terminal(OLT) of central office(CO) and a low cost SFP type transceiver for low-speed upstream in optical network unit(ONU). To split or combine the transmission channels, wavelength MUX/DEMUX are used in the optical line section, and MMFs not longer than 1 km are attached to the SMF lines at the ONU side of the WDM-PON links. We have performed the transmission experiment on the downstream of 2.5 Gbit/s, and 1.25 Gbit/s, and the upstream of 1.25 Gbit/s, and 622 Mbit/s which are recommended by ITU-T G.984.2. The transmission margin and feasibility of the proposed links have been tested to be suitable up to 2.5 Gbit/s transmission.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.2
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• pp.42-42
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• 2001

본 논문은 주파수 천이를 적용시킨 광무선(fiber-radio)시스템의 광링크부에 대한 성능분석을 한다. 제시된 광링크부는 CS(control station)에서 얻어진 밀리미터파 대역 광파일럿톤(optical pilot tone)이 하향링크뿐 아니라 상향링크에도 공급되도록 하여 BS(base station)의 구조를 간단히 하였다. 광파일럿톤을 얻기 위해 CS의 EOM(electro-optic modulator)을 MAB(maximum bias), MIB(minimum bias), QB(quadrature bias)로 바이어스를 달리할 수 있으며 각각의 경우에 따라 링크의 성능을 분석한다. 분석은 레이저 광원의 전력이 일정한 경우와 PD(photo detector)에 수신되는 광 DC 전력이 일정한 경우에 대해서 행하여지며 각 경우에 대해서 최적의 하향링크 CNR 및 상향링크 SFDR(spurious free dynamic range)을 얻기 위해 효과적인 바이어스 방식을 제시한다

• 한국정보통신설비학회:학술대회논문집
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• 2007.08a
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• pp.15-18
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• 2007

RoF 링크 시스템을 적용한 무선 근거리 통신망(IEEE 802.11b/g)의 중심 주파수 대역인 2.4 GHz에서 저가의 Febry-Perot 레이저 다이오드를 이용한 피드포워드 광송신기를 제작 및 측정 하였다. 제작된 피드포워드 광송신기의 측정 결과는 2.4 GHz에서 주신호의 간격이 10 MHz이고 크기가 -4 dBm인 입력 신호에서 피드포워드 보상기법을 적용하기 전보다 3차 상호 변조 왜곡 신호가 22.9 dB 개선되었다. 제작된 피드포워드 광송신기의 전자소자의 사양을 바탕으로 송신기 집적을 위한 RFIC회로(감쇄기, 증폭기)를 0.18 ${\mu}m$ 공정을 이용하여 설계하였다.

• Proceedings of the Korean Information Science Society Conference
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• 2004.04a
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• pp.427-429
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• 2004

최근 광대역 멀티미디어 서비스에 대한 관심이 HD(High Density)방송의 시작과 함께 고조되고 있다. WPEG(Moving Picture Experts Group) HD 방송 채널을 수용하기 위해서 요구되는 방송대역은 20Mbps로 현재 가입자 망으로 한계를 가지고 있다. 궁극적인 해결 방안으로 FTTH(Fiber To The Hone) 광 가입자망이 논의되고 있다. 광 가입자 망의 유력한 방법중의 하나가 Gigabit Ethernet PON으로 IEEE(Institute of Electrical and Electronics) 802.3 EFH(Ethernet First Mile) AH Group을 중심으로 표준화 진행 중에 있다. IEEE 802.3 EFM AH Group에서는 가입자 망 장애에 대한 Protection 링크 이중화가 고려되고 있지 않아 본 논문에서 Gigabit Ethernet PON에서 링크 이중화 방법을 제시 하고자 한다.