• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.10C
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• pp.933-936
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• 2002

One of the problems of a Gigabit-Ethernet system for installation in telecom networks is its relative low reliability compared with SONET, the major telecom network system, which restores from fault within 50 msec. In this study, an optics layer protection for the Gigabit-Ethernet system is proposed. It monitors optical signal quality by comparing the signal level with a calibrated window, and switchs fibers within a time comparable to SONET.

• Journal of KIISE:Information Networking
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• v.34 no.1
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• pp.73-80
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• 2007

This paper presents an approach to support dynamic QoS(Quality of Service) requirements of largely emerging SIP(Session Initiation Protocol) multimedia applications in broadband access networks. The topology of QoS-enabled broadband access networks and its operational model to support SIP QoS are firstly suggested. And then the procedures to bind QoS-enabled SIP signaling into an IP QoS mechanism are presented. In this paper, DiffServ-based IP QoS architecture is deployed due to the complexity problem of the other IntServ architecture, and COPS(Common Open Policy Service) and COPS-PR protocol based signaling mechanisms are used to support dynamic DiffServ QoS, correspondent with dynamic SIP QoS. The broadband access network is assumed to support rapidly expanding Metro Ethernet 802.1 D/Q QoS, and how to translate SIP QoS parameters into IP DiffServ classes and DiffServ classes into 802.1 D/Q QoS parameters is also presented in this paper.

• 한국정보통신설비학회:학술대회논문집
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• 2004.08a
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• pp.204-208
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• 2004

인터넷 기술의 발달로 기존의 ADSL망에서 VDSL 및 메트로 이더넷으로 진화함에 따라 PSTN망에 의한 전화서비스가 인터넷폰으로 점차 대체되어가며, 수 Kbps 대역폭의 웹캐스팅서비스는 수 Mbps 고화질 인터넷방송이 가능하며, 이러한 통신과 방송의 융합은 하나의 대세로 간주되어, 케이블 사업자의 케이블 모뎀을 이용한 방송 및 초고속 인터넷 서비스에 이어, 통신사업자들도 VOD 및 IP-TV, 인터넷폰을 동시에 제공하는 방안을 준비중에 있다. KT도 홈게이트웨이 기반의 상용 VOD 서비스가 2004년 6월에 개시되어 TV를 통한 홈엔터테인먼트의 초석을 다지게 되었으며 앞으로 IP-TV 및 인터넷폰 서비스를 계속적으로 제공할 예정에 있다. 본고에서는 통신사업자 측면에서 통신 및 방송서비스가 어떻게 융합될 것이며 최신 이슈가 되고 있는 트리플 플레이 서비스 및 전망 그리고 해외 사례를 알아보고, KT에서 제공중인 IP망관련 서비스에 대하여 살펴보기로 한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.4C
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• pp.461-471
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• 2004

Recently, subscribers have strong desire to get QoS based personalized services in high-speed Internet access. Service providers have been rapidly replacing ADSL, cable broadband access networks with Metro-Ethernet based VDSL. But, it is difficult for Motto-Ethernet based broadband access networks to provide QoS based personalized services, because already deployed network elements cannot distinguish subscribers by specific traffic characteristics. In this paper, when the access network has tree topology, we show that it is possible to provide QoS for each downstream flow with only per flow traffic shaping at the edge node without QoS functions in access networks. In order to show that our suggested scheduling algorithm at the edge node can support the assured service in tree topology access networks, we evaluated its performance by simulation. The suggested scheduling algorithm can shape per-flow traffic based on the maximum bandwidth, and guarantees minimum bandwidth per flow by modifying the DRR scheduler. Simulation results show that congestion and loss in the access network elements are greatly reduced, TCP performance is highly enhanced and loss for assured CBR service flows is reduced by only shaping per-flow traffic at the edge node using our proposed scheduling algorithm.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.5 s.347
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• pp.59-67
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• 2006

We demonstrate bidirectional long-reach 35-channel dense wavelength division multiplexing-passive optical network(DWDM-PON) based on wavelength-locked Fabry-Perot laser diodes (F-P LDs). The mode control of F-P LD enhances output power at decreased the required injection power. We show packet-loss-free transmission in all 70 channels at 125 Mb/s per channel line rate through 70 km of single mode fiber without optical amplifier The DWDM-PON can consolidate a metro network into an access network by bypassing the central offices within its reach. The proposed DWDM-PON can accommodate about 80 subscribers with an EDFA-based broadband light source. Further expansion up to 100 subscribers is possible with a semiconductor-based BLS.