• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.9
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• pp.31-40
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• 1997

This paper presents a hybrid WDM/TDM channel acess protocol for high speed WDM networks based on passive double star topology. In the proposed scheme, all nodes in a network are splitted into groups forming passive double star topology and each node has a tunable transmitter and a fixed receiver. WDM channels are allocated to the groups, which are used as home channels to transmit or receive packets. TDM frames of the WDM channel are composed of the same number of slots as that of groups, and all nodes in a group transmit packets simultaneously at each slot. The proposed scheme reduces the system complexity and the number of the required WDM channels. It was proved that the proposed protocol is less sensitive to the propagation delay and maintaining its superior transmission performance by employing the efficient transmission schedule based on passive double star topology.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.7
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• pp.1785-1796
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• 1998

This paper is concerned with the relationships between optimal number of wavelengths and tuning time in time division multiplexing(TDM) scheduling on wavelength division multiplexing(WDM) optical passive star networks. We assume that the traffic is nonuniform and each node has a tunable transmitter and a fixed receiver. Each node transmits spckets to all other nodes. Most of the earlier protocols on TDM based scheduling for WDM star networks [7, 8, etc.] use whold given wavelength chnnels. But in this paper, we investigate the optimal number of wavelengths that yidels minimum frame length when tuning time exists. It appears within the availble number of wavelengths that yields minimum frame length when tuning time exists. It appears within the available number of wavelengths. We analyze the relationships between optimal number of wavelengths and tuning time by experiments. We analyze the reationships between optimal number of wavelengths and tuning time by experiments. We also discuss on the possibility of reduction of frame length by increasing the number of nodes trans-mitters and receivers.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.9B
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• pp.777-784
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• 2006

In this paper, we propose the PON-based access network based on conventional TDM-PON architecture, which utilizes WDM wavelength channel and bandwidth dynamically. It is also described a dynamic MAC protocol in order to increase the number of subscribers and efficiency of resource utilization. Of particular importance in the proposed approach for MAC protocol is that the wavelength channel and time slot for up/downlink is dynamically allocated according to the required QoS level and the amount of data in data transmission, through the dedicated control channel between OLT and ONU. We evaluate the performance of average packet end-to-end delay in a statistical analysis and numerical analysis. In addition, through simulations with various traffic models, we verified the superior performance of the proposed approach by comparing with the results of other E-PONs.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.10B
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• pp.1722-1731
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• 2000

In this paper we proposed a new type of the Optical Cell Compressor and Decompressor which are essential modules in TDM of TDM/WDM Hybrid OPtical ATM Switch structure. This proposed structure frastically lessens hardwares for realization by using SOA gates and optical feedback loops in the process of compression and decompression. Also it is able to compress and decompress the large capacity optical pulse stream just with a few of stages cascade connected. We proved it's possibility for systematic application through 4-bit compression experiment.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.2
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• pp.50-58
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• 1996

This paper proposes the channel-access protocol suitable to a very high speed photonic WDM network with star configuration, which can provide a high channel utilization and insensitivity to the propagation delay. The proposed protocol employs a control channel and a simple status table to deal with the propagation delay which has been a major limiting factor in the performance of the very high speed optical communication networks. The control channel transmits control information in order to reserve access on data channels, and each node constitutes a status table after the reception of control pckets which holds information about the availbility of destination node and data channel. The proposed protocol is insensitive to the propagation delay time by removing necessity of the retransmission and by allowing parallel transmission of control packet and data packets. It is proved in analysis and discrete event simulation that the proposed protocol is superior in throughput and mean delay, especially at the high load conditions compared to the existing high speed channel-access protocols.

• Electronics and Telecommunications Trends
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• v.19 no.6 s.90
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• pp.43-54
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• 2004

WDM-PON은 가입자망의 트래픽 병목 현상을 해결하고, 다양한 서비스 품질을 제공하면서 고속화된 데이터 전송을 위해 가입자 당 독립 파장을 할당함으로써 가입자의 요구 대역에 제한을 받지 않으며, 보안성이 보장되는 차세대 WDM 기반 수동형 광가입자망이다. 특히 고성능, 저가인 광소자를 포함한 광모듈의 조기개발이 FTTH 네트워크 초기 시장 및 서비스를 선점하는 척도가 될 것으로 예상된다. 본 논문은 WDM 기반 수동형 광가입자망 동작 방식, 광다중화기 및 역다중화기, 그리고 WDM -PON과 WDM 다중화 기술인WDM/TDM, WDM/SCM, WDM/CDM을 포함한 다양한 광 수동 가입자망 구성 기술을 소개한다.

• Electronics and Telecommunications Trends
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• v.21 no.6 s.102
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• pp.113-123
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• 2006

WDM-PON은 가입자 별로 파장을 독립적으로 할당하여 전송로를 구성하는 방식으로 전송 프로토콜에 관계없이 전송이 가능하고, 전용선 수준의 대역폭 제공, 전송속도의 제한이 없으며, 서비스 품질을 보장하고, 보안성이 뛰어난 차세대 FTTH 기술로 평가받고 있다. 특히 고성능, 저가인 광소자를 포함한 광모듈의 조기 개발이 FTTH 네트워크 초기 시장 및 서비스를 선점하게 될 것으로 예상된다. 본 논문은 WDM 기반 수동형 광가입자망용 광원, 이러한 광원과 다중화 기술에 따른 WDM-PON, WDM/TDM,WDM/SCM 등 다양한 수동형 광가입자망 구성 기술을 소개한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.6
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• pp.1419-1424
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• 2013

Passive optical networks (PONs) are the emerging solution for access networks since PONs provide high bandwidth and the low operation cost. In recent, the new solution in access networks is TWDM PON which is a mixture of WDM (wavelength-division multiplexing) and TDM (time-division multiplexing). This paper proposes a new MAC (media access control) protocol for TWDM PON. In addition, this paper proposes and evaluates a new dynamic bandwidth allocation method for TWDM PON.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.2
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• pp.9-18
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• 1999

In this paper, large capacity Photonic ATM switch structure is proposed. It contains mixed routing structure using TDM and WDM methods. Through this structure, we can get not only required hardware reduction, and optical power loss reduction in cell routing procedure but also the less complexity of electrical parts using passive device. Also, it is designed for ease to simplicity of extension in throughput, so it is suitable structure for large capacity Photonic ATM switching system of the future.

• The Journal of the Korea institute of electronic communication sciences
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• v.3 no.4
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• pp.289-294
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• 2008

Affordable traffic capacity of each node in networks is expected to reach in Tb/s range in proportion to the rapid growth of Internet users. To transmit more than Tb/s per fiber pair, WDM should be used as well as existing TDM. To increase the capacity of transmission in WDM networks, there are two ways, increasing channel speed or channel quantity. To increase the channel quantity, there are two ways, narrow spacing or expanding transmission bandwidth. To expand bandwidth, ultra-broadband optical amplifier technology is necessary. In this paper, we introduce EDFA in effect at C/L band, FRA, and some optical amplifiers in effect at S band, and analyze the development trend of various amplification technologies.