• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.4B
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• pp.153-161
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• 2005

In a multi-channel network based of wavelength division multiplexing (WDM) technology, an efficient protocol is needed in order for the transmitter and receiver to be tuned to the same wavelength during message transmission time. This paper proposes a priority-based reservation protocol that can efficiently support variable-length messages that require different QoS requirements. In this proposed protocol, high-priority nodes can reserve the data channel before low-priority nodes. However, once a node reserves a data channel successfully, it can persistently use the reserved channel till message transmission is finished regardless of the priority of the node. Moreover, the protocol can operate independently of the number of nodes, and any new node can join the network anytime without requiring network re-initialization. The protocol is analyzed with a finite population model and the throughput-delay characteristics are investigated as performance measures.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.1 s.343
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• pp.111-120
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• 2006

In this paper, a node architecture of WDM metro network for connecting broadband access networks to converge wire/wireless networks. In consideration of the proposed node architecture and network requirements we proposed and evaluated medium access control protocols. We review WDM related technologies of sub-carrier multiplexing and optical components in order to resolve the bottleneck between optical backbone networks md access networks, and a access node architecture sharing common wavelength is introduced. Source-stripping (SS) MAC protocol Is evaluated under the proposed functional node architecture. DS+IS (Destination-Stripping and Source-Stripping) and DS+IS (Destination-Stripping and Intermediate-Stripping) MAC protocols are described to increase the slot-reuse factor which is low on SS MAC protocol. The key function of new MAC protocols regards the optical switch module of proposed node architecture and helps intermediate or source access nodes for dropping slots to destinations of different wavelength group. Thus, slot-reuse factor increases as the MAC protocols reduce the unnecessary ring-rotation of transferred slots. We use a numerical analysis to expect bandwidth efficiency and maximum throughput by slot-reuse factor Throughput network simulation, the verification of throughput, queuing delay, and transmission fairness are compared among MAC protocols.

• Proceedings of the Optical Society of Korea Conference
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• 2002.07a
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• pp.150-151
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• 2002

파장 분할 다중화(Wavelength division multiplexing ： WDM) 광전송 장치의 용량확대를 위한 방안으로 여러 가지 방법들이 연구 개발되고 있으며, 최근 들어 테라 급(Tb/s) 광전송 연구 결과들이 발표되고 있다. 이러한 장거리 광전송 장치의 광송신기는 LiNbO$_3$ 마하-젠더(Mach-Zehnder) 간섭계형 외부 변조기를 주로 사용하고 있다. 한편 반도체 레이저 집적된 전계 흡수형 변조기(Electro-absorption modulator integrated laser ： EML)를 이용한 외부 변조 방식 적용을 위해서 여러 연구소 및 기업체에서는 40Gb/s의 성능을 지닌 EML의 개발 결과들을 발표하고 있다. (중략)

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.2
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• pp.1-5
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• 2001

We propose an optical performance monitoring method for WDM optical transmission systems. By assigning a pair of AWG ports to each optical signal channel. the optical power, optical signal-to-noise ratio (OSNIO, and wavelength of all the signal channels are observed simultaneously. The output power ratio of the AWG port pair depended on the wavelength variation of the channel with sensitivity of 1dB/0.026nm. The OSNH results were deviated no more than 0.7dB from the results measured by optical signal analyzer (OSA).

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.4
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• pp.534-543
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• 2000

In this paper, when the current optical communication system is used for the DWDM. The FBG filter for the DWDN is able to reduce the interferences between the adjacent channels. In this paper, therefore, we find the relection spectrums for the three types of induced index changes, that is, uniform, Gaussian apodized, and raised-cosine apodized. From the obtained result in this paper, we can see that uniform FBG does not fit, and that the smaller the maximum induced index change $\sigma$ is and the larger the value of parameter C in the raised-cosine apodized FBG and G in the Gaussian apodized FBG are the fitter they are on the narrow filter for DWDM.

• Journal of Advanced Navigation Technology
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• v.23 no.6
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• pp.570-576
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• 2019

The configuration of dispersion-managed optical link with optical phase conjugator, which is placed at the non-midway of total transmission length, is proposed for implementing of the flexible optical network. The optical phase conjugator is located between the former half transmission section and the latter half transmission section, which are consisted of 6 fiber spans and 14 fiber spans respectively, and the averaged RDPS of each half transmission section are inconsistence. And, the artificial distribution of each fiber span's RDPS, which are gradually increased/decreased as the span numbers are increased, is adopted to compensate for the distorted wavelength division multiplexed channels. From the simulation results, it is confirmed that the compensation in dispersion-managed link configured by a special distribution pattern among 16 proposed patterns, in which the RDPS of each fiber spans are gradually decreased/increased in the former/latter half section with the small deviation, is suitable to compensate for the distorted wavelength division multiplexed channels.

• Journal of Korea Multimedia Society
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• v.14 no.5
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• pp.658-668
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• 2011

Over the past decade, the improvement of communications technologies and the rapid spread of www (World Wide Web) have brought on the exponential growth of users using Internet and real time multimedia multicast services like video conferencing, tele-immersive virtual reality, and Internet games. The dense-wavelength division multiplexing (DWDM) networks have been widely accepted as a promising approach to meet the ever-increasing bandwidth demands of Internet users, especially in next generation Internet backbone networks for nation-wide or global coverage. A major challenge in the next generation Internet backbone networks based on DWDM technologies is the resolution of the multicasting RWA (Routing and Wavelength Assignment) problem; given a set of wavelengths in the DWDM network, we set up light-paths by routing and assigning a wavelength for each connection so that the multicast connections are set-upped as many as possible. Finding such optimal multicast connections has been proven to be Non-deterministic Polynomial-time-complete. In this paper, we suggest a new heuristic multicast routing and wavelength assignment method for multicast sessions called DVS-PMIPMR (Differentiated Virtual Source-based Priority Minimum Interference Path Multicast Routing algorithm). We measured the performance of the proposed algorithm in terms of number of wavelength and wavelength channel. The simulation results demonstrate that DVS-PMIPMR algorithm is superior to previous multicast routing algorithms.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.5
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• pp.407-412
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• 1998

In this paper, we design PHASAR(Phased Array) WDM(Wavelength Dvision Division Multi- and Demultiplexing) filters and evaluate their performance. The PHASAR WDM filter is designed to have flat-passband characteristics by inserting the multimode waveguides between input waveguides and a first star coupler. BPM simulation results show that the excess loss is smaller than 6.5 dB, the crosstalk is less than -22 dB and the 1 dB passband is about 50 GHz. The effect of the path difference error is also investigated.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.5B
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• pp.956-965
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• 2000

In this paper, we propose an efficient traffic grooming algorithm to minimize to number of SONET ADMs which is the dominant cost of system in high speed optical ring networks. It is an optimal traffic grooming algorithm to be applied to both unidirectional ring and bi-directional ring under both uniform traffic and nonuniform traffic. The proposed traffic grooming algorithm consists of two subalgorithms : one is the algorithm to construct full connection-rings as many as possible to minimize gaps by cutting the connections and using redirection method, and the other is the algorithm to groom connection-rings into a wavelength to maximize the number of shared nodes. The simulation results show that the proposed algorithm is superior to conventional algorithm under various network conditions.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.11
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• pp.1607-1617
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• 1993

The performance of Manchester-coded ASK optical wavelength division multiplexing(WDM) systems is evaluated laking into account the shot noise and the four wave mixing(FWM) caused by fiber nonlinearities. The result is compared to conventional non-return-to-zero(NRZ) systems for ASK modulation formats. Further, the dynamic range, defined as the ratio of the maximum input power(limited by the FWM), to the minimum input power(limited by receiver sensitivity), is evaluated. For 1.55 rm 16 channel WDM systems, the dynamic range of ASK Manchester coded systems shows a 2.0 dB improvement with respect to the NRZ. This result holds true for both dispersion-shifted fiber and conventional fiber it has been obtained for 10 GHz channel spacing, 1 Gbps/channel bit rate.