• ETRI Journal
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• v.29 no.4
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• pp.524-526
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• 2007

In this letter, we study the multicast protection problem in sparse-splitting wavelength-division multiplexing (WDM) optical network, and propose a novel multicast protection algorithm called the shared source-leaf path-based protection (SLPP) algorithm. Unlike the proposals in previous studies, the backup paths derived by SLPP can share wavelength with the primary tree in sparse-splitting WDM networks. Simulations are used to evaluate the effectiveness of the SLPP algorithm.

• Fire Science and Engineering
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• v.28 no.5
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• pp.64-70
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• 2014

The neural networks were able to be used by analyze fire source with the optical characteristics of smoke particles. The neural networks were learned the optical characteristics for three types test fire (paper, wood, flammable liquid). These test fires which were adopted in this study were also used to performance test of smoke detector according to UL268. A smoke chamber which was able to detect light extinction and scattering simultaneously was created. The optical characteristics of smoke particles were measured by the smoke chamber. And the results were used to input data for the neural networks. The neural networks distinguished the fire source accurately for paper fire, wood fire or flammable liquid fire. The neural networks distinguished accurately the combined fire source such as paper-wood fire, paper-flammable liquid fire or wood-flammable liquid fire.

• Journal of the Optical Society of Korea
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• v.20 no.5
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• pp.557-562
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• 2016

In this paper, for the first time, the transmission performances of long-haul 100-Gb/s direct detection optical OFDM (DDO-OFDM) and coherent optical OFDM (CO-OFDM) wavelength division multiplexing (WDM) systems are compared by simulation. It provides specific guides for system parameter selection to get a high-performance and cost-effective OFDM WDM system. Specifically, the comparison involves three aspects: launched power is investigated to achieve better system performance; laser linewidth is numerically investigated to choose cost-effective laser; system dispersion tolerances with different laser linewidths are analyzed to further reveal the advantages and disadvantages of these two detecting methods, direct detection and coherent detection, in long-haul OFDM WDM system.

• IE interfaces
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• v.14 no.2
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• pp.148-157
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• 2001

This paper considers a network restoration algorithm for all-optical WDM networks. As the increasing traffic and transmission speed, any failure on the networks will lead to loss of huge data and disruption of the services. Therefore, a network restoration algorithm is necessary for the high-speed all-optical networks. This paper suggests a distributed restoration algorithm for line or channel level failures under the dynamic rerouting. For the algorithm, some measures for performance evaluation are explicitly derived and simulation studies are exploited to evaluate its usability by SLAM(Simulation Language for Alternative Modeling) II.

• ETRI Journal
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• v.30 no.2
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• pp.301-307
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• 2008

As broadband access is evolving from digital subscriber lines to optical access networks, Ethernet passive optical networks (EPONs) are considered a promising solution for next generation broadband access. The point-to-multipoint topology of EPONs requires a time-division multiple access MAC protocol for upstream transmission. In this paper, we propose a new enhanced dynamic bandwidth allocation algorithm with fairness called EFDBA for multiple services over EPONs. The proposed algorithm is composed of a fairness counter controller and a fairness system buffer in the optical line terminal. The EFDBA algorithm with fairness can provide increased capability and efficient resource allocation in an EPON system. In the proposed EFDBA algorithm, the optical line termination allocates bandwidth to the optical network units in proportion to the fairness weighting counter number associated with their class and queue length. The proposed algorithm provides efficient resource utilization by reducing the unused remaining bandwidth made by idle state optical network units.

• ETRI Journal
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• v.29 no.2
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• pp.255-257
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• 2007

We propose an improved selective randomized load balancing (ISRLB) robust scheme under the hose uncertainty model for a special double-hop routing network architecture. The ISRLB architecture maintains the resilience properties of Valiant's load balancing and reduces the network cost/propagation delay in all other robust routing schemes.

• Journal of Communications and Networks
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• v.9 no.4
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• pp.368-376
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• 2007

The large potential bandwidth available in wavelength-division multiplexed optical networks makes this technology of crucial importance for satisfying the ever increasing capacity requirements of the next-generation Internet. In this scenario, the routing and wavelength assignment(RWA) problem that concerns determining the optical paths and wavelengths to be used for connection establishment in a wavelength-routed network, is still one of the most important open issues. In this paper we propose a new online dynamic grooming-capable RWA heuristic scheme working on wavelength division multiplexing(WDM) networks as a multistage selection process. The proposed algorithm is transparent with respect to the presence of wavelength converters, achieves very low connection rejection ratios with minimal computational complexity and is appropriate for the modern multilayer optical circuit and wavelength switched networks with sparse wavelength conversion capability.

• Journal of Communications and Networks
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• v.9 no.4
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• pp.394-401
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• 2007

High speed all optical network is a viable option to satisfy the exponential growth of internet usage in the recent years. Optical networks offer very high bit rates and, by employing technologies like internet protocol over wavelength division multiplexing(IP-over-WDM), these high bit rates can be effectively utilized. However, failure of a network component, carrying such high speed data traffic can result in enormous loss of data in a few seconds and persistence of a failure can severely degrade the performance of the entire network. Designing IP-over-WDM networks, which can withstand failures, has been subject of considerable interest in the research community recently. Most of the research is focused on the failure of optical links in the network. This paper addresses the problem of designing IP-over-WDM networks that do not suffer service degradation in case of a single link failure. The paper proposes an approach based on the framework provided by a recent paper by M. Kurant and P. Thiran. The proposed approach can be used to design large survivable IP-over-WDM networks.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.10C
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• pp.937-944
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• 2002

The current fast-growing Internet traffic is demanding more and more network capacity. Photonic packet switching offers high-speed, data rate/format transparency, and configurability, which are some of the important characteristics needed in future networks supporting different forms of data. In this paper, we define that optical backbone networks for IP transport consist of optical packet core switches and optical fibers. We propose a multi-link photonic packet switch managing as single media which unifies the whole bandwidth of multiple wavelengths on the optical fiber in the WDM optical networks. The proposed switch uses optical packet memories of output link equally as well as using the WDM buffer. So it cuts down the required number of buffers and realizes of the optical packet memory economically.

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.880-883
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• 2002

We propose an effective wavelength converter method using frequency shifter for photonic node, and examine the scalability of Generalized Multiprotocol Label Switching (GMPLS) networks. The ana1ysis is examined based on signal to noise ratio (SNR) for present 2.4 and 10 Gbit/s Synchronous Digital Hierarchy (SDH) networks, and next generation 2.7 and 10.8 Gbit/s Optical Transport Networks (OTN) format The proposed 100 channels GMPLS networks using optical frequency shifters are shown to be applicable to transmission network spanning over 1206 km(24 nodes) in 2.7 Gbit/s trunk networks. Transmission over more than 310 km (6 nodes) is also possible in 2.7 Gbit/s Metroporitan Area Networks(MAN).