• Proceedings of the Korea Information Processing Society Conference
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• 2000.04a
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• pp.715-718
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• 2000

본 논문은 WDM 광 통신망에서 망의 효율적인 설계에 필요한 알고리즘에 관한 것이다. WDM 광 통신망은 경로설정 및 파장할당이 중요한 변수로 s-d 노드 쌍간에 필요한 연결수요가 주어질 때 이 연결수요를 만족시켜주는 광 경로를 설정하고, 파장을 할당해 줌으로써 사용 파장수를 최소화하면서 파장을 재사용 할 수 있는 효율을 최대로 하는 것이 목적이다. WDM 방식을 이용하여 전기적 변환에 따른 지연 없이 전광통신망에서 여러 개의 파장을 다중화하여 동시에 자료를 전송함으로서 수Gbps, 혹은 그이상의 전송이 가능해질 것으로 기대되어 진다. 이들 설계 문제들은 일반적인 토폴로지 망에서 정적인 경로 설정 및 파장할당을 대상으로 하여 발견적인 알고리즘을 얻고자 하였다. 또한 이를 통해 LP모형으로 얻은 하한 한계 값과 휴리스틱 알고리즘의 최소파장수와 동일한 값이 나올 수 있는 알고리즘을 구하였다.

• The Transactions of the Korea Information Processing Society
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• v.5 no.8
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• pp.2013-2026
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• 1998

In optical passive star interconnections, all packets are transmitted between nodes ina broadcast and-select manner. It is assumed that each node has a innable transmitter and a fixed-savelength receiver, ad that all packet lengths are equal so that each transmission can be done in a unit time. The tuning delay, denoted by $\delta$, means the amount of time for transmitter to change its wavelength to another one. The problec is , given ay value of the mumber of nodes N and the number of wavelengths $\kappa$ according to WDM implementations, to find transmission schedules with minimum cycle length for all-to all brondcaxt where no one sends any packet to itself. In this paper, we prove that the cycle length of optimal transcission schedules should be at least $max[[{\frac{N}{k}](N-1)}]$,$k\delta$$+N-1$. A novel algorithm for optimal transmission schedules is then presented when N-1 is divisible by $\kappa$. This algorithm also can be used for any values of N and $\kappa$ if the tuning delay $\delta$ does not affect strictly the cycle length of transmission schedules, i,e, $[\frac{N}{k}](N-1)$ > $\kappa\delta$+N-1.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.8B
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• pp.721-729
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• 2004

In this paper, we applied a group scheduling algorithm to core nodes in an optical burst switching (OBS) network and measured its performance by simulation. For the case of core nodes with multi-channel input/output ports, performance of the group scheduling has been compared to that of the immediate scheduling. Since the group scheduling has a characteristic of scheduling a group of bursts simultaneously in a time window using information collected from corresponding burst header packets arrived earlier to a core node, simulation results show that the group scheduling outperforms the immediate scheduling in terms of both burst loss probability and channel utilization and the difference gets larger as the load increases. Another node configuration in which wavelength converters are equipped at the output ports has also been considered. In this case, even though both performance metrics of the group scheduling are almost the same as those of the immediate scheduling in the offered load range between 0.1 and 0.9, the group scheduling has lower wavelength conversion rate than the immediate scheduling by at least a factor of seven. This fact leads us to the conclusion that the group scheduling makes it possible to implement more economical OBS core nodes.

• Journal of KIISE:Information Networking
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• v.36 no.4
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• pp.286-296
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• 2009

A major challenge in next generation optical Internet (NGOI) networks based on dense-wavelength division multiplexing (DWDM) is the provision of guaranteed quality-of-service (QoS) for a wide variety of multimedia applications. One of the critical issues in NGOI is the routing and wavelength assignment problem that is embossed as very important and plays a key role in improving the global efficiency for capacity utilization. But the previous researches had the delay problem, and the path routed by higher priority nodes may be congested and interfere with potential future multicast session requests. To overcome these problems, in this research we suggest a Priority-based Minimum Interference Path Multicast Routing (PMIPMR) algorithm, a new routing algorithm which finds alternative routes based on node priorities and Virtual Source (VS) nodes that has both splitting and wavelength conversion, and then chooses a path that does not interfere with potential future multicast session requests when congestions occur in the network. The PMIPMR algorithm reduces blocking rate significantly and increases the wavelength utilization by avoiding congestion in future multicast session requests.

• 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.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.6B
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• pp.583-591
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• 2011

We presents the architecture of the 2.5 Gbps hybrid PON link which can increase of the transmission distance and link capability, and split ratio by using a colorless DWDM-PON and O/E/O based reach extender into an existing G-PON link. A RSOA based DWDM-PON to apply the feeder fiber can provide a link capacity of 32 larger that of a legacy G-PON. The reach extender converts the wavelength of DWDM-PON to G-PON through GTC frame regeneration at the remote node, and can provide a burst reset signal in order to extract upstream burst signal, simultaneously. The proposed hybrid PON enable a legacy G-PON to operate over the maximum 60 km distance with a 128-way split per WDM wavelength.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.12
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• pp.41-49
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• 2004

Increase of internet users and new types of applied traffics, have led to demand for more bandwidth for each application. Hence, the amount of internet traffic has risen sharply and it has demanded to use limited resources, such as wavelength and bandwidth, more effectively. These kind of needs can be satisfied with OXC(Optical cross-connects) based on GMPLS that carry out IP packet switching and wavelength switching at the same time and Provide very wide bandwidth. In RSVP-TE signaling of GMPLS studied by IETF. every lambda router in core network should be able to convert wavelength. So, lots of wavelength converters and needed and building and managing cost is high. Another problem is that optimized traffic is limited. In this paper We suggest strengthened GMPLS RSVP-TE signaling algorithm for a better lightpath setup. When setup signaling is blocked suggested algorithm does not send PathErr message to Edge Router, but looks for nearest lambda router which can convert wavelength and carry out setup signaling from that node. Such algorithm can reduce the chance of blocked lightpath setup signaling and provide effective arrangement of lambda router in core network by calculating proper number of wavelength converter.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.11
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• pp.44-52
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• 1998

In this paper, we proposed a node architecture and cell routing strategies for ATM applications in WDM multihop networks. The proposed node architecture employs the optical delay loop for storing the cell which is failed in out-link contention. This optical delay loop allows the delay of one cell without the electro-optic conversion. Therefore, we can get the advantages of S&F(Store-and-Forward) routing in Deflection-based all-optical networks. To support the ATM applications efficiently. we considered the transmission priority of ATM cell so that high priority cell can be transmitted with lower loss and shorter delay than low priority one. Two kinds of routing strategies are designed for this architecture: Scheme-Ⅰand Scheme-Ⅱ. Scheme-Ⅰapplies S&F routing to high cell and Deflection routing to low cell, i.e., high cells are routed along the shortest path based on S&F routing, but low cells are deflected or lost. Schem-Ⅱ is similar to Scheme-Ⅰexcept that low cells can occupy the optical loop if it is available. This Scheme-Ⅱ increases the utilization of network resources without decreasing the throughput of high cell by reducing the low cell loss rate when traffic load is low. Simulation results show that our routing strategies have better performance than conventional ones under non-uniform traffic as well as uniform traffic.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.12B
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• pp.1037-1043
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• 2006

There has been proposed an algorithm to reduce data burst processing delay in group scheduling in core nodes of optical burst switching networks. Since, in this algorithm, look-up tables containing all the void time information in scheduling windows are generated as soon as the primary group scheduling session terminates, it becomes faster to reassign dropped data bursts to proper voids in different data channels by referring to the tables. The group scheduling with this algorithm showed almost the same channel utilization as the one without using the algorithm but performed a little better in both burst loss probability and wavelength conversion rate. On the other hand, per-burst processing time has been reduced dramatically in the load region of higher than 0.8, showing a factor of 2.1 reduction at 0.9.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.10A
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• pp.912-921
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• 2005

Optical burst switching(OBS) is a promising solution for building terabit optical routers and realizing If over WDM. Channel scheduling Algorithm for reduce contention is one of the major challenges in OBS. We address the issue of how to provide basic burst channel scheduling in optical burst switched WDM networks with fiber delay lines(FDLs). In OBS networks the control and payload components or a burst are sent separately with a time gap. If CHP arrives to burst switch node, because using scheduling algorithm for data burst, reservation resources such as wavelength and transmit data burst without O/E/O conversion, because contention and void between burst are happened at channel scheduling process for data burst that happened the link utilization and bust drop probability Existent proposed methods are become much research to solve these problems. Propose channel scheduling algorithm that use Release Time of bust to emphasize clearance between data and data dissipation that is happened in data assignment in this treatise and maximize bust drop probability and the resources use rate (RTUC : Release Time Unscheduled Channel). As simulation results, Confirmed that is more superior in terms of data drop and link utilization than scheduling algorithm that is proposed existing. As simulation results, confirmed improved performance than scheduling algorithm that is proposed existing in terms of survival of burst, efficiency resource and delay. However, In case load were less, degradation confirmed than existent scheduling algorithm relatively, and confirmed that is superior in data drop aspect in case of load increased.