• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.12
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• pp.27-37
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• 2003

In the next generation Internet(NGI) based on dense wavelength division multiplexing(DWDM) technology, QoS RWA considering various QoS parameters of DWDM networks is regard as one of the key issues in providing real-time multimedia services. However, finding a qualified path meeting multi-constraints is generally NP-complete problem. It is insufficient for QoS RWA researches in DWDM networks that must consider QoS parameter as well as wavelength-continuity constraint. This paper proposes qualified path routing (QPR) algorithm with minimum computation and implementation complexity based on flooding method to accomplish QoS routing and wavelength assignment (RWA). We also introduce a QoS-based RWA mechanism considering multi-constraint such as optical signal quality attributes, survivability and wavelength-continuity constraint combined with proposed routing algorithm. Simulation results show superior efficiency of the proposed algorithms in terms of blocking probability, routing overhead and survivability ratio.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.9A
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• pp.1405-1412
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• 2000

In this paper, we propose an efficient dynamic wavelength assignment algorithm in distributed WDM (Wavelength-Division Multiplexing) networks without wavelength conversion. The algorithm tries to assign a locally-most-used wavelength distributedly on a fixed routing path. We first formulate our algorithm by using the concept of a sample space which consists of optical fibers connected to nodes on a routing path of a lightpath to be assigned a wavelength. In particular, we analyze the blocking performance mathematically as compared with that of the most-used (MU) wavelength assignment algorithm previously proposed for WDM networks under centralized control. We also obtain numerical results by simulation on the blocking performance of other centralized/distributed wavelength assignment algorithms as well as our algorithm using the M/M/c/c dynamic traffic model. Consequently, we show that analytical results match simulation results and that our algorithm is efficient in distributed WDM networks in terms of blocking performance, control traffic overhead and computation complexity.

• ETRI Journal
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• v.31 no.2
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• pp.231-233
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• 2009

We propose a nonreciprocal filter based on coarse wavelength division multiplexing (CWDM) that reduces the upstream channel insertion loss in a passive optical network (PON). We also propose a method to increase the number of channels/optical network units (ONUs) in PON systems using the proposed filter to reduce the service cost per subscriber. Experimental results show that the PON system with the proposed 4-channel filter can reduce the power budget of the upstream and increase the number of ONUs by 3 to 4 times that of a conventional time-division multiplexing PON.

• Current Optics and Photonics
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• v.8 no.2
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• pp.156-161
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• 2024

Recently, a new kind of optical multiplexing called optical-receiver-mode (ORM)-division multiplexing (ORMDM) has been proposed, in which an optical channel is a linear sum of ORM subchannels modulated independently. Using coherent-optical (CO) techniques, it has been reported that COORMDM communication systems can have very high spectral efficiencies (SEs). To estimate the SEs of CO-ORMDM communication systems, we introduce a new method of crosstalk analysis. Using this method, we can allocate quadrature-amplitude-modulation (QAM) codes and QAM step sizes unevenly over ORM subchannels to obtain higher SEs. With 50 Gaussian ORMs, we obtain a SE of up to 15.29 bit s^-1 Hz^-1.

• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.73-76
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• 2003

The capacity of backbone networks has largely kept pace with the tremendous of growth of Internet traffic. But there has been little progress in the access networks. In this paper, we introduce the access network that is able to offers high bandwidth and its simple protocol. The network architecture is basically multiple ring and use WDM(Wavelength Division Multiplexing), SCM (SubCarrier Multiplexing), and static WADM (Wavelenth Add/Drop Multiplexer) for simplicity, low cost, and offering high bandwidth.

• Proceedings of the Optical Society of Korea Conference
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• 2003.07a
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• pp.110-111
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• 2003

Holographic demultiplexer for the wavelength-division multiplexing optical communication system is proposed, and some experimental results are presented. To record the multiple holographic grating channels in the Fe：LiNbO$_3$ crystal, angular multiplexing and High-Low thermal fixing method are used.

• ETRI Journal
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• v.24 no.2
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• pp.131-141
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• 2002

This paper considers a routing and wavelength assignment problem (RWAP) for the implementation of efficient Wavelength Division Multiplexing all-optical mesh networks without wavelength conversion. For a given physical network and required connections, the solution to the RWAP consists in how to select a suitable path and wavelength among the many possible choices for each connection so that no two paths using the same wavelength pass through the same link, while minimizing the number of required wavelengths. We introduce an integer programming formulation of the RWAP, which has an exponential number of variables, and propose an algorithm to solve it based on the column generation technique. The proposed algorithm can yield high quality solutions and tight lower bounds at the same time. Though the proposed algorithm cannot guarantee optimal solutions, computational results show that the algorithm yields provably good solutions within a reasonable time.

• The Transactions of the Korea Information Processing Society
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• v.7 no.12
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• pp.3952-3963
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• 2000

This paper considers the WRA(Wavelength and Houting Assignment) problem on all-optical tree networks using WDM(Wavelength Division Multiplexing). Each link between a pair of request nodes on all optical networks is assigned different wavelengths because of technical constraint. On the basis of this, we give an polynomial time algorithm to assign wavelengths to the all patbs of a arbitrary tree network using divide and conquer method. The time complexity of this algorithm is O(Q. R), in which Q is the request nodes for all to'all communication in a tree topology and U is the maximum number of wavelength. Also we implemented our algorithm using C in Pentium II 233MHz and analyzed performance results.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.1
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• pp.33-38
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• 2005

A cost-effective dense WDM-PON employing wavelength-locked Fabry-Perot lasers has been demonstrated. We have successfully demonstrated a dense WDM transmission of 4×622 Mb/s upstream signal with 50-GHz channel spacing over 30-km conventional single mode fiber. We have also investigated the heating noise characteristics of a wavelength-locked Fabry-Perot laser and showed the wavelength-locked Fabry-Perot laser suppresses the intensity noise of the incoherent light injected which enables a dense WDM transmission with a channels spacing of 50 GHz.

• Proceedings of the Optical Society of Korea Conference
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• 2002.07a
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• pp.166-167
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• 2002

광자 크리스탈은 빛의 진행을 제어할 수 있는 잠재적인 능력과 Wavelength Division Multiplexing 통신 시스템에서 광소자의 구현 가능성 때문에 활발히 연구가 진행 중이다. (1-3) 본 논문에서는 광자 크리스탈의 채널 드롭 터널링 현상을 이용하여 1x4 Demultiplexer의 구현 가능성을 고찰하였다. 광자 크리스탈을 이용해서 공진 시스템을 구성하였고, 중앙에 위치한 2개의 작은 디펙트의 크기를 조절하여 채널 드롭 현상을 관찰하였다. (중략)