• Title/Summary/Keyword: WDM networks

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Design and Performance Analysis of a Multi Wavelength Terahertz Modulator Based on Triple-Lattice Photonic Crystals

  • Ji, Ke;Chen, Heming;Zhou, Wen
    • Journal of the Optical Society of Korea
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    • v.18 no.5
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    • pp.589-593
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    • 2014
  • Terahertz (THz) communication has important applications in high-speed and ultra broadband wireless access networks. The THz modulator is one of the key devices in a THz communications system. Wavelength division multiplexing (WDM) can expand the capacity of THz communications systems, so research on multi wavelength THz modulators has significant value. By combining photonic-crystal and THz technology, a novel type of multi wavelength THz modulator based on a triple-lattice photonic crystal is proposed in this paper. Compared to a compound-lattice photonic crystal, a triple-lattice photonic crystal has a larger gap width of 0.196. Simulation results show that six beams of THz waves can be modulated simultaneously with high performance. This modulator's extinction ratio is as large as 34.25 dB, its insertion loss is as low as 0.147 dB, and its modulation rate is 2.35 GHz.

Optical Super-highway Network Maintenance and System Trends (초고속통신망 광케이블의 유지보수 및 시스템 발전방향)

  • Choi, Shin-Ho;Lee, Byeong-Wook;Park, Kap-Seok;Jang, Eun-Sang;Kim, Seong-Il
    • Proceedings of the KIEE Conference
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    • 1998.07g
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    • pp.2495-2497
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    • 1998
  • Fiber optic facilities are increasingly being deployed in loop applications for both busines and residential areas. These facilities support a variety of communications services that include high speed data and video using leading technologies such as Synchronous Optical Network (SONET), Wavelength Division Multiplexing(WDM). This proliferation of fiber optic facilities combined with the increasing pressure on network operators to reduce costs are fostering increased automation to reduce labor costs associated with providing and maintaining communications services. Effective fiber management and accurate records can improve the reliability and integrity of the future telecommunications networks and the quality of customer services. This paper describes the trend forward and the need for the deployment of Fiber Administration System (FAS) into the operations enviroment of a typical network provider.

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Trend of Monitoring Methods of Wavelength Division Multiplexed Optical Networks (파장분할다중방식 광통신망의 모니터링 방식에 관한 기술 동향)

  • Lee, W.R.;Cho, S.H.;Kim, B.K.;Park, J.D.;Kim, B.H.
    • Electronics and Telecommunications Trends
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    • v.19 no.5 s.89
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    • pp.125-133
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    • 2004
  • 파장분할 다중방식 광통신망(WDM -PON) 운영의 신뢰성을 높이기 위해 각 광 채널의 파장과 파워, 그리고 광섬유로 이어진 링크(link)의 절단상태 등을 모니터링(monitoring)하는 것은 필수적이다. 본 원고에서는 이러한 목적을 효율적이고 경제적으로 달성하기 위해 제시되고 검증되었던 방법들을 pilot tone을 이용한 방법, AWG, FBG, tunable filter 등의 파장 선택성 소자를 이용한 방법, electrical processing을 이용한 방법 등의 세 가지로 나누어 소개한다.

Multiple PON repeater/aggregator for the optimization of FTTH based access networks (FTTH 기반 가입자망 최적화를 위한 PON 다중 중계 장치)

  • Yoon, Ho-Sung;Kim, Chong-Ahn;Park, Jae-Hyoung;Kim, Jin-Hee
    • 한국정보통신설비학회:학술대회논문집
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    • 2008.08a
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    • pp.292-295
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    • 2008
  • We propose a PON repeater system which transports multiple PON channels at the same time over the physical limit of the standard E-PON reach. To increase the physical reach up to 60km, we used the O-E-O (optic-electric-optic) signal regeneration on an active remote terminal which is placed between a central office and passive remote nodes. Also, by incorporating the well-established WDM technology to aggregate multiple E-PON channels, we successfully increased the split ratio (the number of subscribers per fiber core) to over 256.

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A Inter-layer Path Provisioning System Architecture in Multi-layer Networks (다계층 광네트워크에서 계층간 경로설정 시스템 구조 연구)

  • Kim, Hyuncheol
    • Convergence Security Journal
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    • v.13 no.3
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    • pp.25-31
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    • 2013
  • Looking at the recent value change of users and the usage pattern of network users, it is changing from simple web information, one-way information acquisition and data transmission to increase of usage of multimedia, increasing demand for security and customization, and increasing demands for free mobility. Due to this change of demand, the services which were provided individually, developed into a form which is merged, the network also seems to develop into the combined network from the individual network for individual service, and the communication network control technology which is the core technology is also rapidly developing. To reflect the users' demands, the next generation network created the multi-layer network which is based on the WDM/IP transmission system and added the to make it easy to restructure. P-OTS (Packet-Optical Transport System) can be defined as a platform that combines SONET/SDH, Ethernet, DWDM, optical transport network (OTN) switching and reconfigurable optical add-drop multiplexers (ROADMs). In this paper, we suggested that the optimum path choice be performed through diversification of the PCE-based path selection using the information of various layers altogether in the multi-layer environment, compared with the established path selection method when the path was selected using the information of each layers.

A Tunable Transmitter - Tunable Receiver Algorithm for Accessing the Multichannel Slotted-Ring WDM Metropolitan Network under Self-Similar Traffic

  • Sombatsakulkit, Ekanun;Sa-Ngiamsak, Wisitsak;Sittichevapak, Suvepol
    • 제어로봇시스템학회:학술대회논문집
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    • 2004.08a
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    • pp.777-781
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    • 2004
  • This paper presents an algorithm for multichannel slotted-ring topology medium access protocol (MAC) using in wavelength division multiplexing (WDM) networks. In multichannel ring, there are two main previously proposed architectures: Tunable Transmitter - Fixed Receiver (TTFR) and Fixed Transmitter - Tunable Receivers (FTTR). With TTFR, nodes can only receive packets on a fixed wavelength and can send packets on any wavelengths related to destination of packets. Disadvantage of this architecture is required as many wavelengths as there are nodes in the network. This is clearly a scalability limitation. In contrast, FTTR architecture has advantage that the number of nodes can be much larger than the number of wavelength. Source nodes send packet on a fixed channel (or wavelength) and destination nodes can received packets on any wavelength. If there are fewer wavelengths than there are nodes in the network, the nodes will also have to share all the wavelengths available for transmission. However the fixed wavelength approach of TTFR and FTTR bring low network utilization. Because source node with waiting data have to wait for an incoming empty slot on corresponding wavelength. Therefore this paper presents Tunable Transmitter - Tunable Receiver (TTTR) approach, in which the transmitting node can send a packet over any wavelengths and the receiving node can receive a packet from any wavelengths. Moreover, the self-similar distributed input traffic is used for evaluation of the performance of the proposed algorithm. The self-similar traffic performs better performance over long duration than short duration of the Poison distribution. In order to increase bandwidth efficiency, the Destination Stripping approach is used to mark the slot which has already reached the desired destination as an empty slot immediately at the destination node, so the slot does not need to go back to the source node to be marked as an empty slot as in the Source Stripping approach. MATLAB simulator is used to evaluate performance of FTTR, TTFR, and TTTR over 4 and 16 nodes ring network. From the simulation result, it is clear that the proposed algorithm overcomes higher network utilization and average throughput per node, and reduces the average queuing delay. With future works, mathematical analysis of those algorithms will be the main research topic.

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QoS Supporting Scheme Considering Service-Differentiation Ratio in Optical Burst Switching Networks (광 버스트 스위칭 망에서 서비스 차등률을 고려한 QoS 제공 기법)

  • 소원호;김영천
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.27 no.12C
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    • pp.1197-1206
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    • 2002
  • Recently, the research on the construction of optical Internet backbone networks using WDM has been actively progressed. In this paper, we propose the offset based service-differentiation scheme in optical burst switching (OBS) networks. We classify the services into two classes; high class and low class. The proposed scheme decides the offset time of high class so as to satisfy the required burst loss rate (BLR) of services according to the service-differentiation ratio (SDR). The SDR may be set depending on the environment of OBS network and user's requirements, our scheme decides the BLR of high class by using the required SDR and conservation law. Finally, we use the offset time decision (OTD) algorithm to determine the offset time of high class. The proposed scheme is evaluated through simulation. The result of simulation is compared with that of analysis to verify the proposed scheme.

Fault-Management Scheme for Recovery Time and Resource Efficiency in OBS Networks (OBS 망에서 복구 시간과 자원의 효율성을 고려한 장애 복구 기법)

  • 이해정;정태근;소원호;김영천
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.28 no.9B
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    • pp.793-805
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    • 2003
  • In OBS (Optical Burst Switching) networks which decouple the burst from its header, the fault of a fiber link can lead to the failure of all the light-path that traverses the fiber. Because each light-path is expected to operate at a rate of a few Gbps by using WDM (Wavelength Division Multiplexing) technology, any failure may lead to large data loss. Therefore, an efficient recovery scheme must be provided. In this paper, we analyze network utilization and BCP (Burst Control Packet) loss rate according to each link failure by applying the conventional restoration schemes in OBS networks. And through these simulation results, an ASPR scheme is proposed improve the fault management scheme in terms of recovery time and throughput. Finally, We compare the performance of our proposed scheme with that of the conventional one with respect to burst loss rate, resource utilization and throughput by OPNET simulations.

Consolidation of Metro Networks and Access Networks by using Long-reach WDM-PON (장거리 전송 파장분할 다중방식 수동형 광가입자망을 이용한 메트로망과 가입자망 통합 방안)

  • Lee Sang-Mook;Mun Sil-Gu;Kim Min-Hwan;Lee Chang-Hee
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.43 no.5 s.347
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    • pp.59-67
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    • 2006
  • We demonstrate bidirectional long-reach 35-channel dense wavelength division multiplexing-passive optical network(DWDM-PON) based on wavelength-locked Fabry-Perot laser diodes (F-P LDs). The mode control of F-P LD enhances output power at decreased the required injection power. We show packet-loss-free transmission in all 70 channels at 125 Mb/s per channel line rate through 70 km of single mode fiber without optical amplifier The DWDM-PON can consolidate a metro network into an access network by bypassing the central offices within its reach. The proposed DWDM-PON can accommodate about 80 subscribers with an EDFA-based broadband light source. Further expansion up to 100 subscribers is possible with a semiconductor-based BLS.

Design and Performance Evaluation of Offset Time Decision Algorithm for Guaranteeing the QoS in Optical Burst Switching Networks (광 버스트 스위칭 망에서 QoS 보장을 위한 Offset 시간 결정 알고리즘 설계 및 성능 평가)

  • So, Won-Ho;Cha, Yun-Ho;Roh, Sun-Sik;Kim, Young-Chon
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.27 no.1C
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    • pp.1-10
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    • 2002
  • With the explosive growth of the number of Internet users and Internet-related services, the research on construction of broadband Optical Internet by using WDM technologies is actively is actively progressed. In this paper, we design the offset time decision (OTD) algorithm for supporting the QoS in optical networks based on optical burst switching (OBS), which is the new switching paradigm, and evaluate the performance of it. The proposed algorithm determines a reasonable offset time considering traffic load of network and the number of wavelengths to guarantee the burst loss rate (BLR) of high priority Internet traffic as a QoS parameter. In order to design the proposed OTD algorithm, firstly we make the new burst loss formula, which includes the effect of offset time. The decision of offset time corresponding to the requested BLR, however, should use the reverse formula of proposed one, thus we are not able to use it without any changes. In this paper, we define the heuristic loss formula (HLF) that can be changed into reversed formula by using the proposed formula and proportional equation considering its characteristics. Finally we show the OTD algorithm to decide the offset time by using HLF. We show that the requested BLR is guaranteed under various traffic load with the determinded offset time by using the proposed OTD algorithm.