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Photonic Networks, 2006 ITG Symposium on

Date 27-28 April 2006

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Displaying Results 1 - 22 of 22
  • Optical Delay Selection in WDM PON¿s using a Multi-Path tunable AWG Maze

    Page(s): 1 - 2
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (595 KB)  

    We described a reconfigurable multi-path maze optical-delay device, based on an active AWG, exhibiting a full-complement of selectable optical delays in a compact, flexible and integrated design. Such a device may find important application in optical packet switching architectures and optical router buffers. View full abstract»

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  • Flexible WDM Solution for DSL Backhaul

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1399 KB)  

    DSL backhaul is an increasingly important access application for metro optical networking. It is driven by massive rollouts of triple-play and IPTV services. Critical challenges for optical networks in supporting DSL mass rollout are simplicity, cost, and scalability. We propose the concept of a Gigabit Ethernet or Multi-Service Add/Drop Multiplexer (GbE/MS- ADM) which is directly combined with CWDM access technology. We show that such a GbE/MS-ADM provides superior access flexibility, together with a net bandwidth gain for multicast services over static solutions, and also enhanced optical parameters which again make it more useful as compared to standard OADM technology. Since the GbE/MS-ADM is based on 4-Gb/s technology, it is also cost-optimized over 2G5 and 10G solutions, and also over Black Link alternatives. View full abstract»

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  • Protected Ethernet Rings for Optical Access Networks

    Page(s): 1 - 8
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (799 KB)  

    In this paper we propose a centralized link layer architecture for providing low latency fault recovery for optical access rings. This architecture exploits the naturally uneven breakdown of network management responsibilities between the components of an access ring. Important administrative operations like ring status checking, fault detection and recovery are aggregated at the HUB component located in the Central Office of the access network. Consequently, when compared with a standardized Rapid Spanning Tree Protocol implementation, the design of the proposed architecture benefits from a simplified link layer design of the Optical Network Unit, in addition to a significantly reduced fault recovery delay in the ring. We also present an Ethernet-based protocol that realizes our centralized protection model. The design principle of this protocol, responsible for the message passing required to react to topology changes in the network, is simple enough to allow quick reaction times, and to supportQoS-aware prioritization of network traffic. The performance of the proposed architecture is evaluated using analytical and simulative means, and the performance aspects of the ring protocol relevant to network protection are compared with those provided by the Rapid Spanning Tree Protocol. View full abstract»

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  • High-speed Transmission based on a 40 Gbaud DQPSK System

    Page(s): 1 - 5
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1065 KB)  

    We describe a high-speed transmission system with a data rate = 80 Gbit/s. The system is based on RZ-DQPSK modulation with a symbol rate of 40 Gbaud. The experimental setup is described and discussed in detail. The transmitter to generate the DQPSK data signal consists of an RZ-pulse source and two cascaded phase modulators. The receiver contains a demodulator and a balanced photodetector. Compared to an OOK system, a DQPSK system with the same data rate has a reduced symbol rate and a higher spectral efficiency. Therefore the combination of DQPSK systems with multiplex techniques is very attractive. In this paper we present experiments where a data rate = 80 Gbit/s is reached by combining DQPK with wavelength-, time division and polarization multiplexing. Error-free transmission (BER < 10(exp -9) without FEC) of 640 Gbit/s in a single wavelength channel over 6 times 80 km is demonstrated. View full abstract»

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  • A robust modulation format for 42.8-Gbit/s long-haul transmission: RZ-DPSK or RZ-DQPSK?

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1265 KB)  

    In this paper we investigate the difference in transmission impairments between 42.8-Gbit/s RZ-DPSK and RZ-DQPSK modulation for long-haul transmission on a 50-GHz grid. We analyze the impact of narrowband filtering and discuss the influence it has on long-haul transmission using the RZ-DPSK and RZ-DQPSK modulation formats. View full abstract»

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  • DWDM Transmission of OTU3 (43 Gb/s) Data over 7000km of Conventional Non-Zero Dispersion Shifted Fiber

    Page(s): 1 - 3
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (428 KB)  

    We report DWDM transmission of 50 x 43 Gb/s (ITU-T G.709 OTU3 format) NRZ-DPSK channels over 7000km of conventional NZDSF, using a mixed Raman/EDFA system with 100km/22dB spans and an advanced FEC implemented in the OTU3 frame. View full abstract»

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  • MPLS Protection: Required Enhancements for Carrier-Grade Functionality

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1339 KB)  

    The article investigates the protection characteristics of MPLS Fast Reroute (FRR), which is the predominant protection and restoration scheme in today¿s MPLS networks. It examines whether fast reroute provides the level of protection that a network operator expects and is used to. Capabilities of FRR are compared with those of SDH protection schemes. Developing a functional model of FRR it is shown where weaknesses of FRR exist and what means are necessary to further enhance this scheme to become carrier-grade. View full abstract»

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  • Backup Capacity Requirements for MPLS Fast Reroute

    Page(s): 1 - 8
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (858 KB)  

    MPLS fast reroute (MPLS-FRR) mechanisms deviate the traffic in case of network failures at the router closest to the outage location to achieve an extremely fast reaction time. We review and compare the one-to-one backup and the facility backup concept that are options for MPLS-FRR to deviate the traffic via a detour or a bypass, respectively. Basically, the backup paths can take the shortest path that avoids the outage location from the point of local repair to the tail-end router or to the merge point. We then evaluate the backup capacity requirements and the configuration overhead in terms of the number of backup paths per primary path in a parametric study depending on the network characteristics. While the facility backup concept imposes clearly less configuration overhead than the one-to-one backup, its standard path layout requires more capacity. This can be reduced by a simple modification. View full abstract»

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  • Simple and robust link design concept for long haul transmission using equalization techniques

    Page(s): 1 - 4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (949 KB)  

    In this work we investigate the impact of adaptive electrical equalizers in long haul optical transparent transmission links (up to 800 or 1600 km). Electrical equalization has the potential to effectively compensate for distortions caused by chromatic dispersion or self phase modulation and therefore making transmission systems very robust. This will simplify the design and installation of new systems. By intensive numerical simulations we show how the application of receiver-sided equalizers can be used to simplify the dispersion management of optical transparent links, where only DCF-modules with limited compensation range are used. These DCF-modules can compensate only for 80, 20 or 5 km SSMF, respectively and distortions caused by this compensation mismatch will then be equalized at the receiver. By random distributed amplifier spacings it is shown, that even simple electrical equalization leads to an increased system performance in systems with direct detection and the aforementioned dispersion compensation mismatch. View full abstract»

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  • Wavelength-Time Coding for Ultra Dense Wavelength Multiplexing

    Page(s): 1 - 8
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (2147 KB)  

    By reducing channel spacing in dense wavelength division multiplexing (U-DWDM), the total bitrate can be significantly increased. To cope with the resulting strong interchannel interference (ICI), a novel coding scheme is presented, which encodes and decodes in both time and wavelength direction (wavelength-time coding, WTC). The scheme is described in quite some detail. Performance is compared to conventional U-DWDM with strict optical filtering to prevent ICI, however to the expense of increased intersymbol interference (ISI). View full abstract»

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  • MUPBED: ASON/GMPLS Architecture, Interworking Solutions and Test Network Implementations

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (480 KB)  

    European research networks are often seen as ¿early adopters¿ of new network functions, which is mostly due to their goal to support future looking, highly demanding applications in terms of e.g. bandwidth, availability, or dynamic behaviour. In the IST project MUPBED (¿Multi-Partner European Test Beds for Research Networking¿) ASON/GMPLS solutions for next generation research networks are evaluated and a European scale test network is setup for experimental assessments. This paper gives an overview on the MUPBED ASON/GMPLS network architecture and network solutions, and their relation to the European research networks, enabling seamless multi-domain multi-layer interworking among multiple network domains for supporting new, upcoming applications. The paper also describes the implementation of the pan-European MUPBED test bed and how this test bed allows to investigate the developed networking concepts in a field trial environment. View full abstract»

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  • Implementation of UNI in optical multi-layer networks

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (143 KB)  

    The introduction of OIF UNI interfaces in GMPLS-controlled networks enables the dynamic and automatic establishment of connections triggered by client requests. Furthermore UNI interfaces can be used to interconnect server layers, e.g. for setting-up multi-layer networks consisting of a client layer and two or more server layers. This paper describes the design, implementation and test of a GMPLS/SDH prototype which provides UNI-N and UNI-C functionality simultaneously in a multi-layer network setup. Across the UNI-N interface the prototype receives connection requests from the client layer and across the UNI-C interfaces the prototype triggers a lower -layer connection setup if the available bandwidth is not sufficient to fulfil the client request. The prototype supports RSVP-TE as signalling protocol and OSPF-TE/CSPF as routing protocol. The automatically setup of lower-layer connections is realized by an automatic LSP controller. The proper functionality of the prototype has been verified in lab experiments using emulated client and server layers as well as in a field trial with real equipment and traffic. View full abstract»

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  • Traffic Demand Modeling for Dynamic Layer 1 VPN Services

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (675 KB)  

    Dynamic Layer 1 Virtual Private Network (L1VPN) services are an emerging and important network service in future transport networks. While on IP layer VPN concepts are already in use, the realization in lower layers is presently a hot topic in research and standardization. For performance evaluation of a network or network dimensioning a general but concise L1VPN modeling approach is needed. However such a model, which integrates population models as well as different VPN characteristics, is currently not available. In this paper, we outline the fundamental characteristics of VPN traffic in comparison to normal point-to-point traffic and present a generic framework for multi-point demand modeling. Our framework is open for adaptation to different service scenarios defined by population models, capacitated connections and virtual topologies. In order to show the behavior of the framework, we apply it to one selected VPN scenario and examine in two case studies the impact on different metrics important for network dimensioning. View full abstract»

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  • Multi-Layer Neighbor Discovery in Dynamic Transport Networks

    Page(s): 1 - 7
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (771 KB)  

    Neighbor Discovery is a service that may be utilized in ASON/GMPLS based networks to derive and verify transport neighbor relationships with as little manual interaction as possible from the current node configuration. These relationships are then used by services like signaling or routing in order to establish transport connections, support protection switching and path restoration, or automate the inventory process of network operators Various aspects of neighbor discovery within a single transport layer have been addressed by standards of the ITU-T (International Telecommunications Union), the IETF (Internet Engineering Task Force) and the OIF (Optical Internetworking Forum). This work focuses on multi-layer aspects of neighbor discovery, taking into account requirements of different technologies and looking at the interdependencies between multiple transport layers such as Synchronous Digital Hierarchy (SDH)/Synchronous Optical Network (SONET) and Optical Transport Network (OTN). Especially when a server layer is not fixed and provides flexibility or multiple adaptations into the client layer, neighbor discovery in the client layer can become a rather dynamic process. Finally this work investigates neighbor discovery aspects for different interface types like User-to-Network Interface (UNI), the External Network-to-Network Interface (E-NNI) and the Internal Network-to-Network Interface (I-NNI). View full abstract»

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  • Availability and Cost Based Evaluation of Demand-wise Shared Protection

    Page(s): 1 - 8
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (301 KB)  

    In this paper, we investigate the connection availabilities for the new protection scheme Demand-wise Shared Protection (DSP) and describe an appropriate approach for their computation. The exemplary case study on two realistic network scenarios shows that in most cases the availabilities for DSP are comparable with that for 1+1 path protection and better than in case of shared path protection. View full abstract»

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  • Physical Layer Control in Optical Transport Systems

    Page(s): 1 - 3
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (443 KB)  

    We discuss the need for fast control functions in the physical layer of a WDM transport system. Eye-shape distortions as well as power fluctuations are considered. View full abstract»

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  • All Optical Network Dimensioning Considering Transmission Impairments and Mitigation using Electronic Equalization

    Page(s): 1 - 5
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1096 KB)  

    For a given physical network, in the design and planning, transmission technology selection and network optimisation are carried out such that the network is designed and dimensioned to meet the given traffic demand. Two aspects are important: sufficient transmission performance and optimised cost. In this paper, we consider an all optical network, looking into the static routing and wavelength assignment incorporating the physical transmission, , with an objective to assign a wavelength path to each demand and place the amplifiers and dispersion compensation suitably in the network to achieve physical feasibility of the light paths and a cost effective network. Simplified transmission rules were given to allow fast computation and verification of the light paths used in the RWA. Electronic equalisation using MLSE is considered in the network to compensate transmission impairments, its benefit in reducing the in-line dispersion compensation and associated amplifiers of a metro network scenario is quantified. We also show the cost benefit of an all optical implementation over the opaque network. View full abstract»

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  • Monitoring of Meshed Optical Networks using Modified End-Terminals

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (849 KB)  

    Modern optical fibre networks are evolving from static point-to-point connections towards meshed networks with some degree of optical transparency and capability for reconfiguration. At the same time installation and operation shall be simplified, while the availability shall be kept high. In the network design this task can be accomplished by allocation of transmission margins and by control of performance parameters. For efficient implementation information about the various sources of degradation shall be extracted at the end-terminals. View full abstract»

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  • Adaptive-Modulation Technique in Wireless Infrared Indoor Communications

    Page(s): 1 - 8
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1420 KB)  

    We consider the idea of rate-adaptive transmission with multiple modulated sub-carriers in order to achieve broadband communication between fixed access point and mobile user terminal in an indoor non-directed infrared wireless system. This technique, known from DSL, and currently under discussion for RF wireless, seems also attractive for IR indoor systems, but needs to be examined under the specific conditions of the wireless optical channel (new problem statement). We perform ideal channel capacity analysis to assess potential data rates in the multi-path IR channel typically present in rooms. Further on, by means of simulations we investigate the throughput maximization for practical systems with the use of bit-loading. View full abstract»

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  • A Flexible Microprogrammed Packet Classifier for Edge Nodes of Transport Networks

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (436 KB)  

    Packet classification is one of the major tasks of packet processing systems at the edge of high-speed transport networks. As existing protocols are evolving and new protocols are constantly being developed, today¿s network systems have to be highly flexible and adaptable to changing requirements. In this paper we present a scalable architecture for a packet classification system for high speed transport network interfaces. This architecture allows the introduction of new protocols and the update of classification rules during operation by using the concept of microprogramming. In the paper we will give a detailed description of the classifiers microprogrammed architecture. Further, the topics performance data concerning the throughput of the classification unit, realization complexity and resource requirements on the chip are also addressed. View full abstract»

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  • Benefits of Transparent Optical Networks in the Presence of Transponder Price Erosion

    Page(s): 1 - 8
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (155 KB)  

    In this paper a detailed cost analysis of several opaque and transparent network architectures is presented taking the impact of many parameters like transponder reach, traffic volume and network protection requirements into account. Cost studies are based on a new equipment cost model and the application of several heuristic network dimensioning algorithms working on different layers. In addition to previous work the sensitivity of cost benefits on the transponder costs is addressed in the paper. This is an important aspect since new technologies are expected to lead to significant transponder price reductions in the future. The results show high cost savings by transparent solutions of up to 50% for current transponder prices provided that the traffic load is high and that transponders with limited reach can be employed. We find that transponder price erosion has only a moderate effect on cost efficiency of transparent networks as compared to opaque solutions. View full abstract»

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  • Minimizing Bit Error Probability for Chromatic and Polarization-Mode Dispersion by Optimized Receiver Filters for Various Optical Modulation Formats

    Page(s): 1 - 8
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (2112 KB)  

    The scope of this paper is two-fold: First, we show how to extend the Karhunen-Loÿve series expansion method to calculate the bit error probability in optical transmission systems with direct detection. The extension allows us to take account of not only chromatic dispersion but also polarization-mode dispersion. Second, we investigate the impact of receiver filter bandwidths on the chromatic and polarization-mode dispersion tolerance of various modulation formats. We show that the chromatic dispersion tolerance can be significantly increased by narrow optical filtering for all investigated modulation formats especially if return-to-zero impulse shaping is applied. View full abstract»

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