Fibre Optics Deployment in Croatian Telecommunications Network
Abstract: The future of telecom operators will depend on the spreading of the spectrum of services they could offer to their subscribers. In order to achieve the transition from current narrowband services towards the broadband, it is necessary to ensure substantial optical capacities in all network’s parts. In order to prepare Croatian infrastructure for the forthcoming "broadband era", HPT started with the technological changes in 1993, beginning with the international/national backbone network level, and spreading to all network levels later on. The scenarios towards broadband based on current trends in evolution of photonics backbone and access network are developed, and their step-by-step implementation are undergoing.
Keywords: broadband, backbone network, access network, fibre optics, SDH, WDM, ATM .
Photonic Networks – An Evolution Scenario
Bernhard Hein, Germany
Abstract: Today WDM is a booming market especially in the USA to upgrade the transport network due to rapid increasing capacity demands. Besides pure point-to-point applications which are solely used currently, the use of optical add/drop-multiplexers and optical crossconnects in the future allow the introduction of a pure optical transport layer. In the paper the possible steps in direction to such a network will be presented and different requirements from the operators point of view will be addressed. Additional some main unsolved problems of signal and network supervision and control will be discussed.
Trade-Offs Between Complexity and Performance in Optical Transport Network Architectures
Abstract: In the frame of the European research project COST 239 "Ultra High Capacity Optical Transmission Systems" various architectures for optical transport networks have been proposed and investigated. These approaches exhibit each a different balance between complexity and performance. In this paper, a summary is given which comprises the trade-offs between regular and arbitrary meshing, static and dynamic optical path layering and a comparison of network partitioning versus distributed interfacing. The architectural approaches are illustrated by two different proposals within the COST 239 case study for a Pan-European fiber optic backbone infrastructure. Conventional hierarchical layering of a network contains both the ideas of establishing long static paths as well as the partitioning of the network in several separate sub-networks. The respective alternatives are dynamic wavelength routing and distributed interfacing in a flat hierarchy. Both features improve the network performance but also imply a significant increase in complexity. A discussion of protection versus restoration schemes rounds off the survey presented in this paper.
Keywords: Communication Network Architectures, Communication Systems Economics, Wide Area Networks, Optical Communications, Optical Cross Connects (OXC), Wavelength Division Multiplexing (WDM), Space Division Multiplexing (SDM), Regular and Arbitrary Network Topologies, Static Bypassing.
Scaling Properties and Design Guidelines in Survivable Wavelength Routed Optical Transport Networks
Abstract:We report analytical results on how many wavelengths are needed to build a static wavelength routed optical network with sufficient redundancy to allow rerouting in the case of link and node failures. Redimensioning a network to allow one link and one node failure typically requires either a 5-15% (l-3 wavelengths) increase in node capacity or reducing the network size with l-3 nodes. The difference is largest for neworks with a small node degree. The model have been applied to three example networks, of which one is a topology for a European Optical Network, demonstrating the applicability of the model.
Project OPEN: WDM Networking on a European Scale
Abstract: The results of comparing four different topology approaches to the design of a pan-European optical network are discussed. We demonstrate that for such an ultra-high capacity large scale network, it is necessary to introduce measures to limit both the transparent path lengths and the optical cross-connect (OXC) complexity.
Evolution towards an Optical Network Layer EURESCOM P615
Abstract: The EURESCOM P615 project has studied various OADM and OXC based optical architectures. Functionalities of the optical architectures were analysed and compared with SDH architectures. Furthermore it was shown with projections of different topologies and traffic demand patterns on the optical architectures, that there are no significant differences between optical and SDH architectures apart from a big difference in installation costs. Finally introduction and growth scenarios of optical networks will be formulated taking into account technical, management, organisational and economical constraints.
Framework for Information Modeling of Optical Network
Abstract: This paper presents the basic principles of an approach to the conceptual information modeling of transport networks with optical elements. The approach was applied in a research program dealing with information models for transport network monitoring and management. The results are expected to become part of network monitoring and management functions in the Croatian Power Utility’s corporate telecom network.
Keywords: network monitoring; optical network, WDM.
Optical Digital Transmission, Regeneration and Networks
David Cotter, UK
Abstract: The vision of future large-scale 'transparent' networks is fading. There is a growing realisation that the existing approaches to photonic networking have significant and fundamental limitations. This paper explores these limitations, and advances the view that future high-capacity photonic networks will demand digital optical techniques—such as 3R regeneration and bit processing—in order to be robust and scaleable. A new approach to photonic networking based on asynchronous digital optical processing is described.
Increasing of the Capacity of Optically Amplified Systems by means of the Dispersion Management Method
F. Matera, M. Settembre, Italy
Abstract: We report a numerical study of the performance of optically amplified systems operating in links with dispersion management. The results show that soliton signals permit to achieve the highest performance when they propagate in links with a sawtooth distribution with a low anomalous average chromatic dispersion.
Numerical Methods for Evaluating the Transmission Performance of High Capacities Optical WDM Systems
Abstract: In this work we present a novel simulation tool that permits to analyze both the propagation in optical fiber and in the erbium doped optical amplifiers. Some results on a 16 x 2.5 WDM system are reported.
Node Architectures for Photonic WDM Networks
A. Jourdan, F. Bruyere, L. Noirie, L. Berthelon, T. Zami, France
Abstract: This presentation will review the various types of network elements that are required to build a photonic network, including both short term and long term views. After a brief analysis of the drivers behind all-optical networks, a particular attention will be given to the relevant network elements, including fibre crossconnects (FXC), semi-flexible optical add-drop multiplexers (OADMs) and reconfigurable wavelength crossconnects, including or not wavelength translation. Some of the most promising technologies relevant to each application will be reviewed, illustrated by some experimental results, including some recent field trials carried out in the ACTS OPEN project.
Physical limitations in photonic networks using such nodes will be addressed, based on numerical results, and the need for partial « 2R » or full « 3R » regeneration will be discussed, with the impact on the transparency.
Finally, monitoring issues will be addressed, illustrated by implementations studied and carried out in several European projects.
Guided Wave Optical Packet Switches: A Comparison
M. C. Chia, D. K. Hunter, I. Andonovic, UK
Abstract: Many optical packet switches have been proposed for Broadband Integrated Services Digital Networks (B-ISDN), each having their own advantages and disadvantages. Although optical packet switches offer data rate and format transparency, and high switching speed, their performance strongly depends on optical device technology. This paper discusses the fundamental limitations of a selected number of guided wave optical packet switches: a comparison in terms of the number of components, buffering capability, control complexity and switching technology is made.
Modelling of an X-Junction Based on Dark Soliton Collision
Krunoslav Trzec, Croatia
Abstract: An X-junction based on dark soliton collision is proposed. The device model was simulated by the beam propagation method. It is shown that colliding dark solitons change the effective refractive index of a waveguide and create the X-junction which can guide weaker beam. The change of refractive index is evaluated. Choosing appropriate waveguide material and operating wavelength, X-junction device is designed.
Objective Function for Planning and Evaluating a WDM-based Photonic Network
Abstract: This paper discusses the importance of an objective function for a network planning process and presents some basic components and general aspects of objective functions. Then, specific aspects of an objective function for planning a photonic network such as wavelength conversion, or scalability and flexibility are discussed. Moreover, selected results on multi-layer planning and consideration of dynamic traffic are presented and summarised. Finally, open points are listed which need further work.
Availability Analysis of Different WDM Network Protection Scenarios
Abstract: The paper presents availability performance results for the core network of the European optical network case study. The availability measures, availability model, and calculation procedure are hereby described. The results for different protection scenarios and different number of wavelength channels per fiber are also presented.
Keywords: availability, all-optical network, wavelength division multiplex.
Multi-Criteria Routing for Optical Networks
Admela Jukan, Arnold Monitzer, Harmen R. van As, Austria
Abstract: In this paper, the principle of multi-criteria routing in optical networks is proposed for accommodation of user requirements and available network resources. For that purpose, two QoS-routing algorithms are presented and discussed as an approach for connection set-up in optical networks.
Keywords: Quality-of-Service (QoS), optical network service, quality attributes, resource allocation.
Synchronisation in Optical Packet Switched Networks
A. Franzen, D. K. Hunter and I. Andonovic, UK
Abstract: This paper discusses synchronisation requirements for optical packet switched networks. The general functionality of the optical node used to buffer and cross-connect packets is outlined, and the input interface required for correct operation is defined. Various approaches to header detection that fulfil the requirements for the alignment of all input packets are described and contrasted. The alignment procedure is described, problems in identifying each cell during synchronisation (both in the header and payload) are addressed and derivation of a master clock (local or distributed) is discussed.
Distortion of Scm Signals Due to Cross–Phase Modulation in Transparent Optical Networks
Lutz Rapp, Switzerland
Abstract: Transparent optical networks using wavelength division multiplexing (WDM) allow to transmit optical signals of different modulation formats. But there are some physical constraints arising from limited bandwidth, noise, chromatic dispersion and fibre nonlinearities. In this paper, an analytical expression describing the spectral characteristics of distortions induced by cross–phase modulation (XPM) is derived. Furthermore, numerical investigations reveal how digital signals with different bitrates affect the various channels of a subcarrier multiplexed (SCM) signal.
Keywords: Optical fibre communication, All–optical networks, Transparency, Wavelength division multiplexing, Subcarrier multiplexing, Nonlinear fibre effects, Cross–phase modulation.
An Availability Analysis of Optical Cables
Irena Jurdana, Branko Mikac, Croatia
Abstract: The paper describes study results of the failure and repair analysis of optical cables installed in Croatian public telecommunication network on the transport network layer. Data collected in the 8 year period, are analyzed by the failure type, causes, frequency and repair intensity. Collected data are compared with the similar ones from other optical networks. Failure rates, unavailabilities and mean down times for optical links are calculated.
Keywords: optical cable, failure rate, repair time, availability.
Photonic Infrastructure for the Information Technology Age - a Proposal for Research
Anton Kuchar, Czech Republic
Abstract: Due to the changing traffic pattern caused by the fast growing message communication and multimedia communication further research is needed with the aim to propose and evaluate suitable network architectures and identify the key photonic components for the infrastructure of the next generation universal networks optimised for the information technology age characterised by interactive and multimedia communication and work out alternative scenarios for the evolution of the present specialised networks towards next generation networks.
Keywords: Telecommunications, Optical communication networks.