Switchless Optical Network for Advanced Transport Architecture
Main Objective
The main objective of SONATA is to define and demonstrate a single-layer network platform for end-to-end optical connections between a large number of terminals for business and residential customers. Time and wavelength-agility at terminals will be heavily exploited simplifying the network structure to only a single node providing passive routing functions and, optionally, actively controlled wavelength conversion.
By eliminating the need for complex nodes within the network, this non-traditional approach will offer an effective and viable solution for the realisation of high capacity all-optical networks, easily able to cope with the predicted traffic increase generated by the new future telecommunication services.
The advantages of this "switchless" network will be fully investigated and evaluated at the technical, management and economic levels, by means of system studies and modelling, component development, laboratory experiments and implementation of network demonstrators.
Technical Approach
The "switchless" network concept, when applied to a geographical area, raises several major issues relating to component requirements, optical transmission feasibility, and network control aspects.
System studies will provide in-depth investigations of such issues as definition of the optimum network structure, ultimate limits, scaleability, protection, feasibility and impact of network control and management, and economic viability.
The development of advanced optical and optoelectronic devices, with enhanced characteristics for fast wavelength switching, burst-mode operation (non-continuous data transmission) and high-density wavelength division multiplexing (HD-WDM), will be addressed by the component workpackage. In particular, the SONATA project will develop the following components: receivers and all-optical wavelength converters able to show fast and wide wavelength tuning and burst mode operation; and wavelength demultiplexers with enhanced characteristics in terms of number of channels, narrow wavelength spacing and crosstalk.
The two SONATA laboratory demonstrators will show the main features of a small size "switchless" network (about 5,000 terminals and 40 optical channels). The demonstrators set-up will be capable of supporting multi-point-to-multi-point connections with a channel spacing of 0.4 nm and fast wavelength agility of transmitters, receivers and wavelength converters. A first demonstrator will be used to test the optical physical layer, while a second demonstrator will concentrate on network control functions and will include transmission of an ATM service. Besides this level, major key functions needed for a large scale network will be demonstrated in test bed experiments: fast and accurate laser wavelength tuning between channels spaced down to 0.05 nm and automatic gating of an amplified WDM upstream signal, to facilitate very large-split passive optical networks (hyperPON).
"Switchless" network reference structure
Summary of Trial
A first demonstrator to test the optical physical layer of a "switchless" network will be realised by integrating wavelength-agile transmitters, wavelength-agile burst-mode receivers, a passive wavelength routing node, a wavelength converter, and optical fibre amplifiers in gated-loops. Burst mode transmission at 622 Mbit/s will be used. The aim of this demonstrator is to assess the capability of a "switchless" network architecture to transport data packets when end-to-end multi-point-to-multi-point connections are established. By means of BER measurements, the effects of optical amplifier noise, crosstalk, and wavelength conversion will be evaluated, and the limits of the optical layer will be found.
A second demonstrator for the network aspects will be realised by integrating wavelength-agile transmitters, wavelength-agile burst-mode receivers, a passive wavelength routing node, a network controller, and external services. Burst-mode transmission at 155 Mbit/s will be used. The terminals will be placed in different rooms and will be able to accept data from 2 external sources: PC application (client service) and cell generator/analyser instrument. The aim of this phase is to show the feasibility of connection set-up and medium access procedures using the same optical network used for the data and to show an example of interconnection of the "switchless" network with an external service.
Outline of the optical physical layer demonstrator
Outline of the network demonstrator
Key Issues
- Optimisation of network architecture including protection.
- Impacts of physical layer limitations on network scaleability.
- Connection Set-up and Medium Access Control protocols.
- Network management strategies.
- Interconnection with other networks and interworking with other transmission protocols.
- Burst-mode operation in optical transmission, detection and wavelength conversion.
- Fast and fine (HD-WDM) wavelength-agility of optical transmitters and receivers.
- WDM gating of the output optical amplifier noise.
- Long haul transmission of HD-WDM signals with cascaded optical amplifiers.
Expected Achievements
To define a managed single-layer transport platform based on the "switchless" optical network concept with characteristics of flexibility, upgradeabilty and economic viability for high capacity end-to-end networking.
To develop and demonstrate key advanced components for wavelength-agile HD-WDM operation in "switchless" optical networks.
To demonstrate the main features of a "switchless" optical network in laboratory demonstrators including ATM traffic transmission tests and to prove the feasibility of the key aspects for network dimensioning on a national scale.
Expected Impact
The SONATA all-optical distributed switching network will allow network operators to realise a single-layer, "switchless" network as an alternative to today's multi-layer paradigm based on relatively large numbers of high-throughput switches and cross-connects. The "switchless" alternative would eliminate the need, within the transport network, for any ATM cross-connects, SDH or optical cross-connect nodes, as well as telephone network switches. As the SONATA network approach shows a strong potential for the distribution and transport of high volume traffic by providing flexible broadband access, the project results will be able to give a valid contribution to current research activities on new network techniques and infrastructures for transport and distribution of new broadband services to the customer, and will become a key factor in the strategies of network operators for the deployment of such network platforms.
| I |
CSELT |
| UK |
BT Laboratories |
| I |
Coritel |
| CH |
ETH - Zürich |
| B |
IMEC |
| F |
Instruments S.A. |
| I |
Politecnico di Torino |
| E |
Polytechnic University of Catalonia |
| F |
Thomson CSF |
Nunzio Caponio
CSELT
via G. Reiss Romoli 274
10148 Torino
Italy
Tel: +39 011 228 5034
Fax: +39 011 228 5840
E-mail: nunzio.caponio@cselt.it
