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Towards broadband access systems for catv optical networks


TOBASCO aims to upgrade existing CATV networks having high splitting counts with broadband interactive services, by applying High-Density Wavelength Division Multiplexing (HDWDM). TOBASCO's main objectives are:
to develop a strategy to upgrade partly-optical CATV networks for provision of interactive broadband services to subscribers' homes;
to develop HDWDM techniques to offer at least 2 Mbit/s (ATM/Ethernet-oriented) connection capability via a partly fibre, partly coaxial-cable based CATV network;
to develop strategies for flexible network reconfiguration by re-allocation of wavelengths, yielding an optimum Quality of Service;
to develop cost-effective HDWDM optical components;
to demonstrate the viability of the system in a field trial with a commercial cable operator.
The project will advance significantly the introduction of interactive services in existing CATV networks. The techno-economic feasibility of an HDWDM upgrade strategy will be assessed. Main achievements to date include:
techno-economic comparison with other access network architectures
field trial definition
prototypes of key optical system components (arrayed-waveguide wavelength (de)multiplexer, monolithic multiwavelength receiver, bidirectional multiwavelength optical fibre amplifier)
prototype wavelength-switchable optical network unit
Expected Impact
TOBASCO contributes to the promotion of Teleworking and Distance Learning, through development of enabling technologies for broadband interactive service provisioning via the vast CATV network infrastructures. As such, TOBASCO addresses the goal of the European Commission to have 10 million teleworking jobs by the year 2000.

Main contributions to the programme objectives:
Main deliverables
WDM hybrid fibre-coax broadband access network demonstrator, adapting existing CATV infrastructure.
Contribution to the programme
Will advance the introduction of interactive TV services in existing established CATV networks.
Technical Approach
HDWDM will be used, to partition in a flexible way, the large group of subscribers connected to a CATV headend into smaller groups. Within such a group, electrical Time Division Multiple Access will be applied to address the individual subscribers. This nested HDWDM/TDMA implementation provides ATM-based interactive services to the Optical Network Units. From there, advanced CDMA modem techniques will deliver the interactive services on ATM/Ethernet basis with a peak data rate per subscriber of 2 to 10 Mbit/s upstream and 10 Mbit/s downstream. Wavelength selection at the ONUs enables easy network rearrangement.
Summary of Trial
A field trial will be carried out using the CATV network of TeveOosT in Ghent (B), a partner of the Belgian National Host Burger Breedband Net (BBN). The system will be evaluated with commercial interactive pilot services for real users. The upgrade of the existing CATV network will be studied with respect to compatibility with present CATV broadcast services, techno-economic aspects, and user acceptance.
Key Issues
network design, covering topology, optical transmission, optical multiple access techniques, interworking, implementation of broadband multiple access on a coax network and infrastructure;
flexible allocation of wavelengths for network reconfiguration and optimum Quality of Service (QoS);
gradual and graceful network evolution towards broadband interactive services;
development of cost-effective integrated active and passive HDWDM components;
protocols exploiting flexible wavelength allocation to meet variable service demands;
advanced spectrally efficient modems for CATV coaxial networks.

Funding Scheme

CSC - Cost-sharing contracts


Lucent Technologies NS-NL

1270 AA Huizen

Participants (10)

Bosch Telecom
Burger Breedband Net
Corning Europe
KPN Research
Mechelen Technologies
United Kingdom
Southampton Ocenagraphic Centre, European Way
SO14 3ZH Southampton
Univ. of Twente