Skip to main content

Wavelength and Time Division Multiplexed Broadband Customer Premises Network

Objective

The aim of this project is to develop a broadband customer premises network (BCPN) suitable for broadband service providers and for a wide range of other corporate applications.
The aim of this project is to develop a broadband customer premises network (BCPN) suitable for broadband service providers and for a wide range of other corporate applications. Work on this project concentrates on system aspects, but includes development of the enabling technology where suitable devices are not available elsewhere. A test bed is being constructed to verify system design concepts and to test the technology involved.
A complete optical path has been publicly demonstrated carrying digital television signals at 155 Mbits{-1} and a pseudorandom binary sequence (PRBS) at 2.5 Gbits{-1}. 2.5 Gbits{-1} laser transmitters at closely controlled wavelengths, 16-wavelength optical coupler, bulk optical demultiplexer, and 2.5 Gbits{-1} optical receivers fully characterized and within the optical power budget. Together, these demonstrate the practical feasibility of 4 nm wavelength spacing for 16 independent channels in a high density wavelength division multiplex (WDM) configuration. The diode coupled optical demultiplexer configuration has also proved successful.
A control system (node controller) for customer premises network (CPN) internal routeing has been demonstrated and interfaced with system test bed.
Research has progressed, with components developed for a planar waveguide coupler, and configurations determined for coupling an optical demultiplexer directly to a receiver array giving encouraging test results.
The equipment testbed layout has been finalised and hardware practice decided for 2.48 Gbits{-1} and 155 Mbits{-1} circuits.
Significant progress has been made in large scale integration (LSI) developments for time division multiplex (TDM) to synchronous digital hierarchy (SDH) standards and design of a 2.5 Gbits{-} 12 x 12 expandable crosspoint switch matrix.
Technical Approach

The BCPN will be capable of carrying signals at a wide range of bit-rates from low speed data signals up to high definition television (HDTV) using a combination of electrical time-division multiplexing (TDM) and optical wavelength-division multiplexing (WDM). At each local routing centre (LRC), signals from the sources are time- multiplexed electronically to form a serial bit-stream at a up to 2.5 Gbit/s. This serial signal modulates a distributed feedback (DFB) laser, and the outputs of all the LRCs (at slightly different wavelengths) are combined in an optical star coupler to give a WDM optical signal with a total payload capacity of over 38 Gbit/s. The optical signal is redistributed to each of the LRCs where it is demultiplexed optically and electrically, without central switching. An IBC 'T' interface will be specified to interconnect the BCPN and the public broadband network. Several different configurations of the system are possible to suit different applications.

Work on this project concentrates on system aspects, but includes development of the enabling technology where suitable devices are not available elsewhere. A test bed is being constructed to verify system design concepts and to test the technology involved.

Key Issues

- High density WDM. High bit-rate TDM.
- Techniques and devices for optical coupling and demultiplexing.
- Integrated circuits for high speed optical receivers and electrical multiplexing. Adoption of synchronous transfer mode standards.

Achievements

- Complete optical path publicly demonstrated carrying digital television signals at 155 Mbit/s (Autumn 1990) and a PRBS at 2.5 Gbit/s (Autumn 1991). 2.5 Gbit/s laser transmitters at closely-controlled wavelengths, 16- wavelength optical coupler, bulk optical demultiplexer, and 2.5 Gbit/s optical receivers fully characterised and within the optical power budget. Together, these demonstrate the practical feasibility of 4 nm wavelength spacing for 16 independent channels in a high density WDM configuration. The diode coupled optical demultiplexer configuration has also proved successful.
- Control system (node controller) for CPN internal routeing demonstrated and interfaced with system test bed.
- 'T' interface being developed for testing in R1081.
- Research progress, with components developed for a planar waveguide coupler and configurations determined for coupling an optical demultiplexer directly to a receiver array giving encouraging test results.
- The equipment testbed layout finalised and hardware practice decided for 2.48 Gbit/s and 155 Mbit/s circuits.
- Significant progress in LSI developments for TDM to SDH standards and design of a 2.5 Gbit/s 12 x 12 expandable crosspoint switch matrix.

15 papers have now been published covering the general area of optical communications and broadband aspects of IBC customer systems. Contributions have been made to an ETSI TM3 workshop on the use of SDH for studio quality video, audio and ancillary services; and to RACE STG 3.3 for the allocation of wavelengths for optical transmission. An initial contribution on the evolution of broadband working in customer premises networks has been made to STG 5.5 recognising the significance of switching video both within and between, future private networks.

Expected Impact

Video communication requires high-bit-rate technology and the multi-channel circuit capacity which high-density WDM affords is likely to be exploited increasingly, especially when HDTV is introduced. The viability of the IBC in the early years will depend on its ability to respond to rapidly expanding demand for video services.

Coordinator

British Broadcasting Corporation (BBC)
Address
Kingswood Warren
KT20 6NP Tadworth
United Kingdom

Participants (8)

Alcatel Standard Electrica SA
Spain
General Electric Company plc
United Kingdom
Address
Hirst Research Centre
Instruments SA
France
NT Optoelectronics plc
United Kingdom
PTT Netherlands Research
Netherlands
SGS Thomson Microelectronics SA
France
Swindon Silicon Systems Ltd
United Kingdom
Address
Radnor Street
SN1 3PR Swindon
Thomson CSF
France
Address
3 Avenue De Belle Fontaine
35510 Cesson-sévigne