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Ultra-Wideband Coherent Optical LAN

Objective

The UCOL-1 project investigated the feasibility of using coherent optical techniques for high-capacity communications in a local area network (LAN).
In applying these techniques to LANs, the project set particular emphasis on the implications of the interactions between the adopted technology, the selected transmission techniques, the statistical characteristics of the traffic and the management confi guration, in order to ensure that the outcome of the design would be an efficient system. The network concept developed within the project provides a total capacity of several Gbit/s. All types of service are supported, and its geographical range exceeds that of conventional LANs.
Binary PSK was selected because it needs the lowest optical signal power for a given error probability. Differential PSK was adopted because it avoids the need for complex circuitry for carrier recovery. The constraints placed upon the receiver response time when operated within a multichannel, multi-user environment are severe if network efficiency is not to be compromised. Rapid inter-message response was a principal design objective from the outset.
The project investigated the feasibility of using coherent optical techniques for high capacity communications in a local area network (LAN).

A laboratory demonstration of the underlying detection principle was successfully staged. The theoretical work on the system concept, and the experimental activity carried out on 3 of the most important building blocks (the narrow lined source, the comb generator and the receiver), indicated that the physical structure necessary to support network operation was feasible and can offer high performance. The ultrawideband coherent optical local area network project showed how it was possible to exploit the star configuration in a high efficiency time division multiplexing (TDM) protocol which regulates access to each individual optical frequency. Time slot division of individual optical channels permits efficient service integration and TDM on each individual optical frequency allows flexibility in bandwidth allocation and therefore agile mixing of high band width and low band width users. Furthermore, delay sensitive applications can be dealt with within their timeconstraints. Frequency domain switching between channels was therefore exploited to obtain inexpensive adaptive network reconfiguration without hardware modifications.
A laboratory demonstration of the underlying detection principle was successfully staged. The theoretical work on the system concept, and the experimental activity carried out on three of the most important building blocks (the narrowlined source, the comb generator and the receiver), indicates that the physical structure necessary to support network operation is feasible and can offer high performance.
UCOL-1 showed how it is possible to exploit the star configuration in a high-efficiency TDM protocol which regulates access to each individual optical frequency. Time-slot division of individual optical channels permits efficient service integration and TDM on each individual optical frequency allows flexibility in bandwidth allocation and therefore agile mixing of high bandwidth and low bandwidth users. Furthermore, delay-sensitive applications can be dealt with within their time constraints. Frequency-domain switching between channels is therefore exploited to obtain inexpensive adaptive network reconfiguration without hardware modifications.
Exploitation
The range of specific applications is extremely large. A preliminary survey was carried out during the UCOL feasibility study to assess its potential and the most suitable application areas. The study proved that with coherent optical techniques it will be possible to build a network with a very high capacity and excellent performance in information-flow handling.
The results of UCOL-1 are being used in project 2054, UCOL-2.

Coordinator

Alcatel Face Standard SpA
Address
Via Nicaragua 10
00040 Pomezia Roma
Italy

Participants (2)

GEC Marconi Research Centre
United Kingdom
Address
West Hanningfield Road Great Baddow
CM2 8HN Chelmsford
Politecnico di Milano
Italy
Address
Piazza Leonardo Da Vinci 32
20133 Milano