Studies are being carried out in Italy concerning the strategy for the introduction in the 1990's of optical fiber systems in the distribution network, in order to supply customers with broad-band services (in particular with video services). This paper deals with some of the main choices that are being done, in particular in view of a field trial which is planned in Rome in 1988.

The echo canceller burst mode (ECBM) is part of a "silicon boutique," a family of devices that offer a cost-effective industrial solution to the problem of ISDN basic access. ECBM takes advantage of both the echo cancellation and the time compression techniques. It leaves a silent period in each direction of transmission; this creates periods in which only the received signal or only the echo is present, which greately simplifies the echo canceller and the timing recovery. The components of the family implement the signal processing, power feed, and line interface functions needed for the ISDN basic access (144 kbits/s); they take into account the requirement of different connection schemes, yet offering flexibility to accommodate possible standards evolution. Their coordination avoids "glue" components and facilitates some basic access functions (e.g., activation, maintenance, monitoring).

An experiment of wide-band switched interactive services (video services) is presented. The experiment, named WISE (Wide-Band Interactive Services Experiment) is limited to a small number of subscribers but is representative of a future domestic environment. After a brief presentation of the scope of the activity, the video services that have been implemented, both unidirectional and bidirectional, are described. The system organization, based on a wide-band switching matrix and on the transmission of video signals on a single optical fiber by wavelength-division multiplexing, is then discussed, and the solutions adopted for the transmission equipment are examined. The structure of the service center is afterwards described, together with the subscriber procedures required to access the different services. Finally, some improvements and future possible developments of wide-band interactire systems are briefly highlighted.

This paper is a review of European field trial experience with fiber optic trunking systems from 1975 to the present. Details of the systems installed and of the experiences in each of the participating European countries are given.