Economics of digital carriers and fiber optic systems in subscriber loop

The authors address the economics of digital loop carriers (DLCs) and fiber-optic systems in the access network with reference to the ongoing digitization of local switching facilities. In the Italian network, DLCs are profitable for serving the growth of subscribers on exhausted cables longer than 1 to 2 km and to replace small-size electromechanical exchanges. These applications lead to an estimated penetration greater than 15% of subscriber lines over the long term. In a multiservice environment the application of DLCs can be further enlarged: in particular, an initial demand for wideband capability is sufficient to justify economically the use of fiber optics to feed DLCs