Recent European policies have very early identified (European Commission, 1999) the immense challenge for the European Union (EU) to promote various liberalization and harmonization measures in the relevant electronic communications markets, especially by supporting a series of particular initiatives for competition, investment, innovation, the single market, and consumer benefits (Chochliouros & Spiliopoulou, 2003). In order to fully seize the growth of the digital, knowledge-based economy, it has been suggested that both businesses and citizens should have access to an inexpensive, world-class communications infrastructure and a wide range of modern services, all appropriate to support “broadband” evolution and a wider multimedia penetration. Moreover, all possible different means of access had to prevent from “info-exclusion,” while information technologies should be used to renew urban and regional development and to promote innovative technologies (Chochliouros & Spiliopoulou, 2005). To achieve all these expectations, an essential European policy was to “initiate” further competition in local access networks and support the “local loop unbundling” (LLU) perspective, in order to help bring about a considerable reduction in the costs (in terms of price, quality, and innovative services) of using the Internet and to promote high-speed and “always-on” access (Bourreau & Dogan, 2005; Commission of the European Communities, 2006b). The local loop mainly referred to the physical copper line circuit in the local access network connecting the customer’s premises to the operator’s local switch, concentrator, or any other equivalent facility. Traditionally, it takes the form of twisted metallic pairs of copper wires (one pair per ordinary telephone line). However, some other potential alternatives can also be taken into account: fiber optic cables are nowadays being increasingly deployed to connect various customers, while other technologies are also being rolled out in the local access network (such as wireless/satellite local loops, power-line networks, or even cable TV networks). Although technology’s evolution and market development are very rapid, the above alternatives—even in a combined use—cannot provide adequate guarantee to ensure sufficient and nationwide spreading for LLU in a quite reasonable time period (Philpot, 2006) and mainly to address the same customer population, if practically compared to the digital subscriber loop (DSL) option which is offered via the existing copper infrastructures.
Discrete Multi-Tone Digital Subscriber Loop Performance in the Face of Impulsive Noise
