Unbundling in Current Broadband and Next-Generation Ultra-Broadband Access Networks

This article overviews the methods that are currently under investigation for implementing multi-operator open-access/shared-access techniques in nextgeneration access ultra-broadband architectures, starting from the traditional “unbundling- of-the-local-loop” techniques implemented in legacy twisted-pair digital subscriber line access networks. A straightforward replication of these copper-based unbundling-of-the-local-loop techniques is usually not feasible on next-generation access networks, including fiber-to-the-home point-to-multipoint passive optical networks. To investigate this issue, the article first gives a concise description of traditional copper-based unbundling-of-the-local-loop solutions, then focalizes on both next-generation access hybrid fiber–copper digital subscriber line fiber-to-the-cabinet scenarios and on fiber to the home by accounting for the mix of regulatory and technological reasons driving the next-generation access migration path, focusing mostly on the European situation.