High-speed copper access: a tutorial overview

Telecommunication companies (telcos) are beginning to exploit further their existing access networks by using new technologies capable of delivering data at up to 30 Mbit/s over unshielded twisted copper wire pairs. This tutorial paper provides a high-level overview of the key issues related to these digital subscriber line (DSL) technologies, including the environment in which they must operate, line codes, standards, and the current state of the market.