ADSL for high-speed broadband data service

Asymmetrical Digital Subscriber Line (ADSL) service, with digital data rates of up to 8 Mbps over ordinary copper telephone lines, will enable major breakthroughs for Internet access and telecommuting. A new modulation technology, called Discrete Multitone (DMT), is the key that allows the transmission of such high speed data. This paper summarizes the concepts and applications of the several existing xDSL technologies and examines the ADSL technology, its uses and its limitations. Pertinent details are given on DMT modulation and its implementation on a microchip. The technology is further explored through the presentation of several system-level reference designs.