ADSL Modems
ADSL Standards
ADSL was first standardized in 1995 by ANSI, enabling data rate of 8 Mbps downstream and 640 Kbps upstream.
In 1999, a lower speed version of ADSL, known as G.lite, was released by the ITU. G.lite enables data rate of 1.5 Mbps downstream and 512 Kbps upstream, without using special filtering equipment as required by the original ADSL standard.
In 2002, the ITU standardized a new family of ADSL standards known as ADSL2.
These standards provide new improvements such as power cutback and on-line reconfiguration.
In 2003 the ITU released ADSL2+, which is based on ADSL2, and increased the data speeds to up to 25 Mbps upstream on phone lines as long as 3,000 feet (20 Mbps out to 5,000 feet).
ADSL Modems
Network Architecture and Physical Connectivity
ADSL Standards