History of DSL
There are three major names that are linked to the origin of DSL or
Digital Subscriber Line. The following outline of DSL development
will help in understanding how DSL came about.
In the late 1980's , Bell Labs discovers a new way to make traditional
copper wires support new digital services. Joseph Lechleider
a former Bellcore employee, was the first to demonstrate the
feasibility of sending broadband signals, and is considered
by many to be the originator of all these technologies. He also
suggested the power of asymmetry( the A in DSL), saying that
it would be very beneficial for the users to have very high
data rates in one direction. His findings inspired many other
pioneers in the field.
The first efforts created ISDN or Integrated Services Digital
Network, and then the two circuit replacement for T-1 lines
that came to be called HDSL. In the early 1990's phone companies
start deploying High-Speed DSL (HDSL) to offer T1 service on
copper lines. ISDN was never effectively marketed in the US,
but was popular in Europe.
John Cioffi is the second name we will bring up. A Stanford
Professor, Cioffi developed DMT (Discrete Multi-tone Modulation),
which is the standard for most DSL circuits. This minimizes
line noise and disturbance by separating the signal into 256
subchannels. He is also the founder of Amati, where equipment
was designed in 1993 that was definitely better than all the
other Bellcore competitors. Thus, it became the most common
standard. In 1995, companies began to promote ADSL as a way
to enter the video market, and soon, new companies began to
rea,ize that ADSL was a way to meet the demand for faster Internet
access.
Kim Maxwell , also an employee of Amati, founded the DSL Forum.
This organization brought the industry together and presently
is the key institution. Soon followed an alliance between telcos
and computer companies (Intel and Compaq, especially) which
became the UAWG or the Universal ADSL Working Group. They were
the ones responsible for the creation of G.lite.
