i3 - November/December 2018 - 35

Consum

er

Techno

logy

"FATHER OF DSL"
(1956 - )

E

r
onsume

arly online internet
access was slow and
inefficient through
plain-old telephone lines. That
is, until Digital Subscriber Line,
or DSL, the first broadband datatransmission technology. Forms
of DSL now connect nearly 75
percent of global internet homes
at faster per customer speeds
than cable broadband, thanks
to Dr. John Cioffi, founder of DSL
modem maker ASSIA and known
as the "father of DSL."
Cioffi was born on November
7, 1956, in Park Forest, south of
Chicago. Cioffi's father, John,
worked in insurance, while his
mother, Lorraine, was a stay-athome mom. Cioffi got a taste
of his future on a family trip to
1964's New York World's Fair,
where a demonstration of AT&T's
videophone fascinated him.
After graduating in 1978 as the
valedictorian of the University
of Illinois' engineering school,
Bell Labs hired him and paid for
his graduate work at Stanford
University. Cioffi spent six years
shuttling cross country between
Bell Labs' Holmdel, NJ, facilities and
Stanford, where he earned both
his master's and Ph.D. in electrical
engineering. Cioffi worked at both
institutions to help quadruple the
speed of 2400 bits per second

C TA . t e c h / i 3

C

Techno

Forms of DSL now connect nearly 75 percent
of global internet homes at faster per
customer speeds than cable broadband,
thanks to Dr. John Cioffi, founder of DSL
modem maker ASSIA and known as the "father
of DSL."
(bps) early voice-band modems to
the then adaptive echo-cancelled
full-duplex modems at speeds
of 9600 bps and later higher.
He also helped Bell Labs solve
echo-cancelation problems for
the then-contemplated Integrated
Services Digital Network (ISDN) -
the beginnings of DSL.
In 1984, Cioffi joined IBM's
San Jose lab to work to increase
hard drive bit density using AI
algorithms. In early 1986, Stanford
promoted Cioffi to an electrical
engineering assistant professor,
where he continued working on
DSL.
Cioffi proposed a significant
architecture change: they
pursed a "single-carrier" method,

which was limited by the lack
of AI. Cioffi's proposed smarter
system learned each phone line's
specific disturbances, and then
applied machine learning to
adjust the transmission format.
Cioffi and Ph.D. candidate Peter
Chow's proposed method was
called Discrete Multi-Tone (DMT)
modulation and the specific
machine-learning algorithm used
"bit-swapping." DMT pushed
data speeds to 1.5 megabits
per second (Mbps) - "good
enough" for video. In 1991, Cioffi
separately co-founded Amati
Communications.
In January 1993, the DSL
"Olympics" was held in Miami
to determine a DSL standard.

Amati's DMT-enabled Prelude
ADSL modem could transmit
faster than 6 Mbps, four times the
speeds of other proposed designs
from AT&T/Lucent, Bellcore and
Broadcom, and was unanimously
agreed to by more than 200
voters. On March 10, 1993, Cioffi's
DSL technology was officially
declared the U.S. standard by the
American National Standards
Institute (ANSI), followed by the
European Telecommunications
Standards Institute (ETSI) a few
months later, and International
Telecommunication Union (ITU)
two years later.
In 1995, Amati successfully
went public and was bought by
Texas Instruments in 1997. Cioffi,
who had returned to Stanford,
and a new group of Ph.D.
students, developed Dynamic
Spectrum Management (DSM)
and "vectored DSLs," which
increased DSL speeds to 150
Mbps. These vectored methods
form the basis for Massive MIMO
LTE and Multi-User MIMO (MUMIMO) Wi-Fi systems.
From 2003 to 2004, Cioffi, his
wife Assia and former students
founded ASSIA (AdaptiveSpectrum-and-SIgnal-Alignment),
which serves 40 telcos globally
with more than 150 million DSL/
wireless subscribers. 

logy

NOVEMBER/DECEMBER 2018

35


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i3 - November/December 2018

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i3 - November/December 2018 - Cover1
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i3 - November/December 2018 - Contents
i3 - November/December 2018 - 2
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