08-05-2012, 04:25 PM
brief history of Wi-Fi
[attachment=21590]
IT STANDS as perhaps the signal success of the computer industry in the last few
years, a rare bright spot in a bubble-battered market: Wi-Fi, the short-range
wireless broadband technology. Among geeks, it has inspired a mania unseen since
the days of the internet boom. Tens of millions of Wi-Fi devices will be sold this year,
including the majority of laptop computers. Analysts predict that 100m people will be
using Wi-Fi by 2006. Homes, offices, colleges and schools around the world have
installed Wi-Fi equipment to blanket their premises with wireless access to the
internet. Wi-Fi access is available in a growing number of coffee-shops, airports and
hotels too. Yet merely five years ago wireless networking was a niche technology.
How did Wi-Fi get started, and become so successful, in the depths of a downturn?
Wi-Fi seems even more remarkable when you look at its provenance: it was, in
effect, spawned by an American government agency from an area of radio spectrum
widely referred to as “the garbage bands”. Technology entrepreneurs generally
prefer governments to stay out of their way: funding basic research, perhaps, and
then buying finished products when they emerge on the market. But in the case of
Wi-Fi, the government seems actively to have guided innovation. “Wi-Fi is a creature
of regulation, created more by lawyers than by engineers,” asserts Mitchell Lazarus,
an expert in telecoms regulation at Fletcher, Heald & Hildreth, a law firm based in
Arlington, Virginia. As a lawyer, Mr Lazarus might be expected to say that. But he
was also educated as an electrical engineer—and besides, the facts seem to bear him
out.
In the beginning
Wi-Fi would certainly not exist without a decision taken in 1985 by the Federal
Communications Commission (FCC), America's telecoms regulator, to open several
bands of wireless spectrum, allowing them to be used without the need for a
government licence. This was an unheard-of move at the time; other than the hamradio
channels, there was very little unlicensed spectrum. But the FCC, prompted by
a visionary engineer on its staff, Michael Marcus, took three chunks of spectrum from
the industrial, scientific and medical bands and opened them up to communications
entrepreneurs.
These so-called “garbage bands”, at 900MHz, 2.4GHz and 5.8GHz, were already
allocated to equipment that used radio-frequency energy for purposes other than
communications: microwave ovens, for example, which use radio waves to heat
food. The FCC made them available for communications purposes as well, on the
condition that any devices using these bands would have to steer around
interference from other equipment. They would do so using “spread spectrum”
technology, originally developed for military use, which spreads a radio signal out
over a wide range of frequencies, in contrast to the usual approach of transmitting
on a single, well-defined frequency. This makes the signal both difficult to intercept
and less susceptible to interference.
Though the 1985 ruling seems visionary in hindsight, nothing much happened at the
time. What ultimately got Wi-Fi moving was the creation of an industry-wide
standard. Initially, vendors of wireless equipment for local-area networks (LANs),
such as Proxim and Symbol, developed their own kinds of proprietary equipment that
operated in the unlicensed bands: equipment from one vendor could not talk to
equipment from another. Inspired by the success of Ethernet, a wireline-networking
standard, several vendors realised that a common wireless standard made sense too.
Buyers would be more likely to adopt the technology if they were not “locked in” to a
particular vendor's products.
In 1988, NCR Corporation, which wanted to use the unlicensed spectrum to hook up
wireless cash registers, asked Victor Hayes, one of its engineers, to look into getting
a standard started. Mr Hayes, along with Bruce Tuch of Bell Labs, approached the
Institute of Electrical and Electronics Engineers (IEEE), where a committee called
802.3 had defined the Ethernet standard. A new committee called 802.11 was set
up, with Mr Hayes as chairman, and the negotiations began.
The fragmented market meant it took a long time for the various vendors to agree
on definitions and draw up a standard acceptable to 75% of the committee
members. Finally, in 1997, the committee agreed on a basic specification. It allowed
for a data-transfer rate of two megabits per second, using either of two spreadspectrum
technologies, frequency hopping or direct-sequence transmission. (The first
avoids interference from other signals by jumping between radio frequencies; the
second spreads the signal out over a wide band of frequencies.)
The
ne
w
sta
nda
rd
was
pub
lish
ed
in
199
7,
and
eng
ine
ers
im
me
diat
ely
beg
an working on prototype equipment to comply with it. Two variants, called 802.11b
(which operates in the 2.4GHz band) and 802.11a (which operates in the 5.8GHz
band), were ratified in December 1999 and January 2000 respectively. 802.11b was
developed primarily by Richard van Nee of Lucent and Mark Webster of Intersil (then
Harris Semiconductor).
Companies began building 802.11b-compatible devices. But the specification was so
long and complex—it filled 400 pages—that compatibility problems persisted. So in
August 1999, six companies—Intersil, 3Com, Nokia, Aironet (since purchased by
Cisco), Symbol and Lucent (which has since spun off its components division to form
Agere Systems)—got together to create the Wireless Ethernet Compatibility Alliance
(WECA).
A rose by any other name...
The idea was that this body would certify that products from different vendors were
truly compatible with each other. But the terms “WECA compatible” or “IEEE802.11b
compliant” hardly tripped off the tongue. The new technology needed a consumerfriendly
name. Branding consultants suggested a number of names, including
“FlankSpeed” and “DragonFly”. But the clear winner was “Wi-Fi”. It sounded a bit like
hi-fi, and consumers were used to the idea that a CD player from one company
would work with an amplifier from another. So Wi-Fi it was. (The idea that this stood
for “wireless fidelity” was dreamed up later.)
The technology had been
standardised; it had a name;
now Wi-Fi needed a market
champion, and it found one in
Apple, a computer-maker
renowned for innovation. The
company told Lucent that, if it
could make an adapter for
under $100, Apple would
incorporate a Wi-Fi slot into all
its laptops. Lucent delivered, and in July 1999 Apple introduced Wi-Fi as an option on
its new iBook computers, under the brand name AirPort. “And that completely
changed the map for wireless networking,” says Greg Raleigh of Airgo, a wireless
start-up based in Palo Alto, California. Other computer-makers quickly followed suit.
Wi-Fi caught on with consumers just as corporate technology spending dried up in
2001.
Wi-Fi was boosted by the growing popularity of high-speed broadband internet
connections in the home; it is the easiest way to enable several computers to share
a broadband link. To this day, Wi-Fi's main use is in home networking. As the
technology spread, fee-based access points known as “hotspots” also began to spring
up in public places such as coffee-shops, though many hotspot operators have gone
bust and the commercial viability of many hotspots is unclear. Meanwhile, the FCC
again tweaked its rules to allow for a new variant of Wi-Fi technology, known as
802.11g. It uses a new, more advanced form of spread-spectrum technology called
orthogonal frequency-division multiplexing (OFDM) and can achieve speeds of up to
54 megabits per second in the 2.4GHz band.
Where next? Many Wi-Fi enthusiasts believe it will sweep other wireless technologies
aside: that hotspots will, for example, undermine the prospects for third-generation
(3G) mobile-telephone networks, which are also intended to deliver high-speed data
to users on the move. But such speculation is overblown. Wi-Fi is a short-range
technology that will never be able to provide the blanket coverage of a mobile
network. Worse, subscribe to one network of hotspots (in coffee-shops, say) and you
may not be able to use the hotspot in the airport. Ken Denman, the boss of iPass, an
internet-access provider based in Redwood Shores, California, insists that things are
improving. Roaming and billing agreements will, he says, be sorted out within a
couple of years.
By that time, however, the first networks based on a new technology, technically
known as 802.16 but named WiMax, should be up and running. As its name
suggests, WiMax is positioned as a wide-area version of Wi-Fi. It has a maximum
throughput of 70 megabits per second, and a maximum range of 50km, compared
with 50m or so for Wi-Fi. Where Wi-Fi offers access in selected places, like phone
boxes once did, WiMax could offer blanket coverage, like mobile phones do.
Wi-Fi is also under threat in the home. At the moment it is the dominant homenetworking
technology: Wi-Fi-capable televisions, CD players and video-recorders
and other consumer-electronics devices are already starting to appear. This will
make it possible to pipe music, say, around the house without laying any cables.
Cordless phones based on Wi-Fi are also in the works. But Wi-Fi may not turn out to
be the long-term winner in these applications. It is currently too power-hungry for
handheld devices, and even 802.11g cannot reliably support more than one stream
of video. And a new standard, technically known as 802.15.3 and named WiMedia,
“Wi-Fi's ultimate significance may
be that it provides a glimpse of
what will be possible with future
wireless technologies”
has been specifically designed as a short-range, high-capacity home networking
standard for entertainment devices.
Wi-Fi's ultimate significance, then, may be that it provides a glimpse of what will be
possible with future wireless technologies. It has also changed the way regulators
and technologists think about spectrum policy. The FCC has just proposed that
broadcast “whitespace”—the airwaves assigned to television broadcasters but not
used for technical reasons—should be opened up too. That is not to say that
spectrum licensing will be junked in favour of a complete free-for-all over the
airwaves. Julius Knapp, the deputy chief of the office of engineering and technology
at the FCC, maintains that both the licensed and unlicensed approaches have merit.
Wi-Fi also shows that agreeing on a common standard can create a market. Its
example has been taken to heart by the backers of WiMax. Long-range wireless
networking gear, like short-range technology before it, has long been dominated by
vendors pushing proprietary standards, none of which has been widely adopted.
Inspired by Wi-Fi's success, the vendors have now thrown their weight behind
WiMax, a common standard with a consumer-friendly name, which they hope will
expand the market and boost all their fortunes. Whatever happens to Wi-Fi in future,
it has blazed a trail for other technologies to follow.
[attachment=21590]
IT STANDS as perhaps the signal success of the computer industry in the last few
years, a rare bright spot in a bubble-battered market: Wi-Fi, the short-range
wireless broadband technology. Among geeks, it has inspired a mania unseen since
the days of the internet boom. Tens of millions of Wi-Fi devices will be sold this year,
including the majority of laptop computers. Analysts predict that 100m people will be
using Wi-Fi by 2006. Homes, offices, colleges and schools around the world have
installed Wi-Fi equipment to blanket their premises with wireless access to the
internet. Wi-Fi access is available in a growing number of coffee-shops, airports and
hotels too. Yet merely five years ago wireless networking was a niche technology.
How did Wi-Fi get started, and become so successful, in the depths of a downturn?
Wi-Fi seems even more remarkable when you look at its provenance: it was, in
effect, spawned by an American government agency from an area of radio spectrum
widely referred to as “the garbage bands”. Technology entrepreneurs generally
prefer governments to stay out of their way: funding basic research, perhaps, and
then buying finished products when they emerge on the market. But in the case of
Wi-Fi, the government seems actively to have guided innovation. “Wi-Fi is a creature
of regulation, created more by lawyers than by engineers,” asserts Mitchell Lazarus,
an expert in telecoms regulation at Fletcher, Heald & Hildreth, a law firm based in
Arlington, Virginia. As a lawyer, Mr Lazarus might be expected to say that. But he
was also educated as an electrical engineer—and besides, the facts seem to bear him
out.
In the beginning
Wi-Fi would certainly not exist without a decision taken in 1985 by the Federal
Communications Commission (FCC), America's telecoms regulator, to open several
bands of wireless spectrum, allowing them to be used without the need for a
government licence. This was an unheard-of move at the time; other than the hamradio
channels, there was very little unlicensed spectrum. But the FCC, prompted by
a visionary engineer on its staff, Michael Marcus, took three chunks of spectrum from
the industrial, scientific and medical bands and opened them up to communications
entrepreneurs.
These so-called “garbage bands”, at 900MHz, 2.4GHz and 5.8GHz, were already
allocated to equipment that used radio-frequency energy for purposes other than
communications: microwave ovens, for example, which use radio waves to heat
food. The FCC made them available for communications purposes as well, on the
condition that any devices using these bands would have to steer around
interference from other equipment. They would do so using “spread spectrum”
technology, originally developed for military use, which spreads a radio signal out
over a wide range of frequencies, in contrast to the usual approach of transmitting
on a single, well-defined frequency. This makes the signal both difficult to intercept
and less susceptible to interference.
Though the 1985 ruling seems visionary in hindsight, nothing much happened at the
time. What ultimately got Wi-Fi moving was the creation of an industry-wide
standard. Initially, vendors of wireless equipment for local-area networks (LANs),
such as Proxim and Symbol, developed their own kinds of proprietary equipment that
operated in the unlicensed bands: equipment from one vendor could not talk to
equipment from another. Inspired by the success of Ethernet, a wireline-networking
standard, several vendors realised that a common wireless standard made sense too.
Buyers would be more likely to adopt the technology if they were not “locked in” to a
particular vendor's products.
In 1988, NCR Corporation, which wanted to use the unlicensed spectrum to hook up
wireless cash registers, asked Victor Hayes, one of its engineers, to look into getting
a standard started. Mr Hayes, along with Bruce Tuch of Bell Labs, approached the
Institute of Electrical and Electronics Engineers (IEEE), where a committee called
802.3 had defined the Ethernet standard. A new committee called 802.11 was set
up, with Mr Hayes as chairman, and the negotiations began.
The fragmented market meant it took a long time for the various vendors to agree
on definitions and draw up a standard acceptable to 75% of the committee
members. Finally, in 1997, the committee agreed on a basic specification. It allowed
for a data-transfer rate of two megabits per second, using either of two spreadspectrum
technologies, frequency hopping or direct-sequence transmission. (The first
avoids interference from other signals by jumping between radio frequencies; the
second spreads the signal out over a wide band of frequencies.)
The
ne
w
sta
nda
rd
was
pub
lish
ed
in
199
7,
and
eng
ine
ers
im
me
diat
ely
beg
an working on prototype equipment to comply with it. Two variants, called 802.11b
(which operates in the 2.4GHz band) and 802.11a (which operates in the 5.8GHz
band), were ratified in December 1999 and January 2000 respectively. 802.11b was
developed primarily by Richard van Nee of Lucent and Mark Webster of Intersil (then
Harris Semiconductor).
Companies began building 802.11b-compatible devices. But the specification was so
long and complex—it filled 400 pages—that compatibility problems persisted. So in
August 1999, six companies—Intersil, 3Com, Nokia, Aironet (since purchased by
Cisco), Symbol and Lucent (which has since spun off its components division to form
Agere Systems)—got together to create the Wireless Ethernet Compatibility Alliance
(WECA).
A rose by any other name...
The idea was that this body would certify that products from different vendors were
truly compatible with each other. But the terms “WECA compatible” or “IEEE802.11b
compliant” hardly tripped off the tongue. The new technology needed a consumerfriendly
name. Branding consultants suggested a number of names, including
“FlankSpeed” and “DragonFly”. But the clear winner was “Wi-Fi”. It sounded a bit like
hi-fi, and consumers were used to the idea that a CD player from one company
would work with an amplifier from another. So Wi-Fi it was. (The idea that this stood
for “wireless fidelity” was dreamed up later.)
The technology had been
standardised; it had a name;
now Wi-Fi needed a market
champion, and it found one in
Apple, a computer-maker
renowned for innovation. The
company told Lucent that, if it
could make an adapter for
under $100, Apple would
incorporate a Wi-Fi slot into all
its laptops. Lucent delivered, and in July 1999 Apple introduced Wi-Fi as an option on
its new iBook computers, under the brand name AirPort. “And that completely
changed the map for wireless networking,” says Greg Raleigh of Airgo, a wireless
start-up based in Palo Alto, California. Other computer-makers quickly followed suit.
Wi-Fi caught on with consumers just as corporate technology spending dried up in
2001.
Wi-Fi was boosted by the growing popularity of high-speed broadband internet
connections in the home; it is the easiest way to enable several computers to share
a broadband link. To this day, Wi-Fi's main use is in home networking. As the
technology spread, fee-based access points known as “hotspots” also began to spring
up in public places such as coffee-shops, though many hotspot operators have gone
bust and the commercial viability of many hotspots is unclear. Meanwhile, the FCC
again tweaked its rules to allow for a new variant of Wi-Fi technology, known as
802.11g. It uses a new, more advanced form of spread-spectrum technology called
orthogonal frequency-division multiplexing (OFDM) and can achieve speeds of up to
54 megabits per second in the 2.4GHz band.
Where next? Many Wi-Fi enthusiasts believe it will sweep other wireless technologies
aside: that hotspots will, for example, undermine the prospects for third-generation
(3G) mobile-telephone networks, which are also intended to deliver high-speed data
to users on the move. But such speculation is overblown. Wi-Fi is a short-range
technology that will never be able to provide the blanket coverage of a mobile
network. Worse, subscribe to one network of hotspots (in coffee-shops, say) and you
may not be able to use the hotspot in the airport. Ken Denman, the boss of iPass, an
internet-access provider based in Redwood Shores, California, insists that things are
improving. Roaming and billing agreements will, he says, be sorted out within a
couple of years.
By that time, however, the first networks based on a new technology, technically
known as 802.16 but named WiMax, should be up and running. As its name
suggests, WiMax is positioned as a wide-area version of Wi-Fi. It has a maximum
throughput of 70 megabits per second, and a maximum range of 50km, compared
with 50m or so for Wi-Fi. Where Wi-Fi offers access in selected places, like phone
boxes once did, WiMax could offer blanket coverage, like mobile phones do.
Wi-Fi is also under threat in the home. At the moment it is the dominant homenetworking
technology: Wi-Fi-capable televisions, CD players and video-recorders
and other consumer-electronics devices are already starting to appear. This will
make it possible to pipe music, say, around the house without laying any cables.
Cordless phones based on Wi-Fi are also in the works. But Wi-Fi may not turn out to
be the long-term winner in these applications. It is currently too power-hungry for
handheld devices, and even 802.11g cannot reliably support more than one stream
of video. And a new standard, technically known as 802.15.3 and named WiMedia,
“Wi-Fi's ultimate significance may
be that it provides a glimpse of
what will be possible with future
wireless technologies”
has been specifically designed as a short-range, high-capacity home networking
standard for entertainment devices.
Wi-Fi's ultimate significance, then, may be that it provides a glimpse of what will be
possible with future wireless technologies. It has also changed the way regulators
and technologists think about spectrum policy. The FCC has just proposed that
broadcast “whitespace”—the airwaves assigned to television broadcasters but not
used for technical reasons—should be opened up too. That is not to say that
spectrum licensing will be junked in favour of a complete free-for-all over the
airwaves. Julius Knapp, the deputy chief of the office of engineering and technology
at the FCC, maintains that both the licensed and unlicensed approaches have merit.
Wi-Fi also shows that agreeing on a common standard can create a market. Its
example has been taken to heart by the backers of WiMax. Long-range wireless
networking gear, like short-range technology before it, has long been dominated by
vendors pushing proprietary standards, none of which has been widely adopted.
Inspired by Wi-Fi's success, the vendors have now thrown their weight behind
WiMax, a common standard with a consumer-friendly name, which they hope will
expand the market and boost all their fortunes. Whatever happens to Wi-Fi in future,
it has blazed a trail for other technologies to follow.