[AI] Wireless speed freaks set to leave Wi-Fi standing

Sanjay ilovecold at gmail.com
Fri Jun 25 03:29:33 EDT 2010


          Can Wi-Fi rise to the challenge of super-fast, high-definition
          downloads or are its days as the "killer app" of connectivity
          numbered?

by Wendy Zukerman

WI-FI as we know it is reaching the limits of its usefulness. It just
can't keep up with our appetite for services, such as new video
formats, that gobble up bandwidth. So what's next in the world of
blisteringly fast home-based wireless technologies?

For clues to where Wi-Fi is going, it helps to delve into the soup of
standards that will shape the future of wireless communications.

To date, most Wi-Fi hotspots use one of three connectivity standards,
802.11a, 802.11b and 802.11g - the current favourite. Wi-Fi devices
connect to the internet over the radio waves in bands around the 2.4
gigahertz and 5 GHz frequencies, as defined by the international
standards body, the Institute of Electrical and Electronics Engineers
(IEEE).

Last year, the IEEE agreed the specification for a new Wi-Fi standard,
802.11n, which operates in both the 2.4 GHz and 5 GHz bands.  This standard
is theoretically capable of transmitting data at
300 megabits per second - up from 802.11g's paltry 54 Mbps. The new
Wi-Fi standard should make streaming high-definition video a less
jerky experience than it has been so far. And further changes may take
speeds up to 600 Mbps.

Even so, based on past experience, additional bandwidth will soon get
eaten up by data-hungry services, so what are the prospects for even
faster wireless transmission?

One method being considered is to transmit data in a different band of
frequencies - generally speaking, the higher the frequency, the more
data can be shifted. Several consortiums are already building systems
which can operate around the 60 GHz band, including the IEEE's
proposed 802.11ad standard.

In mid-2009, the Wireless Gigabit Alliance (WiGig), a consortium
of technology companies including Microsoft and Intel, published its
specification for 60 GHz wireless communication technology. Ali Sadri,
president of WiGig, says that its protocol will support data
transmission rates up to 7 Gbps. At that speed, you could download the
equivalent of a Blu-ray disc onto your laptop in seconds.
At 60 gigahertz you can download the equivalent of a Blu-ray disc onto
your laptop in seconds

While WiGig's speed would easily surpass that of Wi-Fi, its range will
be far shorter, at around 10 metres in open air. This is because radio
waves at 60 GHz are subject to interference in the air, as the bonds
in oxygen molecules resonate with the waves. That means it will not
penetrate walls, confining your super-fast internet to a single room.
Sadri thinks that may actually be an advantage, improving users'
security by preventing outsiders tapping into your network.

The big advantage of 60 GHz is that it is free, says Stan
Skafidas, an electrical engineer at Australia's national technology
research group, NICTA. This is because governments considered it
unusable, so it doesn't require a licence, he says. Skafidas has been
developing a chip that has all the components needed for 60 GHz
connectivity built in.

NICTA's so-called Gi-Fi chip will comply with the 802.11ad standard
when it's finalised and allow downloads of up to 5 Gbps. Because the
chip is built in the same way as most silicon chips, it should be
possible to make them cheaply enough to compete with Wi-Fi, says
Skafidas. NICTA demonstrated prototype chips last year and expects to
go into full-scale production soon.

"Because it's very cheap, you could envisage a situation where every
power point in your house has this chip set into it," says Skafidas,
so the short transmission range of 60 GHz won't be a problem.

Elsewhere, the IEEE has working groups looking at improvements to
Wi-Fi's capability. Its 802.11ac standard will operate around the 5
GHz band, like 802.11a, but data will be transmitted over a greater
range of frequencies around that band to boost data rates. The
standard isn't expected to be finalised until 2012, though it expects
to exceed 1 Gbps.

Others think we should abandon the overcrowded airwaves altogether and
concentrate on light. Mohsen Kavehrad, an electrical engineer at
Pennsylvania State University in University Park and his team have
been working on an optical transmission system that is capable of high
data-transmission rates. One problem with using light is that you
normally need a direct line of sight between transmitter and receiver.
Kavehrad's system gets round this by using a high-power laser diode to
generate pulses of infrared light, which can be bounced off the
ceiling. The reflected light is captured and refocused at the
receiver, where a special semiconductor known as an avalanche photo
diode turns light into a digital signal. The team have been able to
transmit data at 1 Gbps, and think it can go even faster. They
presented the work at the SPIE Phonotics West Conference in San
Francisco last month.

Adding reflectors and more sensors could allow light to be bounced
into separate rooms, claims Kavehrad, getting round one of the
problems with 60 GHz radio systems. Optical systems should also be
"greener" as their components generally use less energy than those
transmitting radio waves. It would not interfere with other electronic
systems, making it suitable for hospitals and aircraft, where Wi-Fi
use has traditionally been restricted, he adds.

While Kavehrad's system is undoubtedly impressive, designing 60 GHz
systems will be easier as the equipment is similar to existing Wi-Fi.
Also, using radio waves to access the internet is a tried-and-tested
technology, says Rod Tucker, an electrical engineer at the
University of Melbourne, Australia.

But even this super-fast wireless connectivity will one day be
superseded, so all approaches will remain in play. "There is an
ever-growing upward demand on bandwidth. We're not just talking HD
video. It's going to be 3D, then super HD video then super 3D. When in
the history of telecommunication has the demand for more data
stopped?" says Tucker. "Never."


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