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by Theresa Carbonneau
fSONA Communications
Originally Published: June 1st, 2001
By: Electronic Component News
For some time now we've been imagining a future of boundless
connectivity, of video on demand and quality online audio,
of real-time high-resolution 3D Internet games and
full-screen HDTV video conferencing. Of instant downloads
and like-you're-there access to corporate networks. We want
full-time, high-speed access. We want it now and we want it
cheap. But there's not enough bandwidth to most homes or
offices to support the services we want — even though
fiber has been laid in metropolitan areas around the world
by long-distance carriers and fiber-backbone companies with
capacity far in excess of what is necessary for current
broadband desires.
Yet, most of us don't have access to it. We will continue to
wait for access for some time, until the cost of materials
and labor necessary to deliver fiber are reduced. This
problem of connecting to the backbone has become commonly
referred to as the "last," "first" or "golden" mile problem.
Despite the lack of fiber access, a great number of
last-mile options exist: digital subscriber lines, cable
modems, passive optical networks, radio and microwave
wireless, and satellite networks. But none of these offer
the speed of free space optics.
Free Space Optics: Wireless Fiber
Many homes are now connected to the Internet via cable
modems which, with speeds up to 30 Mbps downstream, are much
faster than traditional telephone line options but are still
limited by their upstream capabilities — at peak
times traffic may still slow to a crawl no faster than a
regular dial-up connection. Users also worry about the
security of their machines on this shared network, as it is
not difficult for the curious to learn the name and number
of the machine and thus gain access to it.
Meanwhile, fixed wireless, either radio or microwave, offers
impressive downstream rates but is still too expensive for
the home user. Satellite based systems have a number of
issues to overcome — lag times, cost of deployment and
licensing issues all delay common use of these systems (with
the exception of the Direct Broadcast Satellites, which
currently offers TV services such as video-on-demand and
digital cable.)
However, these systems lack interactivity. All of these
systems suffer from a lack of the upstream bandwidth
necessary for high-speed, interactive services such as
multi-player gaming over the Internet. Synchronous speed is
essential to high-end broadband applications and only two
technologies provide it: Fiber optic cable and optical
wireless systems. But optical wireless is the only
technology that offers instant gratification.
Once line of sight access is established, an optical
wireless system can be installed in less than an hour.
Laying fiber can take months of negotiations and a lifetime
of licensing fees. In fact, in metropolitan areas, an
optical wireless link can be more than ten times cheaper to
establish than laying fiber.
Path to Freedom
Free-space optical wireless has a lot more than just
cost-effectiveness to offer the world of networking. Many of
the benefits are experienced through better, faster, more
ubiquitous service. With the ability to create links quickly
and economically, optical wireless complements existing
services including cable, DSL, radio and microwave.
The lower initial outlays also allow service providers to
build out their networks at unprecedented speeds and extend
them to isolated areas. In sparsely populated locales, few
providers can justify bringing fiber close enough to offer
high-speed services. But optical wireless complements these
services by taking the place of fiber, making it economical
to extend service areas and making it possible to cross
previously difficult terrain. And optical wireless also
allows service provider to pay off the initial expense in a
matter of months with no licensing or leasing fees. Easy,
fast deployment and lower link costs for service providers
spell better service to homes and businesses.
Why 'Free Space' Optics?
Optical wireless is also known as "free space" optics. This
is the part of the electro-magnetic spectrum not regulated
by government agencies. A free space optical link transmits
information through the atmosphere on beams of light
created by lasers. The beams of light are similar to those
created by your TV remote and are perfectly safe to skin
and eyes.
The first free space transmission occurred more than 120
years ago and was conducted by Alexander Graham Bell. Bell's
"Photophone" was used for voice communications only. These
days we are a lot more demanding and current optical
wireless units can send digital data at speeds up to 1.25
Gigabits, with tests proving that 10 Gbps and even up to 160
Gbps, is possible. As ever more clever ways of increasing
the amount of information contained within a single stream
of light are discovered, this potential will increase.
The range for optical wireless systems varies depending upon
local weather conditions. Optical wireless links work well
in both rain and snow but have difficulties penetrating a
thick fog. Despite this, 99 percent availability was
achieved during tests conducted by British Telecom Labs in
London fog. Therefore, for mission critical applications,
optical wireless should be supplemented a backup radio or
microwave link. These configurations can achieve the 99.999
percent availability demanded by service providers.
As a shortcut to broadband, free-space optical networking
provides freedom — freedom from licensing
requirements and government regulations, freedom from
prohibitive pricing and inhospitable geography, freedom
from digging restrictions and right-of-way issues, and
freedom from waiting for fiber. Indeed, waiting for
bandwidth can become a thing of the past as the path with
the advent of optical wireless systems.
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