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FSO Technology
What is FSO
History How it Works
FSO: Optical or Wireless
Market Challenges
What is Free
Space Optics (FSO)?
The Technology Behind Optical Wireless
Imagine a technology that offers unsurpassed reliability and
high-speed connectivity. A technology that can be installed globally, is
easy to deploy, license-free and offers a fast, high ROI. That technology
is free-space optics (FSO). This line-of-sight technology approach uses
lasers to provide optical bandwidth connections. It's capable of sending
up to 2.5 Gbps of data, voice, and video communications simultaneously
through the air — enabling optical connectivity without requiring fiber-optic
cable or securing spectrum licenses. It enables optical communications at
the speed of light. And it forms the basis of a new category of products —
optical wireless products from CableFree, the recognized leader in optical
wireless communications.
This site is intended to provide valuable background and resource
information on FSO technology. Whether you're a student, an engineer,
account manager, partner, or customer, this site provides the FSO insight
you may require. And for providing high-speed, "last-mile" connections,
across campuses and into fiber networks, it is the best technology
available.
Free-space optics (FSO) is a line-of-sight technology that uses lasers to
provide optical bandwidth connections that can send and receive voice,
video, and data information on invisible beams of light. Today, FSO
technology — the foundation of CableFree's optical wireless offering — has
enabled the development of a new category of products that can transmit
voice, data, and video at bandwidths up to 2.5 Gbps at distances up to 4
km, over any protocol. This optical connectivity doesn't require expensive
fiber-optic cable or securing spectrum licenses. FSO technology requires
light, which can be focused by using either light emitting diodes (LEDs)
or lasers (light amplification by stimulated emission of radiation). The
use of lasers is a simple concept similar to optical transmissions using
fiber-optic cables; the only difference is the medium. Light travels
through air faster than it does through glass, so it is fair to classify
FSO technology as optical communications at the speed of light.
What is FSO History
How it Works FSO:
Optical or Wireless Market
Challenges
History
Originally developed by the military and NASA, FSO has been used for more
than 30 years to provide fast communication links in remote locations.
CableFree has extensive experience in this area: its experts were in the
labs developing prototype FSO systems in Europe mid '90s, before others
had even started to think about the technology.
While fiber-optic communications has gained acceptance in the
telecommunications industry, FSO communications is still relatively new.
FSO technology enables bandwidth transmission capabilities that are
similar to fiber optics, using similar optical transmitters and receivers
and even enabling WDM-like technologies to operate through free space.
What is FSO History
How it Works FSO:
Optical or Wireless Market
Challenges
How it Works
FSO technology is surprisingly simple. It's based on connectivity between
FSO-based optical wireless units, each consisting of an optical
transceiver with a laser transmitter and a receiver to provide full-duplex
(bi-directional) capability. Each optical wireless unit uses a high-power
optical source (i.e. laser), plus a lens or telescope that transmits light
through the atmosphere to another lens receiving the information. At this
point, the receiving lens or telescope connects to a high-sensitivity
receiver via optical fiber.
This FSO technology approach has a number of advantages:
Requires no spectrum licensing.
Is easily upgradeable, and its open interfaces support equipment from a
variety of vendors, which helps enterprises and service providers protect
their investment in embedded telecommunications infrastructures.
Requires no security software.
Is immune to radio frequency interference or saturation.
Can be deployed behind windows, eliminating the need for costly rooftop
rights.
What is FSO? History How it Works FSO: Optical or Wireless? Market
Challenges
What is FSO History
How it Works FSO:
Optical or Wireless Market
Challenges
FSO:
Optical or Wireless?
Speed of fiber — flexibility of wireless.
Optical wireless, based on FSO-technology, is an optical technology that
provides the speed of fiber, with the flexibility of wireless. It enables
optical transmission at speeds of up to 2.5 Gbps and, in the future, 10
Gbps using WDM. This is not possible with any fixed wireless/RF technology
today. Optical wireless also obviates the need to buy expensive spectrum
(it requires no FCC or municipal license approvals), which further
distinguishes it from fixed wireless technologies. Moreover, its narrow
beam transmission is typically two meters versus 20 meters and more for
traditional, even newer radio-based technologies such as millimeter-wave
radio. Optical wireless products' similarities with conventional optical
solutions enable the seamless integration of access networks with optical
core networks and helps to realize the vision of an all-optical network.
What is FSO? History How it Works FSO: Optical or Wireless? Market
Challenges Top
What is FSO History
How it Works FSO:
Optical or Wireless Market
Challenges
Market
Perspective:
Fueled by the ever-increasing demand for more bandwidth of enterprise
customers and service providers, the global "last mile" has become a
significant opportunity. While many companies are within range of fiber-optic
cable, most are not adequately connected as a result of prohibitive
licensing requirements and the expense of having to dig up streets and
neighborhoods. To date, fewer than 10 percent of buildings worldwide are
connected by fiber — yet 70 percent are within a mile of a fiber
connection. As bandwidth demands increase and businesses turn to
high-speed LANs, it has become even more frustrating to be connected to
the outside world through lower-speed connections such as DSL, cable
modems, or T1s.
Further, most of the recent trenching to lay fiber has been to improve the
metro core (backbone), while the metro access and edge — the " last mile"
— have been ignored. Studies show that gaps occur in the metro network
core, primarily due to cost constraints and the deployment of
non-scalable, non-optical technologies such as LMDS. Metro optical
networks have not yet delivered on their promise. High capacity at
affordable prices still eludes the ultimate end-user.
Market Opportunity:
IDC reports that the worldwide metro Ethernet market, driven by Asia, will
exceed $5 billion in value by 2003, and reach a staggering $25 billion in
2006. Frost & Sullivan sees the U.S. optical Ethernet market growing at a
59 percent CAGR to more than $4 billion by 2007.
There's a huge market opportunity — but which technology can best address
the connectivity bottleneck? Fiber optic? Radio frequency? Wire and
copper-based technologies or FSO?
Fiber Optic Cable:
It's the most obvious first choice. Without a doubt, fiber is the most
reliable means of providing optical communications. But the digging,
delays, and associated costs to lay fiber often make it economically
prohibitive. Moreover, once fiber is deployed, it becomes a "sunk" cost
and cannot be re-deployed if a customer relocates or switches to a
competing service provider, making it extremely difficult to recover the
investment in a reasonable timeframe.
Radio Frequency
Another option is radio frequency (RF) technology. RF is a mature
technology that offers longer-range distances than FSO, but RF-based
networks require immense capital investments to acquire spectrum license.
Also, RF technologies do not scale to gigabit speeds, and are not immune
to interference and saturation in heavily congested RF environments. When
compared to FSO-based optical wireless offerings, RF does not make
economic sense for service providers or enterprises looking to extend
optical networks.
Wire and Copper
This option includes wire- and copper-based technologies, (i.e. cable
modem, T1s or DSL). Although copper infrastructure is available almost
everywhere and the percentage of buildings connected to copper is much
higher than fiber, it is still not a viable alternative for solving the
"last mile" connectivity bottleneck. The biggest hurdle is bandwidth
scalability. Copper technologies may ease some short-term pain, but the
bandwidth limitations of 2 megabits to 3 megabits makes them a marginal
solution, even on a good day.
FSO technology — the "last mile" connectivity answer.
The most viable alternative is FSO technology. It offers the speed of
fiber with the flexibility of wireless. Given its optical foundation,
bandwidth scalability, speed of deployment (hours versus weeks or months),
re-deployment and portability, and cost-effectiveness (on average,
one-fifth the cost of installing fiber-optic cable), FSO technology is the
perfect choice for today's optical wireless products. Further, its layer
one transparency ensures interoperability with all major networking vendor
switches, routers, and other equipment.
Optical wireless products, based on FSO technology, are offering
cost-effective, last-mile connectivity solutions to enterprises and
service providers — handling connectivity across campuses, and into fiber
networks. There are three market segments poised for significant growth:
Enterprise campus networks — for companies of all sizes that need to
connect buildings across campuses and need access to fiber backbones.
Wireline access — aimed at service providers looking for an alternative to
fiber, especially where expensive leased lines are the only current
available solution, and in regions with rapidly developing
infrastructure-China and India.
Mobile Wireless — includes mobile wireless backhaul for today's networks
and next-generation architectures.
Click here to view the FSO Technology Shift Zone — a timeline and market
growth graphic showing FSO technology adoption.
What is FSO? History How it Works FSO: Optical or Wireless? Market
Challenges Top
What is FSO History
How it Works FSO:
Optical or Wireless Market
Challenges
Challenges
While fiber-optic cable and FSO technology share many of the same
attributes, they face different challenges due to the way they transmit
information. While fiber is subject to outside disturbances from wayward
construction backhoes, gnawing rodents, and even sharks when deployed
under sea, FSO technology is subject to its own potential outside
disturbances. Optical wireless networks based on FSO technology must be
designed to combat changes in the atmosphere, which can affect FSO system
performance capacity. And because FSO is a line-of-sight technology, the
interconnecting points must be free from physical obstruction and able to
"see" each other.
All potential disturbances can be addressed through thorough and
appropriate network design and planning. Among the issues to be considered
when deploying FSO-based optical wireless systems:
Fog: The primary challenge to FSO-based communications is fog. Rain and
snow have little effect on FSO technology, but fog is different. Fog is
vapor composed of water droplets, which are only a few hundred microns in
diameter but can modify light characteristics or completely hinder the
passage of light through a combination of absorption, scattering, and
reflection. The primary answer to counter fog when deploying FSO-based
optical wireless products is through a network design that shortens FSO
link distances and adds network redundancies. FSO installations in
extremely foggy cities such as San Francisco have successfully achieved
carrier-class reliability.
Absorption: Absorption occurs when suspended water molecules in the
terrestrial atmosphere extinguish photons. This causes a decrease in the
power density (attenuation) of the FSO beam and directly affects the
availability of a system. Absorption occurs more readily at some
wavelengths than others. However, the use of appropriate power, based on
atmospheric conditions, and use of spatial diversity (multiple beams
within an FSO-based unit) helps maintain the required level of network
availability.
Scattering: Scattering is caused when the wavelength collides with the
scatterer. The physical size of the scatterer determines the type of
scattering. When the scatterer is smaller than the wavelength, this is
known as Rayleigh scattering. When the scatterer is of comparable size to
the wavelength, this is known as Mie scattering. When the scatterer is
much larger than the wavelength, this is known as non-selective
scattering. In scattering — unlike absorption — there is no loss of
energy, only a directional redistribution of energy that may have
significant reduction in beam intensity for longer distances.
Physical obstructions: Flying birds or construction cranes can temporarily
block a single-beam FSO system, but this tends to cause only short
interruptions, and transmissions are easily and automatically resumed.
CableFree's optical wireless products use multi-beam systems (spatial
diversity) to address temporary obstructions, as well as other atmospheric
conditions, to provide for greater availability.
Building sway/seismic activity: The movement of buildings can upset
receiver and transmitter alignment. CableFree's FSO-based optical wireless
offerings use a divergent beam to maintain connectivity. When combined
with tracking, multiple beam FSO-based systems provide even greater
performance and enhanced installation simplicity.
Scintillation: Heated air rising from the earth or man-made devices such
as heating ducts create temperature variations among different air
pockets. This can cause fluctuations in signal amplitude which leads to
"image dancing" at the FSO-based receiver end. CableFree's unique
wide-beam optics is designed to address the effects of this scintillation.
Called "Refractive turbulence," this causes two primary effects on optical
beams
Beam Wander: Beam wander is caused by turbulent eddies that are larger
than the beam.
Beam Spreading: Beam spreading — long-term and short-term — is the spread
of an optical beam as it propagates through the atmosphere.
Safety: To those unfamiliar with FSO technology, safety can be a concern
because the technology uses lasers for transmission. The proper use and
safety of lasers have been discussed since FSO devices first appeared in
laboratories more than two decades ago. The two major concerns involve eye
exposure to laser beams and high voltages within the laser systems and
their power supplies. Strict international standards have been set for
laser safety and performance, and CableFree's optical wireless systems
comply with these standards.
To find out more, please visit:
FSO Primer
FSO Technology
FSO Guide
FSO Comparisons
FSO Laser Guide
FSO Products
FSO Applications
FSO Glossary
FSO FAQ
FSO Technology FAQ
FSO Metro App
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Copyright
2000 CableFree Solutions Limited
Free Space Optics (FSO), Optical Wireless, Infrared
Fixed Wireless Access,
Wireless
Broadband, Laser
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