10-03-2011, 11:07 AM
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Free Space Optics (FOS)
WHAT IS FREE SPACE OPTICS (FSO)?
->The Technology at the Heart of Optical Wireless
Imagine a technology that offers full-duplex Gigabit Ethernet throughput.
A technology that can be installed license-free worldwide, can be installed in less than a day. A technology that offers a fast, high ROI.That technology is free-space optics (FSO).
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 transmitter and a receiver to provide full-duplex (bi-directional) capability. Each optical wireless unit uses an optical source, 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 viaoptical fiber.
This FSO technology approach has a number of advantages:
Requires no RF 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 upgrades.Is immune to radio frequency interference or saturation.
Can be deployed behind windows, eliminating the need for costly rooftop rights.
FSO: Optical or Wireless?
Speed of fiber — flexibility of wireless.
Optical wireless, based on FSO-technology, is an outdoor wireless product category that provides the speed of fiber, with the flexibility of wireless. It enables optical transmission at speeds of up to 1.25 Gbps and, in the future, is capable of speeds of 10 Gbps using WDM. This is not possible with any fixed wireless or RF technology. Optical wireless also eliminates the need to buy expensive spectrum (it requires no FCC or municipal license approvals worldwide), which further distinguishes it from fixed wireless technologies. Moreover, FSO technology’s 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 wired optical solutions enable the seamless integration of access networks with optical core networks and helps to realize the vision of an
all-optical network.
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:
1.Fog
2.Adsorption
3. Scattering
4. Physical obstructions
5. Building sway/seismic activity
Typically scenarios for use are:
* LAN-to-LAN connections on [[campus]]es at [[Fast Ethernet]] or [[Gigabit Ethernet]] speeds.
* LAN-to-LAN connections in a [[city]]. ''example, [[Metropolitan area network]]''.
* To cross a public road or other barriers which the sender and receiver do not own.
* Speedy service delivery of high-bandwidth access to [[optical fiber]] networks.
* Converged Voice-Data-Connection.
* Temporary network installation (for events or other purposes).
* Reestablish high-speed connection quickly ([[disaster recovery]]).
* As an alternative or upgrade add-on to existing wireless technologies.
* As a safety add-on for important fiber connections (redundancy).
* For communications between [[spacecraft]], including elements of a [[satellite constellation]].
CMP-MSI:
3rd Workshop on Chip Multiprocessor Memory Systems and Interconnects held in conjunction with
the 36th International Symposium on Computer Architecture, June 2009.chip communication.
The light beam can be very narrow, which makes FSO hard to intercept, improving security. In any case, it is comparatively easy to encrypt any data traveling across the FSO connection for additional security. FSO provides vastly improved (Electromagnetic interference|EMI) behavior using light instead of microwaves.
== Advantages ==
* Ease of deployment
*( Broadcast license|License)-free long-range operation (in contrast with radio communication)
* High bit rates
* Low bit error rates
* Immunity to electromagnetic interference
* Full Duplex (telecommunications)duplex operation
* Communications protocol transparency
* Very Computer security due to the high directionality and narrowness of the beam(s)
* No Fresnel zone necessary
For terrestrial applications, the principal limiting factors are:
-> Beam dispersion
-> Atmospheric absorption
-> Rain
-> Fog (10..~100 dB/km attenuation)
-> Snow
-> Scintillation
-> Background light
-> Shadowing
-> Pointing stability in wind
-> Pollution / smog
-> If the sun goes exactly behind the transmitter, it can swamp the signal.
These factors cause an attenuated receiver signal and lead to higher bit error ratio (BER). To overcome these issues, vendors found some solutions, like multi-beam or multi-path architectures, which use more than one sender and more than one receiver. Some state-of-the-art devices also have larger fade margin (extra power, reserved for rain, smog, fog). To keep an eye-safe environment, good FSO systems have a limited laser power density and support laser classes 1 or 1M. Atmospheric and fog attenuation, which are exponential in nature, limit practical range of FSO devices to several kilometres.
Free Space Optics (FOS)
WHAT IS FREE SPACE OPTICS (FSO)?
->The Technology at the Heart of Optical Wireless
Imagine a technology that offers full-duplex Gigabit Ethernet throughput.
A technology that can be installed license-free worldwide, can be installed in less than a day. A technology that offers a fast, high ROI.That technology is free-space optics (FSO).
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 transmitter and a receiver to provide full-duplex (bi-directional) capability. Each optical wireless unit uses an optical source, 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 viaoptical fiber.
This FSO technology approach has a number of advantages:
Requires no RF 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 upgrades.Is immune to radio frequency interference or saturation.
Can be deployed behind windows, eliminating the need for costly rooftop rights.
FSO: Optical or Wireless?
Speed of fiber — flexibility of wireless.
Optical wireless, based on FSO-technology, is an outdoor wireless product category that provides the speed of fiber, with the flexibility of wireless. It enables optical transmission at speeds of up to 1.25 Gbps and, in the future, is capable of speeds of 10 Gbps using WDM. This is not possible with any fixed wireless or RF technology. Optical wireless also eliminates the need to buy expensive spectrum (it requires no FCC or municipal license approvals worldwide), which further distinguishes it from fixed wireless technologies. Moreover, FSO technology’s 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 wired optical solutions enable the seamless integration of access networks with optical core networks and helps to realize the vision of an
all-optical network.
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:
1.Fog
2.Adsorption
3. Scattering
4. Physical obstructions
5. Building sway/seismic activity
Typically scenarios for use are:
* LAN-to-LAN connections on [[campus]]es at [[Fast Ethernet]] or [[Gigabit Ethernet]] speeds.
* LAN-to-LAN connections in a [[city]]. ''example, [[Metropolitan area network]]''.
* To cross a public road or other barriers which the sender and receiver do not own.
* Speedy service delivery of high-bandwidth access to [[optical fiber]] networks.
* Converged Voice-Data-Connection.
* Temporary network installation (for events or other purposes).
* Reestablish high-speed connection quickly ([[disaster recovery]]).
* As an alternative or upgrade add-on to existing wireless technologies.
* As a safety add-on for important fiber connections (redundancy).
* For communications between [[spacecraft]], including elements of a [[satellite constellation]].
CMP-MSI:
3rd Workshop on Chip Multiprocessor Memory Systems and Interconnects held in conjunction with
the 36th International Symposium on Computer Architecture, June 2009.chip communication.
The light beam can be very narrow, which makes FSO hard to intercept, improving security. In any case, it is comparatively easy to encrypt any data traveling across the FSO connection for additional security. FSO provides vastly improved (Electromagnetic interference|EMI) behavior using light instead of microwaves.
== Advantages ==
* Ease of deployment
*( Broadcast license|License)-free long-range operation (in contrast with radio communication)
* High bit rates
* Low bit error rates
* Immunity to electromagnetic interference
* Full Duplex (telecommunications)duplex operation
* Communications protocol transparency
* Very Computer security due to the high directionality and narrowness of the beam(s)
* No Fresnel zone necessary
For terrestrial applications, the principal limiting factors are:
-> Beam dispersion
-> Atmospheric absorption
-> Rain
-> Fog (10..~100 dB/km attenuation)
-> Snow
-> Scintillation
-> Background light
-> Shadowing
-> Pointing stability in wind
-> Pollution / smog
-> If the sun goes exactly behind the transmitter, it can swamp the signal.
These factors cause an attenuated receiver signal and lead to higher bit error ratio (BER). To overcome these issues, vendors found some solutions, like multi-beam or multi-path architectures, which use more than one sender and more than one receiver. Some state-of-the-art devices also have larger fade margin (extra power, reserved for rain, smog, fog). To keep an eye-safe environment, good FSO systems have a limited laser power density and support laser classes 1 or 1M. Atmospheric and fog attenuation, which are exponential in nature, limit practical range of FSO devices to several kilometres.
