HISTORY
Historically, Free Space Optics (FSO) or optical wireless communications was first demonstrated by Alexander Graham Bell in the late nineteenth century (prior to his demonstration of the telephone!).
Originally developed by the military and NASA, FSO has been used for more than three decades in various forms to provide fast communication links in remote locations.
Beginning with laser developments in the 1960s, the first serious trials started to develop "Lightphones". Military organizations especially were interested and forced some developments. During the boom period of optical fiber installation civil FSO technology lay dormant, but in military and space laboratories the development didn't really stop. Some features of FSO technology were important for the military and again became important for civil use.
WORKING
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 via
optical fiber.
Free Space Optics (FSO) transmits invisible, eye-safe light beams from one "telescope" to another using low power infrared lasers in the teraHertz spectrum. The beams of light in Free Space Optics (FSO) systems are transmitted by laser light focused on highly sensitive photon detector receivers. These receivers are telescopic lenses able to collect the photon stream and transmit digital data containing a mix of Internet messages, video images, radio signals or computer files.Commercially available systems offer capacities in the range of 100 Mbps to 2.5 Gbps, and demonstration systems report data rates as high as 160 Gbps.
Free Space Optics (FSO) systems can function over distances of several kilometers. As long as there is a clear line of sight between the source and the destination, and enough transmitter power, Free Space Optics (FSO) communication is possible
Unlike radio and microwave systems, Free Space Optics (FSO) is an optical technology and no spectrum licensing or frequency coordination with other users is required, interference from or to other systems or equipment is not a concern, and the point-to-point laser signal is extremely difficult to intercept, and therefore secure. Data rates comparable to optical fiber transmission can be carried by Free Space Optics (FSO) systems with very low error rates, while the extremely narrow laser beam widths ensure that there is almost no practical limit to the number of separate Free Space Optics (FSO) links that can be installed in a given location.
ADVANTAGES
Free space optical (FSO)systems offers a flexible networking solution that delivers on the promise of broadband. Only free space optics or Free Space Optics (FSO) provides the essential combination of qualities required to bring the traffic to the optical fiber backbone – virtually unlimited bandwidth, low cost, ease and speed of deployment. Freedom from licensing and regulation translates into ease, speed and low cost of deployment. Since Free Space Optics (FSO) optical wireless transceivers can transmit and receive through windows, it is possible to mount Free Space Optics (FSO) systems inside buildings, reducing the need to compete for roof space, simplifying wiring and cabling, and permitting the equipment to operate in a very favorable environment. The only essential for Free Space Optics (FSO) is line of sight between the two ends of the link.
. Free Space Optics (FSO) is far more secure than RF or other wireless-based transmission technologies for several reasons:
- Free Space Optics (FSO) laser beams cannot be detected with spectrum analyzers or RF meters
- Free Space Optics (FSO) laser transmissions are optical and travel along a line of sight path that cannot be intercepted easily. It requires a matching Free Space Optics (FSO) transceiver carefully aligned to complete the transmission. Interception is very difficult and extremely unlikely
Main Advantages are:
- Quick link setup
- license free operation
- High transmission security
- High bit rates
- Low bit error rate
- Low snow and rain impact
- Full duplex transmission
- No interference
APPLICATIONS
Typically scenarios for use are:
- LAN-to-LAN connections on campuses at Fast Ethernet or Gigabit Ethernet speeds
- LAN-to-LAN connections in a city. example, Metropolitan area network
- To cross a road or other barriers
- Speedy service delivery of high bandwidth access to fiber networks
- Converged Voice-Data-Connection
- Temporary network installation (for events or other purposes)
- Re-establish high speed connection quickly (Disaster Recovery)
- As an alternative or upgrade to existing wireless technologies.
- For communications between spacecraft, including elements of a satellite constellation
- For interstellar communication
The lightbeam can be very narrow, which makes FSO hard to intercept, improving security. FSO provides vastly improved EMI behavior using light instead of microwaves.
CONCLUSION
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 . This is not possible with any fixed wireless or RF technology. 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.
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