Unlike fiber-optic communication, in which the medium
is a fiber-optic cable, FSO uses free space as its medium. An FSO system consists of three
key subsystems, each of which has achieved maturity as a technology in its own right.
Figure 9.1 Wireless optical mesh network benefits
Wireless Optical
Mesh
Flexibility
Lower cost
Fast deployment
Bandwidth
License free
Interference free
Resiliency
Network capacity
Scalability
Optical
wireless
mesh
Optical Wireless Mesh Networks 237
Communication Channel (Transmitter and Receiver) For the transmission and reception
of data, FSO uses the same underlying technology as fiber-optic technology. Not only is
this underlying technology a mature technology, but also it has the benefit of offering a
significant potential to scale when it comes to delivering fiber-like bandwidth with the
flexibility of being a wireless medium.
Most FSO systems use the infrared (IR) spectrum with wavelengths between 785 nm
and 850 nm. Infrared signals are not visible to human eyes but are ???visible??? to silicon
detectors. Some FSO systems also use 1550 nm wavelength IR beams, a spectrum popular
in long-haul fiber-optic communication.
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