Modern wireless optical communication systems in many aspects overcome wire or radio communications. Their
advantages are license-free operation and broad bandwidth that they offer. The medium in free-space optical (FSO) links
is the atmosphere. Operation of outdoor FSO links struggles with many atmospheric phenomena that deteriorate phase
and amplitude of the transmitted optical beam. This beam originates in the transmitter and is affected by its individual
parts, especially by the lens socket and the transmitter aperture, where attenuation and diffraction effects take place.
Both of these phenomena unfavourable influence the beam and cause degradation of link availability, or its total
malfunction. Therefore, both of these phenomena should be modelled and simulated, so that one can judge the link
function prior to the realization of the system. Not only the link availability and reliability are concerned, but also
In addition, the transmitted beam is not, generally speaking, circularly symmetrical, what makes the link simulation
more difficult. In a comprehensive model, it is necessary to take into account the ellipticity of the beam that is restricted
by circularly symmetrical aperture where then the attenuation and diffraction occur. General model is too
computationally extensive; therefore simplification of the calculations by means of analytical and numerical approaches
will be discussed.
Presented model is not only simulated using computer, but also experimentally proven. One can then deduce the ability
of the model to describe the reality and to estimate how far can one go with approximations, i.e. limitations of the model