Given a RF sender and a receiver, suppose the obstacles between them are fixed, both their material and dielectric properties, does the signal attenuation caused by their shadowing vary over time? If yes, what causes the variation? If not, why is it generally modeled as a random variable (e.g., log-normal) instead of a constant?
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1\$\begingroup\$ Sino, perhaps you could just edit your previous question to cover any additional ground needed: At least at first glance, there seems to be a fair overlap. \$\endgroup\$– Anindo GhoshMay 1, 2013 at 16:43
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It is the WHOLE signal path , not just the obvious blocking/shadowing elements that are varying. It's the atmosphere, humidity, density, air-currents particles etc. that subtly change the propagation. The presence of the shadowing/objects magnifies the effect.
answered May 1, 2013 at 17:19
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\$\begingroup\$ If the blockage of these small-scale objects also contribute to shadowing, why is it still called large-scale fading then? \$\endgroup\$ May 1, 2013 at 17:25
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\$\begingroup\$ What is the scale for "size" ?. In your other question, this is answered very nicely. Multi-path is an interference effect, which means that the scale is wavelength range. \$\endgroup\$ May 1, 2013 at 17:29