Multipath Effects - Rayleigh fading
In a radio link, the RF signal from the transmitter may be reflected from objects such as
hills, buildings, or vehicles. This gives rise to multiple transmission paths at the receiver.
The relative phase of multiple reflected signals can cause constructive or destructive
interference at the receiver. This is experienced over very short distances (typically at
half wavelength distances), thus is given the term fast fading. These variations can vary
from 10-30dB over a short distance. The following figure shows the level of attenuation
that can occur due to the fading.
Typical Rayleigh fading while the Mobile Unit is moving (for at 900MHz)