Small scale fading is used to describe the rapid fluctuation of the amplitude of a radio signal over a short period of time or travel distance. Fading is caused by interference between two or more versions of the transmitted signal which arrive at the receiver at slightly different times. A tree of four different types of fading are shown below:
The factors influencing the small scale fading are:
Multipath propagation: It often lengthens the time required for the base band portion of the signal to reach the receiver which can cause signal smearing due to inter symbol interference (ISI).
Speed of mobile: The relative motion between the base station and mobile results in random frequency modulation due to different Doppler shifts on each of the multipath components. Doppler shift will be positive or negative depending on whether the mobile
Receiver is moving towards or away from base stations.
Speed of surrounding effects: If the surroundingobjects move at a greater rate than the mobile, then this effect dominates the small scale fading.