Rayleigh Distribution

Rayleigh distributions are commonly used to describe the statistical time varying nature of the received envelope of a flat fading signal, or the envelope of an individual multipath component. Envelope of the sum of two quadrature Gaussian noise signals obeys a Rayleigh distribution.

Ricean Fading Distribution

When there is a dominant stationary (non-fading) signal component present, such as a line-of sight propagation path, the small-scale fading envelope distribution is Ricean.