Mathematically, the Rician parameter k is defined as:
The Rician fading profile is generated by adding a DC specular component to a Rayleigh distributed scattering component. var denotes the requested fading variance, which is the variance of the underlying Rayleigh fading profile. The amplitude (A) of the specular DC component is given by the following formula:
By varying K, you can parameterize the extent of the scattering component relative to the LOS component of fading. For a strongly Gaussian channel, K approaches infinity, while K < 0 indicates a strongly scattering (Rayleigh fading) channel.