An analysis of the first order PDF of small-scale fading in multipath radio channels

The first order probability distribution of a signal received over small-scale multipath fading is analyzed and its convergence to a circularly symmetrical Gaussian distribution (Rayleigh fading) is discussed. A criterion for assuming this Gaussianity is proposed which is based on the relation between the symbol interval duration and a reference obtained from parameters closely related to the propagation environment. The analysis here presented also permits to quantify the error implied in Gaussian assumption. A numerical example of its application is presented using indoor propagation environment parameters.