Phenomenological model is investigated which enables separation of two contributions of the total received field, one from direct radiation, and another one from multiple scattering. Using the Beckman distribution, based on this model, we have calculated the higher moments and derived the relationships between the distribution parameters and experimentally measured moments. It has been found that this distribution, due to limitations on the value of its third moment, cannot be used for describing intensity fluctuations along some paths, particularly under strong turbulence. Results are compared with the experiments, in which the Beckman distribution is applicable.