  In this paper, a novel gamma-shadowed two-ray with diffuse power (GS-TWDP)
composite fading model is proposed. The model is intended for modeling
propagation in the emerging wireless networks working at millimeter wave
(mmWave) frequencies, and is obtained as a combination of TWDP distribution for
description of multipath effects and gamma distribution for modeling variations
due to shadowing. After derivation of the exact probability density function
(PDF), cumulative distribution function (CDF) and moment generating functions
(MGF) expressions are obtained. Proposed model is verified by comparing the
analytically obtained results with those measured at 28 GHz and reported in
literature. Two upper bound average symbol error probability (ASEP) expressions
are then derived for M-ary rectangular quadrature amplitude modulation (RQAM)
by employing Chernoff and Chiani approximations of Gaussian Q-function, and are
used to investigate relationship between GS-TWDP parameters and system
performance. All the results are verified by Monte-Carlo simulation.
