Modeling of Non-Stationary Double-Rayleigh Fading Channels for Mobile-to-Mobile Communications

In this paper, we present a novel geometry-based statistical model (GBSM) for non-stationary time-frequency (TF) dispersive channels for mobile-to-mobile (M2M) communication systems. The proposed model has been formulated by assuming that the transmitted signal reaches the receiver antenna through a double interaction by the scattering mechanism with interfering objects (IOs) randomly located in the propagation environment. As a consequence of such interaction, the first-order statistics of the channel model's envelope follow a worse-than-Rayleigh fading distribution; specifically, the envelope is modeled by a double-Rayleigh fading distribution. We characterize the variations in time of the propagation delays and Doppler shifts of the received multipath signal in strict accordance with the principles of plane-wave propagation (PWP). Capitalizing on the mathematical simplicity of this modeling approach, we derive a general expression for the four-dimensional (4D) TF correlation function (TF-CF) of the proposed channel model. The results presented throughout this paper provide theoretical insights into the correlation properties and non-stationary characteristics of double-Rayleigh fading M2M channels.