Polarimetric Modeling of Mobile Fading Channels

This paper presents a geometrical framework for the polarimetric modeling of mobile fading channels. Such a framework is formulated upon a spherical-wave propagation paradigm that allows to account for two important factors pertaining to wave polarization that are not jointly considered in the state of the art, namely: the anisotropic radiation characteristics of practical antennas, and the variations in time and space of the channel depolarization effects. The joint characterization of these two factors is important, e.g., for the analysis of mobile communication systems that rely on highly dynamic radio links, such as vehicular networks. The channel depolarization function is modeled by a linear transformation in the form of a simple rotation matrix that is transparent to the antenna polarization and to the geometry of the propagation scenario. The effects of multipath depolarization on the average power, the first-order envelope distribution, the average per-path Doppler shift, and the mean Doppler shift of mobile fading channels are analyzed mathematically and numerically. An open geometrical configuration of the propagation scenario is considered for the mathematical analysis, whereas a particular configuration given by a new geometrical street model with reflecting surfaces is adopted for the numerical analysis. The obtained results show that the aforementioned statistical quantities are strongly influenced by the anisotropic antenna pattern characteristics and by the time-space variations of multipath depolarization, demonstrating the importance of incorporating both factors into the modeling of mobile fading channels.