A 3D Ellipsoid Model for Isotropic and Non-Isotropic Scatterers Co-existing Massive MIMO Channels

In this paper, we propose a three-dimensional (3D) multi-confocal ellipsoid channel model for massive multiple-input multiple-output (MIMO) communication systems, which considers the coexistence of isotropic scatterers and non-isotropic scatterers. Specifically, the inner ellipsoids are used to model the isotropic scatterers, and the outer ellipsoids are used to model the non-isotropic scatterers. First, under the spherical wavefront assumption, we develop the mathematical relationships between the angle of arrival (AOA) and the angle of departure (AOD), which is more precise than conventional approximation, and can be used to capture the channel non-stationary properties. Second, we study the correlations of the proposed model in detail, and study the impacts of important parameters such as scatterer type and scatterer distribution on it. Finally, our numerical and the simulation results demonstrate that the proposed model can capture features of realistic massive MIMO channels and can be matched well to existing literatures.