Fast and Efficient Estimation of Spatial Correlation Characteristics of Co-Located Dual-polarized Massive MIMO Arrays in 5G Base Stations

In this paper, we analytically evaluate the spatial correlation matrix of massive MIMO arrays consisting of co-located dual-polarized elements, by judiciously integrating the infinitesimal dipole modelling (IDM) technique with cross-correlation Green's functions (CGFs). First, we elaborately formulate the proposed IDM-CGF methodology, to emphasize on the simultaneous impact of element patterns and relative element polarization in accurate correlation computation. Next, we carefully analyze a planar representative 8 × 8 massive MIMO with orthogonally polarized infinitesimal dipoles using the proposed technique, and gain crucial insights regarding the variation in spatial correlation due to mean incidence angle (elevation and azimuth) of incoming signals. The IDM-CGF calculation further illustrates the effect of cross-polar discrimination as well as angular spread of the incoming signal on the overall massive MIMO spatial correlation matrix.