Eigenspace Structure Estimation for Dual-Polarized Massive MIMO Systems Using an IDM-CGF Technique

In this letter, we propose an infinitesimal dipole model, cross-correlation Green's function algorithm suitable for the efficient determination of spatial correlation matrix data for massive multiple-input-multiple-output (MIMO) antennas with arbitrary element polarization and interelement spacing. Through observations of the dominant eigenspace of the massive MIMO correlation matrix, we show that one can easily assess the available degrees of freedom in channel-hardened scenario of user-equipmentto-base-station communication. We provide several examples featuring 8 × 8 and 16 × 16 massive MIMO arrays composed of infinitesimal dipoles, lending crucial insights into the correlation matrix eigenspace structural modifications incurred by changing element polarization, spatial positioning, and interelement spacing.