Multi-polarized Channel Model and Performance Analysis for Massive MIMO Systems

Antenna polarization is a promising resource for improving antenna array compactness in space-limited scenarios that have not been fully exploited. In this paper, we investigate the effect of the multi-polarization on the performance of the massive multiple-input multiple-output (MIMO) system. Traditional MIMO channel modeling and performance analysis methods are based on the plane wavefront, wide-sense stationary, and small-angle assumptions, which is not suitable when the scatterers are distributed within the Rayleigh distance of the antenna arrays for the massive MIMO system. To this end, we first propose a multi-polarized stochastic channel model by considering the antenna pattern and the channel polarization properties. The parabolic wavefront and environment evolution effects are also incorporated into the proposed model to accurately characterize the near-field effect and non-stationary characteristics of the massive MIMO system. We then derive the analytical and closed-form expressions of the spatial cross-correlation function (SCF) to evaluate the statistical channel characteristics of the multi-polarized system. Numerical results show an excellent agreement between the simulated channels and the theoretical ones in terms of the SCF. Besides, simulation results also indicate that it is beneficial to reduce the correlation between antennas and increase channel capacity by employing the multi-polarized antennas, especially for compact antenna arrays.