3-D Geometrical Model for Multi-Polarized MIMO Systems

Multiple-input multiple-output (MIMO) systems capacity is highly influenced by the correlation between antennas, and the high correlation will result in a low capacity. Therefore, the multipolarized antennas have been implemented in MIMO systems to reduce the correlation between antennas and realize the space efficiency. To better understand the performance of multi-polarized MIMO systems, polarization channel modeling is of great importance. In this paper, we establish a 3-D geometrical model for multi-polarized MIMO systems. Antenna cross-polar isolation (XPI), channel cross-polarization discrimination (XPD) and antenna tilt parameters have been considered in our model. The correlation and capacity of multi-polarized MIMO systems are analyzed, and we find that the XPI, XPD, and antenna tilt have an effect on the correlation and capacity simultaneously, which cannot be analyzed separately. Also, we compare our model with the existing measurements for validation, which shows that the proposed model is well in agreement with the measurements. Finally, we compare the performance of multi-polarized MIMO systems with the traditional uni-polarized MIMO systems, which shows that the performance of multipolarized MIMO systems have robustness to the communication environment, and multi-polarized MIMO systems outperform uni-polarized MIMO systems in many communication scenarios.