Investigation of Polarization Configurations and the Impacts on Fading Correlation Characteristics

Polarized antennas equipped in multi-input multi- output (MIMO) systems are anticipated as space-effective alter- natives. In this situation, the impacts of polarization configura- tions on fading correlation should be considered. A novel model with flexible polarization orientation is proposed for calculating spatial correlation. The model demonstrates that introducing of polarization reduces the spatial correlation of antennas. To maximize the performance at mobile station (MS), tradeoff be- tween diversity gain and mean effective gain is investigated. The proposed evaluation model proves that ±45 ◦ polarization at MS is always optimal, as traditionally believed. However, polarized antennas at base station (BS) also have an significant effects on system performance, especially in environment with high cross- polarization ratio (XPR). By applying ±45 ◦ polarization at both