Multipolarized MIMO Channel Characteristics: Analytical Study and Experimental Results

MIMO technologies enable high communication data rates, but suffer from the large antenna spacing that is required to achieve sufficiently low inter-antenna correlation. Cross-polarized antenna systems resolve this problem by using perpendicular antennas. Correlation is reduced while keeping antennas co-located. Inter-antenna correlation and cross-polar discrimination (XPD) are two fundamental parameters of these polarized antenna systems. This paper proposes an analytical channel model, from which closed-form solutions for the correlation coefficient and the XPD are deduced. The environment is supposed to have a truncated Laplacian power azimuth spectrum that is widely used in standardization bodies. The receiving di- or tri-pole antenna can have random orientation. The correlation and the XPD show to be highly sensitive to receiver orientation, azimuth spread and environment depolarization behavior. Measurements have been conducted at 3.5 GHz to validate the solution obtained. Good agreement is achieved when comparing theoretical curves and experimental results for different receiver orientations, both for the correlation coefficient and the XPD