Capacity improvement through selection diversity for dual-polarized antenna systems

In newly developed wireless communication systems, the millimeter wavelength frequency band and massive-MIMO-based beamforming technology provide a channel environment that supports multiplexing transmission using dual-polarization antenna (DPA). In such a channel environment, a DPA system can transmit two independent data streams using the two orthogonal polarizations. However, random rotation angle (PRA) mismatch between the transmitting and receiving DPAs causes interference in cross-polarization antenna, which can degrade the DPA system capacity. To solve the PRA mismatch problem, selection diversity is utilized in this paper, and the capacity gain and PRA mismatch reduction achieved by the selection diversity are mathematically analyzed. Previously, performance analyses have not been conducted on the selection diversity in DPA systems considering the random PRA mismatch in the conventional studies. Through the result of this study, the improved capacity and PRA mismatch reduction of the DPA system can be accurately calculated as the number of mobile terminals (MTs) available increases. Based on this analysis, five practical scheduling schemes corresponding to various types of channel feedbacks are proposed, and their performance is evaluated.