Multiple polarized MIMO with antenna selection

Antenna subset selection in combination with dual-polarized antennas offers a better solution for compact and low-complexity devices using higher order Multiple-Input Multiple-Output (MIMO). In this paper we provide another degree of freedom to the existing dual-polarized MIMO and analyze the performance of antenna selection for triple-polarized MIMO systems with maximum ratio combining receivers. We theoretically analyze the impact of cross-polar discrimination on the achieved antenna selection gain for both dual and triple-polarized MIMO for non line of sight channels. We proceed to derive the outage probabilities and observe that these systems achieve significant performance gains for compact configurations with only a nominal increase in complexity. We observe that at higher cross polarization discrimination and lower transmit signal to noise ratio, the outage performance for a dual-polarized system is almost the same as triple-polarized system with joint transmit/receive antenna selection. With selection at only one end of the link, the triple-polarized system performs better than dual-polarized counterpart at higher values of transmit SNRs. We also found out that the available degrees of freedom significantly increase with lower values of cross polarization discrimination.