Input-to-output cross polarization discrimination (IOXPD) dispersion model for mobile-to-mobile LOS wireless communications MIMO channels

We investigate the channel properties of a dual-polarized MIMO implementation in a mobile-to-mobile line-of-sight (LOS) channel and characterize the channel's input/output cross-polarization discrimination (IOXPD) behavior. From experimental data involving transmissions with 14 MHz bandwidths, we find that the IOXPD is frequency selective and exhibits statistical decorrelation properties in both time and frequency. Short-term variations in the IOXPD are driven primarily by variations in the cross-polarization components. These components exhibit considerable fading and frequency selectivity relative to the copolarized LOS component. Typical XPD characterizations found in literature provide average co-to-cross polarization power ratios across the band, but these are inadequate to model the frequency selectivity and statistical behaviors of the IOXPD that would be needed in higher fidelity system input-output models. We propose a model to capture the frequency selectivity as well as the time and frequency decorrelation behavior of the IOXPD observed in the mobile-to-mobile LOS channel.