Performance analysis of polarization receive diversity in correlated Rayleigh fading channels

The reduction in the average required transmit power in order to achieve the desired system performance is determined when using a receive antenna array employing polarization diversity as opposed to spatial diversity only. Cross-polar-discrimination (XPD) and envelope correlation are used to model the correlation between the horizontal and vertical polarizations. The characteristic function for an M-branch diversity receiver, using maximal-ratio-combining, is used to obtain the analytical expressions for the average required transmit power, assuming Rayleigh fading channels, perfect channel information at the transmitter and the receiver, and perfect fast or average power control. Based on the measurement data of XPD and envelope correlation in an urban environment, two spatially separated dual-polarized antennas are shown to outperform two spatially separated vertical antennas between 2.25-2.4 dB and 4-4.3 dB for the perfect fast power control and the perfect average power control, respectively.