Statistical characteristic of polarization dependent loss

In wireless communications, wideband polarization dependent loss (PDL) has become significant with the development of signal processing in wideband polarization domain. Aiming at deriving PDL statistical characteristic, a polarized time-variant multipath channel transfer function matrix H which considers azimuth power spectra, power delay profile (PDP), polarization power imbalance and polarization correlations is proposed. Closed-form expressions have been derived for various autocorrelation functions and cross-correlation functions for the polarized channel to fully characterize its statistical property. PDL is defined as the ratio between maximum and minimum eigenvalues of HH^H at frequency f. However, due to the difficulty to analytically derive PDL´s statistical characteristic, i.e., the distribution of PDL, numerical sum-of-sinusoids simulator is realized to accurately emulate the channel correlations derived above. Inspired by Weibull distribution, the probability density function (PDF) of PDL is well curve fitted using raw data from numerical simulator. The function is parameterized by scale factor, shape factor and normalization factor which all relate to polarization power imbalance and polarization correlations of the polarized channel. Results show that the degree of attenuation unbalance towards eigen-polarizations is in the descending order as: NLOS macrocell > NLOS microcell > NLOS picocell.