Experimental results of cross polarization discrimination and signal correlation values for a polarization diversity scheme

The paper evaluates experimentally the cross polarization discrimination (XPD) and signal correlation values of a polarization diversity scheme at the base station end. Two orthogonally polarized signals, horizontal and vertical, are received simultaneously. The particular motivation of this study is to find out the performance of polarization diversity technique in a small cell or microcellular environment. The performance can be evaluated based on both of the above mentioned parameters. Two separate polarization diversity measurement campaigns were conducted. First, cross polarization discrimination values were measured at 2 GHz in different type of areas including a microcellular environment. Next, cross polarization discrimination and signal cross-correlation values were measured in the same microcellular environment at both appropriate frequency bands for mobile communications, i.e. 900 MHz and 2 GHz. According to the measurements, cross polarization discrimination values vary between 5-15 dB depending on the environment and frequency. Cross polarization discrimination values depend highly on the radio propagation path between base station and mobile station due to line-of-sight (LOS) and non-line-of-sight (NLOS) situations. Signal cross-correlation values of horizontal and vertical polarizations in measured locations are in both LOS and NLOS situations clearly below 0.7 which is generally accepted value to have a reasonable improvement at the receiving end.