On Polarization Diversity in Mobile Communications

The fundamental principle of polarization diversity is discussed to show that not only the multipath signals, but the polarization vector can also be utilized to improve signal reception over fading channels. Three-dimensional polarization can achieve better performance improvement by utilizing the energy in all components of the incoming signal vector. A three-dimensional polarization diversity scheme with coherent detection and maximal ratio combining is proposed. Coherent detection necessitates estimation of the amplitude and phase of the propagation channel. It is shown that the average SNR is only degraded by errors in estimating the phase, but not the amplitude.