Geometrical-Based Statistical Modeling for Polarized MIMO Mobile-to-Mobile Channels

Abstract

Multipolarized antenna systems are able to reduce equipment size while maintaining low interantenna correlation and are thus attractive for mobile-to-mobile (M2M) wireless communications. In this paper, a polarized multiple-input multiple-output (MIMO) channel model is proposed by using a geometrical theory based on a two-cylinder M2M reference model. A geometrical approach is used to model channel depolarization, where the MIMO signal contributions of the scatterers are determined from a greatly simplified ray-tracing method. The modeling method provides a mechanism for computing MIMO-polarized channel impulse responses analytically, and the cross-polarization discrimination (XPD) and MIMO time–frequency function are further derived. The proposed model shows good agreement with measurements and simulation results from the literature and provides insights on the MIMO channel depolarization behavior. In addition, numerical simulations with appropriate modeling parameters are conducted. The XPD is shown to depend on the distribution of scatterers and MIMO subchannel index. Moreover, the co-polar channel is shown to have a higher time–frequency correlation than the cross-polar channel. This should be carefully considered in a multipolarized antenna system design.