Study Of Radio Propagation Channel And Antenna In Multi-polarized MIMO Communication Systems

The conflict between the limited frequency spectrum resources and the increasing spectrum requirements is the main obstacle that restricts the popularization of the next generation wireless communication systems. Making the best of the limited frequency spectrum resources and improving the spectral efficiency are important method to resolve this problem. Multiple-Input–Multiple-Output (MIMO) is considerred as the key technology of the future communication systems for its ability of greatly improving the channel capacity and the spectral efficiency of the system by making good use of the spatial degree of freedom. Comparing with the outdoor applications, indoor wireless multichannel resource is more abundant, and this is the important basis for the application of MIMO technology in indoor environments. MIMO systems with multi-polarized antennas improve the compactness of the system to meet the demanding dimension requirements of the indoor environments for MIMO devices. Consequently, multi-polarization MIMO techniques become the focus of the wireless communication research.To further explore the multi-polarization resources in multi-path environments, this dissertation focuses on the channel propagation characteristics of multi-polarization in indoor MIMO communication systems. The main study object is the physical propagation characteristics of the multi-polarized mult-ipath channel. The multi-path channels of different polarizations in the actual scenes are accurately measured using the separated method, trying to reveal the propagation characteristics of the polarized MIMO channel, and providing valuable information for the designs and applications of the multi-polarization MIMO systems.To measure the channel characteristics in indoor scenes, a multi-polarized three-dimensional wideband MIMO channel measurement system is designed and established. Several scanning measurement platforms, antennas and other testing equipments are fabricated according to the requirements of the actural measurement. A large number of multi-polarized three-dimensional measurements on MIMO channels in typical indoor scenes are carried out using this measurement system. Based on the existing two-dimensional frequency domain Space-Alternating Generalized Expectation maximization (SAGE) algorithm, a three-dimensional frequency domain SAGE algorithm, which can be used for combined multi-polarization estimation of the transmitter and receiver, is derived and verified by actual simulations and measurements.The actual measurement results of MIMO channels in typical indoor environments show the independence and effectiveness of the channel with different polarization in this kind of environments. The three-dimensional SAGE algorithm is used in channel estimation and parameters extraction of the actual measurement results. Valuable channel parameters and optimized design plan for indoor multi-polarized multipath channel modeling and antenna arrays designing are summarized.