Research On Polarized MIMO Channel Modeling

By exploiting the spatial freedom of wireless channels, MIMO(multiple input multiple output) systems have the potential to achieve high bandwidth efficiency, promoting MIMO to be a key technique in the next generation communication systems. As a basic researching field of MIMO technologies, MIMO channel modeling significantly serve to the performance evaluation of space-time encoding algorithms as well as system level calibration and simulation. Having the superiorities of low inner-antenna correlation and small array size, multi-polarization tends to be a promising technique in future MIMO systems. However, polarization characteristics have not yet been modeled well in current MIMO channel models, so establishing meaningful multi-polarized MIMO channel models has become a hot spot in recent channel modeling investigation. In this thesis, the polarization characteristics are studied based on some channel modeling methods.The main contribution of this thesis and related work are shown as follows:First, polarized antennas for MIMO wireless communications are introduced, and we also review the channel spatial characteristics as well as polarization propagation. Additionally, the state-of-art MIMO channel modeling and the channel modeling procedure are provided generally.Second, as current models are not suitable for varieties of polarized antennas, an analytical model is proposed for calculating the correlation coefficient of arbitrary multi-polarized antennas. This model is flexible to change parameters and is validate for XPD(cross-polar discrimination) evaluation. To extend, this model can be incorporated with Kronecker model to campaign capacity simulation. Then, the simulation results are presented to confirm the validity of this model and show the low correlation properties of polarized antennas.Third, noticing that many polarization investigations are base on Rayleigh channel and indoor environment, the polarized antennas in the long distance outdoor LOS(line-of-sight) scenario are studied via computer simulation compared with conventional co-polarization, showing its capability to combat the capacity loss under limited antenna spacing when using co-polarized antennas. Moreover, a measurement platform is designed and a measurement is campaigned to support the simulation results.