Analysis And Research On Depolarization Effect Of Wireless Channel

With the broadband orientation of future wireless communications, the shortage of wireless communication resources in traditional time, frequency, spatial, and code domain has become the bottleneck of the development of wireless communications. Different from signal’s characteristics in time, frequency, spatial and code domain, polarization state of wireless signal which represents signal’s electro-magnetic vector characteristic has gradually attracted researchers’ attention. However, practical wireless polarized channel displays complex and intricate depolarization effects which restrict the development of polarization signal processing in a large extent. Therefore, analysis and research on wireless polarized channel’s depolarization effects turns out to be the most emergent difficulty.This dissertation is part of results of the project "Spectrum Sensing Theory and Technology Research in Polarization Domain" sponsored by Chinese National Science Foundation (Grant No.60902047). The main issues of this paper are:(1) Classify recent research on wireless polarized channel modeling and analysis of depolarization effects, point out the insufficiency of previous wireless polarized channel modeling and the limitation of the analysis of depolarization effects, and indicate the direction of this research.(2) In order to analyze narrowband wireless channel’s depolarization effect, this dissertation proposes narrowband theoretical polarized channel model based on scatterer’s polarization characteristics using geometrical depolarization theory. According to this model, this dissertation fully analyzes the relationship between polarization power imbalance, polarization correlation and the spatial characteristics of scatterers. Correctness of the modeling method and effectiveness of the research results are validated by comparison with previous experimental and theoretical results.(3) In order to analyze wideband wireless channel’s depolarization effect, this dissertation proposes comprehensive wideband theoretical polarized channel with the introduction of polarization power imbalance and polarization correlation. According to this model and with the combination of numerical simulation and curve fitting method, chapter4characterizes the statistics of polarization mode dispersion and polarization dependent loss for the first time. This dissertation further analyzes their relationship with power angular spectra, power delay spectra, polarization power imbalance, and polarization correlation.