Research On Characteristic Of Indoor Time-variation TR-UWB Channel In A Changing Scattering Environment

Time Reversal(TR) technology enables the ultrawideband(UWB) electromagnetic signals achieve synchronous temperal and spatial focusing, which can be used to simplify the complexity of the receiving end, lower the transmission power, reduce the intersymbol interference and to improve the signal to noise ratio, etc. With the increasing demand for high quality wireless communication, Time Reversed Ultrawideband(TR–UWB) communication is expected as one of the key technologies for the future wireless communications, thus the investigation on which is beginning increasingly active. To study the channel characteristics and further to build the channel model of TR-UWB become a significant research in the TR-UWB communications.At present, the investigations of TR-UWB are mostly carried out under the time invariant environment, but time varying wireless communication is more common in the wireless communication system, thus, it is more important. In order to study TR-UWB well under the time variant environment, the investigation must be started from the channel characteristics first to find the regularity. Second, after the studying, a channel which is most close to the time variant TR-UWB will be built, combining with the TR-UWB model under time invariant environment.In this thesis, an electromagnetic simulation platform based on Finite Difference Time Domain(FDTD) Method is employed to carry out the investigation of the indoor time-varying TR-UWB channel characteristics.Firstly, in this thesis a more precision and efficient platform is selected from two electromagnetic simulation platforms, which are developed by our group, to carry out this research. Next, the indoor time-varying mobile TR-UWB electromagnetic wave propagation characteristics(mainly including focus characteristic) are studied with this electromagnetic simulation platform, and then some valuable results are got.The thesis is devided into five chapters, and the main contents are as follows:The first chapter introduces the research background and significance of the subject, the current research status of TR-UWB, and the research contents of the thesis.The second chapter introduces the simulation principles and the tools. Next, the choice of simulation platform, and the inspection of accuracy and efficiency are provided.The third chapter gives the channel characteristic parameters of the research, including time compression rate, focus gain and spacial correlation coefficient. The arrangement of the simulation environment and the specific steps of this simulation are also introduced.The fourth chapter analyzes the change trend of the channel characteristic parameters, and summarizes the regularity by extracting the channel parameters from the target point and observation points set in the simulation. The channel characteristic parameters of the target point and observation points around are analized comprehensively and comparatively, then some valuable conclusions are gained from this in the end.The last chapter summarizes the whole thesis and the future work prospects.