The Research Of The Spatial-temporal Focusing In Time Reversal And Its Application In Wireless Communication

Time reversal technique has the spatial-temporal focusing property. It was first applied in the field of acoustics. Recently it has been introducted into the field of wireless communications. With the help of FDTD electromagnetic algorithms, this thesis builds a complex multipath environment model and testifies the spatial-temporal focusing property. It can be easily applied to ultra-wideband wireless communication system, improving the signal to noise ratio, reducing multiple user interference, simplifying the design of the receiver, and assuring the information security. In this thesis, the concept of time reversal is extended to a space-time filtering method and then the scheme of TR-OFDM-STBC is proposed.The main content of this thesis is as follows:(1) With the FDTD electromagnetic simulation algorithm, the spatial-temporal focusing property is testified. Besides, we find that the performance of this property is closely related with the environment. The more complex the environment, the more obvious the spatial-temporal focusing property is. At the same time, when the number of antenna increases, the spatial-temporal focusing is more obvious too.(2) According to the above principles, the MISO-TR-UWB system is proposed. With the help of time-reversal, the normal RAKE receiver can be greatly simplified and one related receiver is proposed. In the case of sufficiently complex environment, its performance can approximate the ideal receiver. Then the security performance of the system is studied and self-interference mode secure communication is firstly proposed. Finally, the analysis of the multi-user communication under time-reversal is given, proving that time-reversal can effectively suppress the multi-user interference and increases transmission rate.(3) The concept of time reversal is extended to a spatial-temporal filter method. In OFDM systems, combined with the real space time block code and time reversal filter, the problem that the real space-time block coding scheme can not use higher order modulation was solved. When the number of antenna is greater than 2, we can still get full coding rate. Simulation results show that higher transmission rate can be obtained at the expense of a little performance.