Research On Ultra-Wideband Communication And Imaging Technology Based On Time Reversal

Ultra-wideband(UWB) technology has a wide range of applications in the short-distance wireless communications, radar tracking and pinpointing fields with its high transfer rates, high multipath resolution, low power and low cost advantages. But because of its very wide bandwidth, in order to avoid interfering with the use of existing wireless communication system, realize spectrum sharing with existing radio signals, its transmit power is limited to a very low level, and ultra-wideband channel is a high frequency selective fading channels with rich multipath components, this bring a big problem for the ultra-wideband signal reception. To solve the problem of ultra-wideband technique, this paper proposed UWB communication system based on time reversal technique, which makes use of spatial-temporal focusing property of time reversal technique as a spatial-temporal filter, to improve system performance and reduce receiver complexity. Furthermore, aiming at the time reversal technique application in target detection imaging, the paper investigate the imaging algorithm of decomposition of the time reversal operator(DORT) and the time reversal multiple signals classification(TR-MUSIC) in a deep going way. These techniques have broad application prospects in detecting the scattering objects, locating and imaging field.The main work of this paper is summarized as follows:Firstly, we introduce the basic theory of ultra-wideband communication system, which include the ultra-wideband signal generation and modulation, ultra-wideband propagation channel model and receiver scheme.Secondly, we research the application of ultra-wideband communication based on time reversal technique. We describe the basic principles of UWB communication technique based on time reversal and use FDTD electromagnetic simulation algorithms, through the establishment of model to verify the spatial-temporal focusing property of time reversal technique. Aiming at communication cannot be achieved within a resonant cavity, we proposed UWB communication system based on time reversal technique applied to resonator structure of closed-cabin environment communication, and the system performance is simulated at the same time.Finally, we study the applications of time reversal imaging technique. We analyze the basic principles of time reversal imaging, give the DORT algorithm and TR-MUSIC algorithm implementation of imaging expression, and compared the imaging effect with the two algorithms in the case of well-resolved scatterers and unresolved scatterers. By comparing the results of numerical simulations of TR-MUSIC algorithm and DORT algorithm, we conclude that the former has a higher image resolution.