Channel Characteristics And Channel Estimation For Time Reversal Electromagnetic Communication Based On Space Station Environment

Time reversal(TR) technology can make the electromagnetic wave synchronously focus in the target place by time and spatial domain,while the more spread of the multipath components in the communication environment,the better focusing performance of the signal.The communication environment of the space station is a typical complex multipath environment,and the intersymbol interference caused by the multipath effect seriously affects the quality and performance of wireless communication.Therefore,a new electromagnetic communication system based on the time reversal technique is very suitable for the application of space station environment.In order to design an electromagnetic communication of high rate and stability for the space station environment,we need study the channel characteristics and understand the propagation law of the time reversal signal to provide technical support for the whole system design.Moreover,Channel estimation is also an important part for time reversal electromagnetic system.This paper studies the channel characteristics and channel estimation for time reversal electromagnetic communication in space station environment.The research work can mainly includes by the following three parts:Firstly,the channel characteristics and robustness of time reversal electromagnetic system based on ultra wide band(UWB)system is studied.Analyzing the changes of the path peak-power gain and channel characteristic parameters of TR-UWB system in space station environment,and TR technology can well overcome the sharp signal loss when electromagnetic wave signal pass through the interface angle of two capsules,and the TR channel parameters can keep a good performance in space station of all place.Moreover,the TR-UWB system has a good robustness by analyzing the correlation coefficient and the channel characteristic parameters,when the receiver moves slightly.Secondly,studying the channel characteristics of time reversal multiple antenna super-resolution electromagnetic system in UWB system.By analysing the channel characteristics of sub-wavelength antenna array,the factors that affect time reversal super-resolution focusing performance are studied,and it is helpful for the design of sub-wavelength antenna array for space station environment with better communication capacity and rate.The study found that the number of time reversal mirror,the spacing of time reversal mirror and the envelope correlation coefficient of sub-wavelength antenna array all had an influence on the focusing performance,and envelope correlation coefficient is the most important of all the factors.It can significantly improve the super-resolution focusing effect by choosing suitable working frequency band according to the given antenna array,and vice versa,it can be used for the designing the sub-wavelength antenna array.Finally,channel estimation in time reversal electromagnetic system based on orthogonal frequency division multiplexing(OFDM)system is studied.The TR technique is equivalent to a filter in the OFDM system,and the phase rotation caused by the multipath channel can eliminate by using TR technique because of the adaptive phase conjugate compensation characteristics.The data updating of the filter comes from the result of channel estimation,so the research of channel estimation is very important for TR-OFDM system.The impact of channel estimation for the performance of TR-OFDM system in ordinary multipath and space station complex multipath the two kinds of multipath environment were analyzed,and a channel estimation method that can improve the accuracy of channel estimation in downlink based on TR technology is proposed.