Research On Anti-interference Of UWB Communication System Based On Time Reversal

Communication has always been one of the inseparable technologies under the development of the period.In recent years,the communication industry has been booming.Under the general trend,communication technology has also been continuously improved.Various emerging technologies have emerged continuously,artificial intelligence,Internet of Vehicles,Internet of Things and Cloud Computing.However,the space-time focusing characteristics of time reversal have also played a significant role in the development of 5G.This article first analyzes the characteristics of TR technology and understands TR applications field,constraints,advantages and disadvantages,finally this article choses ultra-wideband communication system as the carrier of TR technology.Then this article considers what problems in UWB system can be solved by introducing TR technology into UWB system,taking the above problems as the starting point,the research subject of this thesis is determined as the anti-interference research of ultra-wideband system based on time reversal.The good space-time focusing characteristics of TR technology can effectively avoid multipath interference and inter-symbol interference in the system,improve the interference tolerance of the system,and also reduce the complexity of receiver.After considering the introduction of TR to UWB system to solve the interference problem,The main work of this article is arranged as follows:Firstly,TR is a physical layer technology that uses its space-time focusing characteristics to effectively suppress interference problems in UWB systems.After TR is introduced into UWB systems,system performance will change to a certain extent.In research,there are many kinds of interference in UWB communication systems: such as inter-symbol interference,multipath interference,multi-user interference,narrow band interference,white Gaussian noise and so on.The above-mentioned interferences are classified.Some are additive interferences,some are multiplicative interferences.After the introduction of TR technology,some interferences can be effectively eliminated,and some interferences cannot.After the above analysis.This thesis finds that the introduction of time inversion into the UWB system can solve the inter-symbol interference and user-to-user interference in the UWB system.These interferences are caused by the fading distortion and delay extension of the transmitted signal after the propagation effect.Therefore,a TR-based anti-interference mechanism is proposed.A TR module is added to the transmitting antenna,combined with the unique channel model of the ultra-wideband communication system,and the TR is used tocompress the channel delay spread in time and space to focus on the desired signal..And the theoretically derived system channel capacity and signal-to-interference and noise ratio of TR-UWB.Finally,Monte Carlo simulation is used to verify that the introduction of TR to UWB system can reduce inter-symbol interference,multi-user interference,reduce bit error rate,and increase system capacity.Secondly,the previous research that TR was introduced into UWB system can solve the problem of inter-symbol interference and multi-user interference,and constructed a TR-UWB system model.Following the above research content,this article further researches on the basis of the above research and finds that UWB The system spectrum is very wide,coexisting with other existing narrowband communication systems,and the Federal Communications Commission strictly specifies the indoor radiation density of UWB to ensure that UWB systems will not cause interference to existing narrowband systems,but on the contrary,wireless narrowband systems It will cause interference to UWB system.However,TR technology can only solve the inter-symbol interference in the system,multi-user interference,and cannot counter NBI.Therefore,this thesis introduces a notch in the original system.This is the second main research in this thesis.content.Aiming at the narrow-band interference problem mentioned earlier,this thesis designs an adaptive infinite impulse response notch at the receiving end,theoretically deriving the adaptive bandwidth at half the power.In addition,this article adaptively finds the best notch design.The steepest descent algorithm is also used in the bandwidth to quickly and accurately suppress the NBI in UWB.Finally,Monte Carlo simulation is used to verify that the adaptive notch filter effectively suppresses NBI in the TR-UWB communication system and improves the system bit error rate.