Research And Implementation Of Multi-domain Interference Suppression Technology For NC-OFDM System

NC-OFDM has the advantages of high spectrum utilization,fast data transmission and strong anti-multipath capability,and it maintains the robustness of traditional OFDM against intersymbol interference and low receiver equalization complexity.With the progress of jamming technology and the development of communication technology,modern electronic warfare is facing unprecedented severe challenges,and the electromagnetic environment is becoming more and more complex.The simple jamming in time domain and frequency domain has been gradually transformed into a complex jamming environment with multiple interference interactions.In the face of such complex interference environment,the single-domain interference suppression method is often unable to completely suppress the interference.Therefore,fully understanding the diversity and complexity of interference,identifying the types of interference,and studying the interference suppression strategy of multi-domain collaboration can help improve the effect of interference suppression and improve the quality of communication.Taking the NC-OFDM system as the background,this paper focuses on the multidomain interference suppression technology,and studies the multi-domain joint interference suppression algorithms such as time-frequency and air-space,timefrequency and air-frequency,and spacial-polarization domains.The actual test was carried out based on ni-usrp platform.This article consists of three parts.The first part introduces the background and research significance of this paper and gives the system design.Firstly,the development of NC-OFDM system is introduced,and the current situation and development trend of interference suppression in time domain,frequency domain and spatial domain,as well as multi-domain cooperative interference suppression are expounded.Then,the scheme of NC-OFDM system is designed,the basic principle of the system is analyzed,the frame format and parameters of the system are designed,and the block diagram of the receiving and sending end system is given.Finally,the principle of multi-domain interference suppression of the system is explained.The second part studies the time domain,frequency domain,spatial domain and multi-domain interference suppression algorithm.For time and frequency domain interference suppression,and studied the packet detection algorithm,maximum likelihood algorithm,wavelet packet decomposition algorithm and VSS-FBLMS algorithm,and simulation analysis,the simulation results show that the wavelet packet decomposition algorithm of interference suppression performance is optimal,VSS-FBLMS algorithm at a relatively low dry letter inhibition effect is poor than maximum likelihood algorithm,in dry is higher,the letter is better than maximum likelihood algorithm;Study airspace interference suppression algorithm and MUSIC algorithm and ESPRIT algorithm simulation contrast the two categories of DOA estimation algorithm and two kinds of spatial filtering based on LCMV algorithm,simulation results show that the algorithm complexity of the MUSIC algorithm is higher,but the DOA estimation performance is better than the ESPRIT algorithm,Capon algorithm and power inversion algorithm can airspace interference to play an effective inhibition;For multi-domain joint interference suppression algorithm,mainly studied two empty with empty frequency interference suppression method,and the simulation comparison with the airspace interference suppression method,multi-domain interference suppression method using time and frequency domain information and spatial information,can effectively solve the time and frequency domain interference suppression algorithm cannot cope with broadband and high power interference problems,and able to handle the airspace interference suppression is unable to restrain the direction of interference,the simulation results show that the multi-domain joint interference suppression algorithm can deal with more the number of interference,interference suppression performance is better than the airspace interference suppression,and the ability to solve the problem of airspace interference suppression cannot cope with the direction of interference.In the third part,the NC-OFDM system is developed based on the NI-USRP software radio platform.The development method of the platform is described,and the detailed design scheme of transmitter and receiver is given.The time-frequency domain interference suppression performance of the system is tested.