Design And Implementation Of Transmission Waveform In Low Interception Wireless Communication System

With the rapid development of wireless communication technology,low-intercept communication is widely used in the fields of military communication,confidential communication and secure communication.For traditional communication,the signal has cyclic stability and ergonomics,and the interceptor can easily obtain its communication parameters through some signal detection methods.In order to break the inherent parameter characteristics of traditional communication signals,this paper designs a nonstationary low-intercept transmission waveform from the perspective of physical layer security.The construction principle of the low intercept transmission waveform is to introduce the three dimensions of symbol domain,time domain,and frequency domain into time-varying communication parameters to break the cyclostationary characteristics caused by fixed parameters.In other words,by constructing a short-term cyclostationary signal to splice into a long-term non-stationary signal,so as to ensure that the transmission waveform is anti-noise and anti-interference,and its anti-interception performance is improved as much as possible.First,the basic principles of low-interception communication are explained,including an overview of low-interception communication,an overview of physical layer security,and the theoretical basis of spread spectrum communication.For spread spectrum communication,the difference between direct spread,frequency hopping,and hybrid spread spectrum communication is briefly analyzed,as well as the principle of multi-ary spread spectrum communication.Next,the construction principle of the low intercept transmission waveform is described in detail.Starting from the security design of the physical layer waveform,time-varying communication parameters are introduced to break the cyclostationary characteristics or cyclostationary characteristics caused by fixed parameters,that is,the symbol domain,time domain,and frequency.The domains are independently randomized to construct low intercept transmission waveforms.Then,an overall design scheme for the transmission waveform of a low intercept wireless communication system based on joint randomization is proposed,which involves parameter design,frame structure design and complete transmission waveform processing flow design.This scheme weakens the independence of randomization,reduces the complexity of hardware implementation,and still has good anti-interception performance.In order to design a better transmission waveform,the spread spectrum method adopts quaternary multi-ary spread spectrum,and compares the influence of different incoherent receiving schemes on the final error performance.It shows that the segment correlation receiving scheme has a certain anti-frequency offset effect..At the same time,starting from carrier frequency estimation and chip rate estimation,the antiinterception performance of low-intercept signals and spread-frequency hopping signals under different signal detection methods is compared,which proves that low-intercept signals have better anti-interception performance.Finally,for the overall design scheme of low intercept wireless communication transmission waveform proposed earlier,the implementation of the principle prototype is carried out on the FPGA platform,which mainly includes the RTL code writing and Modelsim of the key module of the transmitter,the key module of the receiver and the cross-clock domain processing interface module.Simulation waveform verification.At the same time,bandwidth test and bit error rate performance test are carried out on the system principle prototype.The infield test results show that under the condition of low signal-to-noise ratio-18 d B,normal communication with low bit error rate can be achieved,which meets the technical indicators of the project.