Research On Anti-Interception Performance Of Time-Varying Parameters DSSS/FH Communication System

The fixed parameter characteristics of traditional direct sequence spread spectrum /frequency-hopping(DSSS/FH)communication signals provide a breakthrough for the detection and parameter interception of non-cooperative receivers.In response to this weakness,researchers have proposed time-varying parameter DSSS/FH communication technology.By introducing communication parameters such as chip rate and carrier frequency that change rapidly and independently,the anti-interference and anti-intercept advantages of traditional DSSS/FH signals can be combined,and the anti-interception performance can be further improved.In this paper,the construction scheme of timevarying parameter DSSS/FH signal is studied,and through optimization design,a method for constructing joint time-varying signal with a higher parameter is given.By comparing the time-frequency distribution characteristics of the parameter joint time-varying parameter DSSS/FH signal,and the traditional DSSS/FH communication signal,the antiinterception advantage of the time-varying parameter DSSS/FH signal is demonstrated.Secondly,based on the analysis of the characteristics of time-varying parameter DSSS/FH signals and traditional DSSS/FH communication signals,combined with theoretical research and practical experience,an interception process suitable for timevarying parameter DSSS/FH signals and traditional DSSS/FH signals is proposed.Explained the detection target of each stage in the interception process,and briefly explained and explained the basic theory of the interception method adopted in each stage.Then,from the three aspects of instantaneous energy detection,energy accumulation detection and carrier frequency-based presence detection,the presence detection performance of time-varying parameter DSSS/FH signals and traditional DSSS/FH signals are compared and analyzed,and different detections are compared.Under the method,the existence detection rate of time-varying parameter DSSS/FH signals,and traditional DSSS/FH signals with the same parameter conditions verify that the timevarying parameter DSSS/FH signals are superior to the traditional DSSS/FH signals in the presence detection performance.Finally,from the two aspects of carrier frequency estimation and chip rate estimation,the parameter anti-interceptibility of the time-varying parameter DSSS/FH signal and the traditional DSSS/FH signal are compared and analyzed.In the estimation of the carrier frequency,in order to achieve the same detection performance,the denser frequency points characteristic of time-varying parameter DSSS/FH signals increases the length of the detection data required to estimate the carrier frequency set.While under the same detection data length,the correct estimation rate of the carrier frequency for the timevarying parameter DSSS/FH signal is lower,and it continues to decrease with the increase of the number of carrier frequencies.In the estimation of the chip rate,the multi-rate and varying range characteristics of the chip rate set of the time-varying parameter DSSS/FH signal will lead to the dispersion of the spectral line energy in the squared envelope spectrum,thus bringing about an improvement in the anti-detection performance.The simulation results show that under the same signal-to-noise ratio,the correct rate of chip rate estimation for time-varying parameter DSSS/FH signals is lower than that of traditional DSSS/FH signals.Otherwise,for time-varying parameter DSSS/FH signals,the larger the set of chip rates,the lower the correct rate of chip-rate estimation.Combined with the analysis results of carrier frequency and chip rate,the parameter anti-interception performance of time-varying parameter DSSS/FH signals is better than that of traditional DSSS/FH signals.