| The arrival of information age makes society more and more dependent on wireless communication.It plays a significant role in command and control in the practical battlefield and can be used in electronic warfare to determine the course of the war.Communication interference is an important part of communication countermeasures.And suppression interference is the most effective interference method at present.It is an interference method with full-band and full-period,but its requirement for power is relatively high.High performance interference is the development trend of future communication interference and zero/low power electronic warfare can be achieved.Direct Sequence Spread Spectrum(DSSS)technology has many advantages,such as reducing energy density,improving time resolution and multiaddress access.It is widely used in the fields of military and civil communication.The strong anti-interference ability of the DSSS system makes it difficult to implement the effective interference to the DSSS system.Therefore,in this paper,the suppression interference for DSSS communication system is taken as the research content and the interference performance analysis method of DSSS system is studied,which is the basis for efficient electromagnetic interference guidance and real-time control.In this paper,the performance of interference signals for the entire DSSS system is analyzed and the performance of various different types of interference signals is studied.Moreover,the relationship among interference performance,SNR,JSR and other parameters is obtained.Based on interference power allocation,the influence of bandwidth and frequency on DSSS is discussed for band-limited Gaussian white noise and for single-frequency interference respectively.The optimal interference bandwidth and the optimal interference frequency are obtained.Then,the performance of each module for DSSS system,including coding/decoding module,spreading/dispreading module and modulation/demodulation module is analyzed in Alpha stable distribution noise.The main contents are summarized as follow:Firstly,the mathematical principles and characteristics of DSSS system and the interference technologies for the DSSS system are detailed.The interference technology is classified and summarized.After that,the simulation models of DSSS and interference signals are built.Then performance analysis of communication interference system and current situation of Alpha stable distribution used in this paper are studied.Secondly,the principles and characteristics of different types of interference signals,especially the suppression interference,such as the noise interference,tone interference and pulse interference,are studied.The performances of Broadband Noise,Partial-Band Noise,tone interference and pulse interference are analyzed.The relationship among BER,SNR,JSR and other parameters is obtained.The criteria and indexes of interference performance are studied,and the comprehensive analysis is carried out by Analytic Hierarchy Process(AHP).Thirdly,based on interference power allocation,research on optimal interference bandwidth and optimal interference frequency is carried out.For band-limited Gaussian white noise,the power of the band-limited Gaussian white noise at the receiver with different bandwidth is studied from the point of power and optimal interference bandwidth is obtained under this circumstance.For single-frequency interference,the power of single-frequency interference at the receiver with different frequency is analyzed and optimal interference frequency is obtained.Finally,mathematical and simulation models are established for each module of DSSS system,including coding/decoding module,spreading/dispreading module and modulation/demodulation module.Aiming at the deficiency of Gaussian noise channel,a simulation model of Alpha stable distribution noise is established.The interference performance of Alpha stable distribution noise and Gaussian noise to each module is studied and compared. |
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