Radar Communication Integrated Waveform Design Based On Chaotic Direct Sequence Spread Spectrum

As two applications of electromagnetic theory,radar and communication technology have been widely used in various fields.Besides the traditional combat platform,the new intelligent transportation system also needs radar and communication equipment to transmit information and sense the surrounding environment.Both operational and civilian applications want to achieve high integration and multifunctionality of the system.Therefore,under the existing hardware conditions,through the integration of radar communications,It is of great significance to design a system which can simultaneously realize the functions of information transmission and radar detection,in order to reduce the volume of the system,alleviate the shortage of spectrum resources and reduce the electromagnetic interference between equipments.The key to realize the integration of radar communication lies in the design of integrated waveform.In this paper,chaotic sequence is combined with orthogonal frequency division reuse(OFDM)technology,which is used in the design of integrated waveform.The main contents are as follows:(1)Based on the research of OFDM radar communication integration system,aiming at the problem of poor ambiguity of direct information modulation OFDM radar communication integration signal,which leads to the deterioration of system radar performance,spread spectrum technology is used to spread spectrum of communication information.The OFDM technique is combined with the direct sequence spread spectrum(DSSS)technique.Because the spread spectrum sequence will affect the ambiguity function of the signal,it is necessary to select the spread spectrum sequence with ideal correlation.In this paper,chaotic(Chaotic)sequence is introduced into radar communication integrated waveform design,the fourth-order Chebyshev chaotic mapping model is introduced,and the fourth-order Chebyshev chaotic sequence generated by this model is simulated and analyzed.Chaotic sequences with ideal correlation are selected as spread spectrum sequences.A OFDM(CDS-OFDM)radar communication integration waveform based on chaotic direct sequence spread spectrum is designed.The ambiguity function of the signal and the realization process of the system are analyzed theoretically.Finally,the ambiguity function and bit error rate of CDS-OFDM integrated signal are simulated and analyzed.The simulation results show that the CDS-OFDM radar communicationintegrated signal designed in this paper has high speed resolution and range resolution,and the communication performance is good.(2)In the study of chaotic communication system,it is found that the differential chaotic keying system(DCSK)has the same property as direct sequence spread spectrum.The working principle of DCSK system is applied to OFDM system to form a chaotic keying(CSK)system(CSK-OFDM)based on OFDM.On the basis of this system,a multi-group OFDM chaotic keying radar communication integrated waveform is presented in this paper.In this paper,the transmitter and receiver of multi-group CSK-OFDM system are analyzed,and the expression of multi-group CSK-OFDM radar communication integrated signal is given.Compared with the CDS-OFDM radar communication integration system,the multi-group CSK-OFDM system does not require pseudo-code synchronization,and the system implementation is simple.The communication performance and radar performance of the integrated system are verified by simulation analysis of the bit error rate and ambiguity function of the integrated signal.