Research On Radar Communication Integration Technology Based On Delay-Doppler Joint Modulatio

With the development of 5G and even the future 6G wireless communication technology,the electromagnetic spectrum environment is becoming increasingly congested,and the problem of “spectrum scarcity” in communication is becoming more and more serious.In order to explore additional spectrum resources,the wireless communication frequency band is expanding actively and overlapping with the radar working frequency band gradually,resulting in more and more serious mutual interference between radar and communication.In view of this,some scholars have proposed the concept of radar communication integrated signal to share the spectrum.However,theoretically speaking,the traditional time-frequency coded signal cannot take into account the radar and communication performance,and is not competent for high dynamic application scenarios.Therefore,in the case of bypassing the time-frequency dimension,this thesis proposes the idea and method of integrated design in the delay-Doppler domain.The specific research contents are as follows:(1)The formula of the ambiguity function of communication signals is derived,and the effects of cyclic prefix(CP),pilot,and modulation orders of quadrature amplitude modulation(QAM)on the sidelobe of the ambiguity function are analyzed.The limitations of using classical communication signals for radar detection are pointed out,and the correctness of the theoretical derivation is verified through simulation.The results show that CP and pilot can introduce spurious peaks into the ambiguity function,and an increase in the QAM modulation order will raise the sidelobe level of the ambiguity function.(2)A radar communication integration signal technology based on delay-Doppler modulation is proposed,and greatly reduced the time-frequency resources required by the radar through the radar system of multi station cooperation.Then,from the perspective of ambiguity function,the orthogonal time frequency space(OTFS)integration signal and Chirp signal are simulated and compared.The results indicate that the OTFS integrated signal has parameters similar to the Chirp signal ambiguity function.Therefore,this signal not only has radar detection performance similar to Chirp signal,but also inherits the inherent excellent communication performance of OTFS signal.(3)A radar communication integrated signal processing method based on delay-Doppler modulation is proposed.For the processing of communication signals,the cross-correlation method is used to estimate the parameters of the target/channel,and the channel parameters are used to demodulate the communication information.For high-speed target positioning,a threedimensional moving target positioning and velocity measurement model combining range difference and range difference change rate is established.Radar positioning and velocity measurement are completed using the station address,the arrival time difference and frequency difference between the target echo signal and the direct signal.(4)In order to comprehensively verify and evaluate the positioning and velocity measurement performance of OTFS integrated signals in three-dimensional space,the performance boundary of the signal is derived from the perspective of the Cramer Rao Lower Bounds(CRLB),and the feasibility and effectiveness of the method in this thesis is verified through simulation experiments.The results show that the proposed method can effectively balance excellent radar detection performance and high-speed wireless communication performance in high dynamic scenarios.