Research On The Key Technologies Of Radar Communication Integration System With Low Loss Of Detection Performance Based On Linear Frequency Modulation

With the increase of operating frequency,bandwidth,and resource costs of modern wireless information transmission and processing systems such as radar and wireless communication,the spectrum resources overlap between radar and wireless communication systems is becoming more and more serious.Single-function radar and wireless communication systems have the problems of equipment redundancy,low utilization of system resources,and lack of comprehensive information processing abilities.Therefore,a radar-communication integrated technology may share equipment,transmission waveform,and system resources between radar and wireless communication to achieve dual/multi-functionalities while reducing system costs and improving resource utilization,comprehensive information processing efficiency,and non-renewable spectrum efficiency,and this concept has been widely studied and applied.The method of loading communication data modulation on Linear Frequency Modulation(LFM)radar signal to realize radar-communication integrated system has the advantages of excellent pulse compression characteristics,strong anti-Doppler-shift ability,high transmission efficiency,and has become a hot research field in academia and industry.However,the modulated LFM radar signal changes the original waveform parameters,leading to the main lobe widening and the increase of the sidelobe amplitude of the radar range domain profile,and the decrease of the target detection probability,thus deteriorating the radar detection performance.Therefore,the research of the radar detection performance loss mechanism and realization method for this loss minimization in LFM radar-communication integrated system has scientific significance and extensive engineering value,and it is helpful to promote the development and wide application of high-performance LFM radar-communication integrated system technology.This dissertation studies the mechanism of detection performance loss of LFM radar-communication integrated signal caused by communication data modulation,and proposes four communication modulation modes and signal processing methodologies based on amplitude shift keying,phase shift keying,and frequency shift keying,which can effectively reduce the loss of radar detection performance and have the advantages of high communication rate,low complexity of communication receiving link,low complexity of radar receiving link or remote target detection.The main research contents and innovative contributions of this dissertation are as follows:1.Aiming at the problems of the loss of detection performance and low communication rate of Frequency Modulated Continuous Wave(FMCW)Dual Functional Radar-Communication(DFRC)system,the mechanism of detection performance loss of the system is studied and analyzed,and a detection performance loss minimization scheme based on dual-path compensation and splicing is proposed,which compensates the frequency,phase,amplitude,and timing of the received radar signal according to the communication modulation parameters.It obtains a detection performance similar to that of conventional FMCW radar with the same bandwidth,achieving also high communication rate.Simulation results show that if compared with FMCW DFRC detection performance loss suppression method based on waveform screening,the dual-path compensation and splicing method improves the range domain profile sidelobe suppression by 12 dB.Aiming at the problem of increasing Bit Error Rate(BER)caused by Frequency Shift Keying(FSK),a method of FSK modulation with configurable number of available frequency points and configurable frequency range of sub-pulse which can effectively reduce the BER by sub-pulse grouping is proposed.Numerical results show that the required signal-to-noise ratio of full grouping modulation scheme is 17 dB lower than that of non-grouping modulation scheme with the same BER.2.Aiming at the problems of detection performance loss of FMCW DFRC system and high complexity of radar receiving link,a detection performance loss minimization scheme based on delay breakpoint mapping FMCW signal is proposed.The communication data modulation is achieved through data mapping into intra-period breakpoint location,and amplitude and phase between clusters.The amplitude and timing compensation processing is performed by using breakpoint area deletion and splicing method at the digital end of radar receiving link.The obtained detection performance is similar to that of conventional FMCW radar with the same bandwidth,and the radar receiving link is compatible with the link in conventional FMCW system.The simulation results show that if compared with FMCW DFRC detection performance loss suppression method based on waveform screening,the delay breakpoint mapping FMCW signal with compensation method improves the range domain profile sidelobe suppression by 12 dB.The test results show that the range domain profile sidelobe suppression of the delay breakpoint mapping FMCW signal with compensation method is 10 dB higher than the same signal without compensation method.3.Aiming at the problems of detection performance loss and poor anti-interference ability of the radar-communication co-existing FMCW system with frequency division,the mechanism of detection performance loss of the system is studied and analyzed,and a detection performance loss suppression scheme based on frequency division FMCW signal with variable frequency is proposed.The frequency points of radar and communication signal are allocated through small-step Frequency Hopping(FH)within a frame,and maintain a constant frequency difference.The digital end of radar receiving link carries out the corresponding range domain phase compensation processing and abnormal peak detection and elimination processing,increasing the equivalent signal bandwidth through the radar sub-signal traversing the full operating frequency band in a frame,thus improving the radar detection performance and eliminating the in-band radar interference.The simulation results show that if compared with the intra-FMCW-period FH method,the range domain profile sidelobe suppression of small-step FH FMCW is improved by 11 dB,and the in-band interference amplitude is reduced by 30 dB.Aiming at the problems of high complexity of communication receiving link and poor anti-interference ability of communication,a low complexity communication signal receiving method based on two-stage envelope detection is proposed.The spread spectrum characteristic of LFM effectively suppresses in-band communication interference and reduces the communication BER.Numerical results show that if compared with the envelope detection method and coherent demodulation method,the required signal-to-interference ratio of the two-stage envelope detection method is reduced by 6 dB and 2 dB with the same BER level,respectively.4.Aiming at the problems of remote detection performance loss and low communication rate of pulse LFM DFRC systems,the mechanism of detection performance loss of the system is studied and analyzed,and a detection performance loss minimization scheme based on time-domain and frequency-domain characteristic inversion is proposed.By inverting the LFM signal characteristics in time and frequency domains,the spectrum is adjusted to fit a rectangular envelope.By compensating the phase and amplitude of the frequency domain signal at the digital end of radar receiving link,the proposed methodology achieves a detection performance similar to that of conventional pulse LFM radar with the same bandwidth,achieving also high communication rate.The simulation results show that compared with the detection performance loss suppression method based on mismatch filtering,the time-frequency characteristic inversion method of LFM signal improves the range domain profile sidelobe suppression by 9 dB.The test results show that the range domain profile sidelobe suppression of the time-frequency inversion LFM signal is 8 dB larger than that of the sub-band modulated LFM signal.This dissertation studies the detection performance loss mechanism of LFM radar-communication integrated signal due to communication signal data modulation,and develops four efficient communication modulation modes and signal processing methodologies to reduce radar detection performance losses,which effectively improve the efficiency of radar-communication integrated systems,and reduce their complexity and costs.The achievements of this dissertation have a wide application prospect in the field of vehicle networking and unmanned equipment control,promoting the development of radar communication integrated technology and industry.