Research On Sidelobe Suppression Technology Of Radar And Communication Shared Signal

With the development of electronic and information technology,the differences between radar sensing and wireless communication in receiving and transmitting channels,signal processing,management and control are gradually reducing and showing a trend of integration.No matter in the traditional military application or in the field of 5G/B5 G burgeoning civil,people always hope to build a multi-functional integrated electronic system,realize the information and resource sharing between different functions,and solve the problems of large volume,serious electromagnetic interference and fierce competition of spectrum resources caused by traditional systems.Therefore,the joint radar communication system has become a hotspot.At present,European and American have developed integrated hardware system,and focus on the design of integrated signal.Among them,OFDM signal has many advantages,as a mature communication signal,such as high spectrum efficiency,time-domain waveform plasticity,strong anti-jamming ability and so on.It has been regarded as the most potential joint radar and communication signal.However,constrained by the classical radar detection theory and Shannon information theory,the classical OFDM signal is not suitable for radar detection.Specifically,there are too high side-lobes and too many pseudo peaks in the ambiguity function of OFDM communication signals.Therefore,we focuses on the ambiguity function of the communication signal,and intends to break the traditional matched filtering framework,so that the classic OFDM communication signal has excellent radar point spread function.Firstly,based on the application model of typical radar communication integrated system,the ambiguity function of classical OFDM communication signal with complete frame structure is derived,the deterioration relationship between signal parameters and ambiguity function is analyzed,and the core difficulties of the signal used in radar detection are pointed out.Secondly,this paper breaks through the traditional matched filtering framework,and designs a mismatch filtering method that pushes the side lobe and pseudo peak of the classic OFDM communication signal out of the radar observation window.Simulation results show that the proposed algorithm can make the side-lobe of the ambiguity function of the classical OFDM communication signal approximate zero in the radar observation window,and thus has both wireless communication and radar detection performance.Finally,the boundary conditions of mismatch filtering are analyzed quantitatively from the aspects of SNR loss,amplitude phase error and sampling time deviation.At the same time,this paper uses the general software radio platform to carry out the principle verification experiment of the algorithm.According to the experimental results,this algorithm can make the side-lobe and pseudo peak of the classic OFDM communication signal ambiguity function push out the radar observation window,which has the incomparable advantages of the traditional matched filter.