Research On Waveform Design And Performance In Radar-communication Integration

With the rapid development and wide application of various electronic technologies,combat platforms need to be equipped with a variety of electronic systems,which causes numerous problems.At the same time,the demand for data transmission volume also multiplied,exceeding the transmission capacity of existing data links.In addition,the demand for detecting and tracking other targets in the environment is increasing in intelligent transportation.Smart vechiles also need communication links to deliver information.Therefore,it is a feasible solution to combine the radar system with the communication system to form an integrated system.The integration of radar communications can not only improve system utilization and spectrum utilization,but also improve the quality of communications and facilitate the networking and automation of radar and communications.Sinece the waveform has an effect on the performance of the entire system,it is the key point in the design of the integrated system and needs more resaerch.The main work and innovation of this thesis are as follows:1)The three evaluation and design criteria of radar ambiguity function,peak-toaverage power ratio and interception factor are introduced.The ambiguity functions of typical radar signals such as rectangular pulse signal,linear frequency modulation signal and phase coded signal are analyzed.The typical communication signals such as analog phase modulation,QPSK and QAM signals and OFDM signals are analyzed.Three kinds of existing radar communication integrated waveform design schemes are analyzed.2)Propose an integrated waveform that combines a constant-envelope OFDM signal with a linear frequency-modulated signal.The process of waveform generation is elaborated and the structure of the entire system is introduced.The spectrum of the integrated signal was analyzed,and the factors that caused the spectrum expansion were analyzed.The influence of the approximate error rate and Doppler frequency shift on the demodulation of the communication and the influence of various parameters on the system performance are analyzed.Finally,simulation analysis of system communication performance and radar performance performance verified that the integrated waveform can meet the basic requirements of radar detection and communication.3)An integrated waveform design scheme based on the fractional Fourier transform is proposed.The communication uses a set of orthogonal sub-carriers.The radar detection uses a chirp signal and uses different modulation frequencies to distinguish the two.Due to the influence of communication subcarriers,the radar signal needs to be increased in amplitude to be separated by the matched filter.Increasing the radar signal power alone does not affect the peak-to-average power ratio of the overall signal.At the receiving end of the communication,a rough estimate of the radar signal amplitude can be made,subtracting the interference term before demodulation.Finally,the system performance was verified by simulation to meet the basic requirements.