Research On Waveform Design And Signal Processing Of Dual-Functional Radar-Communication

Given the situation of continuous development of radar or communication technology and the increasing shortage of wireless spectrum resources,researching a reliable and feasible dual-functional radar-communication(DFRC)system is considered a promising research strategy,such as the integrated combat platform researched and deployed in the military,Internet of Things applications in the future sixth-generation(6G)wireless communications concept.Although DFRC has great potential requirements,there are still many challenges in research due to the difference between radar and communication itself.DFRC technology for information modulation,waveform optimization design,parameter estimation and performance evaluation will be studied under the working mode of continuous waveform transmission.The main research contents are summarized as follows:In order to solve the problems that DFRC system based on OFDM radar have high PAPR and low communication rate,a signal processing algorithm based on DFT-s-OFDM with index modulation(DFT-s-OFDM-IM)is proposed.The index modulation algorithm modulates the index information in multiple groups of frequency bands and performs DFT precoding for each group.To demodulate the constellation mapping and index modulation information,the detection and decision operations are applied in the signal processing algorithm of the communication receiver.The simulation results show that,compared with OFDM signal,the proposed index modulation algorithm has better communication performance.This method effectively improves the spectral efficiency and BER performance of the system,and obtains a lower peak-to-average power ratio.Furthermore,the parameter estimation performance is studied by simulating the radar ambiguity function of DFT-s-OFDM-IM and two parameter estimation algorithms,as FFT and spatial spectrum estimation.Then the errors of the parameter estimation results are also compared.The simulation results show that DFT-s-OFDM-IM has great resolution.Two parameter estimation algorithms both can distinguish and identify multiple targets,and the MUSIC algorithm has better parameter estimation results.As for un-optimized waveforms cannot achieve a favorable trade-off between radar and communication performance,a joint weighted optimization design method for dualfunctional waveform is proposed.According to the characteristics of multi-antenna and multi-carrier systems,the signal models based on beampattern similarity and communication reliability are considered respectively.Under the condition of different weighting factors,a power-constrained joint optimization problem is formulated with radar and communication performance as optimization objectives.Through the RCG(Riemann Conjugate Gradient)algorithm,the optimal solution of the constrained optimization problem is solved iteratively.Simulation results show that the designed waveform can achieve a favorable trade-off between radar and communication performance.Compared with the communication-only waveform,the proposed method can obtain 3d B-bandwidth main-lobe and low PSLR of radar beampattern.In the case of strict radar condition,it still has good radar detection performance.Compared with radar-only waveform,the proposed method can ensure the communication reliability,improve the BER performance of the system,and achieve better average sum rate.