Research On Waveform Design For The Dual-Function Radar Communication System

The dual-function integrated communication and radar system uses a unified waveform to achieve both communication and radar functions.The joint design of an integrated communication and radar system can reduce the number of antennas,reduce the system size,weight and energy consumption,increase the communication transmission rate,and effectively solve the problem of spectrum congestion.Aiming at the problem of improving the communication rate of the integrated communication and radar system,we extend the index modulation scheme to code,frequency and space domains.Firstly,frequency and space domain index modulation dual-function communication radar waveform are firstly proposed.Combining code domain index modulation,the communication transmission rate is significantly improved.Finally,the maximum likelihood decoder is designed for the hidden waveform.Simulation results show that the multi-domain composite index modulation waveform effectively improves the communication rate without occupying additional spectrum resources.Aiming at the problem of how to covertly embed communication information in radar-based waveforms,we propose an integrated communication and radar covert waveform.Firstly,the linear frequency modulation(LFM)chirp waveform using a novel reduced phase difference modulation is proposed,and the pulse width and modulation phase are randomly generated to make the communication information embedded in the waveform difficult to be detected.Then the code domain index modulation technology is introduced to further enhance the concealment of the information,which can also make use of the large codebook to improve the communication rate.Finally,a low-complexity hidden waveform decoding method based on neural network is designed.Experimental results show that,compared with a scheme that does not adopt index modulation,index modulation can increase the communication rate.The proposed neural network decoder outperformed the maximum likelihood and the coherent demodulation methods,in terms of processing speed and bit error rate performance,respectively.Aiming at the problem of communication and radar resource competition under given power conditions,we provide an integrated communication and radar solution with mutually enhanced functions.First of all,for the communication aspect,the dualfunction radar transmits integrated waveform using index modulation.To improve the communication rate,the communication receiver processes the communication channel and radar channel information at the same time,leading to the enhancement of the communication function.For the radar aspect,the communication transmission signal are treated as the passive radar illumination source.By processing the active and passive radar cooperatively,we greatly improve the target detection performance.Experimental results show that the communication and radar functions are both improved rather than tradeoff,benefitting from the well-designed DFRC/dedicated coexisting communication scheme and the passive/active integrated radar scheme.The mutual enhancement is verified with respect to the Cramér Rao Bound(CRB)and the achievable rate for radar target detection and communication information convey,respectively.