The Waveform Design And Performance Analysis Of MIMO Dual-Functional Radar Communication

With the explosive growth of wireless devices,spectrum resources have become increasingly intensive,and massive wireless devices need to competitively use the spectrum.At the same time,there are demands for both radar and communication equipment in emerging scenarios such as self-driving,so the dual-functional radar communication(DFRC)has become a feasible solution.The core concept of DFRC is based on the similarity of radar and communication in hardware equipment,system structure,signal processing algorithm,etc.By sharing hardware to achieve dual functions on a set of equipment,it can enhance the system performance when radar and communication coexist.For the MIMO DFRC scenario,this thesis studies two integration methods including the resource multiplexing integration and the shared waveform integration.Through the waveform design,the DFRC system under the two methods achieves the trade-off between the radar performance and the communication performance.The main work is as follows:1.A waveform design to maximize the weighted mutual information of DFRC system.The amount of mutual information under MIMO DFRC is studied,and the maximized weighted mutual information in the single-user(SU)scenario and the multi-user(MU)scenarios is achieved through waveform design.We analyse the mutual information between the radar and the communication part of the DFRC system,deduces the relationship between the mutual information and the transmitted waveform of the DFRC system,and establishes the waveform design problems in the scenarios of single communication user and multi-communication user,respectively.The waveform design problem of a single communication user is transformed into a power allocation problem,and the optimal closed-form solution is obtained.The waveform design of multiple communication users is a non-convex problem,and it is difficult to directly obtain its closed-form solution.Therefore,it is converted into an equivalent weighted minimum mean square error problem,and an iterative algorithm is given to solve it.The simulation results verify that the waveform design corresponding to a single communication user and multiple communication users can promote the mutual information of the DFRC system.2.An integrated waveform design based on sidelobe modulation to implement dual functions.We analyse the relationship between the spatial beampattern and the transmit waveform of MIMO radar.We propose that the communication function can be realized by designing the radar waveform,and the designed waveform forms a sidelobe at the user position while keeping the amplitude and width of the mainlobe stable.Since the information data can only be modulated in the radar pulse,the communication rate is limited by the radar pulse repetition frequency.Therefore,a waveform design combined with multi-orthogonal waveform and sidelobe modulation of the QAM signal is proposed to improve the communication rate.An optimization problem based on QAM sidelobe modulation waveform design is established,and the optimal waveform design is obtained by solving the optimization problem.The simulation results show the feasibility of the proposed waveform design,which shows that the MIMO radar using multi-orthogonal waveforms provide higher communication rate and better detection performance.