Hybrid Beamforming Design For DFRC System Based On SINR Performance Metric

In recent years,due to the rapid development of information technology,radar and wireless communication,these two kinds of technology to sense and transmit information have been more widely used in various emerging application scenarios such as intelligent transportation and intelligent industrial,etc.A large number of emerging applications of these two technologies make radio spectrum resources increasingly tight,and the demand of equipment is also rapidly expanding,which will bring high cost.To deal with these challenges,the dual-functional radar communication(DFRC)system,which can realize hardware platform sharing,spectrum resource sharing and dual-function coordination between radar and wireless communication,has aroused extensive attention.Meanwhile,the pursuit of higher frequency and larger antenna array,as well as the demand for low hardware cost and power consumption,have promoted the development and application of hybrid beamforming.Hybrid beamforming technique can be further introduced into the DFRC system to realize radar target detection and user communication functions simultaneously,and the trade-off between radar and communication performance can be achieved.In this thesis,signal to interference plus noise ratio(SINR)is used as the metric to measure radar and communication performance,and the hybrid beamforming design for DFRC system is studied.The main contents of this thesis are as follows:(1)A hybrid beamforming design for DFRC system under the full precision phase shifter is proposed,which can maximize the average SINR of radar receiver while satisfying the SINR threshold constraint of each communication user to achieve the tradeoff between radar and communication performance.To deal with coupling between digital and analog beamforming matrices and the non-convex nonlinearity of hybrid beamforming design problem,the alternate iteration scheme is proposed in this thesis.The problems of digital and analog beamforming design are solved respectively based on semi-positive definite relaxation and feasible point pursuit successive convex approximation algorithm.Simulation results confirm the performance trade-off between radar and communication system,and show that the performance of the proposed alternative iteration algorithm is close to the optimal performance based on full digital structure.(2)To deal with the requirements of lower hardware cost and computational complexity in practical engineering applications,the low complexity hybrid beamforming design scheme with 2-bit resolution phase shifter is studied.First,a codebook based neighborhood searching scheme with better performance is proposed in this thesis,but the time complexity is still high due to the decoupling between digital and analog beamforming.Then,a low complexity analog beamforming algorithm based on 2-bit phase shifter is proposed,which decouples the digital part and the analog part,and it further reduces the time complexity of the algorithm.In addition,to deal with the infeasible case caused by communication SINR threshold constraints,a digital beamforming design problem based on SINR penalty soft constraint is also modeled and solved by the faster conjugate gradient descent method.Simulation results show that the proposed low complexity hybrid beamforming design has a certain performance loss,but the time complexity is also significantly reduced.