Research On Radar-communication Integration Based On Frequency Diverse Array Beampattern

The integration of radar communication can not only improve the utilization rate of the spectrum,but also reduce the volume,cost,and energy consumption of the equipment,so it is a very popular research field at the moment.There are many ways to realize the integration of radar communication.At present,it is mainly realized by sharing radar resources through communication.In this paper,the communication function is realized by sharing the beampattern resources of the radar array,and the traditional phased array(PA),MIMO array and the newly developed frequency diverse array(FDA)are specifically considered;and based on different types of arrays,a radar communication integration scheme based on transmit beampatterns is proposed.The design ideas of the integrated radar communication scheme proposed in this article are: Optimize the design of several sets of beampatterns of the array.These sets of beam patterns have the same main lobe area and different side lobe levels.The common beam main lobe of the pattern is used to achieve radar target detection and control the side lobe amplitude or phase to embed communication information at the communication position,so as to realize the transmission of communication information.This article first studies the integrated design of communication radar based on PA and MIMO array.At this time,the pattern of the array is only related to the angle,and the communication users can only be distinguished in the angle dimension.There is a risk of eavesdropping.In order to further enhance the effectiveness,reliability and security of communication,this article focuses on the FDA and multi-carrier FDA,based on different FDA,the required array beampattern is designed,and a new integrated radar communication design scheme is proposed.The main work of this paper can be summarized as the following aspects.(1)The integration of radar communication based on traditional PA and MIMO array beam pattern is studied.In the MIMO array,by optimizing the transmit waveform set to design a specific array beampattern,a radar communication integration scheme is proposed according to the above design ideas.Among them,the established waveform optimization model is a convex optimization(CVX)model,which is solved by CVX toolbox.(2)The coupling of the FDA pattern hinders its practical application in radar target detection.For this reason,the pattern performance and decoupling method of the FDA are specifically studied.Specifically,the beampattern expression of the FDA is derived,and the theory and simulation explain the distance-angle coupling of the beampattern of the FDA;the effect of different array parameters such as frequency increment,number of array elements,and array element spacing and array weighting on the performance of the FDA pattern is analyzed;Several classical beampattern coupling methods are given,and the decoupling performances of different methods are compared and summarized.Because the control frequency increment can flexibly control the FDA pattern,therefore,combined with the conventional beamforming(CBF),the genetic algorithm(GA)is used to optimize the frequency increment to achieve a FDA pattern with a specific main lobe direction and low side lobes,which ensures effective detection of radar targets.(3)In FDA,by optimizing the weighted vector of the array,the sidelobe amplitude and phase of the FDA pattern at the communication position are controlled,thereby realizing point-to-point amplitude and phase modulation communication.Since the FDA beampattern is related to angle and distance,the proposed communication scheme guarantees the security of communication,that is,the communication information cannot be demodulated correctly at positions other than the communication angle and azimuth.Furthermore,combining the target detection method coupled with the FDA beampattern and the above-mentioned Secure communication method,a radar communication integration scheme based on the FDA beampattern is proposed.By optimizing the design of the FDA's beampattern,it has a higher gain main lobe in the target detection area and a lower side lobe in the non-target detection area,and the side lobe value is designed at the communication position to embed communication information.Taking the frequency increment between the FDA arrays and the weight vector of the array elements as optimization variables,an optimization model of the FDA beampattern is established,and the genetic algorithm is used to solve it.The FDA-based pattern optimization can realize the point-to-point safe information transmission in the two-dimensional distance-angle space.By comparing the bit error rate(BER)of the entire airspace information transmission,the security of communication is verified.(4)Multi-carrier FDA is a generalized FDA,and the multi-carrier FDA pattern does not have coupling problems,and the pattern side lobes are lower.To this end,the multi-carrier FDA array model is first given,and then the pattern performance under different frequency increment distributions is analyzed.Finally,a radar communication integrated design scheme based on the multi-carrier FDA array pattern is proposed.For the first time,this paper studies the integration of radar communication under the FDA with linear frequency increase between carriers,and establishes a corresponding pattern optimization model for this problem;In order to efficiently solve the model,this paper proposes to reduce the dimensionality of the multi-carrier FDA pattern in the two dimensions of angle and distance,and split the pattern optimization problem into two one-dimensional pattern optimization problems about the angle dimension and the distance dimension;the optimization problem obtained by dimensionality reduction is a convex optimization problem,which can be solved separately by convex optimization methods;After the solution,the optimized two-dimensional pattern is combined and restored,and the desired multi-carrier FDA array beampattern can be obtained,thus realizing the integration of radar communication.The simulation results prove that the multi-carrier FDA can effectively realize the integration of radar communication,and it has more obvious advantages than the single-carrier FDA radar communication integration scheme.