Frequency Diverse Array Beamforming Design Based On Convex Optimization Theory

Frequency diverse array(FDA)is a new array proposed in recent year.Differing from traditional phased array,which has only angle-dependent beampattern,FDA can produce range-angle-dependent beampattern and has unique advantages.It has wide application in many fields such as target location and interference suppression.Polarization sensitive array(PSA)is an advanced technology in array signal processing.By acquiring and utilizing polarization information of signals,the performance of signal processing can be improved.Polarization information can increase degrees of freedom to reduce interference when interference and desired signal are spatial indistinguishable.In this work,PSA and FDA are combined as polarization sensitive frequency diverse array(PSFDA)with range dependent beam response.Further,polarization information of signals are utilized to suppress interference and clutter which are spatial indistinguishable from desired signal.Then based on convex theory,by jointly optimizing transmit and receive beamforming and spatial pointing,the maximum signal to interference plus noise(SINR)can be achieved at the target location.Firstly,a subarray-based frequency diverse array-polarization sensitive frequency diverse array(FDA-PSFDA)system is proposed to produce range-angle decoupled beampattern.Based on the analysing of range and angle Cramér–Rao lower bound(CRLB),the optimal frequency increments of each subarray are derived.Then we aim at SINR and formulate the joint optimization problem of FDA transmit beamforming,PSFDA receive beamforming and spatial pointing matrix.Rayleigh quotient,semidefinite programming(SDP)and penalty function method are utilized to solve the problem.Simulation results demonstrate that the proposed system and scheme can provide range-angle decoupled beam response and suppress interference efficiently to estimate target location accurately and improve communication quality.Then the more specific receiver structure is considered based on the subarray-based FDA-PSFDA system.Band-limited and full-band structures are proposed to fully exploit the beampattern characteristics.Based on these two receiver structures,we consider timeinvariant beampattern and derive the optimal frequency increments.Then based on SINR maximization,we jointly optimize the FDA transmit beamforming,PSFDA receive beamforming and spatial pointing matrix by using the Rayleigh quotient,SDP and penalty function method.By simulation results analysing,we compare the two receiver structures and demonstrate that the proposed system and scheme can provide time-invariant beampattern and show the superior performance in both interference suppression and communication quality.