Research On DOA Estimation Based On Digital Beam Forming For Radar Communication Intergration System

Radar communication integration system is a kind of intelligent information system,which integrates the functions of radar and communication system at the signal,RF front end and antenna level.It is widely used in intelligent transportation,mobile communications,sensor networks,weapons and equipment,and other applications.This paper mainly studies the DOA estimation problem based on radar communication integration system in the internet of vehicle.Combining digital beam forming with DOA estimation,the performance of the system in two aspects of communication and radar sensing can be considered.(1)A DOA estimation algorithm based on SS-LLMS digital beamforming algorithm is proposed by analyzing the relationship between several classic digital beam forming algorithms and DOA estimation.This paper put forward a nonlinear function,and we can get a new SS-LLMS algorithm extracting the signal subspace.Then we can use the new algorithm to estimate the weight vector to form a direction map,we can search the peak value of the direction map to estimate the DOA.By comparing and analyzing the CAPON algorithm and MUSIC algorithm,the DOA estimation method based on SS-LLMS algorithm has higher resolution.(2)A fast DOA estimation method based on sub-array beam forming is presented based on the theory of sub-array beam forming.Compared with the previous algorithm,the complexity of the DOA estimation method can be further reduced.Firstly,by comparing the rotation invariance of the maximum overlapping sub-array and the conjugate sub-array,we use the latter which is more suitable for the OFDM signal to digital beam forming.Secondly,according to the structure of the sub-array,this method decomposes the received signal into two signals and reduces the dimensionality of one of the signals.Then,calculating the weight coefficient of data whose dimensionality is reduced and estimating the weight vector.Next,transfering the estimated weight vector to the other signal.Finally,the pilot signal is used to estimate the phase shift,and the DOA is estimated from the phase shift.The simulation shows that the method has a lower complexity and higher resolution.