基于互质阵虚拟阵列空间平滑的相干信号DOA估计方法

DOA estimation method for coherent signals based on coprime array virtual array spatial smoothing

针对相干信号波达方向(direction of arrival,DOA)以空间平滑方法为基础的算法中阵列孔径损失严重以及低信噪比环境下算法估计性能较差等问题,提出一种无需信源数先验信息的互质阵列相干信号DOA估计方法。首先,对互质阵列得到的协方差矩阵矢量化,在虚拟阵元空洞位置内插天线零元,重构协方差矩阵为Toeplitz矩阵,拓展阵列孔径。然后,对重构阵列进行前后向空间平滑处理,消除信号相干性,提高算法估计性能。最后,将前后向平滑矩阵类比均匀对称阵列的协方差矩阵,设计代价函数转化为凸优化问题,通过谱峰搜索进行DOA估计。理论分析及仿真结果表明,该方法无需入射信号信源数,计算复杂度低,且在低信噪比环境下相干信号DOA估计数、估计分辨率以及估计精度都得到了明显改善。

In order to solve the problem of serious array aperture loss and poor performance in low signal noise ratio(SNR)environment of direction of arrival(DOA)estimation algorithm based on spatial smoothing method for coherent signals,a new method for coprime array coherent signals without prior information of source number is proposed.Firstly,the covariance matrix obtained from the coprime array is vectored,and the antenna element is reconstructed into the Toeplitz matrix in the virtual array element to extend array aperture.Then,the reconstructed array is smoothed forward and backward to eliminate the signal coherence and improve the estimation performance.Finally,with reference to the covariance matrix of uniform symmetric array,the cost function is transformed into a convex optimization problem,DOA estimation is performed by spectral peak search.The theoretical analysis and simulation results show that the proposed method does not need the number of incident signal sources,and has low computational complexity.In addition,the number of DOA estimation,estimation resolution and estimation accuracy of coherent signal are improved obviously under the SNR environment.