一种改进的嵌套阵列波束形成算法

Improved Beamforming Algorithm in Nested Array

研究了导向矢量失配情形下嵌套阵列波束形成的优化问题。在导向矢量失配情形下,嵌套阵列波束形成存在稳健性差和收敛速度慢的缺点。针对上述缺点,提出了一种改进的嵌套阵列波束形成算法。改进的算法引入一般线性组合方法修正了样本协方差矩阵。并提出了一种新的干扰噪声协方差矩阵重构方法,新的重构方法详细分析了空间平滑矩阵与干扰噪声协方差矩阵的关系,利用相关向量构建干扰空间,通过将向量化的空间平滑矩阵在干扰空间上投影,重构出新的干扰噪声协方差矩阵。然后基于重构的协方差矩阵,建立二次约束二次规划问题来估计期望信号导向矢量。仿真结果证明,通过改进的算法稳健性更好、收敛速度更快,能够更有效地提高信号矢量失配情形下嵌套阵列波束形成的性能。

The optimization problem of beamforming in the nested array was studied in the steering vector mismatch case. The beamforming in nested array has the shortcomings such as poor robustness and low convergence rate in the steering vector mismatch case. For the shortcomings,an improved beamforming algorithm in the nested array was proposed. Firstly,a modified sample covariance matrix was obtained via a General- Linear- Combination-Based method,an a novel method of the interference- plus- noise covariance matrix reconstruction was proposed,which particularly analyzed the relation between the spatially smoothed matrix and the interference- plus- noise covariance matrix and built interference subspace via the correlation vector,and a new interference- plus- noise covariance matrix can be attained by projecting the spatially smoothed matrix into the interference subspace. Then,based on the reconstructed covariance matrix,a quadratically constrained quadratic programming problem was constructed,which can be used to estimate the steering vector of the desired signal. Simulation results demonstrate that the improved algorithm has better robustness,faster convergence rate and can more effectively increase the beamforming performance of the nested array in the steering vector mismatch.