基于权值约束变换误差的虚拟阵列波束形成

Virtual array beamforming based on the constraint of interpolation mapping errors using orthogonal weights

针对内插变换应用于波束形成时,适用角度范围受限的问题,提出了一种利用权值约束变换误差的改进算法.该方法将权值和变换误差约束为近似正交的关系,在虚拟阵列接收信号的协方差矩阵上加载变换误差协方差矩阵,改善了变换误差过大时波束形成性能下降的问题.仿真结果表明,改进后的算法应用于大角度内插变换波束形成时,在干扰处仍能形成稳定的较深的零点,增加了虚拟阵列波束形成的输出信干噪比(Signal to Interference and Noise Ratio,SINR).与现有方法相比,该方法增加了内插变换应用于虚拟阵列波束形成时的适用角度范围,且能够补偿阵列本身带来的误差,计算复杂度较低.

When the interpolation technology is applied to beamforming, data for a virtual array are required to be obtained using interpolated transformation of real data. However, the interpolation mapping errors will affect the performance of virtual array beamforming, especially at wide angles. In this paper, we present an improved algorithm by optimizing the array weights to constrain the mapping errors. The key feature of this algorithm is keeping the orthogonality between the mapping errors and the weights, which can be achieved by loading the covariance matrix of the mapping errors on that of the signals. By do- ing this, the beamforming performance of the virtual array can be improved, even for relatively large mapping errors. Numerical simulations confirm the validity of proposed algorithm for wide angle beamforming, which shows stable and deep nulls in the direction of interference, and thus, increases the signal to interference and noise ratio（SINR） of the virtual array beamforming. In comparison with the existing methods, the proposed virtual array beamforming method can compensate the real array errors, and be feasible over wide sectors as well, with lower computational complexity.