可变不确定集约束的鲁棒自适应波束形成方法

自适应波束形成方法在存在协方差矩阵误差和导向向量误差的失配条件中性能严重下降。最差情况性能最优。(Worst-Case Performance Optimization,WCPO)方法可以显著增强失配条件下自适应波束形成的鲁棒性,但该方法存在系统性的信号功率过估计问题,并且限定协方差矩阵不确定集与导向向量不确定集的两个关键参数需要人为指定,缺乏具备明确物理意义的求解方法和数据自适应性.本文以WCPO方法为基础,给出了信号功率过估计的理论分析以及相应的改进方法,提出了基于矩阵重构的协方差矩阵不确定集参数的自适应估计方法,最终得到一种可变不确定集约束的鲁棒自适应波束形成方法(WCPO-PCVC).相比WCPO方法,该方法消除了信号功率估计的系统性偏差,且关键参数无需人为指定。数值仿真和海试数据处理结果表明,该方法在失配条件下具有良好的干扰与旁瓣抑制能力,与常规波束形成方法相比具有更好的信号到达角分辨能力,与自适应波束形成方法相比估计的信号功率更为精准。 

A robust adaptive beamforming method based on variable constraint of uncertainty set

The performance of adaptive beamformer is seriously degraded under mismatched conditions with covariance matrix error and steering vector error.The Worst-Case Performance Optimization(WCPO) approach has greatly improved robustness of adaptive beamformer under mismatched conditions.However,WCPO has a problem of systematic overestimation of signal power.Furthermore,two key parameters of WCPO which determine the uncertainty sets of covariance matrix and steering vector respectively,have to be specified by the users,and are lack of solving methods and data adaptiveness.In this paper,a theoretical analysis of power overestimation is provided as well as a corresponding power correction method.Then an adaptive method based on matrix reconstruction to estimate the uncertainty set of covariance matrix is given.Finally,a WCPO-based robust adaptive beamformer with a combination of power correction and variable constraint of uncertainty set(WCPO-PCVC) is proposed.By contrast with WCPO,WCPO-PCVC is a user parameter-free approach that can eliminate the systematic deviation of signal power estimation.Results of simulated and experimental data show that our approach has excellent interference and sidelobe rejection capability under mismatched conditions,better angular resolution than conventional beamformer and more accurate power estimation than adaptive beamformer.