The Effects of Weight-Fluctuations on the Performance of Null-Steering Adaptive Arrays

A new method employing a two-variable perturbation analysis is used to determine the effects of statistical fluctuations in the weights of an adaptive null-steering array. The analysis allows us to analytically determine the effects of additional loop noise caused by the element weight fluctuations and the resulting degradation of the signal-to-interference plus noise ratio (SINR) of the array output. It is shown that the SINR can be significantly degraded by this additional loop noise which is usually ignored in most analyses. Comparison of these results with those found by using the mean value of the weights obtained by standard "averaging" assumptions is given. Numerical solutions of the first-order correction term of the weights are used to present curves which describe the effects of additional loop noise quantitatively.