On the inflation method in adaptive noise-subspace estimator

In this correspondence, it is shown that Yang and Kaveh's inflation method is not necessary to accomplish an adaptive noise-subspace estimator. Withou t the inflation method, an alternative noise-subspace estimator, involving less computation and simpler parallel implementation, is developed, We also prove that if the initial noise-subspace basis consists of a set of mutual ly orthonormal vectors, the proposed estimator has better performance than that with the inflation method both in the mean sense and in the mean-squar e sense. Computer simulations are provided to substantiate the superiority of the estimator without the inflation method.