MUSIC’s and Cramer-Rao Bound in Fourth-Order Cumulant Domain

A unifying asymptotic performance analysis of a class of MUSIC algorithms for direction-of arrival (DOA) estimation in fourth-order cumulant domain (FOCD-MUSIC) is presented in this paper, A simple and explicit formula for the asymptotic variances of DOA estimation by FOCDMUSIC’s is given. The Cram&-Rao bound for DOA estimation in fourth-order cumulant domain (FOCD-CRB) is also derived. The performances of three typical FOCDMUSIC’s and the conventional covariance-based MUSIC are compared. It is shown that the FOCD-MUSIC’S are ineflcient and they are not superior to the conventional MUSIC algorithm in any case. Nevertheless, the FOCDMUSIC’s outperform the conventional MUSIC with reduced variances and improved robustness when the spatial sources are closely spaced and the signal-to-noise ratios (SNR’s) are relatively low. Simulations are included to validate the analytical results.