Blind identifiability of certain classes of multipath channels from second-order statistics using antenna arrays

Recently, Ding (see IEEE Signal Processing Lett., vol.3, p.150-2, May 1996) has pointed out several classes of multipath channels that are not blindly identifiable from fractionally spaced samples and second-order cyclic spectra. In this letter, we consider the blind identification problem using multiple antennas and show that the multipath channels will not give rise to any common roots among the subchannels formed from the antennas and, hence, they can be identified from second-order statistics. In our development, we will point out the role of band-limitedness of the channels in characterizing different classes.