α-repetition/modulation and blind second-order identification

Abstract

In the context of redundant filter-bank precoders, we investigate the so-called /spl alpha/-repetition/modulation, for /spl alpha//spl epsiv/[0, 1/2 ], with regard to the blind second-order identification. For many /spl alpha/'s, an algebraic result shows that the unknown channel can be recovered from the second-order statistics irrespective of both the channel zero location and the model over-determination. Namely, a structured subspace method provides an estimate of the channel. However, in the context of band-limited communication channels, numerical degeneracies appear for certain choices of /spl alpha/. We therefore analyze the numerical behavior of this method resorting to spheroidal wave sequences. We show there exist /spl alpha/'s less than a bound depending on the channel bandwidth making the estimation robust to noise. Simulations are also provided.