Subspace methods for the blind identification of multichannel FIR filters

A class of methods for identifying a single input/multiple output finite impulse response system (SIMO-FIR), from the outputs of the system only is presented. These methods rely on a minimal parametric representation of the system solution. They are based on the orthogonality between a `signal´ and a `noise´ subspaces. This is exploited to build quadratic forms whose minimization yields the desired estimates up to a scale factor. It is shown (by numerical simulations) that these methods provide significantly better (in terms of bias and variance) estimates than the method by Tong et al. (1991), while requiring about one half the number of computations. They are thus very attractive for applications, in particular, for narrowband TDMA channel equalization