Effects of propagation delays and sampling rate on feed-back BSS and comparative studies with feed-forward BSS

Feed-forward (FF-) and Feed-back (FB-) structures have been proposed for Blind Source Separation (BSS) systems. The FF-BSS system has some degrees of freedom in the solution space, and signal distortion is likely to occur in convolutive mixtures. On the other hand, in the FB-BSS structure, the signal distortion is automatically suppressed after the sources are separated. However, it requires some condition on propagation delays in the mixing process. In this paper, source separation performance in the FB-BSS is analyzed taking the propagation delays into account. Based on this analysis, separation performances of the FF-BSS and the FB-BSS are compared. Furthermore, an over-sampling method is proposed for the FB-BSS in order to relax the constraint of the propagation delays. Simulation results support theoretical analysis and usefulness of the over sampling FB-BSS. Consequently, the FB-BSS expands its application fields.