Polyphase IIR filter banks for subband adaptive echo cancellation applications

Polyphase IIR structures are known to be very attractive for very high performance filters that can be designed using very few coefficients. This combined with their reduced sensitivity to coefficient quantization in comparison to standard FIR and IIR structures makes them very applicable to very fast filtering especially when implemented in fixed point arithmetic. In this paper we suggest replacing standard FIR filter banks used in subband adaptive polyphase FFT echo cancellation applications with such a structure. We demonstrate here that such an alternative approach results in a much more computationally efficient implementation combined with more accurate channel detection and improvement in the adaptation speed.