Oversampled modulated filter banks

Oversampled filter banks (FBs) offer increased design freedom and noise immunity as compared to critically sampled FBs. Since these advantages come at the cost of greater computational complexity, oversampled FBs allowing an efficient implementation are of particular interest. In this chapter, we discuss oversampled DFT FBs and oversampled cosine modulated FBs (CMFBs) which allow efficient FFT- or DCT/DST- based implementations. We provide conditions for perfect reconstruction and a frame-theoretic analysis. We show that, concerning both perfect reconstruction properties and frame-theoretic properties, oversampled cosine modulated filter banks are closely related to DFT filter banks with twice the oversampling factor.