Computationally efficient realization of MDFT filter banks

A realization of the Modified DFT (MDFT) filter bank introduced in [1, 2, 3] was proposed in [4]. The analysis and synthesis filter bank consist each of two DFT polyphase filter banks, one without delay and one delayed by M/2 samples where M represents the number of channels of the MDFT filter bank. In this paper, we will show that the two DFTs can be reduced to a single one for prototypes of the lengths N = r · M + 1 and N = r · M + M/2 +1, respectively, by doing some simple combinations with the input signals. Hereby the modulation cost is nearly halved.