  In many applications such as wireless communications and subband adaptive
filtering, we need to design non-uniform filter banks (NUFB), which may lead to
better performances and reduced hardware complexity when compared to uniform
filter bank. NUFB satisfying linear phase property for all the constituent
filters, are desirable in applications such as speech and image processing and
in communication. This paper proposes a novel design of non-uniform modified
discrete fourier transform filter bank (MDFT FB). Here, each non-uniform
channel is obtained by merging the nearby channels of a uniform MDFT FB. The
reported works of non-uniform cosine modulated filter banks (CMFBs) do not
satisfy linear phase property for all the constituent filters. In this work, we
introduce the design of a non-uniform MDFT FB which satisfies linear phase
property for all the constituent filters. The proposed design of the
non-uniform MDFT FB is checked utilizing the alias cancellation among the
channels, distortion and flatness condition of the channels. A condition is
derived to find the channels when merged with adjacent channels, will cause
aliasing in M channels. In the design and implementation of the proposed
non-uniform MDFT FB, the structure of the uniform MDFT filter bank is preserved
and hence all the advantages of MDFT FB over the DFT filter bank, are
guaranteed. Hence without increasing the design complexity, the non-uniform
MDFT FB is designed.
