Efficient implementation of complex exponentially-modulated filter banks

In an Exponentially-Modulated Filter Bank (EMFB) the complex subfilters are generated from a real-valued prototype filter by multiplying the filter impulse response with complex exponential sequences. This allows the possibility of using block transforms with computationally fast algorithms. Our definition for the EMFB is based on the Extended Lapped Transform (ELT). Then we apply Fast ELT based algorithms for cosine-modulated and sine-modulated filter banks (CMFB, SMFB) as basic building blocks in the implementation of this complex filter bank. Alternatively, a modified polyphase structure with 2 branches can be used. The latter structure can be employed with non-perfect reconstruction filter bank designs that allow some additional degrees of freedom in the optimization. In this paper, we explore these alternative realization structures for CMFBs and SMFBs.