DFT modulated filter bank design for oversampled subband systems

Abstract

Filter banks are widely used in digital signal processing, often integrated in a multirate scheme, to reduce the implementation cost and to improve algorithmic performance. DFT modulated filter banks are commonly used to design oversampled subband schemes. Oversampled subband schemes are attractive as they trade off between complexity gain and aliasing distortion. Ideally, the overall effect of a subband system is that of a pure delay, i.e. the subband system is perfectly reconstructing. In this paper we present design techniques for perfect and nearly perfect reconstruction oversampled DFT modulated filter banks. One of the disadvantages of a perfect reconstruction filter bank design is that the stopband attenuation of the filters is typically small, which could have a negative impact on intermediate subband operations such as subband adaptive filtering. Nearly perfect reconstruction filter banks can be designed to overcome this problem, leading to a better performance of the intermediate algorithms.