A method to improve the frequency characteristics in transition period for time-varying cosine modulated filter banks

This paper presents an approach to improve the frequency characteristics in transition periods for time-varying cosine modulated filter banks. The prototype window is so designed that the total reconstruction distortion in presence of coefficient quantization is minimized. This leads to time-varying minimum mean square error (MMSE) cosine modulated filter banks. A suboptimal simplified window design method without directly minimizing the distortion equation is suggested. As an example a transform coding scheme for wideband speech and audio signals is given to show how to design the prototype window