E$cient biorthogonal cosine-modulated "lter banks

Biorthogonal modulated "lter banks, when compared to paraunitary ones, provide the advantage that the overall system delay can be chosen independently of the "lter length, thus allowing to design low delay "lter banks. They have recently been studied by several authors. In this paper, we connect two di!erent design methods, namely the quadratic constrained least-squares optimization and the principle of cascading sparse self-inverse matrices. Moreover, we show how factorizations into zero-delay and maximum-delay matrices can be utilized in order to achieve desirable features such as structure-inherent perfect reconstruction, no DC leakage of the "lter bank, and a low implementation cost. 2001 Elsevier Science B.V. All rights reserved.