New insights in adaptive cascaded FIR structure: Application to fully adaptive interpolated FIR structures

This paper presents the development of the least-mean-square (LMS) and normalized LMS (NLMS) algorithms for adapting cascaded FIR filters and the application of such algorithms to the whole adaptation of interpolated FIR filters. The obtained expressions are general and can be extended to any structure composed of the cascade of two FIR filters. The considered approach allows verifying the main characteristics of the adaptive process as well as the limitations of the existing adaptive interpolated FIR structures using adaptive interpolators. Numerical simulation results are presented aiming to confirm the effectiveness of the obtained advances.