Variable step size filtered sign algorithm for acoustic echo cancellation

A new class of variable step size sign algorithms, tailored for acoustic echo cancellation, is proposed. The choice of the step size depends on the status of the algorithm: transient state, steady state or ´double talk presence´ state. The switching rules between step sizes depend on the previous state, and employ some kind of hysteresis to ensure algorithm stability and effectiveness. Furthermore, the concept of input pre-whitening is used to drive the adaptive filter, yielding faster convergence rate. Simulation results are presented to support the proposed algorithm and to compare it with classical ones (sign and dual sign algorithms).