Two-staged nonlinear acoustic echo cancellation and its convergence analysis

Hand-free telephone system commonly drives the power-amplification and loudspeaker into saturated nonlinear region such that performance of conventional acoustic echo cancellation (AEC) is degraded. A computationally efficient cascade AEC model is used to include a memoryless piecewise linear (PWL) processor and a linear filter. In order to overcome the start-up divergence problem encountered in nonlinear AEC adaptation, a two-stage update scheme is adopted that starts with the linear filter update, and then joint adaptation of PWL and linear coefficients follows. Theoretical convergence analysis and stability criterion will be derived and validated by the computer simulation.