| Summary: | 碩士 === 國立交通大學 === 電信工程系所 === 96 === Hand-free phone or teleconferencing system drives the power-amplification and loudspeaker commonly into saturated nonlinear region, leading to that the performance of conventional acoustic echo cancellation (AEC) reduced. In this thesis, we will build a cascade model which consists of a memoryless piece-wise linear (PWL) processor and a linear filter for AEC. It is beneficial to reduce the computation. Besides, in order to overcome the divergence problem in a cascade system, we will adopt the two-stage adaptation that starts with a linear filter, and then joint adaptation of PWL and linear coefficients follows. Further, the convergence analysis and stability criterion will be derived and the computer simulation will justify our analysis. Finally, LMS algorithms with optimum time-variant and time-&tap- variant step-sizes are developed to improve convergence rate. Their practical implementations and computer simulations are also provided.
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