Adaptive filter for concurrent echo cancellation and equalization using fast Kalman estimation

High performance is needed from echo cancellation and equalization coefficient update algorithms in full-duplex wire transmission systems that employ adaptive filters to minimize echo and intersymbol interference. As shown by Falconer and Ljung the fast Kalman algorithm is an applicable optimal (minimum MSE) tap coefficient estimation algorithm. We describe and investigate a new algorithm for concurrent echo cancellation and equalization based on the fast Kalman algorithm. Three filter sections are used to perform simultaneous echo cancellation, linear equalization and decision-feedback equalization. The rapid convergence properties of this algorithm and filter structure are confirmed by simulation for a 144-kb/s ISDN local-loop transmission application.