New recursive structures for echo cancellation

The authors present two recursive structures for adaptive signal processing. They show, by computer simulation of echo cancellers for baseband data transmission, that the proposed structures can have a better performance than conventional IIR (infinite impulse response) and FIR (finite impulse response) structures if the poles are not too near the unit circle. The authors have restricted the results reported to the LMS (least mean squares) algorithm in its usual form. They have found that by making a minor change in the computation of the gradient components a_ik it is possible to retain the superior performance of the structures, even for poles near the unit circle. Although the authors work was restricted to the context of echo cancellers for data transmission, they believe that these structures could be advantageous for echo cancellers for speech transmission, or for other applications of adaptive signal processing