An all pole IIR echo canceller

An all-pole type of infinite impulse response (IIR) linear echo canceller is proposed. An IIR echo canceller can potentially achieve equivalent performance equal to a finite impulse response (FIR) structure, but with a significant reduction in the number of filter stages required. The proposed canceller identifies the inverse of the echo-path impulse response in terms of poles. With the estimated inverse echo-path response, the echo canceller reconstructs estimated echoes to cancel the real echoes. The inverse echo-path estimation can be realized with a conventional least-mean-square (LMS) algorithm. The canceller works well for echo paths with only stable poles and small zeros. A real echo path usually consists of stable poles and big zeros. In practice, the all-pole IIR echo canceller can be applied following a conventional FIR echo canceller with a reduced number of stages