A fast convergence algorithm for echo cancellers in full duplex transmission using back projection from slicer

The problem of accelerating echo canceller tracking, during full duplex transmission, in single carrier (data) receivers with adaptive equalization is addressed. The scheme presented accelerates the convergence rate by orders of magnitude, with a minor increase in complexity, which can be traded for speed. The complexity may be reduced to a fraction of that of previously published acceleration schemes, while providing substantial speedup factors with respect to conventional echo cancellers. The new scheme is based on measuring the residual echo signal at the slicer (symbol-by-symbol detector) but applying the correction to the conventional echo canceller. Measuring changes in a low-noise (post-slicer) environment enables speedup of the adaptation. Updating the pre-equalizer echo canceller both reduces complexity and distills the echo from the noisy equalizer input.