Study of adaptive nonlinear echo canceller with Volterra expansion

A nonlinear echo canceller with Volterra series expansion is presented. A model of the data transmission system is used to study its performance. It is shown that the Volterra expansion method is a good solution to the problem of nonlinear echo cancellation. To sufficiently reduce the nonlinearities caused by A/D and D/A (analog/digital and digital/analog) converters, an adaptive third-order Volterra filter with a nonlinear memory of length three can be applied. The far-end signal has a very strong influence on the canceller. To reduce this, a training sequence without a far-end signal is used, and different values of the step-size μ are chosen for the transient period (larger μ) and for the steady state. Simulations have shown that the canceller can achieve 15-dB improvement with a training sequence and 8-dB improvement without the training sequence