Echo cancellation for asymmetrical digital subscriber lines

Discrete multitone modulation has been chosen to provide the high speed link for asymmetrical digital subscriber lines (ADSL). Modulating bidirectional digital traffic over the existing twisted pair loop plant necessitates the used of a high performance echo canceller. This paper investigates an echo canceller structure for ADSL. A combination frequency domain echo canceller and a time domain echo synthesizer are detailed along with timing and fixed point effects. Detailed simulation results show the canceller performance is more than adequate and does not limit the transceiver´s performance. Complexity issues are addressed and show that an effective canceller can be implemented with only modest computational requirements. Hence, there exists an effective and efficient echo canceller for ADSL