Double talk cancellation in echo cancelled dmt-systems

The existing ADSL standard allows for two possible trans-mission systems: frequency division duplexing (FDD) and echo cancelling (EC). Echo cancelling is particularly attrac-tive for its ability to achieve higher data rates compared with FDD schemes. A disadvantage of EC is that adaptive schemes exhibit slow tracking properties in the presence of a far end signal or double talker. This paper presents an efcient method for updating echo canceller taps in ADSL transceivers in the presence of a far end signal, by effectively cancelling most of the received far end energy. The pre-sented scheme extends existing multicarrier echo cancelling schemes with a feedback of decisions on the far end signal. As a result the convergence is much faster and hence fast tracking properties are possible at a low computational com-plexity.