Per tone echo cancellation for DMT-based systems

A new echo cancellation structure for discrete multitone (DMT) systems is presented where each used tone has its own per tone echo canceller in addition to a per tone equalizer [8] [9] which provides an alternative to current employed time domain and time/frequency domain approaches. The per tone approach enables us to optimize the Signal-to-Noise Ratio (SNR) for each tone separately by solving a Minimum Mean Square Error (MMSE) problem for each tone, with implicit so-called joint shortening. Complexity during data transmission is compared for time domain echo cancellation and per tone echo cancellation. Structures with reduced complexity are derived for an interpolated and a decimated rate set-up. Finally, simulation results for an ADSL setting demonstrate improved performance over time domain (or time/frequency domain) echo cancellation