An efficient implementation for DMT-based full-duplex DSL modems

The paper describes a two-stage echo canceler designed for a full-duplex, discrete multi-tone (DMT) based digital subscriber loop (DSL) modem. The two-stage feature is incorporated to reduce the dynamic range of the input to the FFT processor. In addition, fast convolution with overlap-save is used for reducing the computation load. The proposed DMT-specific approach makes use of FFTs available within the DMT structure at the transmitter. Simulation results demonstrate the reduction in processor-word size requirement that can be obtained by the two-stage approach. Analytical results show the reduction in computation load that results as a consequence of the fast-convolution and DMT-specific FFT-reuse implementation.