Finite length equalization for FFT-based multicarrier systems-an error-whitening viewpoint

Discrete multitone modulation (DMT) is a useful waveform in the communication systems engineer´s toolbox. For certain applications, DMT produces designs which are easier to implement than a single-carrier-based design, while attaining higher performance. An important component in the asymmetric digital subscriber loop (ADSL) the DMT system is the finite-length equalizer which truncates the channel impulse response, greatly reducing the requisite FFT size. This paper argues that the preferred channel-truncating equalizer is one which whitens the composite error sequence. A white error sequence tends to achieve information-transmission optimality.