Equalizer design for discrete multitone systems combining response shortening and spectral shaping

In this paper the problem of time domain equalizer (TEQ) design for discrete-multitone (DMT) transmission system is analyzed. The proposed algorithm uses combined objective of line impulse response shortening and frequency shaping (weighting) of signal and noise before demodulation. Suboptimal shaping, being simple noise whitening, is shown to compensate FFT noise spreading. The resulting design algorithm defines the desirable impulse response both outside and inside a target window. The equalizer taps are evaluated by linear weighted least squares fit. Achievable levels of SNR and capacity outperform simpler shortening algorithms and approach matched filter bound. They also behave stably with an increase of TEQ length.