Reduction of guard interval by impulse compression for DMT modulation on twisted pair cables

In multicarrier modulation schemes like orthogonal frequency division multiplexing (OFDM) or discrete multi tone (DMT) a guard interval represented by a cyclic prefix is inserted between successive multicarrier symbols in order to reduce intersymbol interference (ISI). The length of the guard interval is determined by the length of the channel impulse response (CIR). For a fixed guard interval, the longer the CIR, the higher the ISI is. In this paper, we have designed a time domain equalizer (TEQ) to compress the impulse response of several twisted pair lines with and without bridged taps. The reduction of ISI is shown as well as the resulting signal to noise ratio (SNR) in the presence of white Gaussian noise, near and far end crosstalk (NEXT, FEXT) for various equalizer designs.