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In multicarrier modulation schemes like Orthogonal Frequency Division Multiplex (OFDM) or Discrete Multi Tone (DMT) a guard interval represented by a cyclic prefix (CP) 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 IS1 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 IS1 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.

In today's multicarrier modulation systems such as orthogonal frequency division multiplexing (OFDM) a circular extended guard interval is inserted between successive multicarrier symbols in order to reduce intersymbol and interchannel interference. The length of the guard interval is determined by the length of the channel impulse response. In this paper, we consider an equalizer to compress the channel impulse response for OFDM transmission. Due to the compression effect, the guard interval can be reduced and the efficiency of the OFDM system increases. The system performance is demonstrated for transmission over several time-varying multipath channels with additive white Gaussian noise (AWGN).

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Due to the enormous growth of telecommunication services during the last decade, the need for a modulation technique that can transmit reliably high data rates with high band‐width efficiency arises. In this context, multicarrier modulation schemes have become very popular for wireless, mobile as well as fixed networks. A well known applications is digital subscriber line (DSL) communication over wired media using the discrete multitone (DMT) modulation scheme. In this article we present the principles of DMT modulation. We start from the basics of analogue and digital transmission and consecutively develop the main concepts of DMT, as there are: the incorporation of the discrete Fourier transform (DFT) into the modulation scheme, the use of the guard interval to combat interference, the principle of the generalized Nyquist theorem for perfect reconstruction of the signal, the cost‐effective equalization and the adaptive bit‐loading scheme.