Zero-forcing frequency-domain equalization for generalized DMT transceivers with insufficient guard interval

  • Authors:

  • Tanja Karp;Steffen Trautmann;Norbert J. Fliege

  • Affiliations:

  • Department of Electrical and Computer Engineering, Texas Tech University, Lubbock, TX;Infineon Technologies Austria AG, Development Center Villach Siemens Strasse, Villach, Austria;Institute of Computer Engineering, Mannheim University, Mannheim, Germany

  • Venue:
  • EURASIP Journal on Applied Signal Processing
  • Year:
  • 2004

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Abstract

We propose a zero-forcing frequency domain block equalizer for discrete multitone (DMT) systems with a guard interval of insuffcient length. In addition to the insuffcient guard interval in the time domain, the equalizer takes advantage of frequency domain redundancy in the form of subcarriers that do not transmit any data. After deriving suffcient conditions for zero-forcing equalization, that is, complete removal of intersymbol and intercarrier interference, we calculate the noise enhancement of the equalizer by evaluating the signal-to-noise ratio (SNR) for each subcarrier. The SNRs are used by an adaptive loading algorithm. It decides how many bits are assigned to each subcarrier in order to achieve a maximum data rate at a fixed error probability. We show that redundancy in the time domain can be traded off for redundancy in the frequency domain resulting in a transceiver with a lower system latency time. The derived equalizer matrix is sparse, thus resulting in a low computational complexity.