Precoding for egress reduction in DMT transmitters

Discrete multi tone (DMT) uses an inverse discrete fourier transform (IDFT) to modulate data on the carriers. The high side lobes of the IDFT filter bank can lead to spurious emissions (egress) in unauthorised frequency bands. Applying a window function within the DMT symbol alleviates this, but introduces distortions that are generally not easy to compensate for. In this paper a special class of window functions is constructed that corresponds to a precoding at the transmitter and that requires only a modest amount of processing at the receiver for this compensation. 1 Precoding for egress reduction in DMT transmitters Gert Cuypers Member, IEEE, Geert Ysebaert Student Member, IEEE, Koen Vanbleu Student Member, IEEE, Marc Moonen Member, IEEE. Abstract Discrete multi tone (DMT) uses an inverse discrete fourier transform (IDFT) to modulate data on the carriers. The high side lobes of the IDFT filter bank can lead to spurious emissions (egress) in unauthorised frequency bands. Applying a window function within the DMT symbol alleviates this, but introduces distortions that are generally not easy to compensate for. In this paper a special class of window functions is constructed that corresponds to a precoding at the transmitter and that requires only a modest amount of processing at the receiver for this compensation.Discrete multi tone (DMT) uses an inverse discrete fourier transform (IDFT) to modulate data on the carriers. The high side lobes of the IDFT filter bank can lead to spurious emissions (egress) in unauthorised frequency bands. Applying a window function within the DMT symbol alleviates this, but introduces distortions that are generally not easy to compensate for. In this paper a special class of window functions is constructed that corresponds to a precoding at the transmitter and that requires only a modest amount of processing at the receiver for this compensation. Index Terms Digital Subscriber Loop, Discrete Multitone, Multicarrier Modulation, Egress, Windowing EDICS Designation: 3-COMM Signal Processing for Communications Submitted March 1, 2004. G. Cuypers, K. Vanbleu, G. Ysebaert and M. Moonen are with the Katholieke Universiteit Leuven, ESAT/SCD-SISTA, Belgium. This research work was carried out at the ESAT laboratory of the Katholieke Universiteit Leuven, in the frame of the Belgian Programme on Interuniversity Attraction Poles, initiated by the Belgian Federal Science Policy Office IUAP P5/22 (‘Dynamical Systems and Control: Computation, Identification and Modelling’) and P5/11 (‘Mobile multimedia communication systems and networks’), the Concerted Research Action GOA-MEFISTO-666 and the Research Project FWO nr.G.0196.02. Correspondence: Gert Cuypers, Katholieke Universiteit Leuven ESAT/SCD-SISTA, Kasteelpark Arenberg 10, B-3001 Leuven Belgium, tel.: 32/16/32 19 27, fax: 32/16/32 19 70, email: [email protected]