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Open Access

Joint Multiuser Detection and Optimal Spectrum Balancing for Digital Subscriber Lines

EURASIP Journal on Advances in Signal Processing20062006:080941

Received: 1 December 2004

Accepted: 8 July 2006

Published: 27 July 2006


In a digital subscriber line (DSL) system with strong crosstalk, the detection and cancellation of interference signals have the potential to improve the overall data rate performance. However, as DSL crosstalk channels are highly frequency selective and multiuser detection is suitable only when crosstalk is strong, the set of frequency tones in which multiuser detection may be used must be carefully chosen. Further, this problem of tone selection is highly coupled with the transmit power spectra of both direct and interfering signals, so the optimal solution requires the tone selection problem to be solved jointly with the multiuser spectrum optimization problem. The main idea of this paper is that the above joint optimization may be done efficiently using a dual decomposition technique similar to that of the optimal spectrum balancing algorithm. Simulations show that multiuser detection can increase the bit rate performance in a remotely deployed ADSL environment. Rate improvement is also observed when near-end crosstalk is estimated and cancelled in a VDSL environment with overlapping upstream and downstream frequency bands.


Rate PerformanceSelection ProblemInterference SignalRate ImprovementDecomposition Technique


Authors’ Affiliations

The Edward S. Rogers Sr. Department of Electrical and Computer Engineering, University of Toronto, Toronto, Canada


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© Chan and Yu 2006