Publications:Duality-gap bounds for multi-carrier systems and their application to periodic scheduling

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Title Duality-gap bounds for multi-carrier systems and their application to periodic scheduling
Author M. Wolkerstorfer and D. Statovci and Tomas Nordström
Year 2010
PublicationType Conference Paper
HostPublication 2010 IEEE International Conference on Communications : ICC 2010 : 23-27 May 2010, Capetown, South Africa
Conference IEEE International Conference on Communications (ICC), Cape Town, South Africa, May 23-27, 2010
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Abstract We investigate a novel cross-layer optimization problem for jointly performing dynamic spectrum management (DSM) and periodic rate-scheduling in time. The large number of carriers used in digital subscriber lines (DSL) makes DSM a large-scale optimization problem for which dual optimization is a commonly used method. The duality-gap which potentially accompanies the dual optimization for non-convex problems is typically assumed to be small enough to be neglected. Also, previous theoretical results show a vanishing duality-gap as the number of subcarriers approaches infinity. We will bound the potential performance improvements that can be achieved by the additional rate-scheduling procedure. This bound is found to depend on the duality-gap in the physical layer DSM problem. Furthermore, we will derive bounds on the duality-gap of the two most important optimization problems in DSL, namely the maximization of the weighted sum-rate and the minimization of the weighted sum-power. These bounds are derived for a finite number of subcarriers and are also applicable to the respective problems in orthogonal frequency division multiplex (OFDM) systems. ©2010 IEEE.