Semi-Blind Power Allocation for Digital Subscriber Lines

Digital subscriber lines (DSL) are today one of the most important means for delivering high-speed data transmission. An emerging technique for dealing with one of the technology´s most harmful problems, crosstalk, is dynamic spectrum management (DSM). DSM literature already counts with some half a dozen important solutions. These solutions can be classified according to four different aspects: optimality, computational cost, distribution and required crosstalk channel information. In this work we present an algorithm, named semi- blind spectrum balancing, which achieves a compelling trade-off between these four aspects. The scheme is based on the idea of optimization against a virtual line, a fictitious line to represent the damage caused to other users in the network. This line is adjusted with the aid of limited message-passing between modems and a central agent and very simple crosstalk channel information. Crosstalk channel knowledge required should be much simpler to obtain than full channel estimation.