Optimal Multiuser Spectrum Balancing for Digital Subscriber Lines

Optimal Multiuser Spectrum Balancing for Digital Subscriber Lines Crosstalk is a major issue in modern digital subscriber line (DSL) systems such as ADSL and VDSL. Static spectrum management, the traditional way of ensuring spectral compatibility, employs spectral masks that can be overly conservative and lead to poor performance. This paper presents a centralized algorithm for optimal spectrum balancing in DSL. The algorithm uses a dual decomposition to optimize spectra in an efficient and computationally tractable way. The algorithm shows significant performance gains over existing DSM techniques, e.g., in one of the cases studied, the proposed centralized algorithm leads to a factor of four increase in data rate over the distributed DSM algorithm iterative waterfilling.