Low-complexity optimal discrete-rate spectrum balancing in digital subscriber lines

• DOI: 10.1016/j.sigpro.2012.06.007
• Publication Date: 2012-06-18T14:28:24Z
• Authors: Martin Wolkerstorfer; Joakim Jaldén; Tomas Nordström
• Keywords: 0202 electrical engineering, electronic engineering, information engineering; 02 engineering and technology

Discrete-rate spectrum balancing in interference-limited multi-user and multi-carrier digital subscriber lines (DSL) is a large-scale, non-convex and combinatorial problem. Previously proposed algorithms for its (dual) optimal solution are only applicable for networks with few users, while the suboptimality of less complex bit-loading algorithms has not been adequately studied so far. We deploy constrained optimization techniques as well as problem-specific branch-and-bound and search-space reduction methods, which for the first time give a low-complexity guarantee of optimality in certain multi-user DSL networks of practical size. Simulation results precisely quantify the suboptimality of multi-user bit-loading schemes in a thousand ADSL2 scenarios under measured channel data.