On the loading of peak-energy-limited multicarrier systems transmitting over spectrally-shaped crosstalk-impaired DSLs

We develop the solution for optimal loading of digital subscriber loop (DSL) multicarrier (MC) systems that present constraints both on overall available energy and maximum energy per carrier. In the emerging ADSL3 systems planned for high-throughput multimedia applications the constraint on the peak-energy arises from spectral compatibility issues. However, up till now none of the published loading algorithms apparently account for peak-energy limitations neither optimal solutions for loading peak-energy constrained MC systems seem available. Therefore, starting from some results about the maximization of ∩-convex functions which generalize the usual Kuhn-Tucker conditions, we present the analytical relationships characterizing the optimal peak-energy limited Loading. Thus, a low-complexity iterative algorithm implementing the optimal solution is also developed and its performance is numerically tested on an ANSI-standard ADSL3-type DSL impaired by crosstalk. Furthermore, a suitably modified version of the presented loading algorithm which guarantees integer-bit rates is presented