Dynamic Spectrum Management in DSL With Asynchronous Crosstalk

In this paper we focus on discrete multitone (DMT) dynamic spectrum management (DSM) in digital subscriber lines (DSL) networks with asynchronous crosstalk. DSM aims to optimally allocate per-user transmit spectra so that the effect of multi-user crosstalk is minimized and the capabilities of the network maximized. Most DSM solutions so far address an idealized situation, one in which all users DMT blocks in the network are perfectly synchronized and crosstalk is dealt with on a per-tone basis. We focus on the case in which the DMT blocks of the various users are offset amongst each other, which leads to inter-carrier interference (ICI). ICI significantly impacts the performance of the system and complicates the DSM optimization problem considerably, as the per-tone decoupling used for the synchronous case is no longer directly applicable. Our contribution is twofold: First, we derive a new and accurate model for the effect of the ICI; Second, we provide a novel DMT DSM algorithm that outperforms the existing state-of-the-art.