Dynamic Spectrum Management for Green DSL

Dynamic spectrum management (DSM) has been recognized as a key technology for tackling multi-user cros stalk interference in DSL broadband access. Up to now, DSM design has mainly been focusing on maximization of data rates. Howe v r, recently, reducing the total power has become a main target, as IT power consumption has been identified as a significant contributor to global warming. In this paper we extend tradi tional DSM design towards a much wider power-efficient scope and sho w how to tackle the corresponding optimization problems. Thi s leads to a unifying mathematical representation of more general DSM problems which will be referred to as ‘green DSL’. Using this ‘green DSL’ approach, we quantify the power-rate trade-off for different practical settings with some surprising numerical results. We demonstrate that for some VDSL scenarios power savings of up to 50% can be achieved while still guaranteeing 95% of full-power data rate performance. This somewhat surprising trade-offresult is due to not just the logarithmic dependence of rate on SINR b ut also the characteristics of crosstalk in DSL systems. Final ly, the analysis is extended towards suboptimal DSM algorithms, le ading to a power-rate-complexity trade-off.