Low complexity crosstalk cancellation through line selection in upstream VDSL

Abstract

Crosstalk is the major source of performance degradation in VDSL. A number of crosstalk cancellation techniques have been proposed to address this. Whilst these schemes lead to large performance increases they also have high run-time complexities, a problem which grows rapidly with the number of lines within a binder. Since the majority of crosstalk typically comes from only a few dominant crosstalkers, it is possible to do partial crosstalk cancellation. We present a low-complexity, partial crosstalk cancellation technique for VDSL based on line selection. We derive the optimal line selection technique, and several low-complexity selection algorithms which give near-optimal performance in most scenarios. These techniques lead to significant reductions in runtime complexity whilst giving similar performance to full crosstalk cancellation.