Arbitrary Partial FEXT Cancellation in Adaptive Precoding for Multichannel Downstream VDSL

In this paper, we present and analyze a simplified, adaptive precoder for arbitrary partial far-end cross talk (FEXT) cancellation in the downstream of multichannel VDSL. The precoder is based on error signal feedback and is computationally efficient. Furthermore, the partial precoding makes it possible to operate the precoder at any desired complexity, and the system´s performance increases with any increase in system complexity. Unlike previous works, in which each user experienced either complete FEXT cancellation or no cancellation at all, the presented precoder can mitigate the FEXT from any desired subset of interfering users for each user. We derive sufficient conditions for convergence of the adaptive precoder, for any partial cancellation scheme, and provide closed form steady state error analysis. The precoder´s performance and convergence properties are also demonstrated through simulations.