MMSE-Based Partial Crosstalk Cancellation for Upstream VDSL

In current DSL systems, crosstalk is a major source of performance degradation. In the case of in-domain crosstalk and AWGN, it has been shown that the crosstalk can be effectively mitigated using a linear zero-forcing canceler. Furthermore, the complexity can be reduced by only canceling the crosstalk from major crosstalkers on each tone, which is reffered to as partial cancellation. However, such approach does not work e.g. in the case of out-of-domain (alien) crosstalk. As alien crosstalk is spatially correlated, the zero-forcing canceler performs very poorly, hence an alternative linear canceler has to be examined. In this paper, we demonstrate that an MMSE crosstalk canceler provides improved performance compared to the zero-forcing canceler in this scenario and additionally, we also present an efficient algorithm to perform MMSE partial cancellation.