Combined equalization and alien crosstalk cancellation in ADSL receivers

We address the problem of mitigating a dominant alien near-end crosstalker such as HDSL, SDSL or HPNA in DMT-based ADSL and VDSL receivers. Due to the different symbol rates of crosstalker and signal of interest, linear time-invariant filtering is not appropriate. Recently, Zeng et al. presented a method to tackle this problem [4]. In this paper, we present an alternative procedure, which, unlike the solution of [4], does not require any prior knowledge (such as transmission and crosstalk channel, noise characteristics, etc.) other than the crosstalker symbol rate. Moreover, it is fully adaptive, integrates equalization and crosstalk cancellation and optimizes the signal-to-noise ratio for each tone separately. Both algorithms exploit spectral correlation in the received crosstalking signal, thanks to oversampling and excess bandwidth. The method present here is based on the application of so called FREquency-SHift (FRESH) filtering.