Application of Stationary Wavelet Transform for improvement of Rate-Reach performance in ADSL interference environment

This paper discusses the mitigation of Near End Crosstalk (NEXT) and Far End Crosstalk (FEXT) using Stationary Wavelet Transform (SWT). Crosstalk noise is estimated using Heuristic Stein's Unbiased Risk Estimate (SURE) and Bayesian risk minimization threshold function. The noise level estimated by a threshold function is used by thresholding rules to mitigate the effect of noise in the signal. A comparison of rates achieved with three thresholding techniques viz; soft thresholds, hard thresholds and a garrote threshold have been presented. Results obtained with AWGN, NEXT, FEXT disturbers show a significant improvement in Rate reach performance upwards of 4 Mbps 5 Mbps. With SWT more accurate noise estimation and cancellation is achieved. The computational complexity in the wavelet denoising technique is independent of the number of crosstalk sources and hence can be suitable candidate for a practical deployment of mitigation of cross talk.