DSL wideband crosstalk cancellation for mixed DSL technologies using common mode information

Abstract

Data services delivered on telephone twisted pair wiring can potentially suffer from crosstalk due to data services on other twisted pairs in proximity, limiting the data rate, the maximum loop length and the quantity and variety of data services that a bundle can support. The crosstalk from other data services couples to the twisted pair in common mode and leaks to differential mode due to imperfect line balance. This thesis uses the common mode signal as a reference to an adaptive wideband crosstalk canceller, in an attempt to remove or at least lower the effect of crosstalk on the useful differential signal. Simulation results show the potential benefits of using this technique to reduce the level of crosstalk on an ADSL differential signal with crosstalk coming from data services commonly found in the telephone bundles. This technique is not limited to ADSL but can be applied to any technology using twisted pair wiring as its transmission medium.