On the Capacity of a Twisted-Wire Pair: Gaussian Model

The performance of a twisted-pair channel is assumed to be dominated by near-end crosstalk (NEXT) from other pairs in the same cable. Both, intrabuilding local and central office loop channels may be modeled as NEXT-dominated channels. In this paper, the capacity of this type of channel is found, using a Gaussian model. It is shown that, the capacity is independent of the transmitted power spectral density. The results also indicate that present systems operate far below theoretical capacity. The capacity of a twisted-pair channel with both NEXT and white Gaussian noise present is also addressed.