Analyzing and modeling of far-end crosstalk in twisted multi-pair metallic cables

Crosstalk and especially far-end crosstalk represents the most serious source of disturbance in today´s digital transmission systems. It mostly limits the information capacity of current xDSL digital subscriber lines and also local data networks with unshielded and or shielded twisted pairs (UTP/STP). For the proper and efficient operation of Vectored Discrete Multi-tone modulation (VDMT), which could reduce the influence of far-end crosstalk, it will be necessary to implement advanced methods for modeling of FEXT to obtain the required predictions of crosstalk behavior in a cable. The standard simple FEXT model is not very accurate and does not provide realistic results. That is why a new method for modeling of FEXT was developed and is presented in this paper. The main idea of the model is based on the assumptions concerning the propagation of electromagnetic waves through the cable and its simulation by proper harmonic functions. The results of the model are also compared with measured characteristics for a typical UTP a PEPKFH cable. On the other hand, proposed advanced FEXT model with minor modifications is applicable for any metallic cable to provide accurate and realistic FEXT characteristics.