An analytical model for the probability distributions of crosstalk power sum for a subset of pairs in a twisted pair cable

摘要

This work presents a new and more accurate crosstalk model that is used for calculating the probability distributions of crosstalk power sum for M randomly selected pairs in an N-pair twisted pair cable. The calculation is based on averaged measurements of crosstalk in each individual pair combination. Probability distributions are calculated both for near end crosstalk (NEXT) and far end crosstalk (FEXT) in one specific type of commonly used cable that contains one 10-pair binder group. The results for the 10-pair cable show the same type of variation for the 99% point of crosstalk power sum as in the standard model used for DSL systems, which is based on 50-pair binder groups. However, the parameters are different for the two cases. For the 10-pair cable, there is a smaller variation in crosstalk as a function of the active number of pairs. The results for FEXT in a 10-pair group are in close correspondence with the standard model, while the level of NEXT is 1 2.5 dB weaker in the 10-pair group than in the standard model.