Wideband Unshielded-Twisted-Pair (UTP) Cable Measurements and Modeling for Multiple-Input–Multiple-Output (MIMO) Systems

The study of multiple-input-multiple-output (MIMO) systems over unshielded-twisted-pair (UTP) cables relies on or assumes models of the cable´s transmission and crosstalk parameters. Several cable models have been proposed; however, there has been a lack of wide-scale line surveys to verify the applicability of these models. This paper presents the results of wideband-crosstalk and transmission-parameter measurements on UTP cables conducted at the laboratories of BTExact. The measurement results are then used to verify Joffe´s MIMO channel model, which is one of the two available but mathematically equivalent models. It is shown that crosstalk estimates from measurements taken on very short cable lengths fail to account for the effects from the pair and bundle twisting. Model parameters measured on longer cable pieces yield more realistic frequency-dependent model predictions; these are, however, distorted at high frequencies due to resonance effects. In general, the model tends to overestimate far-end crosstalk and underestimate near-end crosstalk.