For over two decades, digital subscriber line (DSL) technology has played an important role in bridging the information highway from Malaysia to the rest of the world. Current copper twisted pair cables deployed to the customer premises in Malaysia are mainly consist of Category 3 copper cables which are meant to operate only up to 16 MHz frequency. The new gigabit fast access to subscriber terminals (G.fast) standard aims to operate beyond ADSL2+ (less than 2 MHz) and VDSL (less than 30 MHz) which G.fast can operates up to 106 MHz frequency, thus a study need to be done to characterize the existing copper cables to observe whether the current copper cable can support the new standard at a shorter distances (below 250 meters). Scattering Parameters (4 port S-Parameters) measurements on the Telekom Malaysia's (TM) twisted-pair copper cable were done to obtain the channel transfer function or the insertion loss of the cable up until 350 MHz. The cable bundle contains 50 pairs of twisted pair copper cable with FullyFilled cable construction which is meant to be used for underground cabling. Based on the transfer function measurement, 3 cable models, the RLCG, the TNO 6-Parameters and the MAR models were selected to be curve fitted to the measured result to get the best fit for the transfer function. The curve fitted models will then be used to predict the maximum achievable attainable rate for G.fast technology at 106 MHz. This paper will attempt to do a benchmarking for the available cable model to best represent the TM's twisted pair cable in terms of channel transfer function.

Summary The new International Telecommunication Union Telecommunication G.fast standard for next‐generation ultra‐broadband digital subscriber line systems has stipulated mandatory use of vectoring for crosstalk mitigation. In this paper, we study the performance of downstream precoders in G.fast networks utilising the extended bandwidth up to 212 MHz. In particular, the issue of strong crosstalk encountered in practical copper cable bundles at high frequencies giving rise to channel matrices which are not row‐wise diagonally dominant (RWDD) as predicted theoretically, as well as the ramification of deploying precoders designed based on the RWDD assumption in practical G.fast channels are studied. To serve these purposes, an enhanced stochastic far‐end crosstalk (FEXT) model which provides distinct FEXT transfer functions with the dispersion range characterised experimentally whilst encompassing the dual‐slope FEXT encountered in non‐RWDD cables is used for evaluating the performance of precoders in diverse G.fast deployment scenarios. Furthermore, the performance sensitivity of precoders under realistic amount of channel estimation errors is investigated on a common framework, allowing a direct and fair comparison between linear and non‐linear precoders. Results show that the nonlinear optimal precoder outperforms linear precoders in all channel conditions; however, the former is found to be slightly more sensitive to channel estimation errors on shorter loops. Copyright © 2016 John Wiley & Sons, Ltd.

No abstract

No abstract

No abstract