The effect of customer premises wiring on the performance of ADSL and VDSL

The loop plant is the only part of the telephone network that has stayed structurally almost the same for the best part of a century. Due to the increasing demand for broadband services, the time has come for a powerful upgrade of the entire outside loop plant, which includes upgrading the network to optical fibre. Initial provisioning of new services, such as asymmetric digital subscriber line (ADSL) and high-bit-rate digital subscriber line (HDSL), has to take place on the existing loop plant, because of the high costs associated with optic fibre for the so-called 'last mile'. Very-high-bit-rate digital subscriber line (VDSL) paves the way to a total fibre solution, introducing a hybrid copper/fibre solution for delivering high speed broadband services at up to 52 Mbps asymmetric and 26 Mbps symmetric. This paper investigates the possible effect that current premises wiring might have on the performance of ADSL and VDSL services. Basic channel modelling principles are applied for a twisted-pair transmission line. A number of scenarios are investigated and compared, and recommendations regarding future customer premises wiring are made.