Single-carrier modulation technology for very high-speed digital subscriber line

This article gives an overview of very highspeed digital subscriber lines, including the main issues of VDSL system design, such as its basic architec ture, applications, and data rates, as well as the technological challenges of practical implementation due to different loop plant realities and spec tral compatibility considerations. Some specific characteristics of the VDS L transceiver startup procedure and high-level architecture, as well as a s ummary of first laboratory tests and field trials, are also presented. The article concentrates on VDSL implementations using single-carrier modulatio n, which integrates the well-known carrierless amplitude/phase modulation a nd quadrature amplitude modulation technologies. Currently, SCM technology is considered one of the main candidates for the VDSL standard in the Unite d States and Europe, and internationally.