Bandwidth selection for the very high-rate digital subscriber line (VDSL) system

Work is under way to develop a very high-rate digital subscriber line (VDSL) system capable of operating over twisted-pair media at data rates in excess of 10 Mbps. The twisted-pair channel is characterized by both an attenuation and crosstalk susceptibility which increase with frequency and length. The signaling bandwidth for such a channel can be selected to maximize the bit rate. This optimization is carried out for loop lengths in the 1-5 kft range. It is shown that the optimal signal bandwidth is quite sensitive to the loop length. For example, the optimal bandwidth for a 1 kft loop is more than twice that of the 3 kft loop.