THE VDSL TRANSMISSION CHALLENGE

Demand for high speed digital transmission on ordinary phone lines mot ivates the introduction of VDSL. This paper investigates the VDSL tran smission environment. The channel is shown to be difficult for high sp eed digital transmission and sophisticated signal processing methods a re required for reliable transmission. This paper also describes vario us transmission schemes that are proposed to support high data rates i n the difficult transmission environment. Two schemes, SDMT and QAM/CA P, are compared in terms of SNR margins and computational complexity.