Spectral compatibility of asymmetrical digital subscriber lines (ADSL) with basic rate DSLs, HDSLs, and T1 lines

The results of an analysis of the spectral compatibility of asymmetrical digital subscriber lines (ADSLs) with other digital transport technologies that might coexist in the same binder group are presented. The near-end crosstalk and far-end crosstalk effects of digital subscriber line (DSL)-based transport schemes, such as basic-rate and high-bit-rate DSL (HDSL) and T1 lines, are investigated. Two categories of loop environment design rules are considered. The ADSL transceiver is assumed to be based on either a 16- or 64-point quadrature amplitude modulation (QAM) symbol constellation for a data rate of 1.6 Mb/s. The guardband of the transmit spectrum is assumed to fall within the range of 20 to 110 kHz. The receiver is assumed to be an ideal decision feedback equalizer with a quarter-baud spaced fractionally spaced feedforward equalizer. It is concluded that a 16-point QAM ADSL system, with the carrier frequency at 250 kHz, is a potentially viable transport scheme.<>