Applicability of ADSL to support video dial tone in the copper loop

An ADSL-3 architecture providing a downstream payload above 6 Mb/s has been proposed for operation over carrier serving area (CSA) loops. To determine whether such a system can be reliably deployed in the telephone company copper loop plant, a detailed model for loops and noise is presented. Results show that a sophisticated system, including echo cancellation and trellis coding, can reliably achieve CSA coverage, if T1 is not present in the plant. In the presence of assumed T1 worst case conditions, either the downstream bit rate must be reduced, or the operating range needs to be decreased to a serving area smaller than the CSA. A smaller "mid-CSA" serving area is proposed, and it is demonstrated that a 6.3-Mb/s ADSL (asymmetric digital subscriber line) system can operate in the presence of T1 in adjacent binder groups over this smaller serving area, which is roughly defined by 6 kilofeet of 26 gauge and 8 kilofeet of 24 gauge. A statistical study utilizing actual T1 line data suggests that if CSA coverage is attempted in the presence of T1 in adjacent binder groups, a success rate of greater than 92 percent can be expected.<
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