DETERMINING DOWNSTREAM POWER BACK-OFF PARAMETERS

Methods, systems, and apparatus for determining values of downstream power back-off parameters are disclosed. In one aspect, a method includes receiving cable loss data of a cable configured to deliver a digital subscriber line (DSL) signal; identifying a cable model that characterizes a cable loss value at a frequency over a length of the cable; and determining a set of downstream power back-off (DPBO) parameter values of the cable model based on a product of a pseudo-inverse of a frequency matrix including a plurality of different frequencies and a vector of the cable loss data that includes a plurality of cable loss values with respect to the plurality of different frequencies of the pseudo-inverse of the frequency matrix.