Method of optimizing bit rate capacities of DSL user lines

A method of optimizing the bit rate capacities ( R u ) of DSL user lines ( u ) subject to far-end crosstalk by adjusting the transmit power spectral densities ( P u ) at the far ends of the user lines by means of parameterized power back-off functions ( P u,R ) is characterized by the steps of: a) selecting a desired bit rate share ( p u ) for each user line ( u ), b) measuring the noise and losses N u n ¢ H u ¢ u n on each user line ( u ), and c) determining an individual set of power back-off parameters (± u , ² u ) for each user line ( u ) by calculating a global sum ˆ‘ u = 1 U R u of the bit rates of all user lines and iterating the power back-off parameters (± u , ² u ) until a maximum value of the global sum ˆ‘ u = 1 U R u is found under the constraint that the desired bit rate shares ( p u ) are met.