Method and apparatus for determining a transmit PSD at a remote location
The present invention relates to a method for determining a transmit PSD over a remotely-deployed line, which method comprising the steps of: modeling a first far-end crosstalk originating from the line and coupling into a centrally-deployed victim neighboring line, modeling a second far-end crosstalk originating from a further centrally-deployed neighboring line and coupling into the victim neighboring line, determining the transmit PSD from the first modeled far-end crosstalk and the second modeled far-end crosstalk. A method according to the invention further comprises the steps of: expressing the transmit PSD as a function of a line parameter characterizing a line segment of the further neighboring line, carrying out channel measurements of a spare line that connects the central location to the remote location, and that shares common transmission characteristics with the line segment, estimating from said channel measurements a value of the line parameter, determining therefrom the transmit PSD. The present invention also relates to a power control unit.
1. A method for determining a transmit power spectral density to be applied at a remote location over at least one line connecting said remote location to at least a first customer location, by using a power control unit including a computing portion, a measurement portion, and an estimating portion, said method comprising:
modeling, by the computing portion, a first far-end crosstalk originating from said at least one line and coupling into a victim neighboring line as a first modeled far-end crosstalk, said victim neighboring line connecting a central location through said remote location to a second neighboring customer location,
modeling, by the computing portion, a second far-end crosstalk originating from at least one additional neighboring line and coupling into said victim neighboring line as a second modeled far-end crosstalk, said additional neighboring line connecting said central location through said remote location to at least a third neighboring customer location,
determining, by the computing portion, by using a mathematical derivation, said transmit power spectral density from said first modeled far-end crosstalk and said second modeled far-end crosstalk,
expressing, by the computing portion, as part of said mathematical derivation, said transmit power spectral density as a function of a line parameter said line parameter characterizing a line segment of said additional neighboring line spanning from said central location to said remote location;
carrying out, by the measurement portion, channel measurements of a spare line that connects said central location to said remote location, said spare line and said line segment share common transmission characteristics,
estimating, by the estimation portion, from said channel measurements a value of said line parameter, and
determining, by the computing portion, said transmit power spectral density from said value of said line parameter.
2. A method according to claim 1 , wherein said channel measurements are obtained by using time-domain reflectometry.
3. A method according to claim 1 , wherein said channel measurements are obtained by initializing a communication path over said spare line between a first transceiver unit and a second transceiver unit.
4. A method according to claim 1 , wherein said channel measurements comprise measurements of a response signal, and said response signal Is a response to a preliminary-known excitation signal that propagates through said spare line.
5. A method according to claim 1 , wherein said line parameter is a length.
6. A method according to claim 1 , wherein said line parameter is a loop insertion gain magnitude.
7. A power control unit configured to determine a transmit power spectral density to be applied at a remote location over at least one line connecting said remote location to at least a first customer location, wherein the power control unit comprises:
a computing portion configured to determine, by a mathematical derivation, said transmit power spectral density from a first modeled far-end crosstalk and a second modeled far-end crosstalk,
said first modeled far-end crosstalk representing a first far-end crosstalk originating from said at least a first line and coupling into a victim neighboring line,
said victim neighboring line connecting a central location through said remote location to a second neighboring customer location,
said second modeled far-end crosstalk representing a second far-end crosstalk originating from at least a second neighboring line and coupling into said victim neighboring line,
said second neighboring line connecting said central location through said remote location to at least a third neighboring customer location,
said computing portion being further configured to express, as part of said mathematical derivation, said transmit power spectral density as a function of a line parameter, said line parameter characterizing a line segment of the second neighboring line spanning from said central location to said remote location,
a measurement portion configured to carry out channel measurements of a spare line than connects said central location to said remote location, said spare line and said line segment sharing common transmission characteristics, and
an estimation portion coupled to said measurement portion, and configured to estimate a value of said line parameter from said channel measurements.