Method for testing a component of a vectoring system and line termination equipment configured to carry out said method

Abstract

The invention pertains to a method and apparatus for testing a component of a vectoring system, such as a DSLAM performing crosstalk cancellation. The method is based on the insight that line termination equipment, such as a DSLAM, and in particular the crosstalk canceller, can be used to simulate a multiline network. A signal is exchanged between the line termination equipment and attached network termination equipment, passing through the crosstalk canceller which acts as a multiline simulator. Information indicative of an error component in a received version of the signal is used to assess the operation the vectoring system.

The invention claimed is: 
     
       1. A method for testing a component of a vectoring system, said vectoring system comprising line termination equipment having a crosstalk canceller and network termination equipment attached to said line termination equipment, the method comprising:
 configuring said crosstalk canceller with a first set of crosstalk canceller parameters representing a simulated multi-wireline network, the crosstalk canceller parameters being used to mitigate crosstalk between more than two wirelines within the simulated multi-wireline network; 
 exchanging a first signal between said line termination equipment and said network termination equipment, said first signal being coded by said crosstalk canceller; 
 obtaining at said line termination equipment information indicative of an error component in a received version of said first signal; and 
 using said information to assess the operation of said component in said simulated multi-wireline network, 
 wherein the component of the vectoring system is one of a vectoring function in the line termination equipment and a functionality of the network termination equipment. 
 
     
     
       2. The method of  claim 1 , wherein said using of said information comprises:
 determining at said line termination equipment a second set of crosstalk 
 canceller parameter in function of said information; and 
 verifying whether said second set of crosstalk canceller parameters 
 substantially cancels said first set of crosstalk canceller parameters. 
 
     
     
       3. The method of  claim 2 , wherein said verifying comprises obtaining said second set of crosstalk canceller parameters from said line termination equipment, and ascertaining whether said second set of crosstalk canceller parameters is substantially a matrix-inverse of said first set of crosstalk canceller parameters. 
     
     
       4. The method of  claim 2 , wherein said verifying comprises:
 calculating a third set of crosstalk canceller parameters as a function of said first set of crosstalk canceller parameters and said second set of crosstalk canceller parameters; 
 reconfiguring said crosstalk canceller with said third set of crosstalk canceller parameters; exchanging a second signal between said line termination equipment and said network termination equipment, said second signal being coded by said crosstalk canceller; and 
 detecting an error component of said coded second signal. 
 
     
     
       5. The method of  claim 1 , wherein said crosstalk canceller comprises a precoder, wherein said exchanging of said first signal comprises transmitting said first signal from said line termination equipment to said network termination equipment, and wherein said error component is determined by said network termination equipment. 
     
     
       6. The method of  claim 1 , wherein said crosstalk canceller comprises a postcoder, wherein said exchanging of said first signal comprises transmitting said first signal from said network termination equipment to said line termination equipment, and wherein said error component is determined by said line termination equipment. 
     
     
       7. The method of  claim 1 , wherein
 said line termination equipment has a management interface for performing 
 said configuring, said management interface being adapted to receive an 
 instruction to select said first set of crosstalk canceller parameters from 
 among a group of pre-stored sets of crosstalk canceller parameters. 
 
     
     
       8. The method of  claim 1 , wherein said line termination equipment has a management interface for performing said configuring, said management interface being adapted to receive an instruction specifying attenuation and crosstalk coupling coefficients constituting said first set of crosstalk canceller parameters. 
     
     
       9. A line termination apparatus suitable for testing a component of a vectoring system, said line termination apparatus being connectable to network termination equipment and comprising:
 a crosstalk canceller adapted to be configured with a first set of crosstalk canceller parameters representing a simulated multi-wireline network, the crosstalk canceller parameters being used to mitigate crosstalk between more than two wirelines within the simulated multi-wireline network, wherein said line termination apparatus is configured to:
 exchange a first signal with a line termination equipment, said first signal being coded by said crosstalk canceller; 
 obtain information indicative of an error component in a received version of said first signal; and 
 use said information to assess the operation of said component in said simulated multi-wireline network, 
 wherein the component of the vectoring system is one of a vectoring function in the line termination equipment and a functionality of the network termination equipment. 
 
 
     
     
       10. The line termination apparatus of  claim 9 , configured to determine a second set of crosstalk canceller parameters in function of said information and to verify whether said second set of crosstalk canceller parameters substantially cancels said first set of crosstalk canceller parameters. 
     
     
       11. The line termination apparatus of  claim 10 , configured to ascertain whether said second set of crosstalk canceller parameters is substantially a matrix-inverse of said first set of crosstalk canceller parameters. 
     
     
       12. The line termination apparatus of  claim 10 , wherein said crosstalk canceller is further adapted to be reconfigured with a third set of crosstalk canceller parameters, said line termination apparatus being further configured to:
 calculate said third set of crosstalk canceller parameters as a function of said first set of crosstalk canceller parameters and said second set of crosstalk canceller parameters; 
 reconfigure said crosstalk canceller with said third set of crosstalk canceller parameters; 
 exchange a second signal with said line termination equipment, said second signal being coded by said crosstalk canceller; and 
 obtain a detected error component of said coded second signal. 
 
     
     
       13. The line termination apparatus of  claim 9 , wherein said crosstalk canceller comprises a precoder, wherein said line termination equipment is configured to exchange said first signal by transmitting said first signal to said network termination equipment, and to obtain said information from said network termination equipment. 
     
     
       14. The line termination apparatus of  claim 9 , wherein said crosstalk canceller comprises a postcoder, wherein said line termination apparatus is configured to exchange said first signal by receiving said first signal from said network termination equipment, and to obtain said information by analyzing said received version of said first signal. 
     
     
       15. The line termination apparatus of  claim 9 , further comprising a management interface adapted to receive an instruction to select said first set of crosstalk canceller parameters from among a group of pre-stored sets of crosstalk canceller parameters. 
     
     
       16. The line termination apparatus of  claim 9 , further comprising a management interface adapted to receive an instruction specifying attenuation and crosstalk coupling coefficients constituting said first set of crosstalk canceller parameters. 
     
     
       17. A program stored on non-transitory memory for a processor of a piece of line termination equipment having a crosstalk canceller, the program comprising instructions to carry out the method of  claim 1 .