Systems and methods for characterizing transmission lines using broadband signals in a multi-carrier DSL environment

• US 20020114383A1
• Filed: 08/10/2001
• Published: 08/22/2002
• Est. Priority Date: 08/10/2000
• Status: Abandoned Application

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Inventors: Padir, Halil, Belge, Murat, Tzannes, Michael A.
• Application Number:
  US09/925,509
• Publication Number:
  US 20020114383A1
• Time in Patent Office: Days
• US Class Current: 375/222
• CPC Class Codes: H04B 3/46 Monitoring; Testing
• CPC Class Codes: H04B 3/487 Testing crosstalk effects
• CPC Class Codes: H04L 1/0002 by adapting the transmission rate
• CPC Class Codes: H04L 1/18 Automatic repetition systems, e.g. Van Duuren systems
• CPC Class Codes: H04L 1/24 Testing correct operation
• CPC Class Codes: H04L 1/245 by using the properties of transmission codes
• CPC Class Codes: H04L 25/0202 Channel estimation
• CPC Class Codes: H04L 5/0046 Determination of how many bits are transmitted on different sub-channels
• CPC Class Codes: H04L 5/1438 Negotiation of transmission parameters prior to communication modified according to link quality H04L1/0001
• CPC Class Codes: H04M 3/2209 for lines also used for data transmission
• CPC Class Codes: H04M 3/2227 Quality of service monitoring
• CPC Class Codes: H04M 3/306 for frequencies above the voice frequency, e.g. xDSL line qualification test methods, test equipment and test arrangements for subscriber lines using xDSL modems H04M3/304; systems modifying transmission characteristics according to link quality H04L1/0001; monitoring and/or testing of line transmission systems H04B3/46
• CPC Class Codes: Y02D 30/50 in wire-line communication networks, e.g. low power modes or reduced link rate

Abstract

Using DSL modems as data collectors, the modems processes the data to, for example, allow easier interpretation of the line characteristics. In particular, the modems postprocess the data including calibration, filter compensation, determination of the SNR medley from the bits and gains tables and rate conversion. The interpretation process uses the postprocessed data and determines loop characterization, interferer detection, a data reduction estimation and a data rate estimation. The outputs of these determinations least allow for the characterization of the line conditions between the two modems.

Claims

1. A multicarrier communication line characterization system comprising:

a data postprocessing module; and

a data interpretation module, wherein raw data received from one or more modems via a data collection module is used to determine the characteristics of a communications link.

2. The system of claim 1, wherein the data processing module performs at least one of a calibration, a filter compensation, a determination of the SNR Medley from a bits and gains table and a data rate conversion.

3. The system of claim 1, wherein the data interpretation module performs at least one a loop characterization, a interferer detection, a data reduction estimation and a data rate estimation.

4. The system of claim 1, wherein the communications link is a portion of at least one of a digital subscriber line communications system, a discrete multi-tone communications system or discrete wavelet multi-tone communications system, and the multicarrier communications line characterization system outputs visually displayable data about the communications link based on data obtained from one or more of a CO or CPE modem.

5. A multicarrier communications line characterization system comprising:

a calibrated data determination module, wherein a calibrated data is determined based on a data array, a number of elements in the data array, a programmable gain amplifier setting and a scaling factor.

6. The system of claim 5, wherein the calibrated data is determined in accordance with:

CalibratedData[i]=10*Log₁₀(RawData[i]*2^GScale)−

PGA

wherein CalibratedData[i] is a calibrated data array, RawData[i] is data received from a modem, GScale is a gain scaling and PGA is a programmable gain amplifier setting that was used to collect the data array.

7. A multicarrier communications line characterization system comprising:

a filter compensated data array determination module that determines a filter compensated data array based on a calibrated data array, a frequency domain filter function, and a number of elements in the calibrated data array.

8. The system of claim 7, wherein the frequency domain filter function is based on a device specific frequency domain response of one or more analog front end filters.

9. A multicarrier communications line characterization system comprising:

a filter compensated data array determination module that reduces the effects of one or more of a time domain and a frequency domain equalization filter.

10. The system of claim 9, wherein the filter compensated data array is based on a calibrated data array, one or more time domain equalizer coefficients, one or more frequency domain filter coefficients, and a number of elements in the calibrated data array.

11. A multicarrier communications line characterization system comprising:

a far-end signal to noise ratio table estimator that estimates a far-end signal to noise ratio table based on a far-end bit loading table, a far-end fine gains table, a number of bits in the far-end bit loading table and the far-end fine gains table, a required signal to noise ratio and a margin.

12. The system of claim 11, wherein the margin is based on the amount the signal to noise ratio will be reduced in determining the far-end bit loading table.

14. The system of claim 13, wherein the estimate is determined based on a loop length and bridged tap length that minimizes an error function.

16. The system of claim 15, wherein the minimization is based on varying the power of a disturber and a power of a white noise.

18. The system of claim 17, wherein the estimation module outputs an array containing one or more tone numbers corresponding to a detected AM disturber.

19. The system of claim 17, wherein the estimation module outputs an array containing a power level of a detected AM disturber.

20. The system of claim 17, wherein the estimation module outputs a number representing the number of detected AM disturbers.

22. The system of claim 17, wherein the estimation module outputs an array containing one or more tone numbers corresponding to a detected EMI disturber.

23. The system of claim 17, wherein the estimation module outputs an array containing a power level of a detected EMI disturber.

24. The system of claim 17, wherein the estimation module outputs a number representing the number of detected EMI disturbers.

26. The system of claim 25, wherein the rate estimate is also based on an array containing idle channel noise, an array containing idle channel noise with no crosstalk nor AM/EMI disturbers, a SNR Medley, a margin, a framing mode, a coding gain, a number of the elements in a SNR table and a data rate.

28. The system of claim 27, where the estimation is based on performing a bit loading on a SNR.

30. The method of claim 29, wherein the postprocessing comprises at least one of a calibration, a filter compensation, a determination of the SNR Medley from a bits and gains table and a data rate conversion.

31. The method of claim 29, wherein the data interpretation comprises at least one of a loop characterization, a interferer detection, a data reduction estimation and a data rate estimation.

32. The method of claim 29, wherein the communications link is a portion of at least one of a digital subscriber line communications system, a discrete multi-tone communications system or discrete wavelet multi-tone communications system, and wherein visually displayable data about the communications link based on data obtained from one or more of the CO or the CPE modem is output.

13. A multicarrier communications line characterization system comprising:

a loop length and bridged tap estimation module that determines an estimate of the loop lengths and presence of one or more bridged taps based on an echo waveform a time domain reflectivity waveform and a comparison to a model of a communications channel response.

15. A multicarrier communications line characterization system comprising:

a distrubance estimation module that determines a disturbance on a communications link based on an idle channel noise quantity and a minimization of mean square error.

17. A multicarrier communications line characterization system comprising:

an AM disturber estimation module that determines the presence of one or more AM disturbers based on an array containing channel noise, a second difference of the array and a comparison of one or more carrier frequencies to a threshold.

21. A multicarrier communications line characterization system comprising:

an EMI disturber estimation module that determines the presence of one or more EMI disturbers based on an array containing channel noise, a second difference of the array and a comparison of one or more carrier frequencies to a threshold.

25. A multicarrier communications line characterization system comprising:

a rate degradation estimating module that estimates a rate degradation based on an estimated maximum data rate and a SNR reduction caused by one or more disturbers.

27. A multicarrier communications line characterization system comprising:

a data rate estimation module that estimates a data rate for a communications channel based on a channel attenuation, a noise on an idle channel, a margin, information about a framing mode, a coding gain and a SNR table.

29. A method of characterizing a multicarrier communications link comprising:

postprocessing data received from one or more of a CO and a CPE modem; and

interpreting the data to determine the characteristics of the communications link.

33. A method of characterizing a multicarrier communications link comprising:

calibrating data based on a data array, a number of elements in the data array, a programmable gain amplifier setting and a scaling factor.

34. The method of claim 33, wherein the calibrated data is determined in accordance with:

CalibratedData[i]=10*Log₁₀(RawData[i]*2^Gscale)−

PGA

wherein CalibratedData[i] is a calibrated data array, RawData[i] is data received from a modem, GScale is a gain scaling and PGA is a programmable gain amplifier setting that was used to collect the data array.

36. The method of claim 35, wherein the frequency domain filter function is based on a device specific frequency domain response of one or more analog front end filters.

38. The method of claim 37, wherein the filter compensated data array is based on a calibrated data array, one or more time domain equalizer coefficients, one or more frequency domain filter coefficients, and a number of elements in the calibrated data array.

40. The method of claim 39, wherein the margin is based on the amount the signal to noise ratio will be reduced in determining the far-end bit loading table.

35. A method of characterizing a multicarrier communications link comprising:

determining a filter compensated data array based on a calibrated data array, a frequency domain filter function, and a number of elements in the calibrated data array.

37. A method of characterizing a multicarrier communications link comprising:

determining a filter compensated data array based on reducing the effects of one or more of a time domain and a frequency domain equalization filter.

39. A method of characterizing a multicarrier communications link comprising:

estimating a far-end signal to noise ratio table based on a far-end bit loading table, a far-end fine gains table, a number of bits in the far-end bit loading table and the far-end fine gains table, a required signal to noise ratio and a margin.

41. A method of characterizing a multicarrier communications link comprising:

estimating a loop length and bridged tap based on an echo waveform, a time domain reflectivity waveform and a comparison to a model of a communications channel response.

42. The method of claim 41, wherein the estimate is determined based on a loop length and bridged tap length that minimizes an error function.

43. A method of characterizing a multicarrier communications link comprising:

estimating a disturbance on a communications link based on an idle channel noise quantity and a minimization of a mean square error.

44. The method of claim 43, wherein the minimization is based on varying the power of a disturber and a power of a white noise.

46. The method of claim 45, further comprising outputting an array containing one or more tone numbers corresponding to a detected AM disturber.

47. The method of claim 45, further comprising outputting an array containing a power level of a detected AM disturber.

48. The method of claim 45, further comprising outputting a number representing the number of detected AM disturbers.

50. The method of claim 49, further comprising outputting an array containing one or more tone numbers corresponding to a detected EMI disturber.

51. The method of claim 49, further comprising outputting an array containing a power level of a detected EMI disturber.

52. The method of claim 49, further comprising outputting a number representing the number of detected EMI disturbers.

45. A method of characterizing a multicarrier communications link comprising:

estimating the presence of one or more AM disturbers based on an array containing channel noise, a second difference of the array and a comparison of one or more carrier frequencies to a threshold.

49. A method of characterizing a multicarrier communications link comprising:

estimating a presence of one or more EMI disturbers based on an array containing channel noise, a second difference of the array and a comparison of one or more carrier frequencies to a threshold.

53. A method of characterizing a multicarrier communications link comprising:

estimating a rate degradation based on an estimated maximum data rate and a SNR reduction caused by one or more disturbers.

54. The method of claim 53, wherein the rate estimate is also based on an array containing idle channel noise, an array containing idle channel noise with no crosstalk nor AM/EMI disturbers, a SNR Medley, a margin, a framing mode, a coding gain, a number of the elements in a SNR table and a data rate.

55. A method of characterizing a multicarrier communications link comprising:

estimating a data rate for a communications channel based on a channel attenuation, a noise on an idle channel, a margin, information about a framing mode, a coding gain and a SNR table.

56. The method of claim 55, where the estimation is based on performing a bit loading on a SNR.

57. An information storage media comprising information for characterizing a multicarrier communications link comprising:

information that postprocesses data received from one or more of a CO and a CPE modem; and

information that interprets the data to determine the characteristics of the communications link.