Systems, methods and computer program products for identifying digital impairments in modem signals

• US 6,650,657 B1
• Filed: 10/29/1999
• Issued: 11/18/2003
• Est. Priority Date: 10/29/1999
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Ye, Hua, Ware, Malcolm Scott, Neeser, Fredy D., Dholakia, Ajay, Davis, Gordon Taylor, Hwang, Dongming, Abdelilah, Youssef
• Primary Examiner(s): Patel, Ajit
• Assistant Examiner(s): SHAH, CHIRAG G
• Application Number:
  US09/429,859
• Time in Patent Office: 1,481 Days
• Field of Search: 370/522, 370/523, 370/465, 370/474, 370/476, 375/222, 375/356, 375/377
• US Class Current: 370/474
• CPC Class Codes: H04J 3/125 One of the channel pulses or the synchronisation pulse is also used for transmitting monitoring or supervisory signals

Abstract

Robbed Bit Signaling (RBS) and PAD digital impairments in sets of Digital Impairment Learning (DIL) signals that are repeatedly transmitted from a server modem to a client modem during DIL intervals are identified by identifying a PAD level for the sets of DIL signals in the DIL intervals and then identifying an RBS type for individual sets of DIL signals based upon the PAD levels so identified. The PAD level may be identified using model DIL signals that correspond to PAD levels that are not subject to RBS. The RBS type may be identified using model DIL signals that correspond to multiple RBS types that are subject to the identified PAD level. More specifically, one of the DIL intervals that contains DIL signals that are not subject to RBS is identified. A PAD level for the DIL signals in the one of the DIL intervals so identified then is determined. The PAD level that was determined is applied to the DIL signals in remaining ones of the DIL intervals, to identify an RBS for the DIL signals in the remaining ones of the DIL intervals.

Claims

1. A method of identifying Robbed Bit Signaling (RBS) and PAD digital impairments in a plurality of sets of Digital Impairment Learning (DIL) signals that are repeatedly transmitted from a server modem to a client modem during a corresponding plurality of DIL intervals, the method comprising the steps of:

identifying one of the DIL intervals that contains DIL signals that are not subject to RBS;

determining a PAD level for the DIL signals in the one of the DIL intervals so identified; and

applying the PAD level so determined to the DIL signals in remaining ones of the DIL intervals, to identify an RBS type for the DIL signals in the remaining ones of the DIL intervals.

2. A method according to claim 1 wherein the step of identifying comprises the steps of:

obtaining a plurality of sets of model DIL signals that correspond to a plurality of PAD levels that are not subject to RBS;

comparing the sets of DIL signals in the plurality of DIL intervals to the plurality of sets of model DIL signals; and

selecting one of the DIL intervals in the plurality of DIL intervals, based on results of the step of comparing, to thereby identify one of the DIL intervals that contains DIL signals that are not subject to RBS.

3. A method according to claim 2 wherein the step of comparing comprises the step of computing a sum of squares of differences between the sets of DIL signals in the plurality of DIL intervals and the plurality of sets of model DIL signals.

4. A method according to claim 2 wherein the step of selecting comprises the step of selecting one of the DIL intervals in the plurality of DIL intervals that contains the DIL signals that most closely match one of the sets of model DIL signals.

5. A method according to claim 1 wherein the step of determining a PAD level comprises the steps of:

obtaining a plurality of sets of model DIL signals that correspond to a plurality of PAD levels that are not subject to RBS;

comparing the DIL signals in the one of the DIL intervals so identified to the plurality of sets of model DIL signals; and

selecting one of the plurality of sets of model DIL signals based on results of the step of comparing, to thereby determine a PAD level for the DIL signals in the one of the DIL intervals so identified.

6. A method according to claim 5 wherein the step of comparing comprises the step of computing a sum of squares of differences between the model DIL signals.

7. A method according to claim 5 wherein the step of selecting comprises the step of selecting one of the plurality of sets of model DIL signals that most closely matches the DIL signals in the one of the DIL intervals so identified.

8. A method according to claim 5 wherein the plurality of sets of model DIL signals are scaled to account for equalizer training in the presence of the corresponding PAD level.

9. A method according to claim 1 wherein the step of applying comprises the steps of:

obtaining a plurality of sets of model DIL signals that correspond to a plurality of RBS types for the PAD so determined;

comparing the DIL signals in the remaining ones of the DIL intervals to the plurality of sets of model DIL signals; and

for each of the remaining ones of the DIL intervals, selecting one of the plurality of sets of model DIL signals, based on results of the step of comparing, to thereby identify an RBS type for the DIL signals in the remaining ones of the DIL intervals.

10. A method according to claim 9 wherein the step of comparing comprises the step of computing a sum of squares of differences between the DIL signals in the remaining ones of the DIL intervals and the plurality of sets of model DIL signals.

12. A method according to claim 9 wherein the plurality of sets of model DIL are scaled to account for equalizer training in the presence of the PAD so determined.

13. A method according to claim 1 wherein the following step is performed if the applying step identifies one of the remaining ones of the DIL intervals as not subject to RBS:

comparing the DIL signals in the one of the DIL intervals to the DIL signals in the one of the remaining ones of the DIL intervals.

14. A method according to claim 1 wherein the steps of identifying, determining and applying are performed only on selected ones of the DIL signals in the DIL intervals.

11. A method according to clam 9 wherein the step of selecting comprises the step of selecting one of the plurality of sets of model DIL signals that most closely matches the DIL signals in the remaining one of the DIL intervals.

15. A method of identifying Robbed Bit Signaling (RBS) and PAD digital impairments in a plurality of sets of Digital Impairment Leaning (DIL) signals that are repeatedly transmitted from a server modem to a client modem during a corresponding plurality of DIL intervals, the method comprising the steps of:

generating the models of DIL signals having combinations of RBS types and PAD levels;

computing sums of squares of differences between selected ones of the DIL signals in the plurality of sets and model DIL signals having combinations of RBS types and PAD levels; and

for each DIL interval, selecting a model that matches the selected DIL signals in the DIL interval to thereby identify RBS and PAD impairments for each DIL interval.

16. A method of identifying Robbed Bit Signaling (RBS) and PAD digital impairments in a plurality of sets of Digital Impairment Leaning (DIL) signals that are repeatedly transmitted from a server modem to a client modem during a corresponding plurality of DIL intervals, the method comprising the steps of:

responsive to a plurality of model DIL signals that correspond to a plurality of PAD levels that are not subject to RBS;

identifying a PAD level for the plurality of sets of DIL signals in the plurality of DIL intervals; and

responsive to a plurality of model DIL signals that correspond to a plurality of RBS types that are subject to the PAD level so identified; and

identifying an RBS type for individual sets of DIL signals, based upon the PAD level so identified.

17. A modem comprising:

means for receiving a plurality of sets of Digital Impairment Learning (DIL) signals from a server modem during a corresponding plurality of DIL intervals;

means for identifying one of the DIL intervals that contains DIL signals that are not subject to Robbed Bit Signaling (RBS) digital impairments;

means for determining a Packet Assenbler/Disassembler (PAD) level digital impairment for the DIL signals in the one of the DIL intervals so identified; and

means for applying the PAD level so determined to the DIL signals in remaining ones of the DIL intervals, to identify an RBS type for the DIL signals in the remaining ones of the DIL intervals.

18. A modem according to claim 17 wherein the means for identifying comprises:

means for obtaining a plurality of sets of model DIL signals that correspond to a plurality of PAD levels that are not subject to RBS;

means for comparing the sets of DIL signals in the plurality of DIL intervals to the plurality of sets of model DIL signals; and

means for selecting one of the DIL intervals in the plurality of DIL intervals, in response to the means for comparing, to thereby identify one of the DIL intervals that contains DIL signals that are not subject to RBS.

19. A modem according to claim 17 wherein the means for comparing comprises means for computing a sum of squares of differences between the sets of DIL signals in the plurality of DIL intervals and the plurality of sets of model DIL signals.

20. A modem according to claim 17 wherein the means for selecting comprises means for selecting one of the DIL intervals in the plurality of DIL intervals that contains the DIL signals that most closely match one of the sets of model DIL signals.

21. A modem according to claim 17 wherein the means for determining a PAD level comprises:

means for obtaining a plurality of sets of model DIL signals that correspond to a plurality of PAD levels that are not subject to RBS;

means for comparing the DIL signals in the one of the DIL intervals so identified to the plurality of sets of model DIL signals; and

means for selecting one of the plurality of sets of model DIL signals in response to the means for comparing, to thereby determine a PAD level for the DIL signals in the one of the DIL intervals so identified.

22. A modem according to claim 21 wherein the means for comparing comprises means for computing a sum of squares of differences between the model DIL signals.

23. A modem according to claim 21 wherein the means for selecting comprises means for selecting one of the plurality of sets of model DIL signals that most closely matches the DIL signals in the one of the DIL intervals so identified.

24. A modem according to claim 21 wherein the plurality of sets of model DIL signals are scaled to account for equalizer training in the presence of the corresponding PAD level.

25. A modem according to claim 17 wherein the means for applying comprises:

means for obtaining a plurality of sets of model DIL signals that correspond to a plurality of RBS types for the PAD so determined;

means for comparing the DIL signals in the remaining ones of the DIL intervals to the plurality of sets of model DIL signals; and

means for selecting one of the plurality of sets of model DIL signals for each of the remaining ones of the DIL intervals, in response to the means for comparing, to thereby identify an RBS type for the DIL signals in the remaining ones of the DIL intervals.

26. A modem according to claim 25 wherein the means for comparing comprises means for computing a sum of squares of differences between the DIL signals in the remaining ones of the DIL intervals and the plurality of sets of model DIL signals.

27. A modern according to claim 25 wherein the means for selecting comprises means for selecting one of the plurality of sets of model DIL signals that most closely matches the DIL signals in the remaining one of the DIL intervals.

28. A modem according to claim 25 wherein the plurality of sets of model DIL are scaled to account for equalizer training in the presence of the PAD so determined.

29. A modem according to claim 17 further comprising:

means for comparing the DIL signals in the one of the DIL intervals to the DIL signals in the one of the remaining ones of the DIL intervals in response to the means for applying identifying one of the remaining ones of the DIL intervals as not subject to RBS.

30. A modem according to claim 17 wherein the means for identifying, determining and applying are responsive to only selected ones of the DIL signals in the DIL intervals.

31. A modem comprising:

means for receiving a plurality of sets of Digital Impairment Learning (DIL) signals from a server modem during a corresponding plurality of DIL intervals;

means for generating the models of DIL signals having combinations of RBS types and PAD levels; and

means for computing sums of squares of differences between selected ones of the DIL signals in the plurality of sets and said generated model DIL signals; and

means for selecting a model that matches the selected DIL signals for each DIL interval to thereby identify RBS and PAD impairments for each DIL interval.

32. A modem comprising:

means for receiving a plurality of sets of Digital Impairment Learning (DIL) signals from a server modem during a corresponding plurality of DIL intervals;

means responsive to a plurality of model DIL signals that correspond to a plurality of PAD levels that are not subject to RBS, said means for identifying a PAD level for selected ones of the plurality of sets of DIL signals in the plurality of DIL intervals; and

means responsive to a plurality of model DIL signals that corresponds to a plurality of RBS types that are not subject to the identified PAD level, said means for identifying an RBS type for the selected sets of DIL signals, based upon the identified PAD level.

33. A computer program product for identifying Robbed Bit Signaling (RBS) and PAD digital impairments in a plurality of sets of Digital Impairment Learning (DIL) signals that are repeatedly transmitted from a server modem to a client modem during a corresponding plurality of DIL intervals, the computer program product comprising a computer-readable storage medium having computer-readable program code embodied in the medium, the computer-readable program code comprising:

computer-readable program code for identifying one of the DIL intervals that contains DIL signals that are not subject to RBS;

computer-readable program code for determining a PAD level for the DIL signals in the one of the DIL intervals so identified; and

computer-readable program code for applying the PAD level so determined to the DIL signals in remaining ones of the DIL intervals, to identify an RBS type for the DIL signals in the remaining ones of the DIL intervals.

34. A computer program product according to claim 33 wherein the computer-readable program code for identifying comprises the steps of:

computer-readable program code for obtaining a plurality of sets of model DIL signals that correspond to a plurality of PAD levels that are not subject to RBS;

computer-readable program code for comparing the sets of DIL signals in the plurality of DIL intervals to the plurality of sets of model DIL signals; and

computer-readable program code for selecting one of the DIL intervals in the plurality of DIL intervals, based on results of the computer-readable program code for comparing, to thereby identify one of the DIL intervals that contains DIL signals that are not subject to RBS.

35. A computer program product according to claim 34 wherein the computer-readable program code for comparing comprises computer-readable program code for computing a sum of squares of differences between the sets of DIL signals in the plurality of DIL intervals and the plurality of sets of model DIL signals.

36. A computer program product according to claim 34 wherein the computer-readable program code for selecting comprises computer-readable program code for selecting one of the DIL intervals in the plurality of DIL intervals that contains the DIL signals that most closely match one of the sets of model DIL signals.

37. A computer program product according to claim 33 wherein the computer-readable program code for determining a PAD level comprises:

computer-readable program code for obtaining a plurality of sets of model DIL signals that correspond to a plurality of PAD levels that arc not subject to RBS;

computer-readable program code for comparing the DIL signals in the one of the DIL intervals so identified to the plurality of sets of model DIL signals; and

computer-readable program code for selecting one of the plurality of sets of model DIL signals based on results of the computer-readable program code for comparing, to thereby determine a PAD level for the DIL signals in the one of the DIL intervals so identified.

38. A computer program product according to claim 37 wherein the computer-readable program code for comparing comprises computer-readable programcode for computing a sum of squares of differences between the model DIL signals.

39. A computer program product according to claim 37 wherein the computer-readable program code for selecting comprises computer-readable program code for selecting one of the plurality of sets of model DIL signals that most closely matches the DIL signals in the one of the DIL intervals so identified.

40. A computer program product according to claim 37 wherein the plurality of sets of model DIL signals are scaled to account for equalizer training in the presence of the corresponding PAD level.

41. A computer program product according to claim 33 wherein the computer-readable program code for applying comprises;

computer-readable program code for obtaining a plurality of sets of model DIL signals that correspond to a plurality of RBS types for the PAD so determined;

computer-readable program code for comparing the DIL signals in the remaining ones of the DIL intervals to the plurality of sets of model DIL signals; and

computer-readable program code for selecting one of the plurality of sets of model DIL signals for each of the remaining ones of the DIL intervals, based on results of the computer-readable program code for comparing, to thereby identify an RBS type for the DIL signals in the remaining ones of the DIL intervals.

42. A computer program product according to claim 41 wherein the computer-readable program code for comparing comprises computer-readable program code for computing a sum of squares of differences between the DIL signals in the remaining ones of the DIL intervals and the plurality of sets of model DIL signals.

43. A computer program product according to claim 41 wherein the computer-readable program code for selecting comprises computer-readable program code for selecting one of the plurality of sets of model DIL signals that most closely matches the DIL signals in the remaining one of the DIL intervals.

44. A computer program product according to claim 41 wherein the plurality of sets of mode DIL are scaled to account for equalizer training in the presence of the PAD so determined.

45. A computer program product according to claim 33 further comprising;

computer-readable program code for comparing the DIL signals in the one of the DIL intervals to the DIL signals in the one of the remaining ones of the DIL intervals in response to the computer-readable program code for identifying one of the remaining ones of the DIL intervals as not subject to RBS.

46. A computer program product according to claim 33 wherein the computer-readable program code for identifying, determining and applying only are responsive to selected ones of the DIL signals in the DIL intervals.

47. A computer program product for identifying Robbed Bit Signaling (RBS) and PAD digital impairments in a plurality of sets of Digital Impairment Learning (DIL) signals that are repeatedly transmitted from a server modem to a client modem during a corresponding plurality of DIL intervals, the computer program product comprising a computer-readable storage medium having computer-readable program code embodied in the medium, the computer-readable program code comprising:

computer-readable program code for generating models of DIL signals having combinations of RBS types and PAD levels; and

computer-readable program code for computing sums of squares of differences between selected ones of the DIL signals in the plurality of sets and the generated mode DIL signals having; and

computer-readable program code for selecting a model that matches the selected DIL signals for each DIL interval to thereby identify RBS and PAD impairments for each DIL interval.