Method for performing subscriber loop disturber recognition by comparing measured sample power spectral densities with a set of known power spectral densities

• US 6,760,847 B1
• Filed: 04/13/2000
• Issued: 07/06/2004
• Est. Priority Date: 04/13/2000
• Status: Expired due to Fees

• Current Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Stone, Gary T., Campbell, Michael A., Yao, Liqian, Liu, Gin
• Primary Examiner(s): Lee, Thomas
• Assistant Examiner(s): YANCHUS III, PAUL B
• Application Number:
  US09/548,746
• Time in Patent Office: 1,545 Days
• Field of Search: 713/300, 713/340, 375/222, 375/296, 379/417, 341/58
• US Class Current: 713/300
• CPC Class Codes: H04L 1/0002 by adapting the transmission rate
• CPC Class Codes: H04L 1/20 using signal quality detector
• CPC Class Codes: H04M 3/18 with means for reducing interference or noise; with means for reducing effects due to line faults with means for protecting lines
• CPC Class Codes: H04M 3/30 for subscriber's lines , for the local loop
• CPC Class Codes: H04M 3/34 Testing for cross-talk

Abstract

To identify interference from other data carrying subscriber loops (i.e., from loop disturbers), a power spectral density sample may be obtained from the subscriber loop under consideration based on at least one measurement while the loop is not transmitting data. The sample power spectral density may then be correlated with each one of a set of known power spectral densities. Each known power spectral density represents a power spectral density in a loop which is not transmitting data in the presence of one of (i) no subscriber loop disturbers, (ii) a particular subscriber loop disturber, and (iii) particular subscriber loop disturbers. Based on the correlations, subscriber loop disturbers may be recognized.

Claims

1. A method of subscriber loop disturber recognition, comprising:

receiving a sample power spectral density of said subscriber loop based on at least one measurement obtained while said subscriber loop is not transmitting data;

at each of a plurality of frequencies, comparing an amplitude of said sample power spectral density with a threshold;

based on said comparing, selecting from a universe of known power spectral densities a set of one or more known power spectral densities, each known power spectral density in said set being representative of a power spectral density in a loop which is not transmitting data and is in the presence of one of (i) no subscriber loop disturbers, (ii) a particular subscriber loop disturber, and (iii) particular subscriber loop disturbers;

correlating said sample power spectral density with each one of said set of known power spectral densities; and

based on said correlating, determining present subscriber loop disturbers.

2. The method of claim 1 further comprising:

prior to said receiving, obtaining at least one power spectral density measurement from said subscriber loop while said subscriber loop is not transmitting data.

3. A method of subscriber loop disturber recognition, comprising:

receiving a sample power spectral density of said subscriber loop based on at least one measurement obtained while said subscriber loop is not transmitting data;

at each of a plurality of frequency bands, comparing a measure of power of said measured power spectral density with a threshold;

based on said comparing, selecting from a database of known power spectral densities a set of one or more known power spectral densities, each known power spectral density in said set being representative of a power spectral density in a loop which is not transmitting data and is in the presence of one of (i) no subscriber loop disturbers, (ii) a particular subscriber loop disturber, and (iii) particular subscriber loop disturbers;

correlating said sample power spectral density with each one of said set of known power spectral densities; and

based on said correlating, determining present subscriber loop disturbers.

4. The method of claim 3 wherein said measure is average power density over each of said frequency bands.

5. The method of claim 4 further comprising:

prior to said receiving, obtaining a plurality of power spectral density measurements from said subscriber loop while said subscriber loop is not transmitting data;

determining a measure of power in each of said power spectral density measurements,

identifying a power spectral density measurement having a largest measure of power;

determining, as said sample power spectral density, an average power spectral density based on each of said power spectral density measurements save said identified power spectral density measurement.

6. Apparatus for subscriber loop disturber recognition, comprising:

means for receiving a sample power spectral density of said subscriber loop based on at least one measurement obtained while said subscriber loop is not transmitting data;

means for comparing a measure of power of said sample power spectral density with a threshold at each of a plurality of frequency bands;

means for selecting based on said comparing a set of one or more known power spectral densities from a database of known power spectral densities, each known power spectral density in said set being representative of a power spectral density in a loop which is not transmitting data and is in the presence of one of (i) no subscriber loop disturbers, (ii) a particular subscriber loop disturber, and (iii) particular subscriber loop disturbers;

means for correlating said sample power spectral density with each one of said set of known power spectral densities; and

means for, based on said correlating, determining present subscriber loop disturbers.

7. A computer readable medium storing computer executable instructions that when loaded by a computing device, adapt said computing device to:

receive a sample power spectral density of said subscriber loop based on at least one measurement obtained while said subscriber loop is not transmitting data;

at each of a plurality of frequency bands, compare a measure of power of said sample power spectral density with a threshold;

based on said comparing, select from a database of known power spectral densities said a set of one or more known power spectral densities, each known power spectral density in said set being representative of a power spectral density in a loop which is not transmitting data and is in the presence of one of (i) no subscriber loop disturbers, (ii) a particular subscriber loop disturber, and (iii) particular subscriber loop disturbers from a universe of known power spectral densities;

correlate said sample power spectral density with each one of said set of known power spectral densities; and

based on said correlating, determine present subscriber loop disturbers.

8. A memory storing information for use by a computing device in the determination of present subscriber line disturbers, comprising:

a first data structure stored in said memory, said first data structure comprising power spectral density patters for different loop disturber types singly and in combinations; and

a second data structure stored in said memory, said second data structure comprising frequency band indications and associated threshold values for said different loop disturber types.

9. The memory of claim 8 wherein said first data structure further comprises correlation threshold values associated with each of said power spectral density patterns.

10. The memory of claim 9 wherein said first data structure further comprises a power spectral density pattern for a loop in the presence of no disturbers.

11. A method of subscriber loop disturber recognition, comprising:

receiving a sample power spectral density of said subscriber loop based on at least one measurement obtained while said subscriber loop is not transmitting data;

at each of a plurality of frequency bands, comparing an amplitude of said sample power spectral density with a threshold;

based on said comparing, determining present subscriber loop disturbers.

12. The method of claim 11 wherein said comparing and said determining comprises accessing records, each associating a frequency band with a threshold and a disturber type.

13. A method of subscriber loop disturber recognition, comprising:

receiving a sample power spectral density (PSD) of said subscriber loop based on at least one measurement obtained while said subscriber loop is not transmitting data;

determining a set of candidate disturber types based on a measure of power of said sample PSD;

selecting from a universe of known PSD patterns a set of one or more known PSD patterns, each PSD pattern in said set being representative of a PSD in a loop which is not transmitting data and is in the presence of one or more disturbers of any of said candidate disturber types;

correlating said sample PSD with each of said PSD patterns in said set; and

based on said correlating, determining present subscriber loop disturbers.

14. The method of claim 13, wherein said determining a set of candidate disturber types based on a measure of power of said sample PSD comprises:

for each known disturber type;

in a frequency band encompassing a peak frequency for said known disturber type, comparing said measure of power of said sample PSD with a threshold associated with said known disturber type; and

based on said comparing, adding said known disturber type to said set of candidate disturber types.

15. The method of claim 14, wherein said known disturber type is added to said set of candidate disturber types when said measure of power exceeds said threshold.

16. The method of claim 14, wherein said threshold is a power value less than an average power for said known disturber type in said frequency band.

17. The method of claim 13, wherein said measure of power comprises an amplitude.

18. The method of claim 13, wherein said measure of power comprises an average power density.

19. The method of claim 18, wherein said average power density is computed from a plurality of PSD measurements obtained from said subscriber loop while said subscriber loop is not transmitting data.

20. The method of claim 19, wherein said average power density computation excludes a largest measured PSD of said plurality of PSD measurements.

21. The method of claim 13, wherein each PSD pattern in said set of known PSD patterns stores a maximum number N of different candidate disturber types, where N is an integer greater than one and less that the total number of different candidate disturber types.