SYSTEMS AND METHODS FOR MONITORING IMPULSE NOISE

• US 20090252234A1
• Filed: 04/07/2008
• Published: 10/08/2009
• Est. Priority Date: 04/07/2008
• Status: Active Grant

• Current Assignee: Ikanos Communications Incorporated (Qualcomm, Inc.)
• Original Assignee: Conexant Systems Incorporated (Synaptics Incorporated)
• Inventors: Mahadevan, Amitkumar, Garg, Rahul, Duvaut, Patrick, Levonas, Robin, Samdani, Hemant, Raheja, Kunal, Day, Robert A.
• Granted Patent: US 7,978,756 B2
• Time in Patent Office: Days
• US Class Current: 375/254
• CPC Class Codes: H04B 3/487 Testing crosstalk effects
• CPC Class Codes: H04L 27/2647 Arrangements specific to the receiver only equalisation H04L27/01

Abstract

Systems and methods for monitoring impulse noise are described. At least one embodiment is a method, which comprises detecting whether impulse noise is present and in response to detecting the presence of impulse noise, performing time domain analysis to determine whether one or more impulse noise sources are present based on minimum interarrival time and maximum impulse length. The method further includes performing frequency domain analysis to estimate frequencies associated with the one or more impulse noise sources and based on the time domain analysis and frequency domain analysis, providing a total number of impulse noise sources and frequencies associated with the impulse noise sources. In this regard, the embodiments described herein provide dual-speed monitoring of impulse noise in the form of short-term and long-term monitoring. The use of dual-speed monitoring ensures that dynamic changes in the impulse noise environment are quickly addressed and also ensures better characterization of multiple impulse noise sources in order to provide better impulse noise protection.

Claims

1. A method comprising:

detecting whether impulse noise is present;

in response to detecting the presence of impulse noise, performing time domain analysis;

performing frequency domain analysis to estimate frequencies associated with the one or more impulse noise sources; and

based on the time domain analysis and frequency domain analysis, providing a total number of impulse noise sources and frequencies associated with the impulse noise sources.

2. The method of claim 1, further comprising:

in response to detecting the presence of impulse noise, suspending updates to one or more of the following;

frequency domain equalizers (FEQ), bit swapping, and seamless rate adaptation (SRA).

3. The method of claim 2, wherein suspending updates is performed for a predetermined period of time.

4. The method of claim 3, further comprising re-enabling updates to the FEQ and re-enabling bit swapping and SRA once the pre-determined period of time has passed, wherein the pre-determined period of time is an estimated impulse noise duration plus a guard time.

5. The method of claim 1, wherein performing time domain analysis further comprises performing at least one of:

generating statistical data based on interarrival time and impulse length;

estimating a lowest interarrival time of one or more impulse noise sources based on the statistical data;

estimating a highest length of the one or more impulse noise sources based on the statistical data; and

indicating whether one or more impulse noise sources are present.

6. The method of claim 1, wherein performing time domain analysis further comprises:

in response to determining that a single impulse noise source exists, estimating a frequency of the single impulse noise source.

7. The method of claim 1, wherein the time domain analysis is performed based on a first predetermined block size and wherein the frequency domain analysis is performed based on a second predetermined block size.

8. The method of claim 7, wherein the first predetermined block size is less than the second predetermined block size.

9. The method of claim 1, wherein performing frequency domain analysis comprises:

defining a range of frequencies in which to search for impulse noise sources;

dividing the range of frequencies into a plurality of observation windows;

calculating an FFT peridogram across all the observation windows;

identifying frequencies of impulse noise sources;

performing a multi-level threshold consistency check for each identified frequency based on the FFT periodogram across all the observation windows, wherein the consistency check is performed to verify each identified frequency of impulse noise sources; and

performing spectral subtraction after the each identified frequency is verified to identify a next impulse noise source.

10. A method comprising:

detecting whether impulse noise is present and generating an impulse noise pattern;

receiving the impulse noise pattern;

performing time domain analysis to determine whether one or more impulse noise sources are present;

performing frequency domain analysis to estimate frequencies associated with the one or more impulse noise sources; and

combining the time domain analysis and frequency domain analysis to provide a total number of impulse noise sources and frequencies associated with the impulse noise sources.

11. The method of claim 10, wherein the time domain analysis is performed based on a first predetermined block size, wherein the frequency domain analysis is performed based on a second predetermined block size, and wherein the first predetermined block size is less than the second predetermined block size.

12. The method of claim 10, further comprising:

in response to detecting the presence of impulse noise, suspending updates to a frequency domain equalizer (FEQ) and suspending bit swapping and seamless rate adaptation (SRA) to avoid bit errors.

13. A system comprising:

an impulse noise detector for detecting the presence of impulse noise; and

a time domain analysis module configured to receive the detected impulse noise and perform analysis in the time domain to indicate whether one or more impulse noise sources are present.

14. The system of claim 13, wherein the time domain analysis module is further configured to determine at least one of:

an estimate of lowest interarrival time among the one or more impulse noise sources;

a highest length of impulse noise among the one or more impulse noise sources; and

an indication of whether one or more impulse noise sources are present.

15. A system of claim 14, wherein upon determining that a single impulse noise source exists, the time domain analysis module is further configured to estimate a frequency of the single impulse noise source.

16. A system of claim 14, wherein the time domain analysis module determines the estimate of lowest interarrival time and the highest length of impulse noise by analyzing statistics relating to interarrival time and statistics relating to impulse length.

17. The system of claim 13, further comprising:

a frequency domain analysis module configured to perform analysis in the frequency domain to determine frequencies associated with the one or more impulse noise sources;

an intelligence module configured to receive information from the time domain analysis module and the frequency domain analysis module, wherein the intelligence module is configured to determine the number of impulse noise sources and frequencies of the impulse noise sources; and

a protection module for avoiding bit errors upon detection of impulse noise.

18. The system of claim 17, wherein the frequency domain analysis module is configured to determine frequencies using one of:

non-parametric spectral estimation and parametric spectral estimation,

wherein the non-parametric spectral estimation is a window-based approach and wherein the parametric spectral estimation is based on signal modeling.

19. The system of claim 17, wherein a number of symbols used by the time domain analysis module is less than a number of symbols used by the frequency domain analysis module.

20. The system of claim 17, wherein the frequency domain analysis module is further configured to:

define a range of frequencies in which to search for impulse noise sources;

divide the range of frequencies into a plurality of observation windows;

calculate an FFT periodogram across the plurality of observation windows;

identify frequencies of impulse noise sources, wherein for each identified frequency;

perform a multi-level threshold consistency check for each identified frequency based on the FFT periodogram across the plurality of observation windows, wherein the consistency check is performed to verify each identified frequency of impulse noise sources; and

perform spectral subtraction after the each identified frequency is verified to identify a next impulse noise source.

21. The system of claim 20, wherein the frequency domain analysis module is further configured to perform spectral subtraction and process a next identified frequency, wherein spectral subtraction is performed in a recursive fashion until a mean power of the FFT periodogram is less than a predetermined level.

22. The system of claim 20, wherein the consistency check is performed on harmonics of each identified frequency.

23. The system of claim 20, wherein the frequency domain analysis module is configured to utilize a plurality of observation windows to monitor different ranges of impulse noise sources.

24. The system of claim 20, wherein the frequency analysis module is configured to perform sub-band analysis to perform a consistency check of all potential impulse noise sources.

25. The system of claim 20, wherein the frequency analysis module utilizes a plurality of thresholds to perform a consistency check based on harmonics of frequencies of potential impulse noise sources.

26. The system of claim 17, wherein the protection module comprises:

a suspender module configured to suspend updates to a frequency domain equalizer (FEQ), bit swapping, and seamless rate adaptation (SRA); and

a timer module for tracking time based on DMT symbols, wherein the protection module is further configured to re-enable updates to the FEQ, bit swapping, and SRA when the timer module determines that a predetermined number of DMT symbols have been received.

27. A system comprising:

an impulse noise detector for detecting the presence of impulse noise; and

a frequency domain analysis module configured to perform analysis in the frequency domain to determine frequencies associated with the one or more impulse noise sources.

28. The system of claim 27, wherein the frequency domain analysis module is further configured to:

define a range of frequencies in which to search for impulse noise sources;

divide the range of frequencies into a plurality of observation windows;

calculate an FFT periodogram across the plurality of observation windows;

identify frequencies of impulse noise sources, wherein for each identified frequency;

perform a multi-level threshold consistency check for each identified frequency based on the FFT periodogram across the plurality of observation windows, wherein the consistency check is performed to verify each identified frequency of impulse noise sources; and

perform spectral subtraction after the each identified frequency is verified to identify a next impulse noise source.

29. A system comprising:

an impulse noise detector for detecting the presence of impulse noise; and

a protection module for avoiding bit errors upon detection of impulse noise, wherein the protection module comprises;

a suspender module configured to suspend updates to one or more of the following;

a frequency domain equalizer (FEQ), bit swapping, and seamless rate adaptation (SRA); and

a timer module for tracking time based on DMT symbols, wherein the protection module is further configured to re-enable updates to the FEQ, bit swapping, and SRA when the timer module determines that a predetermined number of DMT symbols have been received.