System and method for linear distortion estimation by way of equalizer coefficients

• US 8,422,605 B2
• Filed: 12/02/2011
• Issued: 04/16/2013
• Est. Priority Date: 08/17/2004
• Status: Expired due to Fees

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Kolze, Thomas J., Currivan, Bruce J.
• Primary Examiner(s): TSE, YOUNG TOI
• Application Number:
  US13/310,275
• Publication Number:
  US 20120076193A1
• Time in Patent Office: 501 Days
• Field of Search: 375/229, 375/232, 375/346, 375/348, 375/350, 708/322, 708/323
• US Class Current: 375/346
• CPC Class Codes: H04B 1/1027 assessing signal quality or detecting noise/interference for the received signal
• CPC Class Codes: H04B 1/123 using adaptive balancing or compensation means adaptive filter circuits and algorithms H03H
• CPC Class Codes: H04L 2025/03617 Time recursive algorithms H04L2025/03643 takes precedence
• CPC Class Codes: H04L 25/022 of frequency response
• CPC Class Codes: H04L 25/03019 adaptive, i.e. capable of adjustment during data reception
• CPC Class Codes: H04L 25/03343 Arrangements at the transmitter end

Abstract

Provided is a method and system for estimating distortion in a communications channel including an adaptive equalizer. The method includes determining one or more adaptive filter coefficients associated with a signal passed through the equalizer. The method also includes estimating un-equalized channel distortion based upon the determined adaptive filter coefficients.

Claims

1. A method comprising:

normalizing one or more adaptive filter coefficients h₁(n) associated with a signal by an adaptive equalizer to unit energy; and

differencing the normalized one or more adaptive filter coefficients h₁(n) with an ideal response h₀(n) of a communications channel, the differencing producing an error sequence h₂(n).

2. The method of claim 1, further comprising determining an energy of the error sequence h₂(n).

3. The method of claim 1, further comprising:

converting the error sequence h₂(n) to frequency domain, the converting producing a frequency response H₂(k) of the error sequence h₂(n); and

removing a delay offset of the frequency response H₂(k) to produce a delayed offset response H₃(k).

4. The method of claim 3, further comprising:

summing the delayed offset response H₃(k) and an ideal channel frequency response and inverting the sum to produce an inverted response H₄(k);

normalizing the inverted response H₄(k) to unit power, thus producing a normalized inverted response H₅(k); and

removing a phase offset from the normalized inverted response H₅(k), the removing producing an estimated channel response H₆(k).

5. The method of claim 4, further comprising:

differencing the estimated channel response H₆(k) with the ideal channel frequency response, the differencing producing an error filter response H₇(k); and

determining an error power of the error filter response H₇(k).

6. The method of claim 3, wherein the converting is based upon a fast Fourier transform of the error sequence h₂(n).

7. The method of claim 3, wherein the converting is based upon padding the error sequence h₂(n) with zeros and applying a fast Fourier transform (FFT) to the padded error sequence.

8. The method of claim 7, wherein the FFT includes at least 4096 samples.

9. An apparatus for estimating channel distortion in a communications channel including an adaptive equalizer, comprising:

means for normalizing one or more adaptive filter coefficients h₁(n) associated with a signal by the adaptive equalizer to unit energy; and

means for differencing the normalized one or more adaptive filter coefficients h₁(n) with an ideal response h₀(n) of the communications channel, the differencing producing an error sequence h₂(n).

10. The apparatus of claim 9, further comprising means for determining an energy of the error sequence h₂(n).

11. The apparatus of claim 9, further comprising:

means for converting the error sequence h₂(n) to frequency domain, the converting producing a frequency response H₂(k) of the error sequence h₂(n); and

means for removing a delay offset of the frequency response H₂(k) to produce a delayed offset response H₃(k).

12. The apparatus of claim 11, further comprising:

means for summing the delayed offset response H₃(k) and an ideal channel frequency response and (ii) inverting the sum to produce an inverted response H₄(k);

means for normalizing the inverted response H₄(k) to unit power, thus producing a normalized inverted response H₅(k); and

means for removing a phase offset from the normalized inverted response H₅(k), the removing producing an estimated channel response H₆(k).

13. The apparatus of claim 12, further comprising:

means for differencing the estimated channel response H₆(k) with the ideal channel frequency response, the differencing producing an error filter response H₇(k); and

means for determining an error power of the error filter response H₇(k).

14. A non-transitory computer readable medium having stored thereon computer executable instructions that, if executed by a processor, cause the computing device to perform a method comprising:

normalizing one or more adaptive filter coefficients h₁(n) associated with a signal by an adaptive equalizer to unit energy; and

differencing the normalized one or more adaptive filter coefficients h₁(n) with an ideal response h₀(n) of a communications channel, the differencing producing an error sequence h₂(n).

15. The non-transitory computer readable medium of claim 14, further comprising determining an energy of the error sequence h₂(n).

16. The non-transitory computer readable medium of claim 14, further comprising:

converting the error sequence h₂(n) to frequency domain, the converting producing a frequency response H₂(k) of the error sequence h₂(n); and

removing a delay offset of the frequency response H₂(k) to produce a delayed offset response H₃(k).

17. The non-transitory computer readable medium of claim 16, further comprising:

summing the delayed offset response H₃(k) and an ideal channel frequency response and inverting the sum to produce an inverted response H₄(k);

normalizing the inverted response H₄(k) to unit power, thus producing a normalized inverted response H₅(k); and

removing a phase offset from the normalized inverted response H₅(k), the removing producing an estimated channel response H₆(k).

18. The non-transitory computer readable medium of claim 17, further comprising:

differencing the estimated channel response H₆(k) with the ideal channel frequency response, the differencing producing an error filter response H₇(k); and

determining an error power of the error filter response H₇(k).

19. The non-transitory computer readable medium of claim 16, wherein the converting is based upon a fast Fourier transform of the error sequence h₂(n).

20. The non-transitory computer readable medium of claim 16, wherein the converting is based upon padding the error sequence h₂(n) with zeros and applying a fast Fourier transform (FFT) to the padded error sequence.

21. The non-transitory computer readable medium of claim 20, wherein the FFT includes at least 4096 samples.