System and Method for Linear Distortion Estimation by Way of Equalizer Coefficients

• US 20100002760A1
• Filed: 09/17/2009
• Published: 01/07/2010
• Est. Priority Date: 08/17/2004
• Status: Active Grant

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Kolze, Thomas J., Currivan, Bruce J.
• Granted Patent: US 8,073,086 B2
• Time in Patent Office: Days
• US Class Current: 375/232
• 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 for estimating channel distortion in a communications channel including an adaptive equalizer, comprising:

determining one or more adaptive filter coefficients h₁(n) associated with a signal by the adaptive equalizer;

normalizing the determined one or more adaptive filter coefficients to unit energy; and

differencing the normalized one or more adaptive filter coefficients with an ideal response h₀(n) of the 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.

3. The method of claim 1, further comprising:

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

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

4. The method of claim 3, further comprising:

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

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

removing a phase offset from the normalized inverted response, 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 difference.

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

7. The method of claim 3, wherein the converting is based upon (i) padding the error sequence with zeros and (ii) 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. A method for estimating channel distortion in a communications channel including an adaptive equalizer, comprising:

receiving data within the communications channel and converging taps of the adaptive equalizer when the data is received;

determining a sum of tap power values, the sum including a power of a main tap;

normalizing the taps to unity power;

determining a difference filter from the normalized taps; and

summing a power of taps of the difference filter.

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

means for determining one or more adaptive filter coefficients h₁(n) associated with a signal by the adaptive equalizer;

means for normalizing the determined one or more adaptive filter coefficients to unit energy; and

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

11. The apparatus of claim 10, further comprising means for determining an energy of the error sequence.

12. The apparatus of claim 11, further comprising:

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

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

13. The apparatus of claim 12, further comprising:

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

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

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

14. The apparatus of claim 13, 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 difference.