Tap weight initializer for an adaptive equalizer

• US 7,190,720 B2
• Filed: 05/09/2002
• Issued: 03/13/2007
• Est. Priority Date: 07/03/2001
• Status: Active Grant

• Current Assignee: Zenith Electronics Corporation (LG Corporation)
• Original Assignee: Zenith Electronics Corporation (LG Corporation)
• Inventors: Fimoff, Mark, Zoltowski, Michael D., Ozen, Serdar
• Primary Examiner(s): Bayard; Emmanuel
• Application Number:
  US10/142,110
• Publication Number:
  US 20030063665A1
• Time in Patent Office: 1,769 Days
• Field of Search: 375/229, 375/230, 375/231, 375/232, 375/234, 375/350, 375/233
• US Class Current: 375/232
• CPC Class Codes: H04L 25/03063 using fractionally spaced delay lines or combinations of fractionally and integrally spaced taps

Abstract

Initial values of the tap weights for the taps of a linear equalizer are determined based on a channel impulse response of a channel so that the values corresponding to the weights of the equalizer taps achieve optimum initialization of the equalizer. These values are determined through use of a nested summation where the number of summations is dependent upon the number of multi-paths characterizing the channel.

Claims

1. A method for determining the initial values of the tap weights for the taps wherein the nested summation has the following general form:

$\underset{k_0=a}{\overset{k_{0_{\max }}}{\sum <br><br>}}<br><br><br><br>\underset{k_{1=b}}{\overset{k_{1_{\max }}}{\sum <br><br>}}<br><br><br><br>\mathrm{\dots <br><br>}<br><br><br><br>\underset{k_{m-1}=n}{\overset{k_{m-1_{\max }}}{\sum <br><br>}}<br><br><br><br>f\left(k_0,k_1,\mathrm{\dots <br><br>}<br><br><br><br>k_{m-1}\right)$

Wherein a, b, . . . , n are initial summing points for the corresponding summations, and wherein m>

1 such that if m=2 there are only two summations and such that if m>

2 there are more than two summations of a linear equalizer comprising;

determining a channel impulse response of a channel; and

,

performing a nested summation to determine, from the channel impulse response, the initial values corresponding to the weights of the equalizer taps.

2. The method of claim 1 wherein the performing of a nested summation comprises:

determining a number of dominant multi-paths characterizing the channel; and

,

performing the nested summation based on a number of summations corresponding the number of dominant multi-paths.

3. The method of claim 2 wherein each of the dominant multi-paths is characterized by a delay, wherein the delay of at least one of the dominant multi-paths is shortest compared to the delays of the other dominant multi-paths, and wherein the outermost of the nested summation is performed over limits between 0 and the number of equalizer taps divided by the shortest delay characterizing the dominant multi-paths.

4. A method for determining values for the tap weights of the taps of a linear equalizer wherein the nested summation has the following general form:

$\underset{k_0=a}{\overset{k_{0_{\max }}}{\sum <br><br>}}<br><br><br><br>\underset{k_{1=b}}{\overset{k_{1_{\max }}}{\sum <br><br>}}<br><br><br><br>\mathrm{\dots <br><br>}<br><br><br><br>\underset{k_{m-1}=n}{\overset{k_{m-1_{\max }}}{\sum <br><br>}}<br><br><br><br>f\left(k_0,k_1,\mathrm{\dots <br><br>}<br><br><br><br>k_{m-1}\right)$

Wherein a, b, . . . , n are initial summing points for the corresponding summations, and wherein m>

1 such that if m=2 there are only two summations and such that if m>

2 there are more than two summations comprising;

determining a channel impulse response of a channel; and

,

performing a nested summation to determine from the channel impulse response only values corresponding to the weights of the equalizer taps necessary to achieve optimum initialization of the equalizer.

5. The method of claim 4 wherein the performing of a nested summation comprises determining a number of dominant multi-paths characterizing the channel, and wherein the nested summation has a number of summations equal to the number of dominant multi-paths.

6. The method of claim 5 wherein each of the dominant multi-paths is characterized by a delay, wherein the delay of at least one of the dominant multi-paths is shortest compared to the delays of the other dominant multi-paths, and wherein the outermost of the summations is performed over limits between 0 and the number of equalizer taps divided by the shortest delay characterizing the dominant multi-paths.

7. The method of claim 4 wherein the performing of a nested summation comprises performing a nested summation based only on the channel impulse response.

8. The method of claim 7 wherein the performing of a nested summation comprises determining a number of dominant multi-paths characterizing the channel, and wherein the nested summation has a number of summations equal to the number of dominant multi-paths.

9. The method of claim 8 wherein each of the dominant multi-paths is characterized by a delay, wherein the delay of at least one of the dominant multi-paths is shortest compared to the delays of the other dominant multi-paths, and wherein the outermost of the summations is performed over limits between 0 and the number of equalizer taps divided by the shortest delay characterizing the dominant multi-paths.

10. A method for determining values for the tap weights of the taps of a linear equalizer wherein the nested summation has the following general form:

$\underset{k_0=a}{\overset{k_{0_{\max }}}{\sum <br><br>}}<br><br><br><br>\underset{k_1=b}{\overset{k_{1_{\max }}}{\sum <br><br>}}<br><br><br><br>\mathrm{\cdots <br><br>}<br><br>\underset{k_{m-1}=n}{\overset{k_{m-1_{\max }}}{\sum <br><br>}}<br><br><br><br>f<br><br>\left(k_0,k_1,\mathrm{\dots <br><br>}<br><br><br><br>k_{m-1}\right)$

Wherein a, b, . . . , n are initial summing points for the corresponding summations, and wherein m>

1 such that if m=2 there are only two summations and such that if m>

2 there are more than two summations comprising;

cross-correlating data received over a channel with a stored representation of the data as transmitted so as to produce a correlation vector, wherein the correlation vector is characterized by a known noise component resulting from the finiteness of the correlation;

subtracting the known noise component from the correlation vector so as to produce a channel impulse response related to the channel; and

,

performing a nested summation to determine from the channel impulse response only values corresponding to the weights of the equalizer taps necessary to achieve optimum initialization of the equalizer.

11. The method of claim 10 wherein the performing of a nested summation comprises determining a number of dominant multi-paths characterizing the channel, and wherein the nested summation has a number or summations equal to the number of dominant multi-paths.

12. The method of claim 11 wherein each of the dominant multi-paths is characterized by a delay, wherein the delay of at least one of the dominant multi-paths is shortest compared to the delays of the other dominant multi-paths, and wherein the outermost of the summations is performed over limits between 0 and the number of equalizer taps divided by the shortest delay characterizing the dominant multi-paths.

13. The method of claim 10 wherein the performing of a nested summation comprises performing a nested summation based only on the channel impulse response.

14. The method of claim 13 wherein the performing of a nested summation comprises determining a number of dominant multi-paths characterizing the channel, and wherein the nested summation has a number of summations equal to the number of dominant multi-paths.

15. The method of claim 14 wherein each of the dominant multi-paths is characterized by a delay, wherein the delay of at least one of the dominant multi-paths is shortest compared to the delays of the other dominant multi-paths, and wherein the outermost of the summations is performed over limits between 0 and the number of equalizer taps divided by the shortest delay characterizing the dominant multi-paths.

16. The method of claim 10 wherein the known noise component includes a middle data element having a substantially zero value.

17. The method of claim 16 wherein the known noise component is subtracted from the correlation vector with the zero data element of the correlation vector and the middle data element of the known noise component in alignment.

18. The method of claim 17 wherein a subsequent subtraction of the known noise component from the correlation vector is performed only if the next largest data element of the correlation vector exceeds a threshold value.

19. The method of claim 17 wherein a subsequent subtraction of the known noise component from the correlation vector is performed with the next largest data element of the correlation vector in alignment with the middle data element of the known noise component.

20. The method of claim 19 wherein the subsequent subtraction of the known noise component from the correlation vector is performed only if the next largest data element of the correlation vector exceeds a threshold value.

21. The method of claim 20 wherein the performing of a nested summation comprises determining a number of dominant multi-paths characterizing the channel, and wherein the nested summation has a number of summations equal to the number of dominant multi-paths.

22. The method of claim 21 wherein each of the dominant multi-paths is characterized by a delay, wherein the delay of at least one of the dominant multi-paths is shortest compared to the delays of the other dominant multi-paths, and wherein the outermost of the summations is performed over limits between 0 and the number of equalizer taps divided by the shortest delay characterizing the dominant multi-paths.

23. The method of claim 20 wherein the performing of a nested summation comprises performing of a nested summation based only on the channel impulse response.

24. The method of claim 23 wherein the performing of a nested summation comprises determining a number of dominant multi-paths characterizing the channel, and wherein the nested summation has a number of summations equal to the number of dominant multi-paths.

25. The method of claim 24 wherein each of the dominant multi-paths is characterized by a delay, wherein the delay of at least one of the dominant multi-paths is shortest compared to the delays of the other dominant multi-paths, and wherein the outermost of the summations is performed over limits between 0 and the number of equalizer taps divided by the shortest delay characterizing the dominant multi-paths.

26. The method of claim 10 wherein the subtracting of the known noise component from the correlation vector comprises iteratively subtracting the known noise component from the correlation vector.

27. A method for determining initial values for tap weights to be applied to taps of a linear equalizer wherein the nested summation has the following general form:

$\underset{k_0=a}{\overset{k_{0_{\max }}}{\sum <br><br>}}<br><br><br><br>\underset{k_1=b}{\overset{k_{1_{\max }}}{\sum <br><br>}}<br><br><br><br>\mathrm{\cdots <br><br>}<br><br><br><br>\underset{k_{m-1}=n}{\overset{k_{m-1_{\max }}}{\sum <br><br>}}<br><br><br><br>f<br><br>\left(k_0,k_1,\mathrm{\dots <br><br>}<br><br><br><br>k_{m-1}\right)$

Wherein a, b, . . . , n are initial summing points for the corresponding summations, and wherein m>

1 such that if m=2 there are only two summations and such that if m>

2 there are more than two summations comprising;

determining a channel impulse response of a channel; and

,

performing a nested summation on the channel impulse response to determine the initial values for the tap weights to be applied to the taps of the linear equalizer.

28. The method of claim 27 wherein the performing of a nested summation comprises determining a number of dominant multi-paths characterizing the channel, and wherein the nested summation has a number of summations equal to the number of dominant multi-paths.