Systems, methods, and apparatus for mitigation of nonlinear distortion

• US 20070098090A1
• Filed: 10/31/2005
• Published: 05/03/2007
• Est. Priority Date: 08/12/2005
• Status: Active Grant

• Current Assignee: ATI Technologies Incorporated (Advanced Micro Devices, Inc.)
• Original Assignee: ATI Technologies Incorporated (Advanced Micro Devices, Inc.)
• Inventors: Touzni, Azzedine, Ma, Xiaoqiang
• Granted Patent: US 7,583,755 B2
• Time in Patent Office: Days
• US Class Current: 375/260
• CPC Class Codes: H04L 2025/03496 as a prediction filter
• CPC Class Codes: H04L 2025/03611 Iterative algorithms
• CPC Class Codes: H04L 25/0212 of impulse response
• CPC Class Codes: H04L 25/0232 by interpolation between sounding signals
• CPC Class Codes: H04L 25/025 using least-mean-square [LMS] method
• CPC Class Codes: H04L 27/2647 Arrangements specific to the receiver only equalisation H04L27/01

Abstract

A method among the embodiments includes calculating a value of a parameter of a nonlinear model of a signal as transmitted into a transmission channel, and applying the calculated value to obtain an estimate of data values carried by the signal. Applications to multicarrier signals are described.

Claims

1. A method of signal processing, said method comprising:

based on a signal received over a transmission channel, estimating a response of the transmission channel at each of a plurality of different carrier frequencies of the received signal;

based on the estimated response of the transmission channel at each of the plurality of different carrier frequencies, calculating a first estimate of a set of data values carried by the received signal;

based on the first estimate, calculating at least one value of a parameter of a nonlinear model of the signal; and

based on the at least one value of the parameter, calculating a second estimate of the set of data values.

2. The method of signal processing according to claim 1, wherein a ratio between (A) the estimated response of the transmission channel at one of the plurality of carrier frequencies and (B) the estimated response of the transmission channel at another of the plurality of carrier frequencies varies over time.

3. The method of signal processing according to claim 1, wherein said calculating a first estimate of a set of data values comprises equalizing the received signal according to the estimated response of the transmission channel.

4. The method of signal processing according to claim 1, wherein said calculating at least one value of a parameter of a nonlinear model of the signal comprises calculating a value of a parameter of a nonlinear model of the signal as transmitted into the transmission channel.

5. The method of signal processing according to claim 1, wherein said calculating at least one value of a parameter comprises calculating, based on the first estimate, a weight of a nonlinear term of the nonlinear model.

6. The method of signal processing according to claim 1, wherein the nonlinear model comprises a sum of a linear term and a nonlinear term, and

wherein said calculating at least one value of a parameter comprises calculating, based on the first estimate, a weight of the nonlinear term.

7. The method of signal processing according to claim 1, said method comprising calculating a representation of a nonlinear variable of the nonlinear model of the signal,

wherein said calculating a second estimate is based on the calculated representation.

8. The method of signal processing according to claim 1, wherein said calculating at least one value of a parameter of a nonlinear model comprises calculating, based on the first estimate, a value of a coefficient of a polynomial model of the signal as transmitted into the transmission channel.

9. The method of signal processing according to claim 8, wherein said calculating a value of a coefficient comprises calculating a value of a coefficient of a term having an odd-numbered order greater than one.

10. The method of signal processing according to claim 1, said method comprising:

calculating a time-domain representation of the first estimate; and

raising the time-domain representation to the power of a nonlinear term of the nonlinear model,

wherein said calculating at least one value of a parameter is based on the time-domain representation.

11. The method of signal processing according to claim 10, said method comprising calculating a frequency-domain representation of the raised time-domain representation, wherein said calculating at least one value of a parameter is based on the frequency-domain representation.

12. The method of signal processing according to claim 10, wherein said calculating a time-domain representation comprises calculating an estimate of the transmitted signal at baseband.

13. The method of signal processing according to claim 10, wherein said calculating a second estimate comprises subtracting from the first estimate a set of values based on the frequency-domain representation.

14. The method of signal processing according to claim 1, wherein said calculating a second estimate comprises subtracting from the first estimate a set of values based on the at least one value of the parameter.

15. A method of signal processing, said method comprising:

based on a signal received over a transmission channel, estimating a response of the transmission channel at each of a plurality of different carrier frequencies of the received signal;

based on the estimated response of the transmission channel at each of the plurality of different carrier frequencies, calculating a first estimate of a set of data values carried by the received signal;

based on the first estimate, calculating at least one value of a parameter of a nonlinear model of the signal; and

based on the at least one value of the parameter, calculating a second estimate of the set of data values,

wherein the signal as received includes a nonlinearity introduced by an amplifier in the signal path, and

wherein an effect of the nonlinearity is reduced in the second estimate of the set of data values as compared to an effect of the nonlinearity in the first estimate of the set of data values.

16. The method of signal processing according to claim 15, wherein said calculating at least one value of a parameter comprises calculating, based on the first estimate, a weight of a nonlinear term of the nonlinear model.

17. The method of signal processing according to claim 15, wherein the nonlinear model comprises a sum of a linear term and a nonlinear term, and

wherein said calculating at least one value of a parameter comprises calculating, based on the first estimate, a weight of the nonlinear term.

18. An apparatus comprising:

means for estimating, based on a signal received over a transmission channel, a response of the transmission channel at each of a plurality of different carrier frequencies of the received signal;

means for calculating, based on the estimated response of the transmission channel at each of the plurality of different carrier frequencies, a first estimate of a set of data values carried by the received signal;

means for calculating, based on the first estimate, at least one value of a parameter of a nonlinear model of the signal; and

means for calculating, based on the at least one value of the parameter, a second estimate of the set of data values.

19. The apparatus according to claim 18, wherein a ratio between (A) the estimated response of the transmission channel at one of the plurality of carrier frequencies and (B) the estimated response of the transmission channel at another of the plurality of carrier frequencies varies over time.

20. The apparatus according to claim 18, wherein said means for calculating at least one value of a parameter of a nonlinear model of the signal is configured to calculate a value of a parameter of a nonlinear model of the signal as transmitted into the transmission channel.

21. The apparatus according to claim 18, said apparatus comprising means for calculating a representation of a nonlinear variable of the nonlinear model of the signal,

wherein said means for calculating a second estimate is configured to calculate the second estimate based on the calculated representation.

22. The apparatus according to claim 18, wherein said means for calculating at least one value of a parameter is configured to calculate a value of a coefficient of a term of a model of the signal as transmitted into the transmission channel, and

wherein said term has an odd-numbered order greater than one.

23. The apparatus according to claim 18, said apparatus comprising means for calculating, based on the first estimate, a time-domain representation of the transmitted signal at baseband,

wherein said means for calculating at least one value of a parameter is configured to calculate the at least one value based on the time-domain representation.

24. The apparatus according to claim 18, wherein said means for calculating a second estimate is configured to subtract from the first estimate a set of values based on a frequency-domain representation of a nonlinear variable of the nonlinear model of the signal.

25. The apparatus according to claim 18, wherein the signal as received includes a nonlinearity introduced by an amplifier in the signal path, and

wherein said means for calculating a second estimate of the set of data values is configured to reduce an effect of the nonlinearity in the second estimate as compared to an effect of the nonlinearity in the first estimate of the set of data values.

26. An apparatus comprising:

a channel estimator configured to estimate, based on a signal received over a transmission channel, a response of the transmission channel at each of a plurality of different carrier frequencies of the received signal;

a first signal estimator configured to calculate, based on the estimated response of the transmission channel, a first estimate of a set of data values carried by the received signal;

a parameter estimator configured to calculate, based on the first estimate, a value of a parameter of a nonlinear model of the signal; and

a second signal estimator configured to calculate, based on the value of the parameter, a second estimate of the set of data values.

27. The apparatus according to claim 26, wherein a ratio between (A) the estimated response of the transmission channel at one of the plurality of carrier frequencies and (B) the estimated response of the transmission channel at another of the plurality of carrier frequencies varies over time.

28. The apparatus according to claim 26, wherein said parameter estimator is configured to calculate a value of a parameter of a nonlinear model of the signal as transmitted into the transmission channel.

29. The apparatus according to claim 26, wherein said parameter calculator includes:

a power calculator configured to raise a time-domain representation of the first estimate to the power of a nonlinear term of the nonlinear model; and

a coefficient calculator configured to calculate a value of the parameter based on the raised estimate.

30. The apparatus according to claim 29, wherein said parameter estimator is configured to calculate a representation of a nonlinear variable of the nonlinear model of the signal, based on the raised estimate,

wherein said second signal estimator is configured to calculate the second estimate based on the calculated representation.

31. The apparatus according to claim 26, wherein said parameter estimator is configured to calculate a value of a coefficient of a term of a model of the signal as transmitted into the transmission channel, and

wherein said term has an odd-numbered order greater than one.

32. The apparatus according to claim 26, wherein said second signal estimator is configured to subtract from the first estimate a set of values based on a frequency-domain representation of a nonlinear variable of the nonlinear model of the signal.

33. The apparatus according to claim 26, wherein the signal as received includes a nonlinearity introduced by an amplifier in the signal path, and

wherein said second signal estimator is configured to reduce an effect of the nonlinearity in the second estimate of the set of data values as compared to an effect of the nonlinearity in the first estimate of the set of data values.