Adaptive frequency-domain reference noise canceller for multicarrier communications systems

• US 20100091827A1
• Filed: 10/10/2008
• Published: 04/15/2010
• Est. Priority Date: 10/10/2008
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Iyer, Jayasuryan, Wiese, Brian R., Desjardins, Philip
• Granted Patent: US 8,605,837 B2
• Time in Patent Office: Days
• US Class Current: 375/225
• CPC Class Codes: H04B 1/10 Means associated with receiver for limiting or suppressing noise or interference
• CPC Class Codes: H04L 25/022 of frequency response
• CPC Class Codes: H04L 25/0226 sounding signals per se
• CPC Class Codes: H04L 5/00 Arrangements affording multiple use of the transmission path

Abstract

A method and apparatus to align data blocks in a data signal and a reference signal to increase cross-correlation between the data signal and the reference signal as compared to the unaligned data and reference signals and cancel interference in the data signal in the frequency-domain under changing conditions and in the presence of the data signal.

Claims

1. A method comprising:

receiving a data signal and a reference signal; and

aligning data blocks in the data signal with data blocks in the reference signal to increase cross-correlation between the data signal and the reference signal as compared to the unaligned data and reference signals.

2. The method of claim 1, wherein aligning the data blocks comprises introducing a first delay into the data signal and introducing a second delay into the reference signal.

3. The method of claim 2, wherein introducing a first delay comprises programming a first programmable delay First in, First out (FIFO) buffer and introducing a second delay comprises programming second programmable delay FIFO buffer.

4. The method of claim 2, wherein introducing a first delay and a second delay comprises adjusting the group delay of a first programmable finite impulse response (FIR) filter and a second programmable FIR filter.

5. The method of claim 3 further comprising:

generating an interference estimate by multiplying the aligned reference signal by a single complex tap for each of one or more frequency bins of the reference signal; and

subtracting the interference estimate from the aligned data signal.

6. An apparatus comprising:

a block aligner configured to align data blocks in a data signal received from a data line with data blocks in a reference signal received from a reference lineto increase cross-correlation between the data signal and the reference signal as compared to the unaligned data and reference signals.

7. The apparatus of claim 6, wherein the block aligner comprises a first delay module coupled to the data line and configured to introduce a first delay into the data signal and a second delay module coupled to the reference line and configured to introduce a second delay into the reference signal.

8. The apparatus of claim 7, wherein the first and second delay modules comprise programmable delay First in, First out (FIFO) buffers.

9. The apparatus of claim 7, wherein the first and second delay modules comprise programmable finite impulse response (FIR) filers.

10. The apparatus of claim 7, further comprising:

a tone-by-tone canceller coupled to the block aligner and configured to operate in the frequency domain and cancel interference in the data signal.

11. A method comprising:

generating an interference estimate for a received data signal; and

adaptively updating an interference canceller with the interference estimate to cancel changing sources of interference during data transmission.

12. The method of claim 11, wherein generating an interference estimate comprises:

generating an error estimate in the data signal;

adaptively updating canceller taps with the error estimate; and

multiplying a reference signal by a single complex canceller tap for each of one or more frequency bins of the reference signal.

13. The method of claim 12, wherein generating an error estimate comprises subtracting an output of a constellation decision logic module from an input of the constellation decision logic module.

14. The method of claim 12, wherein adaptively updating the canceller tap comprises using the error estimate in a least-mean-square algorithm.

15. The method of claim 12, wherein adaptively updating the canceller tap comprises using the error estimate in a recursive least square algorithm.

16. The method of claim 11, wherein adaptively updating the interference canceller comprises subtracting the interference estimate from the data signal.

17. The method of claim 16, further comprising:

aligning blocks of the data signal with blocks of a reference signal to increase cross-correlation between the data signal and the reference signal as compared to the unaligned data and reference signals.

18. An apparatus comprising:

a tone-by-tone canceller operating in the frequency domain, configured to reduce interference in a data signal.

19. The apparatus of claim 18, wherein the tone-by-tone canceller comprises:

a constellation decision logic module to perform constellation decoding;

a first adder coupled to the constellation decision logic module and configured to subtract an output of the constellation decision logic module from an input of the constellation decision logic module to form an error estimate;

an interference estimator module coupled to the first adder and configured to receive the error estimate; and

a second adder coupled to the interference estimator module and configured to subtract the interference estimate from the data signal.

20. The apparatus of claim 19, wherein the constellation decision logic module comprises a trellis decoder.

21. The apparatus of claim 19, wherein the constellation decision logic module comprises an un-coded constellation decoder.

22. The apparatus of claim 19, further comprising:

a block aligner coupled to the tone-by-tone canceller, wherein the block aligner is configured to align data blocks in the data signal and a reference signal to increase cross-correlation between the data signal and the reference signal as compared to the unaligned data and reference signals.

23. A method comprising:

aligning blocks of a received data signal with blocks of a received reference signal to increase cross-correlation between the data signal and the reference signal as compared to the unaligned data and reference signals; and

canceling interference in the data signal in the frequency domain.

24. The method of claim 23, further comprising:

dropping unneeded samples corresponding to a cyclic extension of the data signal from the aligned data and reference signals.

25. The method of claim 24, further comprising:

transforming the aligned data and reference signals from the time-domain to the frequency-domain.

26. The method of claim 25, further comprising:

normalizing a power of one or more frequency bins of both the transformed data signal and the transformed reference signal.

27. The method of claim 26, further comprising:

generating an interference estimate by multiplying the transformed reference signal by a single complex tap for each of the one or more frequency bins of the reference signal.

28. The method of claim 27, wherein canceling interference in the data signal comprises subtracting the interference estimate from the transformed data signal.

29. An apparatus comprising:

a block aligner configured to align data blocks in a data signal and a reference signal to increase cross-correlation between the data signal and the reference signal as compared to the unaligned data and reference signals; and

a tone-by-tone canceller coupled to the block aligner, the canceller operating in the frequency domain to cancel interference in the data signal.

30. The apparatus of claim 29, wherein the block aligner comprises a first delay module configured to introduce a first delay into the data signal and a second delay module configured to introduce a second delay into the reference signal.

31. The apparatus of claim 30, wherein the tone-by-tone canceller comprises:

a constellation decision logic module to perform constellation decoding;

a first adder coupled to the constellation decision logic module and configured to subtract an output of the constellation decision logic module from an input of the constellation decision logic module to form an error estimate;

a interference estimator module coupled to the first adder and configured to receive the error estimate; and

a second adder coupled to the interference estimator module and configured to subtract the interference estimate from the data signal.

32. The apparatus of claim 31, further comprising:

a cyclic extension removal and serial-to-parallel module coupled to the block aligner and configured to remove a number of redundant samples from the data signal; and

a sample drop and serial-to-parallel module coupled to the block aligner and configured to remove a same number of samples from the reference signal as were removed from the data signal.

33. The apparatus of claim 32, further comprising:

a first fast Fourier transform (FFT) module coupled to the cyclic extension and serial-to-parallel module to transform the data signal from the time-domain to the frequency-domain; and

a second FFT module coupled to the sample drop and serial-to-parallel module to transform the reference signal from the time-domain to the frequency-domain.

34. The apparatus of claim 33, further comprising:

a channel flattening frequency domain equalizer (CF-FEQ) module coupled to the first FFT module and configured to receive an output of the first FFT module and provide an output to an adder;

a gain inversion and constellation scaling (GICS) module coupled to the second adder and configured to receive an output of the adder; and

a bin power normalization module coupled to the second FFT module and configured to receive an output of the second FFT module.

35. The apparatus of claim 34, wherein the GICS module is further configured to decouple on-line reconfiguration (OLR), seamless rate adaptation (SRA) and bitswap from the tone-by-tone canceller.

36. An apparatus, comprising:

means for receiving a data signal and a reference signal; and

means for aligning data blocks in the data signal with data blocks in the reference signal to maximize cross-correlation between the data signal and the reference signal.

37. The apparatus of claim 36, wherein the means for receiving comprises means for performing time-domain filtering of the data signal and the reference signal.

38. The apparatus of claim 36, further comprising:

means for collecting 2N time-domain samples of the data signal and the reference signal.

39. The apparatus of claim 38, further comprising:

means for performing cross-correlation of the data signal and the reference signal and computing a peak offset value of the samples.

40. The apparatus of claim 39, further comprising:

means for introducing a first delay into the data signal and a second delay into the reference signal.

41. The apparatus of claim 40, further comprising:

means for generating an interference estimate for the data signal; and

means for adaptively updating an interference canceller with the interference estimate during data transmission.