Correlation shaping matched filter receiver

• US 20020146066A1
• Filed: 02/20/2001
• Published: 10/10/2002
• Est. Priority Date: 02/20/2001
• Status: Active Grant

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Oppenheim, Alan V., Eldar, Yonina C.
• Granted Patent: US 7,751,469 B2
• Time in Patent Office: Days
• US Class Current: 375/152
• CPC Class Codes: G06F 18/00 Pattern recognition
• CPC Class Codes: H04B 1/7093 Matched filter type
• CPC Class Codes: H04B 1/71052 using decorrelation matrix
• CPC Class Codes: H04L 25/03299 with noise-whitening circuitry

Abstract

The present invention is directed toward an apparatus and method for receiving signals, demodulating the signals and shaping the correlation of the output of a correlation demodulator. The present invention can be used irrespective of whether the received signals have noise components that are Gaussian or non-Gaussian. Moreover, the present invention can be utilized when a predetermined set of received signals is linearly independent or linearly dependent.

Claims

1. A receiver comprising:

a correlation demodulator for receiving signals; and

a correlation shaper operating on an output from the correlation demodulator.

2. The receiver of claim 1 wherein the correlation demodulator is a matched filter demodulator.

3. The receiver of claim 1, wherein the correlation shaper is a whitening transformation performed on the output from the correlation demodulator.

4. The receiver of claim 3, wherein the whitening transformation is determined by minimizing the mean squared error between the output from the correlation demodulator and the output from the correlation shaper.

5. The receiver of claim 1, wherein the correlation shaper is comprised of a transformation, said transformation is determined by minimizing the mean squared error between the output of the correlation demodulator and the output of the correlation shaper.

6. The receiver of claim 1, wherein the correlation shaper is chosen so that the covariance matrix of the output has the property that the second and subsequent rows are permutations of the first row.

7. The receiver of claim 6, wherein the correlation shaper is determined by minimizing the mean squared error between the output from the correlation demodulator and the output from the correlation shaper.

8. The receiver of claim 1, wherein the correlation shaper is a subspace whitening transformation performed on the output signal of the correlation demodulator.

9. The receiver of claim 8, wherein the subspace whitening transformation is determined by minimizing the mean squared error between the output from the correlation demodulator and the output from the correlation shaper.

10. The receiver of claim 5, wherein the transformation is performed on a subspace.

11. The receiver of claim 1, wherein the correlation shaper is chosen so that the covariance matrix of the representation of the output of the correlation shaper in the space in which it lies has the property that the second and subsequent rows are permutations of the first row.

12. The receiver of claim 11, wherein the correlation shaper is determined by minimizing the mean squared error between the output from the correlation demodulator and the output from the correlation shaper.

13. The receiver of claim 1, wherein the correlation demodulator is comprised of a bank of correlators that cross-correlate a received signal with a set of orthogonal signals.

14. The receiver of claim 13, wherein the set of orthogonal signals is determined by minimizing the least-squares error between the set of orthogonal signals and the predetermined set of signals.

15. The receiver of claim 1, wherein the correlation demodulator is comprised of a bank of correlators that cross-correlate a received signal with a set of geometrically uniform signals.

16. The receiver of claim 15, wherein the set of geometrically uniform signals is determined by minimizing the least-squares error between the set of geometrically uniform signals and the predetermined set of signals.

17. The receiver of claim 1, wherein the correlation demodulator is comprised of a bank of correlators that cross-correlate a received signal with a set of projected orthogonal signals.

18. The receiver of claim 17, wherein the set of projected orthogonal signals is determined by minimizing the least-squares error between the set of projected orthogonal signals and the predetermined set of signals.

19. The receiver of claim 1, wherein the correlation demodulator is comprised of a bank of correlators that cross-correlate a received signal with a set of projected geometrically uniform signals.

20. The receiver of claim 19, wherein the set of projected geometrically uniform signals is determined by minimizing the least-squares error between the set of projected geometrically uniform signals and the predetermined set of signals.

21. A method for processing signals comprising the steps of:

receiving a member of a predetermined set of signals that has undergone some distortion;

demodulating the received signal of the predetermined set of signals;

outputting a demodulated signal; and

shaping the correlation of the demodulated signal.

22. The method of claim 21, wherein the shaping of the correlation of the demodulated signal is comprised of performing a whitening transformation on the demodulated signal.

23. The method of claim 22, wherein the whitening transformation is comprised of the step of minimizing the mean squared error between the demodulated signal and an output signal from the whitening transformation.

24. The method of claim 21, wherein shaping of the correlation of the demodulated signal is further comprised of performing a transformation on the demodulated signal, said transformation is determined by minimizing the mean squared error between the demodulated signal and the output of the correlation shaper.

25. The method of claim 21, wherein shaping of the correlation of the demodulated signal is comprised of performing a transformation of the demodulated signal such that the covariance matrix of the output of the transformation has the property that the second and each subsequent row is a permutation of the first.

26. The method of claim 25, wherein the transformation is comprised of the step of minimizing the mean squared error between the demodulated signal and an output signal from the transformation.

27. The method of claim 21, wherein shaping of the correlation of the demodulated signal is comprised of performing a subspace whitening transformation on the demodulated signal.

28. The method of claim 27, wherein the whitening transformation is comprised of the step of minimizing a mean squared error between the demodulated signal and an output signal from the whitening transformation.

29. The method of claim 21, wherein shaping of the correlation of the demodulated signal is comprised of performing a transformation of the demodulated signal such that the covariance matrix of the representation of the output of the transformation on the space in which it lies has the property that the second and each subsequent row is a permutation of the first.

30. The method of claim 29, wherein the transformation is comprised of the step of minimizing a mean squared error between the demodulated signal and an output signal from the transformation.

31. The method of claim 21, wherein whitening the demodulated signal is comprised of the step of cross-correlating the member of a predetermined set of signals with a set of orthogonal signals.

32. The method of claim 31, further comprising the step of minimizing the least- squares error between the predetermined set of signals and the set of orthogonal signals.

33. The method of claim 21, wherein shaping the correlation of the demodulated signal is comprised of the step of cross-correlating the member of a predetermined set of signals with a set of geometrically uniform signals.

34. The method of claim 33, further comprising the step of minimizing the least- squares error between the predetermined set of signals and the set of geometrically uniform signals.

35. The method of claim 21, wherein shaping the correlation of the demodulated signal on a subspace is comprised of the step of cross-correlating the member of a predetermined set of signals with a set of projected orthogonal signals.

36. The method of claim 35, comprising the step of minimizing the least-squares error between the projected orthogonal signals and the predetermined set of signals.

37. The method of claim 21, wherein shaping the correlation of the demodulated signal on a subspace is comprised of the step of cross-correlating the member of a predetermined set of signals with a set of projected geometrically uniform signals.

38. The method of claim 37, comprising the step of minimizing the least-squares error between the projected geometrically uniform signals and the predetermined set of signals.