Interference matrix construction

• US 7,577,186 B2
• Filed: 09/07/2004
• Issued: 08/18/2009
• Est. Priority Date: 09/20/2002
• Status: Active Grant

• Current Assignee: III Holdings 1, LLC
• Original Assignee: TensorComm, Inc. (Rambus Inc.)
• Inventors: Thomas, John K., Narayan, Anand P., Olson, Eric S.
• Primary Examiner(s): Ahn, Sam K
• Application Number:
  US10/935,015
• Publication Number:
  US 20050031060A1
• Time in Patent Office: 1,806 Days
• Field of Search: 375/285, 375/298, 375/346, 375/316, 375/218, 375/347, 375/229, 375/312, 702/196, 370/320, 370/335, 370/342
• US Class Current: 375/148
• CPC Class Codes: H04B 1/7105 Joint detection techniques, e.g. linear detectors
• CPC Class Codes: H04B 1/7107 Subtractive interference cancellation
• CPC Class Codes: H04B 1/7117 Selection, re-selection, allocation or re-allocation of paths to fingers, e.g. timing offset control of allocated fingers

Abstract

The present invention provides systems and methods for interference matrix construction. Such an interference matrix may be used to generate a cancellation operator that when applied to a signal may substantially remove selected interfering signals. In one embodiment of the invention, a system comprises an interference selector configured for selecting one or more interferers for interference cancellation. The system also comprises a matrix generator communicatively coupled to the interference selector and configured for receiving selected interferers from the interference selector. The matrix generator is also configured for generating a matrix having one or more vectors, wherein each vector comprises elements of at least one of the selected interferers. Such an interference matrix and the subsequent generation of the cancellation operator may advantageously provide interference cancellation to systems employing CDMA (e.g., such as cdmaOne and cdma2000), WCDMA, Broadband CDMA, UMTS and GPS signals.

Claims

1. A system, comprising:

circuitry, comprising an analog to digital converter configured for converting a received analog signal into a digital signal;

a processing engine communicatively coupled to the circuitry and comprising an interference selector comprising a signal path selector configured for selecting one or more interfering paths for interference cancellation;

one or more interference vector constructors coupled to the interference selector configured for constructing one or more interference vectors using at least one of estimated amplitude information, estimated sign information or estimated phase information; and

a matrix generator communicatively coupled to the at least one or more interference vector constructors and configured for receiving selected said one or more interference vectors from the one or more interference vector constructors and for generating a matrix that is a linear combination of said one or more interference vectors.

2. The system of claim 1, further comprising a processor communicatively coupled to the matrix generator and configured for using the matrix to generate a cancellation operator.

3. The system of claim 2, wherein the cancellation operator substantially comprises the following form:

P_s^⊥

=I−

S(S^TS)<sup>−

1</sup>S^T,

where P_s^⊥

is the cancellation operator, I is an identity matrix, S is the matrix and S^T is a transpose of the matrix.

4. The system of claim 2, further comprising an applicator configured for applying the cancellation operator to an input signal to substantially cancel the selected said one or more interfering paths from the input signal and to generate a substantially interference cancelled signal.

5. The system of claim 4, wherein the input signal is one of a received digital signal or a reference code.

6. The system of claim 1, wherein the system is configurable with a receiver to provide a substantially interference cancelled received signal to a processing finger of the receiver.

7. The system of claim 6, wherein the receiver is configurable with a base station or a handset.

8. The system of claim 1, wherein the system further comprises a phase estimator configured for estimating phase information of the one or more interfering paths for application to the elements of the one or more interference vectors, wherein each interference vector has a phase estimate imposed thereon.

9. The system of claim 1, wherein the system further comprises a sign detector configured for detecting sign information of one or more interferers for application to the elements of the one or more interference vectors.

10. The system of claim 1, wherein the system further comprises an amplitude estimator configured for estimating amplitude information of one or more interferers for application to the elements of the one or more interference vectors.

11. The system of claim 10, wherein the estimated amplitude information is estimated relative amplitude information.

12. The system of claim 10, wherein the estimated amplitude information is estimated absolute amplitude information.

13. The system of claim 1, wherein the interference selector is further configured for selecting one or more interferers based upon a threshold.

14. The system of claim 1, wherein the interference selector is further configured for selecting the one or more interferers based upon a predetermined number.

15. The system of claim 1, wherein at least one of the vectors comprises a nominal length number of elements.

16. The system of claim 15, wherein the elements comprise covering code elements and spreading code elements.

17. The system of claim 16, wherein the elements further comprise estimated phase elements.

18. The system of claim 1, wherein the matrix generator is further configured for summing at least two of the one or more interference vectors to generate a composite vector.

19. The system of claim 1, wherein the signal path selector is further configured for transferring tracking information for the one or more selected interfering paths to the interference vector constructor.

20. The system of claim 19, wherein the interference selector further comprises a channel selector communicatively coupled to the signal path selector and configured for selecting one or more channels for channel cancellation from one or more signal paths.

21. The system of claim 1, wherein at least one of the vectors comprises elements from a sub-symbol, a single symbol or multiple symbols.

22. The system of claim 1, wherein the system is configurable as an Application Specific Integrated Circuit.

23. The system of claim 1, wherein the system is configurable as a Digital Signal Processor.

24. The system of claim 1, wherein the system is configurable as a Field Programmable Gate Array.

25. The system of claim 1, wherein the system is configurable as an Advanced RISC Machine.

26. The system of claim 1, wherein the system is configurable with a handset.

27. A receiver, comprising:

circuitry, comprising an analog to digital converter configured for converting a received analog signal into a digital signal;

a processing engine communicatively coupled to the circuitry and comprising

a phase estimator configured to compute the phase of at least one digital signal;

an amplitude estimator configured to compute the amplitude of at least one channel in said digital signal; and

a processing engine configured to compute a composite interference vector computed from a linear combination of one or more interference vectors, wherein the one or more interference vectors is computed using at least one of estimated amplitude information, estimated phase information, and estimated sign information and wherein the composite interference vector is used to substantially remove interference from a received signal or a reference signal.

28. The receiver of claim 27, wherein the estimated phase information is derived using a channel.

29. A receiver, comprising:

circuitry, comprising an analog to digital converter configured for converting a received analog signal into a digital signal;

a processing engine communicatively coupled to the circuitry and comprising

a signal path selector configured for selecting one or more interfering signal paths for cancellation,

at least one interference vector constructor coupled to the signal path selector configured for constructing one or more interference vectors using at least one of estimated amplitude information, estimated sign information or estimated phase information; and

a matrix generator communicatively coupled to the at least one interference vector constructor and configured for generating a matrix that is a linear combination of the one or more interference vectors, wherein the matrix is used to generate a cancellation operator that substantially cancels said one or more interfering signal paths from the digital signal.

30. The receiver of claim 29, wherein the receiver is configurable within a base station or a handset.

31. The receiver of claim 29, wherein the selected said one or more interfering signal paths comprise a Code Division Multiple Access signal.

32. The receiver of claim 29, wherein the selected said one or more interfering signal paths comprise a Wideband Code Division Multiple Access signal.

33. The receiver of claim 29, wherein the selected said one or more interfering signal paths comprise a Global Positioning System signal.

34. The receiver of claim 29, wherein the selected said one or more interfering signal paths comprise a Universal Mobile Telephone Service signal.

35. The receiver of claim 29, wherein at least one of the selected said one or more interfering signal paths comprises a signal path and wherein the interference selector comprises a path selector configured for selecting one or more signal paths from the selected said one or more interfering signals.

36. The receiver of claim 35, wherein the interference selector further comprises a channel selector communicatively coupled to the path selector and configured for selecting one or more channels for cancellation from selected said one or more signal paths.

37. A method, comprising:

selecting in a receiver one or more signal paths for cancellation from a received signal;

generating in a processor at least one interference vector using at least one of estimated amplitude information, estimates sign information, code information and phase information for each of said one or more signal paths; and

generating a matrix that is a linear combination of one or more said interference vectors, wherein the matrix is used for generating a cancellation operator.

38. The method of claim 37, further comprising generating the cancellation operator from the matrix, wherein the cancellation operator is used to substantially cancel interference from an input signal.

39. The method of claim 38, wherein the received signal is one of a received digital signal or a reference code.

40. The method of claim 38, wherein said generating the cancellation operator substantially comprises generating the cancellation operator according to the following form:

P_s^⊥

=I−

S(S^TS)<sup>−

1</sup>S^T,

where P_s^⊥

is the cancellation operator, I is an identity matrix, S is the matrix and S^T is a transpose of the matrix.

41. The method of claim 37, wherein said generating a matrix comprises summing two or more interference vectors to form a composite interference vector.

42. The method of claim 37, further comprising estimating phase of at least a first signal path.

43. The method of claim 37, further comprising estimating a relative amplitude or an absolute amplitude of one or more channels.

44. The method of claim 37, further comprising estimating a sign of said at least one selected said one or more channels in response to selecting the one or more channels.

45. The method of claim 44, wherein the sign of said at least one selected said one or more channels is the sign of a symbol.

46. The method of claim 37, further comprising selecting one or more channels for cancellation from a second signal path in response to selecting the one or more channels for cancellation from the first signal path.

47. The method of claim 46, further comprising estimating phase of the second signal path.

48. The method of claim 47, further comprising imposing the estimated phase on vector elements associated with the second signal path.

49. The method of claim 46, further comprising estimating a relative amplitude or an absolute amplitude of selected said one or more channels from the second signal path in response to selecting the one or more channels for cancellation.

50. The method of claim 49, further comprising imposing the relative amplitude or the absolute amplitude on the vector elements of said at least one vector.

51. A system, comprising:

means for selecting in a receiver one or more signal paths for cancellation from a set of received signal paths;

means for generating in a processor at least one interference vector comprising elements from at least one selected said one or more signal paths using at least one of estimated amplitude information, estimated sign information and estimates phase information; and

means for generating a matrix from said at least one interference vector that is a linear combination of one or more interference vectors, wherein the matrix is used for generating a cancellation operator.

52. The system of claim 51, further comprising means for generating a cancellation operator from the matrix, wherein the cancellation operator is used to substantially cancel the selected said one or more signal paths from an input signal.

53. The system of claim 52, wherein the input signal is one of a received digital signal or a reference code.

54. The system of claim 52, wherein the means for generating the cancellation operator substantially comprises means for generating the cancellation operator according to the following form:

P_s^⊥

=I−

S(S^TS)<sup>−

1</sup>S^T,

where P_s^⊥

is the cancellation operator, I is an identity matrix, S is the matrix and S^T is a transpose of the matrix.

55. The system of claim 51, wherein the means for generating said at least one interference vector comprises means for generating said at least one interference vector from elements of two or more selected channels to generate the interference vector.

56. The system of claim 51, further comprising means for estimating phase of one or more signal paths.

57. The system of claim 51, further comprising means for estimating a relative amplitude or an absolute amplitude of one or more channels.

58. The system of claim 51, further comprising means for estimating a sign of one or more channels.

59. The system of claim 58, wherein the sign of said at least one selected said one or more channels is the sign of a symbol.

60. The system of claim 51, further comprising means for selecting one or more channels for cancellation of a second signal path in response to selecting the one or more channels from the second signal path.

61. The system of claim 60, further comprising means for estimating phase of the second signal path.

62. The system of claim 61, further comprising means for imposing the estimated phase on elements associated with the second signal path.

63. The system of claim 60, further comprising means for estimating a relative amplitude or an absolute amplitude of selected said one or more channels from the second signal path in response to selecting the one or more channels for cancellation.

64. The system of claim 63, further comprising means for imposing the relative amplitude or the absolute amplitude on the elements of said at least one interference vector.

65. The system of claim 60, further comprising means for estimating sign information associated with each symbol of selected said one or more channels from the second signal path in response to selecting the one or more channels for cancellation.

66. The system of claim 65, further comprising means for imposing the sign information on the elements of said at least one interference vector.