Interference matrix construction

• US 20050031060A1
• Filed: 09/07/2004
• Published: 02/10/2005
• Est. Priority Date: 09/20/2002
• Status: Active Grant

• Current Assignee: III Holdings 1, LLC
• Original Assignee: TensorComm, Inc. (Rambus Inc.)
• Inventors: Narayan, Anand P., Thomas, John K., Olson, Eric S.
• Granted Patent: US 7,577,186 B2
• Time in Patent Office: Days
• US Class Current: 375/346
• 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:

an interference selector configured for selecting one or more interferers for interference cancellation; and

a matrix generator communicatively coupled to the interference selector and configured for receiving selected said one or more interferers from the interference selector and for generating a matrix having one or more vectors, wherein each vector comprises elements of at least one of the selected said one or more interferers.

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 interferers 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 interferers for application to the elements of the one or more vectors, wherein each 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 the one or more interferers for application to the elements of the one or more vectors.

10. The system of claim 1, wherein the system further comprises an amplitude estimator configured for estimating amplitude information of the one or more interferers for application to the elements of the one or more 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 the 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 1, 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 combining at least two of the one or more vectors to generate a composite vector.

19. The system of claim 1, wherein the interference selector comprises a signal path selector configured for selecting one or more signal paths, wherein said one or more interferers comprise the one or more signal paths.

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 the 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 system, comprising:

a channel selector configured for selecting two or more channels for channel cancellation; and

a matrix generator communicatively coupled to the channel selector and configured for receiving selected said two or more channels from the channel selector and for generating a matrix having a vector comprising elements from at least two of the selected said two or more channels.

28. An interference matrix, comprising:

a vector of elements, wherein each element is a composite of elements from selected interfering channels and wherein the interference matrix is used to substantially remove the selected interfering channels from a received signal or a reference signal.

29. The interference matrix of claim 28, wherein the vector is a composite vector and wherein the elements from the selected interfering channels are summed elements of two or more interfering channels.

30. A receiver, comprising:

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

a processing engine communicatively coupled to the circuitry and comprising

an interference selector configured for selecting one or more interfering signals for cancellation, and

a matrix generator communicatively coupled to the interference selector and configured for receiving selected said one or more interfering signals from the interference selector and for generating a matrix having a vector comprising elements from at least two of the selected said one or more interfering signals, wherein the matrix is used to generate a cancellation operator that substantially cancels said at least two of the selected said one or more interfering signals from the digital signal.

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

32. The receiver of claim 30, wherein the selected said one or more interfering signals comprise a Code Division Multiple Access signal.

33. The receiver of claim 30, wherein the selected said one or more interfering signals comprise a Wideband Code Division Multiple Access signal.

34. The receiver of claim 30, wherein the selected said one or more interfering signals comprise a Global Positioning System signal.

35. The receiver of claim 30, wherein the selected said one or more interfering signals comprise a Universal Mobile Telephone Service signal.

36. The receiver of claim 30, wherein at least one of the selected said one or more interfering signals 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.

37. The receiver of claim 36, 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.

38. A method, comprising:

selecting one or more channels for cancellation from a first signal path;

generating at least one vector comprising elements from at least one selected said one or more channels; and

generating a matrix from said at least one vector, wherein the matrix is used for generating a cancellation operator.

39. The method of claim 38, further comprising generating a cancellation operator from the matrix, wherein the cancellation operator is used to substantially cancel the selected said one or more channels from an input signal.

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

41. The method of claim 39, wherein 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.

42. The method of claim 38, wherein there are at least two channels and wherein generating said at least one vector comprises generating said at least one vector from elements of said at least two selected channels to generate a composite interference vector.

43. The method of claim 38, further comprising estimating phase of the first signal path in response to selecting the one or more channels, wherein the one or more channels are associated with the first signal path via an on-time PN code.

44. The method of claim 38, further comprising estimating a relative amplitude or an absolute amplitude of said at least one or more channels in response to selecting the one or more channels.

45. The method of claim 38, 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.

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

47. The method of claim 38, 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.

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

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

50. The method of claim 47, 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.

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

52. A system, comprising:

means for selecting one or more channels for cancellation from a first signal path;

means for generating at least one vector comprising elements from at least one selected said one or more channels; and

means for generating a matrix from said at least one vector, wherein the matrix is used for generating a cancellation operator.

53. The system of claim 52, 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 channels from an input signal.

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

55. The system of claim 53, 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.

56. The system of claim 52, wherein the means for generating said at least one vector comprises means for generating said at least one vector from elements of two or more selected channels to generate a composite interference vector.

57. The system of claim 52, further comprising means for estimating phase of the first signal path in response to selecting the one or more channels, wherein the one or more channels are associated with the first signal path via an on-time PN code and phase.

58. The system of claim 52, further comprising means for estimating a relative amplitude or an absolute amplitude of said at least one selected said one or more channels in response to selecting the one or more channels.

59. The system of claim 52, further comprising means for estimating a sign of said at least one selected said one or more channels in response to selecting the one or more channels.

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

61. The system of claim 52, 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.

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

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

64. The system of claim 61, 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.

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

66. The system of claim 61, 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.

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