Interference cancellation in a receive diversity system

• US 20060125689A1
• Filed: 12/10/2004
• Published: 06/15/2006
• Est. Priority Date: 12/10/2004
• Status: Abandoned Application

• Current Assignee: Rambus Inc.
• Original Assignee: Rambus Inc.
• Inventors: Narayan, Anand P., Olson, Eric S.
• Application Number:
  US11/009,981
• Publication Number:
  US 20060125689A1
• Time in Patent Office: Days
• US Class Current: 342/381
• CPC Class Codes: G01S 19/21 Interference related issues ; Issues related to cross-correlation, spoofing or other methods of denial of service
• CPC Class Codes: G01S 19/36 relating to the receiver frond end
• CPC Class Codes: H04B 7/0842 Weighted combining

Abstract

Systems and methods for employing substantial interference cancellation with a receive-diversity system are presented. A Coded Signal Processing Engine (“CSPE”) is communicatively coupled to each receiver chain of a receive-diversity system and is configured for substantially canceling one or more interfering signals from a digital baseband signal of one or more of the receiver chains. For example, either one receiver chain or a combination of receiver chains may be activated by the controller to process a signal. The CSPE may cancel interfering signals from the digital baseband signals of the activated receiver chains to generate one or more interference-canceled signals for each activated receiver chain. The interference-canceled signals may then be processed by processing fingers of the receiver chains and a controller may determine the number of receiver chains to keep active based on a signal parameter of the processed signal.

Claims

1. A receive-diversity system, comprising:

a plurality of receiver chains;

a controller communicatively coupled to the receiver chains and configured for selecting one or more of the receiver chains to process a received signal; and

a processing engine communicatively coupled to the receiver chains and configured for substantially canceling one or more interferers from the received signal.

2. The receive-diversity system of claim 1, wherein the received signal comprises a plurality of communication signals selected from a group consisting of Code Division Multiple Access signals, Wideband Code Division Multiple Access signals, Global Positioning System signals, and Universal Mobile Telephone Service signals.

3. The receive-diversity system of claim 1, wherein at least one receiver chain comprises a plurality of processing fingers and wherein at least one of the plurality of processing fingers is configured for processing an interference-canceled signal.

4. The receive-diversity system of claim 3, wherein the controller is configured for combining processed signals from the plurality of processing fingers.

5. The receive-diversity system of claim 1, wherein the controller is configured for combining a processed signal from each of the plurality of receiver chains.

6. The receive-diversity system of claim 1, wherein the processing engine comprises a matrix generator configured for generating an interference matrix from at least one of the one or more interferers in a digital signal from one of the plurality of receiver chains.

7. The receive-diversity system of claim 6, wherein the processing engine comprises a processor configured for generating a cancellation operator from the interference matrix.

8. The receive-diversity system of claim 7, wherein the cancellation operator is a projection operator substantially comprising the form:

P_s^⊥

=I−

S(S^TS)<sup>−

1</sup>S^T,

where P_s^⊥

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

9. The receive-diversity system of claim 8, wherein the projection operator is configured for projecting a received signal onto a subspace substantially orthogonal to at least one interfering signal.

10. The receive-diversity system of claim 1, wherein the controller is further configured for comparing a signal parameter to a predetermined threshold to control a number of the plurality of receiver chains.

11. The receive-diversity system of claim 10, wherein the signal parameter is selected from a group consisting of Signal to Noise Ratio, Frame Error Rate, and Bit Error Rate.

12. A method, comprising:

providing for receiving a signal with a first receiver chain;

providing for substantially canceling one or more interferers from the signal;

providing for selecting either a second receiver chain or a combination of the first receiver chain and the second receiver chain to receive the signal based on a signal parameter.

13. The method of claim 12, wherein providing for selecting either the second receiver chain or the combination of the first receiver chain and the second receiver chain comprises providing for comparing the signal parameter to a predetermined value.

14. The method of claim 13, wherein the signal parameter is selected from a group consisting of Signal to Noise Ratio, Frame Error Rate, and Bit Error Rate.

15. The method of claim 12, wherein providing for substantially canceling the one or more interferers comprises providing for generating an interference matrix from the one or more interferers.

16. The method of claim 15, wherein providing for substantially canceling the one or more interferers further comprises providing for generating a cancellation operator from the interference matrix.

17. The method of claim 16, wherein providing for generating the cancellation operator comprises providing for generating a projection operator substantially according to the following form:

P_s^⊥

=I−

S(S^TS)<sup>−

1</sup>S^T,

where P_s^⊥

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

18. The method of claim 16, wherein providing for substantially canceling the one or more interferers further comprises providing for applying the cancellation operator to the signal to substantially cancel the one or more interferers from the signal.

19. The method of claim 17, wherein providing for substantially canceling the one or more interferers further comprises providing for applying the projection operator to the signal to substantially cancel the one or more interferers from the signal.

20. The method of claim 12, further comprising providing for combining a first processed signal of the first receiver chain and a second processed signal of the second receiver chain to improve processing of the signal, wherein the first processed signal and the second processed signal are correlated signals of a signal of interest.

21. The method of claim 20, wherein providing for combining the first processed signal and the second processed signal comprises providing for combining using a Maximal Ratio Combining algorithm or a Minimum Mean Squared Error algorithm.

22. The method of claim 12, further comprising providing for combining processed signals from processing fingers of at least one receiver chain, wherein the processed signals are digital representations of a correlated signal of interest of the at least one receiver chain.

23. The method of claim 21, wherein providing for combining the processed signals comprises providing for combining using a Maximal Ratio Combining algorithm or a Minimum Mean Squared Error algorithm.

24. A digital computer system programmed to perform the method of claim 12.

25. A computer-readable medium storing a computer program implementing the method of claim 12.

26. A method, comprising:

providing for receiving a signal with at least one of a plurality of receiver chains;

providing for substantially canceling one or more interferers from the signal; and

providing for comparing a signal parameter of the signal to a predetermined threshold to control use of the receiver chains.

27. The method of claim 26, further comprising providing for selecting either a first receiver chain or a combination of the first receiver chain and a second receiver chain to process the signal.

28. The method of claim 27 further comprising providing for selecting based on the signal parameter from a group consisting of Signal to Noise Ratio, Frame Error Rate and Bit Error Rate.

29. The method of claim 26, wherein providing for substantially canceling the one or more interferers comprises providing for generating an interference matrix from the one or more interferers.

30. The method of claim 29, wherein providing for substantially canceling the one or more interferers further comprises providing for generating a cancellation operator from the interference matrix.

31. The method of claim 30, wherein providing for generating the cancellation operator comprises providing for generating a projection operator substantially according to the following form:

P_s^⊥

I−

S(S^TS)<sup>−

1</sup>S^T,

where P_s^⊥

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

32. The method of claim 30, wherein providing for substantially canceling the one or more interferers further comprises providing for applying the cancellation operator to the signal to substantially cancel the one or more interferers from the signal.

33. The method of claim 31, wherein providing for substantially canceling the one or more interferers further comprises providing for applying the projection operator to the signal to substantially cancel the one or more interferers from the signal.

34. The method of claim 26, further comprising providing for combining a first processed signal of a first receiver chain and a second processed signal of a second receiver chain to improve processing of the signal, wherein the first and the second processed signals are correlated signals of a signal of interest.

35. The method of claim 34, wherein providing for combining the first processed signal and the second processed signal comprises providing for combining using a Maximal Ratio Combining algorithm or a Minimum Mean Squared Error algorithm.

36. The method of claim 26, further comprising providing for combining processed signals of processing fingers of at least one receiver chain to improve processing of the signal, wherein the processed signals are correlated signals of a signal of interest.

37. The method of claim 35, wherein providing for combining the processed signals comprises combining using a Maximal Ratio Combining algorithm or a Minimum Mean Squared Error algorithm.

38. A digital computer system programmed to perform the method of claim 26.

39. A computer-readable medium storing a computer program implementing the method of claim 26.

40. A receiver, comprising:

a plurality of receiver chains, wherein each receiver chain is configured for receiving a radio signal when directed by a controller and wherein each receiver chain comprises an analog to digital converter configured for converting a received radio signal to a digital signal; and

a processing engine communicatively coupled to each receiver chain and configured for substantially canceling one or more interfering signals from the digital signal of at least one receiver chain to generate an interference-canceled signal.

41. The receiver of claim 40, further comprising the controller, wherein the controller is configured for directing which of the receiver chains is to receive the radio signal.

42. The receiver of claim 41, wherein said at least one receiver chain comprises a plurality of processing fingers and wherein at least one processing finger of said at least one receiver chain is configured for processing the interference-canceled signal.

43. The receiver of claim 42, wherein the controller is further configured for combining processed signals from the processing fingers using a Maximal Ratio Combining algorithm or a Minimum Mean Squared Error algorithm.

44. The receiver of claim 41, wherein the controller is further configured for combining a first processed signal output from the first receiver chain and a second processed signal output from the second receiver chain to improve processing of the digital signal using a Maximal Ratio Combining algorithm or a Minimum Mean Squared Error algorithm, wherein the first and the second processed signals are digital representations of a correlated signal of interest received by the first and the second receiver chains.

45. The receiver of claim 40, wherein the processing engine comprises a matrix generator configured for generating an interference matrix from at least one of the one or more interfering signals of the digital signal.

46. The receiver of claim 45, wherein the processing engine comprises a processor configured for using the interference matrix to generate a cancellation operator.

47. The receiver of claim 46, wherein the cancellation operator is a projection operator substantially comprising the form:

P_s^⊥

=I−

S(S^TS)<sup>−

1</sup>S^T,

where P_s^⊥

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

48. The receiver of claim 47, wherein the projection operator is configured for projecting a digital signal onto a subspace substantially orthogonal to the at least one of the one or more interfering signals.

49. The receiver of claim 46, wherein the processing engine comprises an applicator configured for applying the cancellation operator to the digital signal to generate an interference-canceled signal.

50. The receiver of claim 48, wherein the processing engine comprises an applicator configured for applying the projection operator to the digital signal to generate an interference-canceled signal.

51. The receiver of claim 40, wherein the plurality of receiver chains is adapted to receive a plurality of communications signals selected from a group consisting of Code Division Multiple Access signals, Wideband Code Division Multiple Access signals, Global Positioning System signals and Universal Mobile Telephone Service signals.

52. A receive-diversity system, comprising:

a plurality of receiver chains, wherein at least one receiver chain comprises a processing engine configured for substantially canceling one or more interferers from at least one radio signal received by said at least one receiver chain; and

a controller communicatively coupled to the plurality of receiver chains and configured for selecting one or more of the plurality of receiver chains to process the at least one radio signal.

53. The receive-diversity system of claim 52, wherein a received radio signal comprises a plurality of communication signals selected from a group consisting of Code Division Multiple Access signals, Wideband Code Division Multiple Access signals, Global Positioning System signals, and Universal Mobile Telephone Service signals.

54. The receive-diversity system of claim 52, wherein the at least one receiver chain comprises a plurality of processing fingers and wherein at least one processing finger of said at least one receiver chain is configured for processing an interference-canceled signal generated by the processing engine of the at least one receiver chain.

55. The receive-diversity system of claim 54, wherein the controller is configured for combining processed signals from the processing fingers.

56. The receive-diversity system of claim 52, wherein the controller is configured for combining a processed signal from each of the plurality of receiver chains.

57. The receive-diversity system of claim 52, wherein each of the plurality of receiver chains comprises an Analog to Digital converter configured for converting a received radio signal to a digital signal.

58. The receive-diversity system of claim 57, wherein the processing engine comprises a matrix generator configured for generating an interference matrix from at least one of the one or more interferers in the digital signal.

59. The receive-diversity system of claim 58, wherein the processing engine comprises a processor configured for using the interference matrix to generate a cancellation operator.

60. The receive-diversity system of claim 59, wherein the cancellation operator is a projection operator substantially comprising the form:

P_s^⊥

=I−

S(S^TS)<sup>−

1</sup>S^T,

where P_s^⊥

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

61. The receive-diversity system of claim 60, wherein the projection operator is configured for projecting a digital signal onto a subspace substantially orthogonal to at least one interfering signal.

62. The receive-diversity system of claim 52, wherein the controller is further configured for comparing a signal parameter to a predetermined threshold to control a number of the plurality of receiver chains.

63. The receive-diversity system of claim 62, wherein the signal parameter is selected from a group consisting of Signal to Noise Ratio, Frame Error Rate, and Bit Error Rate.

64. A handset, comprising:

a plurality of receiver chains;

a controller communicatively coupled to the receiver chains and configured for selecting one or more of the receiver chains to process a received signal; and

a processing engine communicatively coupled to the receiver chains and configured for substantially canceling one or more interferers from the received signal.

65. The handset of claim 64, wherein the received signal comprises a plurality of communication signals selected from a group consisting of Code Division Multiple Access signals, Wideband Code Division Multiple Access signals, Global Positioning System signals, and Universal Mobile Telephone Service signals.

66. The handset of claim 64, wherein at least one receiver chain comprises a plurality of processing fingers and wherein at least one of the plurality of processing fingers is configured for processing an interference-canceled signal.

67. The handset of claim 66, wherein the controller is configured for combining processed signals from the plurality of processing fingers.

68. The handset of claim 64, wherein the controller is configured for combining a processed signal from each of the plurality of receiver chains.

69. The handset of claim 64, wherein the processing engine comprises a matrix generator configured for generating an interference matrix from at least one of the one or more interferers in a digital signal from one of the plurality of receiver chains.

70. The handset of claim 69, wherein the processing engine comprises a processor configured for generating a cancellation operator from the interference matrix.

71. The handset of claim 70, wherein the cancellation operator is a projection operator substantially comprising the form:

P_s^⊥

=I−

S(S^TS)<sup>−

1</sup>S^T,

where P_s^⊥

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

72. The handset of claim 71, wherein the projection operator is configured for projecting a received signal onto a subspace substantially orthogonal to at least one interfering signal.

73. The handset of claim 64, wherein the controller is further configured for comparing a signal parameter to a predetermined threshold to control a number of the plurality of receiver chains.

74. The handset of claim 73, wherein the signal parameter is selected from a group consisting of Signal to Noise Ratio, Frame Error Rate, and Bit Error Rate.