Systems and methods for parallel signal cancellation

• US 7,474,690 B2
• Filed: 09/07/2004
• Issued: 01/06/2009
• Est. Priority Date: 11/15/2002
• Status: Active Grant

• Current Assignee: III Holdings 1, LLC
• Original Assignee: TensorComm, Inc. (Rambus Inc.)
• Inventors: Narayan, Anand P., Olson, Eric S.
• Primary Examiner(s): Bayard, Emmanuel
• Application Number:
  US10/935,669
• Publication Number:
  US 20050031023A1
• Time in Patent Office: 1,582 Days
• Field of Search: 375/130, 375/136, 375/143, 375/146, 375/147, 375/148
• US Class Current: 375/148
• CPC Class Codes: H04B 1/71075 Parallel interference cancellation
• CPC Class Codes: H04B 1/7115 Constructive combining of multi-path signals, i.e. RAKE receivers
• CPC Class Codes: H04J 13/0022 PN, e.g. Kronecker

Abstract

The present invention provides systems and methods for parallel interference suppression. A processing engine is used to substantially cancel a plurality of signal paths and selected channel(s) of these signal paths interfering with a selected signal. The processing engine includes a plurality of matrix generators that are used to generate matrices with each matrix comprising elements of one or more of the interfering signal paths and channels selected for cancellation. The processing engine also includes one or more processors for processing the matrices to generate cancellation operators. A plurality of applicators applies the cancellation operators to parallel input signals to substantially cancel the interfering signal from each input signal. These input signals may include received signals and/or reference codes. The embodiments disclosed herein may be particularly advantageous to systems employing CDMA (e.g., such as cdmaOne and cdma2000), Wideband CDMA, Broadband CDMA, UMTS and Global Positioning System (“GPS”) signals.

Claims

1. A processing engine, comprising:

a plurality of matrix generators, wherein each matrix generator is configured for generating a matrix and wherein each matrix comprises one or more vectors with each vector comprising elements of a signal path selected for cancellation;

a processor communicatively coupled to the matrix generators and configured for generating a cancellation operator from each matrix; and

a plurality of applicators, wherein each applicator is communicatively coupled to the processor and configured for applying one or more of the cancellation operators in parallel to an input signal to substantially cancel one or more selected channels.

2. The processing engine of claim 1, wherein the processing engine is configurable with a receiver and wherein the processing engine further comprises a connection element configured for receiving output signals from the applicators and for selecting received said output signals as inputs to processing fingers of the receiver.

3. The processing engine of claim 2, wherein the connection element comprises a plurality of selectors wherein each selector is configured for receiving one or more of the output signals and for selecting said one of the output signals as one of the inputs to one of the processing fingers.

4. The processing engine of claim 3, wherein each selector is further configured for receiving a digitized radio signal comprising one or more Code Division Multiple Access signals and for selecting the digitized radio signal as said one of the inputs to said one of the processing fingers.

5. The processing engine of claim 3, wherein each selector is further configured for receiving a digitized radio signal comprising one or more Wideband Code Division Multiple Access signals and for selecting the digitized radio signal as said one of the inputs to said one of the processing fingers.

6. The processing engine of claim 3, wherein each selector is further configured for receiving a digitized radio signal comprising one or more Global Positioning System signals and for selecting the digitized radio signal as said one of the inputs to said one of the processing fingers.

7. The processing engine of claim 3, wherein the output signals comprise substantially interference canceled signals.

8. The processing engine of claim 7, wherein at least one of the substantially interference canceled signals has selected channels of both a first signal path and a second signal path substantially canceled from the input signal.

9. The processing engine of claim 1, wherein each cancellation operator is a projection operator configured for projecting a signal substantially orthogonal to the selected channels.

10. The processing engine of claim 9, wherein the projection operator comprises 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 one of the matrices and S^T is a transpose of S.

11. The processing engine of claim 1, wherein each application of the cancellation operators comprises the form:

y′

=y−

S(S^TS)<sup>−

1</sup>S^Ty,

where y′

is an output canceled signal, y is a received signal, S is one of the matrices and S^T is a transpose of S.

12. The processing engine of claim 1, at least one application of the cancellation operators is an approximated projection operation comprising the form:

13. The processing engine of claim 1, further comprising an interference selector configured for selecting the signal paths as inputs to the matrix generators.

14. The processing engine of claim 13, wherein the interference selector is further configured for selecting one or more channels of the signal paths for cancellation.

15. The processing engine of claim 13, wherein the interference selector is further configured for providing PN codes of the signal paths to the matrix generators.

16. The processing engine of claim 13, wherein the interference selector selects the signal paths based on a pre-determined criteria selected from a group consisting of amplitude, timing offset and phase.

17. The processing engine of claim 1, wherein the input signal is a reference PN code.

18. The processing engine of claim 1, wherein the input signal is a digitized radio signal.

19. The processing engine of claim 1, wherein each signal path comprises a plurality of channels associated with one PN code.

20. A method of canceling interference, comprising:

generating a plurality of matrices, wherein each matrix comprises one or more vectors with each vector comprising elements of a signal path and one or more channels of the signal path selected for cancellation;

generating one or more cancellation operators from each of the matrices; and

applying each cancellation operator in parallel to an input signal to substantially cancel one or more selected channels.

21. The method of claim 20, wherein generating the cancellation operator comprises generating a projection operator having a 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 one of the matrices and S^T is a transpose of S.

22. The method of claim 20, wherein applying comprises substantially canceling said one or more selected signals according to the form:

y′

=y−

S(S^TS)<sup>−

1</sup>S^Ty,

where y′

is an output canceled signal, y is a received signal, S is one of the matrices and S^T is a transpose of S.

23. The method of claim 20, wherein applying results in an approximated projection operation comprising the form:

24. The method of claim 20, further comprising selecting the signal paths used in generating the plurality of matrices according to a predetermined criteria.

25. The method of claim 24, further comprising providing PN codes of the signal paths to the matrices in response to selecting the signal paths.

26. The method of claim 24, further comprising selecting the one or more channels used in generating the plurality of matrices according to a predetermined criteria.

27. The method of claim 26, further comprising providing selected said one or more channels to the matrices in response to selecting the one or more channels.

28. The method of claim 20, further comprising:

selecting output signals generated in response to applying; and

assigning the output signals as inputs to processing fingers of a receiver.

29. The method of claim 28, further comprising transferring the output signals to the processing fingers in response to assigning the output signals as said inputs to the processing fingers.

30. The method of claim 28, wherein the output signals comprise substantially interference canceled signals.

31. The method of claim 30, wherein at least one of the substantially interference canceled signals has selected channels of both a first signal path and a second signal path substantially canceled from the input signal.

32. The method of claim 28, wherein selecting the output signals comprises:

selecting a first substantially interference canceled output signal for a first of the processing fingers;

selecting a second substantially interference canceled output signal for a second of the processing fingers; and

selecting a third substantially interference canceled output signal for a third of the processing fingers.

33. The method of claim 32, wherein the first substantially interference canceled output signal has selected channels of a first signal path substantially canceled from the input signal, wherein the second substantially interference canceled output signal has selected channels of a second signal path substantially canceled from the input signal, and wherein the third substantially interference canceled output signal has selected channels of both the first and the second signal paths substantially canceled from the input signal.

34. The method of claim 20, further comprising receiving a Code Division Multiple Access signal from which a signal path or channel is selected.

35. The method of claim 20, further comprising receiving a Wideband Code Division Multiple Access signal from which a signal path or channel is selected.

36. The method of claim 20, further comprising receiving a Global Positioning System signal from which a signal path or channel is selected.

37. The method of claim 20, wherein the input signal comprises a reference PN code.

38. The method of claim 20, wherein the input signal is a digitized radio signal.

39. The method of claim 20, wherein each signal path comprises a plurality of channels associated with one PN code.

40. A system for canceling interference, comprising:

means for generating a plurality of matrices, wherein each matrix comprises one or more vectors with each vector comprising elements of a signal path and one or more channels of the signal path selected for cancellation;

means for generating a cancellation operator from each of the matrices; and

means for applying one or more cancellation operators in parallel to an input signal to substantially cancel one or more selected channels.

41. The system of claim 40, wherein the means for generating the cancellation operator comprises means for generating a projection operator having a 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 one of the matrices and S^T is a transpose of S.

42. The system of claim 40, wherein the means for applying comprises means for substantially canceling said one or more selected channels according to the form:

y′

=y−

S(S^TS)<sup>−

1</sup>S^Ty,

where y′

is an output canceled signal, y is a received signal, S is one of the matrices and S^T is a transpose of S.

43. The system of claim 40, wherein the means for applying results in an approximated projection operation comprising the form:

44. The system of claim 40, further comprising means for selecting the signal paths used in generating the plurality of matrices.

45. The system of claim 44, further comprising means for providing PN codes of the signal paths to the matrices in response to selecting.

46. The system of claim 44, further comprising means for selecting the one or more channels used in generating the plurality of matrices.

47. The system of claim 46, further comprising means for providing selected said one or more channels to the matrices in response to selecting the one or more channels.

48. The system of claim 40, further comprising:

means for selecting output signals generated in response to applying; and

means for assigning the output signals as inputs to processing fingers of a receiver.

49. The system of claim 48, further comprising means for transferring the output signals to the processing fingers in response to assigning the output signals as said inputs to the processing fingers.

50. The system of claim 48, wherein the output signals comprise substantially interference canceled signals.

51. The system of claim 50, wherein at least one of the substantially interference canceled signals has selected channels of both a first signal path and a second signal path substantially canceled from the input signal.

52. The system of claim 48, wherein the means for selecting the output signals comprises:

means for selecting a first substantially interference canceled output signal for a first of the processing fingers;

means for selecting a second substantially interference canceled output signal for a second of the processing fingers; and

means for selecting a third substantially interference canceled output signal for a third of the processing fingers.

53. The system of claim 52, wherein the first substantially interference canceled output signal has selected channels of a first signal path substantially canceled from the input signal, wherein the second substantially interference canceled output signal has selected channels of a second signal path substantially canceled from the input signal, and wherein the third substantially interference canceled output signal has selected channels of both the first and the second signal paths substantially canceled from the input signal.

54. The system of claim 40, further comprising means for receiving a Code Division Multiple Access signal from which a signal path or channel is selected.

55. The system of claim 40, further comprising means for receiving a Wideband Code Division Multiple Access signal from which a signal path or channel is selected.

56. The system of claim 40, further comprising means for receiving a Global Positioning System signal from which a signal path or channel is selected.

57. The system of claim 40, wherein the input signal comprises a reference PN code.

58. The system of claim 40, wherein the input signal is a digitized radio signal.

59. The system of claim 40, wherein each signal path comprises a plurality of channels associated with one PN code.

60. A mobile handset, comprising:

a receiver configured for receiving a radio signal; and

a processing engine communicatively coupled to the receiver and comprising

a plurality of matrix generators, wherein each matrix generator is configured for generating a matrix and wherein each matrix comprises one or more vectors with each vector comprising elements of one or more selected channels of a signal path selected for cancellation,

a processor communicatively coupled to the matrix generators and configured for generating one or more cancellation operators from each matrix, and

a plurality of applicators, wherein each applicator is communicatively coupled to the processor and configured for applying one or more of the cancellation operators to an input signal to substantially cancel one or more selected channels.

61. The mobile handset of claim 60, wherein the processing engine further comprises a connection element configured for receiving output signals from the applicators and for selecting received said output signals as inputs to processing fingers of the receiver.

62. The mobile handset of claim 61, wherein the connection element comprises a plurality of selectors wherein each selector is configured for receiving one or more of the output signals and for selecting said one of the output signals as one of the inputs to one of the processing fingers.

63. The mobile handset of claim 62, wherein each selector is further configured for receiving a digitized radio signal comprising one or more Code Division Multiple Access signals and for selecting the digitized radio signal as said one of the inputs to said one of the processing fingers.

64. The mobile handset of claim 62, wherein each selector is further configured for receiving a digitized radio signal comprising one or more Wideband Code Division Multiple Access signals and for selecting the digitized radio signal as said one of the inputs to said one of the processing fingers.

65. The mobile handset of claim 62, wherein each selector is further configured for receiving a digitized radio signal comprising one or more Global Positioning System signals and for selecting the digitized radio signal as said one of the inputs to said one of the processing fingers.

66. The mobile handset of claim 62, wherein the output signals comprise substantially interference canceled signals.

67. The mobile handset of claim 66, wherein at least one of the substantially interference canceled signals has selected channels of both a first signal path and a second signal path substantially canceled from the input signal.

68. The mobile handset of claim 60, wherein each cancellation operator is a projection operator configured for projecting a signal substantially orthogonal to the one or more selected channels.

69. The mobile handset of claim 68, wherein the projection operator comprises 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 one of the matrices and S^T is a transpose of S.

70. The mobile handset of claim 60, wherein each application of the cancellation operators comprises the form:

y′

=y−

S(S^TS)<sup>−

1</sup>S^Ty,

where y′

is an output canceled signal, y is a received signal, S is one of the matrices and S^T is a transpose of S.

71. The mobile handset of claim 60, at least one application of the cancellation operators is an approximated projection operation comprising the form:

72. The mobile handset of claim 60, further comprising an interference selector configured for selecting the signal paths as inputs to the matrix generators.

73. The mobile handset of claim 72, wherein the interference selector is further configured for providing PN codes of the signal paths to the matrix generators.

74. The mobile handset of claim 72, wherein the interference selector selects the signal paths based on a pre-determined criteria selected from a group consisting of amplitude, timing offset and phase.

75. The mobile handset of claim 72, wherein the interference selector is further configured for selecting interfering channels as inputs to the matrix generators.

76. The mobile handset of claim 60, wherein the input signal is a reference PN code.

77. The mobile handset of claim 60, wherein the input signal is a digitized radio signal.

78. The mobile handset of claim 60, wherein each signal path comprises one or more channels associated with one PN code.

79. A processing engine, comprising:

a plurality of matrix generators, wherein each matrix generator is configured for generating a matrix and wherein each matrix comprises one or more vectors with each vector comprising elements of a signal path and one or more channels selected for cancellation;

a processor communicatively coupled to the matrix generators and configured for generating a cancellation operator from each matrix; and

a plurality of applicators, wherein each applicator is communicatively coupled to the processor and configured for applying one of the cancellation operators to an input signal to substantially cancel one or more selected channels,

wherein each cancellation operator is a projection operator configured for projecting a selected signal substantially orthogonal to the one or more selected channels.

80. The processing engine of claim 79, wherein the processing engine is configurable with a receiver and wherein the processing engine further comprises a connection element configured for receiving output signals from the applicators and for selecting received said output signals as inputs to processing fingers of the receiver.

81. The processing engine of claim 80, wherein the connection element comprises a plurality of selectors wherein each selector is configured for receiving one or more of the output signals and for selecting said one of the output signals as one of the inputs to one of the processing fingers.

82. The processing engine of claim 81, wherein each selector is further configured for receiving a digitized radio signal comprising one or more Code Division Multiple Access signals and for selecting the digitized radio signal as said one of the inputs to said one of the processing fingers.

83. The processing engine of claim 81, wherein each selector is further configured for receiving a digitized radio signal comprising one or more Wideband Code Division Multiple Access signals and for selecting the digitized radio signal as said one of the inputs to said one of the processing fingers.

84. The processing engine of claim 81, wherein each selector is further configured for receiving a digitized radio signal comprising one or more Global Positioning System signals and for selecting the digitized radio signal as said one of the inputs to said one of the processing fingers.

85. The processing engine of claim 81, wherein the output signals comprise substantially interference canceled signals.

86. The processing engine of claim 85, wherein at least one of the substantially interference canceled signals has selected channels of both a first signal path and a second signal path substantially canceled from the input signal.

87. The processing engine of claim 79, wherein the projection operator comprises 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 one of the matrices and S^T is a transpose of S.

88. The processing engine of claim 79, wherein each application of the cancellation operators comprises the form:

y′

=y−

S(S^TS)<sup>−

1</sup>S^Ty,

where y′

is an output canceled signal, y is a received signal, S is one of the matrices and S^T is a transpose of S.

89. The processing engine of claim 79, at least one application of the cancellation operators is an approximated projection operation comprising the form:

90. The processing engine of claim 79, further comprising an interference selector configured for selecting the signal paths as inputs to the matrix generators.

91. The processing engine of claim 90, wherein the interference selector is further configured for providing PN codes of the signal paths to the matrix generators.

92. The processing engine of claim 90, wherein the interference selector selects the signal paths based on a pre-determined criteria selected from a group consisting of amplitude, timing offset and phase.

93. The processing engine of claim 90, wherein the interference selector is further configured for selecting channels as inputs to the matrix generators.

94. The processing engine of claim 79, wherein the input signal is a reference PN code.

95. The processing engine of claim 79, wherein the input signal is a digitized radio signal.

96. The processing engine of claim 79, wherein each signal path comprises one or more channels associated with one PN code.