Systems and methods for serial cancellation

• US 20050123080A1
• Filed: 12/03/2004
• Published: 06/09/2005
• Est. Priority Date: 11/15/2002
• Status: Abandoned Application

• Current Assignee: Rambus Inc.
• Original Assignee: Rambus Inc.
• Inventors: Narayan, Anand P., Olson, Eric S.
• Application Number:
  US11/003,881
• Publication Number:
  US 20050123080A1
• Time in Patent Office: Days
• US Class Current: 375/346
• CPC Class Codes: H04B 1/7097 Interference-related aspects

Abstract

The systems and methods described and illustrated herein provide for serial interference suppression. In one embodiment, a Coded Signal Processing Engine (“CSPE”) serially cancels a plurality of channels corresponding to a plurality of signal paths interfering with a selected signal. For example, in a first interference cancellation, the CSPE may generate a first cancellation operator that is used to project a signal onto a subspace that is substantially orthogonal to a subspace of an interfering signal path and channels of that path. The CSPE may subsequently perform another signal cancellation on the interference canceled output signal of the first signal cancellation by generating a second cancellation operator that projects the signal onto a subspace that is substantially orthogonal to a subspace of another interfering signal path and associated channels. The interference canceled output signal of the second cancellation, therefore, has at least two signals substantially canceled.

Claims

1. A processing engine, comprising:

a first input configured for receiving an input signal;

a plurality of outputs, wherein each output is configured for providing a substantially interference canceled signal;

at least one second input configured for receiving one of the substantially interference canceled signals from one of the outputs,

wherein the processing engine is configured for substantially canceling an interfering signal from the input signal and from at least one of the substantially interference canceled signals.

2. The processing engine of claim 1, wherein the processing engine is configurable with at least one of a handset receiver and a base station receiver.

3. The processing engine of claim 1, further comprising an interference selector configured for receiving the input signal and the substantially interference canceled signal and for selecting an interfering signal from each of the input signal and said at least one substantially interference canceled signal.

4. The processing engine of claim 3, further comprising a plurality of matrix generators, wherein each of the plurality of matrix generators is communicatively coupled to the interference selector and configured for generating a matrix based on a selected interfering signal provided by the interference selector.

5. The processing engine of claim 4, wherein each of the plurality of matrix generators is configured to generate a matrix constructed from at least one vector to produce a plurality of matrices, and wherein each of the at least one vector comprises elements from the selected interfering signal.

6. The processing engine of claim 4, wherein the processing engine is further configured for substantially canceling a plurality of interfering signals from the input signal or from at least one of the substantially interference canceled signals wherein each matrix generator is configured for generating a matrix based on a selected plurality of interfering signals.

7. The processing engine of claim 6, wherein the plurality of matrix generators are adapted to construct the plurality of matrices from at least one vector, and wherein at least one of the at least one vector is a composite vector comprising elements from at least two of the selected plurality of interfering signals.

8. The processing engine of claim 1, further comprising a processor configured for generating a plurality of cancellation operators, wherein each cancellation operator is used to substantially cancel one of the interfering signals to produce at least one substantially interference canceled signal.

9. The processing engine of claim 8, further comprising a plurality of applicators, wherein each applicator is communicatively coupled to the processor and configured for applying one of the cancellation operators to either the input signal or said at least one substantially interference canceled signal.

10. The processing engine of claim 9, wherein at least one of the applicators is configured for applying one of the cancellation operators according to the form:

y=y−

S(S^TS)<sup>−

1</sup>S^T y,

where y′

is an output canceled signal, y is a received signal, S is an interference matrix and S^T is a transpose of S.

11. The processing engine of claim 8, wherein each cancellation operator is a projection operator configured for projecting either the input signal or said at least one substantially interference canceled signal onto a subspace that is substantially orthogonal to one of the interfering signals.

12. The processing engine of claim 11, wherein each projection operator comprises the form:

P_s^⊥

=I−

S(S^TS)<sup>−

1</sup>S^T,

wherein P_s^⊥

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

13. The processing engine of claim 8, wherein at least one of the cancellation operators is configured to substantially cancel one of the interfering signals via an approximated projection operation comprising the form:

14. The processing engine of claim 1, wherein the input signal comprises a plurality of digital signals selected from a group consisting of a Code Division Multiple Access signal, a Wideband Code Division Multiple Access signal, a broadband Code Division Multiple Access signal, a Global Positioning Signal, and a Universal Mobile Telephone Service signal.

15. The processing engine of claim 1, further comprising at least one delay element, wherein each of the at least one delay element is used for compensating delay introduced by the processing engine.

16. The processing engine of claim 1, further comprising at least one advance element, wherein each of the at least one advance element is adapted to advance an on-time PN code by a duration substantially equal to delay introduced by the processing engine.

17. A method, comprising:

providing for receiving an input signal;

providing for substantially canceling a signal interfering with the input signal to generate a first substantially interference canceled signal;

providing for receiving the first substantially interference canceled signal; and

providing for substantially canceling a signal interfering with the first substantially interference canceled signal to generate a second substantially interference canceled signal.

18. The method of claim 17, further comprising providing for generating a cancellation operator in response to receiving the input signal.

19. The method of claim 18, wherein providing for generating the cancellation operator comprises providing for generating a projection operator according to the form:

P_s^⊥

=I−

S(S^TS)<sup>−

1</sup>S^T,

wherein P_s^⊥

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

20. The method of claim 17, wherein providing for substantially canceling the signal interfering with the input signal comprises providing for performing a cancellation operation on the input signal according to the form:

y′

=y−

S(S^TS)<sup>−

1</sup>S^T y,

where y′

is the first substantially interference canceled signal, y is a received signal, S is an interference matrix and S^T is a transpose of S.

21. The method of claim 17, wherein providing for substantially canceling the signal interfering with the input signal comprises providing for performing a cancellation operation on the input signal resulting in an approximated projection comprising the form:

22. The method of claim 17, further comprising providing for generating a cancellation operator in response to receiving the first substantially interference canceled signal.

23. The method of claim 22, wherein providing for generating the cancellation operator comprises providing for generating a projection operator according to the form:

P_x^⊥

=I−

S(S^TS)<sup>−

1</sup>S^T,

wherein P_s^⊥

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

24. The method of claim 17, wherein providing for substantially canceling the signal interfering with the first substantially interference canceled signal comprises providing for performing a cancellation operation on the first substantially interference canceled signal according to the form:

y″

=y′

−

S(S^TS)<sup>−

1</sup>S^T y,

where y″

is the second substantially interference canceled signal, y′

is the first substantially interference canceled signal, S is an interference matrix and S^T is a transpose of S.

25. The method of claim 17, wherein providing for substantially canceling the signal interfering with the first substantially interference canceled signal comprises providing for performing a cancellation operation on the first substantially interference canceled signal resulting in an approximated projection operation comprising the form:

26. The method of claim 17, further comprising providing for transferring the first substantially interference canceled signal and the second substantially interference canceled signal to a receiver.

27. The method of claim 26, wherein the receiver is configurable with a handset or a base station.

28. The method of claim 17, wherein the input signal comprises a plurality of digital signals selected from a group consisting of a Code Division Multiple Access signal, a Wideband Code Division Multiple Access signal, a broadband Code Division Multiple Access signal, a Global Positioning Signal and a Universal Mobile Telephone Service signal.

29. The method of claim 17, further comprising providing for delaying the input to compensate for delay introduced by the processing engine.

30. The method of claim 17, further comprising providing for advancing an on-time PN code by a duration substantially equal to delay introduced by the processing engine.

50. A digital computer system programmed to perform the method of claim 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 46, 47, 48, or 49.

51. A computer-readable medium storing a computer program implementing the method of claim 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 46, 47, 48, or 49.

31. A system, comprising:

an input signal coupler configured for receiving an input signal;

an interference canceller configured for substantially canceling a signal interfering with the input signal to generate a first substantially interference canceled signal;

an interference canceled signal coupler configured for receiving the first substantially interference canceled signal, wherein the interference canceller is further configured for substantially canceling a signal interfering with the first substantially interference canceled signal to generate a second substantially interference canceled signal.

32. The system of claim 31, further comprising means for generating a cancellation operator in response to receiving the input signal.

33. The system of claim 32, wherein the means for generating the cancellation operator comprises means for generating a projection operator according to the form:

P_s^⊥

=I−

S(S^TS)<sup>−

1</sup>S^T,

wherein P_s^⊥

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

34. The system of claim 31, wherein the means for substantially canceling the signal interfering with the input signal comprises means for performing a cancellation operation on the input signal according to the form:

y′

=y−

S(S^TS)<sup>−

1</sup>S^T y,

where y′

is the first substantially interference canceled signal, y is a received signal, S is an interference matrix and S^T is a transpose of S.

35. The system of claim 31, wherein the means for substantially canceling the signal interfering with the input signal comprises means for performing a cancellation operation on the input signal resulting in an approximated projection comprising the form:

36. The system of claim 31, further comprising means for generating a cancellation operator in response to receiving the first substantially interference canceled signal.

37. The system of claim 36, wherein the means for generating the cancellation operator comprises means for generating a projection operator according to the form:

P_s^⊥

=I−

S(S^TS)<sup>−

1</sup>S^T,

wherein P_s^⊥

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

38. The system of claim 31, wherein the means for substantially canceling the signal interfering with the first substantially interference canceled signal comprises means for applying a cancellation operator to the input signal according to the form:

y″

=y′

−

S(S^TS)<sup>−

1</sup>S^T y,

where y′

is the second substantially interference canceled signal, y′

is the first substantially interference canceled signal, S is an interference matrix and S^T is a transpose of S.

39. The system of claim 31, wherein the means for substantially canceling the signal interfering with the first substantially interference canceled signal comprises means for performing a cancellation operation on the first substantially interference canceled signal according to the form:

y″

=y′

−

S(S^TS)<sup>−

1</sup>S^T y,

where y″

is the second substantially interference canceled signal, y′

is the first substantially interference canceled signal, S is an interference matrix and S^T is a transpose of S.

40. The system of claim 31, wherein the means for substantially canceling the signal interfering with the first substantially interference canceled signal comprises means for performing a cancellation operation on the first substantially interference canceled signal resulting in an approximated projection operation comprising the form:

41. The system of claim 31, further comprising means for transferring the first substantially interference canceled signal and the second substantially interference canceled signal to a receiver.

42. The system of claim 41, wherein the receiver is configurable with a handset or a base station.

43. The system of claim 31, wherein the input signal comprises a plurality of digital signals selected from a group consisting of a Code Division Multiple Access signal, a Wideband Code Division Multiple Access signal, a broadband Code Division Multiple Access signal, a Global Positioning Signal, and a Universal Mobile Telephone Service signal.

44. The system of claim 31, further comprising one or more delay elements, wherein each of the one or more delay elements is configured for compensating delay introduced by the processing engine.

45. The system of claim 31, further comprising one or more advance elements, wherein each of the one or more advance elements is configured for advancing an on-time PN code by a duration substantially equal to delay introduced by the processing engine.

46. A method, comprising:

providing for receiving an input signal in an Coded Signal Processing Engine;

providing for selecting a first set of one or more interfering signals from the input signal to generate a selected first set of one or more interfering signals;

providing for generating a cancellation operator from the selected first set of one or more interfering signals;

providing for using the cancellation operator to substantially cancel the selected first set of one or more interfering signals and to generate a first substantially interference canceled signal;

providing for transferring the first substantially interference canceled signal to the Coded Signal Processing Engine; and

providing for selecting a second set of one or more interfering signals from the first substantially interference canceled signal to generate a selected second set of one or more interfering signals;

providing for generating a cancellation operator from the selected second set of one or more interfering signals;

providing for using the cancellation operator to substantially cancel the selected second set of one or more interfering signals and to generate a second substantially interference canceled signal;

47. The method of claim 46, wherein providing for generating the cancellation operator comprises providing for generating a projection operator according to the form:

P_s^⊥

=I−

S(S^TS)<sup>−

1</sup>S^T,

wherein P_s^⊥

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

48. The method of claim 46, wherein providing for using the cancellation operator to substantially cancel either the selected said first set of one or more interfering signals or the selected said second set of one or more interfering signals comprises providing for applying a cancellation operator according to the form:

y′

=y−

S(S^TS)<sup>−

1</sup>S^T y,

where y is either an uncanceled signal or an interference canceled signal, y′

is a new interference canceled signal, S is an interference matrix and S^T is a transpose of S.

49. The method of claim 46, wherein providing for using the cancellation operator to substantially cancel either the selected first set of one or more interfering signals or the selected second set of one or more interfering signals comprises means for performing a cancellation resulting in an approximated projection operation according the form:

52. A handset comprising a processing engine, the processing engine comprising:

a first input configured for receiving an input signal;

a plurality of outputs, wherein each output is configured for providing a substantially interference canceled signal;

at least one second input configured for receiving one of the substantially interference canceled signals from one of the outputs,

wherein the processing engine is configured for substantially canceling an interfering signal from the input signal and from at least one of the substantially interference canceled signals.

53. The handset recited in claim 52, further comprising an interference selector configured for receiving the input signal and the substantially interference canceled signal and for selecting an interfering signal from each of the input signal and said at least one substantially interference canceled signal.

54. The handset of claim 53, further comprising a plurality of matrix generators, wherein each of the plurality of matrix generators is communicatively coupled to the interference selector and configured for generating a matrix based on a selected interfering signal provided by the interference selector.

55. The handset of claim 54, wherein each of the plurality of matrix generators is configured to generate a matrix constructed from at least one vector to produce a plurality of matrices, and wherein each of the at least one vector comprises elements from the selected interfering signal.

56. The handset of claim 54, wherein the processing engine is further configured for substantially canceling a plurality of interfering signals from the input signal or from at least one of the substantially interference canceled signals wherein each matrix generator is configured for generating a matrix based on a selected plurality of interfering signals.

57. The handset of claim 56, wherein the plurality of matrix generators are adapted to construct the plurality of matrices from at least one vector, and wherein at least one of the at least one vector is a composite vector comprising elements from at least two of the selected plurality of interfering signals.

58. The handset of claim 52, further comprising a processor configured for generating a plurality of cancellation operators, wherein each cancellation operator is used to substantially cancel one of the interfering signals to produce at least one substantially interference canceled signal.

59. The handset of claim 58, further comprising a plurality of applicators, wherein each applicator is communicatively coupled to the processor and configured for applying one of the cancellation operators to either the input signal or said at least one substantially interference canceled signal.

60. The handset of claim 59, wherein at least one of the applicators is configured for applying one of the cancellation operators according to the form:

y′

=y−

S(S^TS)<sup>−

1</sup>S^T y,

where y′

is an output canceled signal, y is a received signal, S is an interference matrix and S^T is a transpose of S.

61. The handset of claim 58, wherein each cancellation operator is a projection operator configured for projecting either the input signal or said at least one substantially interference canceled signal onto a subspace that is substantially orthogonal to one of the interfering signals.

62. The handset of claim 61, wherein each projection operator comprises the form:

P_s^⊥

=I−

S(S^TS)<sup>−

1</sup>S^T,

wherein P_s^⊥

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

63. The handset of claim 58, wherein at least one of the cancellation operators is configured to substantially cancel one of the interfering signals via an approximated projection operation comprising the form:

64. The handset of claim 52, wherein the input signal comprises a plurality of digital signals selected from a group consisting of a Code Division Multiple Access signal, a Wideband Code Division Multiple Access signal, a broadband Code Division Multiple Access signal, a Global Positioning Signal, and a Universal Mobile Telephone Service signal.

65. The processing engine of claim 52, further comprising at least one delay element, wherein each of the at least one delay element is used for compensating delay introduced by the processing engine.

66. The processing engine of claim 52, further comprising at least one advance element, wherein each of the at least one advance element is adapted to advance an on-time PN code by a duration substantially equal to delay introduced by the processing engine.

67. A handset, comprising:

an antenna configured for receiving a radio signal, wherein the radio signal comprises at least one signal of interest and one or more interfering signals;

an analog to digital converter configured for converting the radio signal to a digital signal;

an input signal coupler configured for receiving the digital signal to produce an input signal;

an interference canceller configured for substantially canceling a signal interfering with the input signal to generate a first substantially interference canceled signal;

an interference canceled signal coupler configured for receiving the first substantially interference canceled signal, wherein the interference canceller is further configured for substantially canceling a signal interfering with the first substantially interference canceled signal to generate a second substantially interference canceled signal.

68. The handset of claim 67, further comprising means for generating a cancellation operator in response to receiving the input signal.

69. The handset of claim 68, wherein the means for generating the cancellation operator comprises means for generating a projection operator according to the form:

P_s^⊥

=I−

S(S^TS)<sup>−

1</sup>S^T,

wherein P_s^⊥

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

70. The handset of claim 67, wherein the interference canceller comprises means for performing a cancellation operation on the input signal according to the form:

y′

=y−

S(S^TS)<sup>−

1</sup>S^T y,

where y′

is the first substantially interference canceled signal, y is a received signal, S is an interference matrix and S^T is a transpose of S.

71. The handset of claim 67, wherein the interference canceller comprises means for performing a cancellation operation on the input signal resulting in an approximated projection comprising the form:

72. The handset of claim 67, further comprising means for generating a cancellation operator in response to receiving the first substantially interference canceled signal.

73. The handset of claim 72, wherein the means for generating the cancellation operator comprises means for generating a projection operator according to the form:

P_s^⊥

=I−

S(S^TS)<sup>−

1</sup>S^T,

wherein P_s^⊥

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

74. The handset of claim 67, wherein the interference canceller comprises means for applying a cancellation operator to the input signal according to the form:

y″

=y′

−

S(S^TS)<sup>−

1</sup>S^T y,

where y′

is the second substantially interference canceled signal, y′

is the first substantially interference canceled signal, S is an interference matrix and S^T is a transpose of S.

75. The handset of claim 67, wherein the interference canceller comprises means for performing a cancellation operation on the first substantially interference canceled signal according to the form:

y″

=y′

−

S(S^TS)<sup>−

1</sup>S^T y,

where y″

is the second substantially interference canceled signal, y′

is the first substantially interference canceled signal, S is an interference matrix and S^T is a transpose of S.

76. The handset of claim 67, wherein the interference canceller comprises means for performing a cancellation operation on the first substantially interference canceled signal resulting in an approximated projection operation comprising the form:

77. The handset of claim 67, further comprising means for transferring the first substantially interference canceled signal and the second substantially interference canceled signal to a receiver.

78. The handset of claim 77, wherein the receiver is configurable with a handset or a base station.

79. The handset of claim 67, wherein the input signal comprises a plurality of digital signals selected from a group consisting of a Code Division Multiple Access signal, a Wideband Code Division Multiple Access signal, a broadband Code Division Multiple Access signal, a Global Positioning Signal, and a Universal Mobile Telephone Service signal.

80. The system of claim 67, further comprising one or more delay elements, wherein each of the one or more delay elements is configured for compensating delay introduced by the processing engine.

81. The system of claim 67, further comprising one or more advance elements, wherein each of the one or more advance elements is configured for advancing an on-time PN code by a duration substantially equal to delay introduced by the processing engine.