Systems and methods for analog to digital conversion with a signal cancellation system of a receiver

• US 20050163039A1
• Filed: 12/07/2004
• Published: 07/28/2005
• Est. Priority Date: 01/23/2004
• 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 7,477,710 B2
• Time in Patent Office: Days
• US Class Current: 370/204
• CPC Class Codes: H04B 1/7103 the interference being multiple access interference
• CPC Class Codes: H04B 1/7107 Subtractive interference cancellation

Abstract

The present invention provides systems and methods for signal cancellation with a receiver. The receiver comprises a discretizer configured for generating digital signals at different resolutions from a received analog signal. Processing fingers of the receiver generate spreading codes from at least one of the digital signals while a Coded Signal Processing Engine (“CSPE”) substantially cancels interference from at least another one of the digital signals. The spreading codes are transferred to the CSPE where they may be used to construct an interference matrix. One or more cancellation operators may be generated and subsequently applied to the digital signal(s) input to the CSPE to substantially cancel the interference therefrom. The CSPE may adjust the number of bits of the substantially interference cancelled signal(s) to meet a requisite bit width or dynamic range of the receiver. The substantially cancelled signal(s) is then transferred to the processing fingers for further processing.

Claims

1. A system, comprising:

a receiver front end configured for receiving an analog signal and comprising a plurality of discretizers, wherein each of said plurality of discretizers is configured for converting the analog signal to a digital signal, wherein a first discretizer of said plurality of discretizers is configured to sample the analog signal at a first resolution to generate a first digital signal for processing by a receiver at a first bit width, wherein a second discretizer of the said plurality of discretizers is configured to sample the analog signal at a second resolution to generate a second digital signal at a second bit width, and wherein the first bit width is different from the second bit width; and

a processing engine communicatively coupled to the second discretizer and configured for substantially canceling one or more interfering signals of the second digital signal.

2. The system of claim 1, wherein the second bit width is greater than the first bit width.

3. The system of claim 1, wherein each of said plurality of discretizers comprises an analog to digital converter configured for converting the analog signal.

4. The system of claim 1, wherein each of said plurality of discretizers comprises a gain controller configured for adjusting gain.

5. The system of claim 1, wherein the receiver front end is configurable with a receiver selected from a group consisting of a handset receiver and a base station receiver.

6. The system of claim 1, wherein the processing engine comprises a matrix generator configured for generating an interference matrix from at least one code of the one or more interfering signals.

7. The system of claim 6, wherein the processing engine comprises a canceller configured for generating a cancellation operator from the interference matrix and for applying the cancellation operator to the second digital signal to generate a substantially interference cancelled second digital signal.

8. The system of claim 7, wherein the cancellation operator comprises a projection operator configured for projecting the second digital signal onto a subspace substantially orthogonal to a subspace of the one or more interfering signals.

9. The system of claim 8, wherein the projection operator substantially 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 the interference matrix and S^T is a transpose of S.

10. A mobile handset, comprising:

a receiver front end configured for receiving a radio signal, converting the radio signal to a baseband signal and filtering the baseband signal;

a discretizer communicatively coupled to the receiver front end and configured for generating first and second digital signal streams from a filtered said baseband signal, wherein the first digital signal stream has a first number of bits and the second digital signal stream has a second number of bits;

a processing engine communicatively coupled to the discretizer and configured for substantially canceling one or more interfering signals of the first digital signal stream and for scaling a substantially cancelled said first digital signal stream to comprise the second number of bits; and

one or more processing fingers, wherein a processing finger of said one or more processing fingers is communicatively coupled to the processing engine for processing the substantially cancelled said first digital signal stream comprising the second number of bits.

11. The mobile handset of claim 10, wherein the processing finger of said one or more processing fingers comprises a spreading code generator configured for generating at least one code of the one or more interfering signals and for transferring said at least one code to the processing engine.

12. The mobile handset of claim 10, wherein the processing finger of said one or more processing fingers comprises a tracking element configured for receiving and tracking the substantially cancelled said first digital signal stream comprising the second number of bits.

13. The mobile handset of claim 10, wherein the processing finger of said one or more processing fingers comprises a correlator configured for demodulating the substantially cancelled said first digital signal stream comprising the second number of bits.

14. The mobile handset of claim 10, wherein the processing engine comprises a matrix generator configured for generating an interference matrix from at least one code of the one or more interfering signals.

15. The mobile handset of claim 14, wherein the processing engine comprises a canceller configured for generating a cancellation operator from the interference matrix and for applying the cancellation operator to the first digital signal stream to generate the substantially cancelled said first digital signal stream.

16. The mobile handset of claim 15, wherein the cancellation operator comprises a projection operator configured for projecting the first digital stream onto a subspace substantially orthogonal to the one or more interfering signals.

17. The mobile handset of claim 16, wherein the projection operator substantially 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 the interference matrix and S^T is a transpose of S.

18. The mobile handset of claim 10, wherein the discretizer comprises:

a first analog to digital converter configured for generating the first digital signal stream with the first number of bits; and

a second analog to digital converter configured for generating the second digital signal stream with the second number of bits.

19. The mobile handset of claim 18, wherein the discretizer further comprises a first gain controller communicatively coupled to the first analog to digital converter and configured for adjusting gain of the first digital signal stream.

20. The mobile handset of claim 18, wherein the discretizer further comprises a second gain controller communicatively coupled to the second analog to digital converter and configured for adjusting gain of the second digital signal stream.

21. The mobile handset of claim 20, wherein the first number of bits is greater than the second number of bits.

22. The mobile handset of claim 10, wherein the processing engine comprises a gain configured for scaling a substantially cancelled said first digital signal stream to comprise the second number of bits.

23. A method of performing signal cancellation within a receiver, comprising:

receiving an analog signal;

sampling the analog signal at a first resolution to generate a first digital signal;

sampling the analog signal at a second resolution to generate a second digital signal;

generating an interference code from the first digital signal; and

using the interference code to substantially cancel an interfering signal from the second digital signal.

24. The method of claim 23, wherein using the interference code comprises generating a cancellation operator from the interference code.

25. The method of claim 24, wherein generating the cancellation operator comprises generating an interference matrix from the interference from the code.

26. The method of claim 24, wherein generating the cancellation operator comprises generating a projection operator configured for projecting the second digital signal onto a subspace that is substantially orthogonal to the interfering signal.

27. The method of claim 26, wherein generating the projection operator comprises generating the projection operator substantially according to 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 an interference matrix and S^T is a transpose of S.

28. The method of claim 23, further comprising sampling the second digital signal at the first resolution in response to using the interference code to substantially cancel the interfering signal.

29. The method of claim 28, further comprising processing the second digital signal to extract information in response to sampling the second digital signal at the first resolution.

30. The method of claim 29, wherein processing the second digital signal comprises correlating the second digital signal to demodulate the second digital signal.

31. The method of claim 23, further comprising transferring the first digital signal to at least one processing finger of a receiver to generate one or more interference codes.

32. The method of claim 31, further comprising transferring the second digital signal to a processing engine of a receiver to substantially cancel one or more interfering signals of the second digital signal using said one or more interference codes.

34. A digital computer system programmed to perform the method of claim 23.

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

36. A digital computer system programmed to perform the method of claim 25.

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

38. A digital computer system programmed to perform the method of claim 27.

39. A digital computer system programmed to perform the method of claim 28.

40. A digital computer system programmed to perform the method of claim 29.

41. A digital computer system programmed to perform the method of claim 30.

42. A digital computer system programmed to perform the method of claim 31.

43. A digital computer system programmed to perform the method of claim 32.

45. A computer-readable medium storing a computer program implementing the method of claim 23.

46. A computer-readable medium storing a computer program implementing the method of claim 24.

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

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

49. A computer-readable medium storing a computer program implementing the method of claim 27.

50. A computer-readable medium storing a computer program implementing the method of claim 28.

51. A computer-readable medium storing a computer program implementing the method of claim 29.

52. A computer-readable medium storing a computer program implementing the method of claim 30.

53. A computer-readable medium storing a computer program implementing the method of claim 31.

54. A computer-readable medium storing a computer program implementing the method of claim 32.

33. A method of improving data extraction of a receiver, comprising:

receiving an analog signal;

sampling the analog signal at a first resolution to generate a first digital signal;

sampling the analog signal at a second resolution to generate a second digital signal;

processing the first digital signal with a processing finger of the receiver to generate a code of an interfering signal;

transferring the code of the interfering signal to a processing engine of the receiver to generate an interference matrix;

generating a cancellation operator from the interference matrix;

applying the cancellation operator to the second digital signal to cancel the interfering signal from the second digital signal to generate a substantially interference cancelled signal; and

scaling the substantially interference cancelled signal to configure the substantially interference cancelled signal with a number of bits of the first digital signal; and

processing the substantially interference cancelled signal with the processing finger of the receiver to extract data in response to scaling the substantially interference cancelled signal.

44. A digital computer system programmed to perform the method of claim 33.

55. A computer-readable medium storing a computer program implementing the method of claim 33.

56. A receiver, comprising:

a discretizer configured for generating first and second digital signals from a received analog signal, wherein the first and the second digital signals comprises respective first and second numbers of bits;

a processing engine communicatively coupled to the discretizer and configured for substantially canceling one or more interfering signals of the second digital signal; and

at least one processing finger configured for processing either the first digital signal or the second digital signal after substantial cancellation of the one or more interfering signals.

57. The receiver of claim 56, wherein the receiver is configurable with either or both of a handset and a base station.

58. The receiver of claim 56, wherein said at least one processing finger comprises a spreading code generator configured for generating, from the first digital signal, a code of an interfering signal of said one or more interfering signals.

59. The receiver of claim 58, wherein the processing engine comprises a matrix generator configured for using the code to generate an interference matrix.

60. The receiver of claim 59, wherein the processing engine comprises a signal canceller configured for generating a cancellation operator from the interference matrix.

61. The receiver of claim 60, wherein the cancellation operator comprises a projection operator configured for projecting the second digital signal onto a subspace substantially orthogonal to a subspace of the one or more interfering signals.

62. The receiver of claim 61, wherein the projection operator substantially 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 the interference matrix and S^T is a transpose of S.

63. The receiver of claim 56, wherein the processing engine is further configured for receiving first digital signal and for canceling said one or more interfering signals from the first digital signal to generate a substantially cancelled first digital signal.

64. The receiver of claim 63, wherein the processing engine comprises a selector configured for selecting and transferring either the substantially cancelled said first digital signal or the second digital signal to said at least one processing finger.

65. A system for performing signal cancellation within a receiver, comprising:

means for receiving an analog signal;

means for sampling the analog signal at a first resolution to generate a first digital signal;

means for sampling the analog signal at a second resolution to generate a second digital signal;

means for generating an interference code from the first digital signal; and

means for using the interference code to substantially cancel an interfering signal from the second digital signal.

66. The system of claim 65, wherein the means for generating a cancellation operator from the interference code comprises means for generating the interference code.

67. The system of claim 66, wherein the means for generating the cancellation operator comprises means for generating an interference matrix from the interference from the code.

68. The system of claim 66, wherein the means for generating the cancellation operator comprises means for generating a projection operator configured for projecting a second digital signal onto a subspace that is substantially orthogonal to a subspace of the interfering signal.

69. The system of claim 68, wherein the means for generating the projection operator comprises means for generating the projection operator substantially according to the form:

P_s<sup>=I−

S</sup>(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.

70. The system of claim 65, further comprising means for sampling the second digital signal at the first resolution in response to using the interference code to substantially cancel the interfering signal.

71. The system of claim 70, further means for comprising processing the second digital signal to extract information in response to sampling the second digital signal at the first resolution.

72. The system of claim 71, wherein the means for processing the second digital signal comprises means for correlating the second digital signal to demodulate the second digital signal.

73. The system of claim 65, further comprising means for transferring the first digital signal to at least one processing finger of a receiver to generate one or more interference codes.

74. The system of claim 73, further comprising means for transferring the second digital signal to a processing engine of a receiver to substantially cancel one or more interfering signals of the second digital signal using said one or more interference codes.

75. A system of improving data recovery of a receiver, comprising:

means for receiving an analog signal;

means for sampling the analog signal at a first resolution to generate a first digital signal;

means for sampling the analog signal at a second resolution to generate a second digital signal;

means for processing the first digital signal with a processing finger of the receiver to generate a code of an interfering signal;

means for transferring the code of the interfering signal to a processing engine of the receiver to generate an interference matrix;

means for generating a cancellation operator from the interference matrix;

means for applying the cancellation operator to the second digital signal to cancel the interfering signal from the second digital signal to generate a substantially interference cancelled signal; and

means for scaling the substantially interference cancelled signal to configure the substantially interference cancelled signal with a number of bits of the first digital signal; and

means for processing the substantially interference cancelled signal with a processing finger of the receiver to extract data in response to scaling the substantially interference cancelled signal.