Gain control for interference cancellation

• US 20050101277A1
• Filed: 12/14/2004
• Published: 05/12/2005
• Est. Priority Date: 11/19/2001
• Status: Abandoned Application

• Current Assignee: Rambus Inc.
• Original Assignee: Rambus Inc.
• Inventors: Narayan, Anand P., Olson, Eric S.
• Application Number:
  US11/012,817
• Publication Number:
  US 20050101277A1
• Time in Patent Office: Days
• US Class Current: 455/232.100
• CPC Class Codes: H03G 3/3089 Control of digital or coded signals
• CPC Class Codes: H04B 1/7107 Subtractive interference cancellation

Abstract

Systems and methods for adjusting amplitude of an input signal through the application of a gain term are presented. In one embodiment, the gain controller comprises a scaling element that scales the overall signal energy after interference cancellation is performed. This scaling may compensate for overall signal energy reduction resulting from interference cancellation that improves the SNR of the signals of interest. Since prior art receivers typically adjust signal amplitude at the front-end, the gain controller may adjust the amplitude of an interference-canceled signal to a level that is substantially comparable to the level after front-end scaling. The gain controller also comprises a receiving element configured for receiving either an output canceled signal or an uncanceled received signal as an input. For example, the gain controller may receive an interference-canceled signal output from a Coded Signal Processing Engine or a signal with no interfering components removed.

Claims

1. A system, comprising:

a processing engine configured for substantially canceling one or more interfering signals from an input signal to generate an interference-canceled signal; and

a gain controller configured for receiving the interference-canceled signal, the interference-canceled signal having an amplitude and for amplitude adjusting the interference-canceled signal for producing an amplitude adjusted interference-canceled signal.

2. The system of claim 1, wherein the gain controller is an automatic gain control.

3. The system of claim 1, wherein the gain controller is configured for amplitude adjusting the interference-canceled signal to a predetermined amplitude value.

4. The system of claim 1, wherein the gain controller comprises a receiving element configured for receiving either the input signal or the interference-canceled signal.

5. The system of claim 4, wherein the gain controller is further configured for amplitude adjusting the input signal for producing an amplitude adjusted input signal upon receiving the input signal.

6. The system of claim 5, wherein the gain controller comprises a selector configured for selecting either the amplitude adjusted input signal or the amplitude adjusted interference-canceled signal.

7. The system of claim 6, configurable with a receiver to provide either the amplitude adjusted input signal or the amplitude adjusted interference-canceled signal to the receiver.

8. The system of claim 6, wherein the gain controller comprises memory configured for storing a previous gain value of the amplitude adjusted interference-canceled signal.

9. The system of claim 8, further comprising a memory location used to store the previous gain value of a lookup table.

10. The system of claim 8, wherein the gain controller comprises a comparator configured for receiving a bypass signal used by the comparator to retrieve the previous gain value.

11. The system of claim 10, wherein the gain controller is further configured for restoring the amplitude of the interference-canceled signal to substantially a previous amplitude in response to a change in the bypass signal.

12. The system of claim 8, wherein the gain controller comprises a selector configured for receiving a bypass signal used by the selector to specify whether the amplitude adjusted interference-canceled signal or the amplitude adjusted input signal is transferred to the receiver.

13. The system of claim 8, wherein the gain controller comprises a comparator configured for receiving a reset signal used by the comparator for deleting the previous gain value.

14. The system of claim 13, wherein the reset signal used by the comparator is configured to specify an initial value.

15. The system of claim 14, wherein the initial value is a fixed value.

16. The system of claim 14, wherein the initial value is determined from energy of an interfering signal.

17. A gain controller, comprising:

a receiving element configured for receiving either an interference-canceled signal or an input signal; and

a scaling element configured for amplitude adjusting either a received said interference-canceled signal or a received said input signal based on a characteristic of the received said interference-canceled signal or the received said input signal.

18. The gain controller of claim 17, wherein the scaling element is configured as an automatic gain controller.

19. The gain controller of claim 17, wherein the amplitude of the received said interference-canceled signal or the received said input signal is adjusted to a predetermined value to provide either an amplitude adjusted said input signal or an amplitude adjusted said interference-canceled signal.

20. The gain controller of claim 19, wherein the predetermined value is determined by front-end circuitry of a receiver.

21. The gain controller of claim 19, wherein the scaling element comprises a selector configured for selecting the amplitude adjusted said input signal or the amplitude adjusted said interference-canceled signal.

22. The gain controller of claim 21, wherein the gain controller is configurable with a receiver and wherein the selector is further configured to provide either the amplitude adjusted said input signal or the amplitude adjusted said interference-canceled signal to the receiver.

23. The gain controller of claim 19, wherein the scaling element comprises memory configured for storing a previous gain value of the amplitude adjusted said interference-canceled signal.

24. The gain controller of claim 23, wherein the scaling element comprises a comparator configured for receiving a bypass signal used by the comparator to retrieve the previous gain value.

25. The gain controller of claim 24, wherein the scaling element is further configured for substantially restoring the amplitude of the interference-canceled signal by applying the previous gain value in response to a change in the bypass signal.

26. The gain controller of claim 23, wherein the scaling element comprises a comparator configured for receiving a reset signal used by the comparator for deleting the previous gain value.

27. The gain controller of claim 26, wherein the reset signal used by the comparator is configured to specify an initial gain value.

28. The gain controller of claim 27, wherein the initial gain value is a fixed value.

29. The gain controller of claim 27, wherein the initial gain value is determined from energy of an interfering signal.

30. The gain controller of claim 17, wherein the scaling element comprises a memory location for storing a previous gain value of a lookup table.

31. The gain controller of claim 19, wherein the scaling element comprises a selector configured for receiving a bypass signal used by the selector to specify whether the amplitude adjusted interference-canceled signal or the amplitude adjusted said input signal is transferred to the receiver.

32. A mobile handset, comprising:

a receiver configured for receiving an analog signal and for converting the analog signal into a digital signal;

a processing engine configured for receiving the digital signal and substantially canceling one or more interfering components of the digital signal to generate an interference-canceled signal; and

a gain controller configured for receiving the interference-canceled signal and for amplitude adjusting the interference-canceled signal to produce an amplitude adjusted interference-canceled signal.

33. The mobile handset of claim 32, wherein the gain controller is an automatic gain control.

34. The mobile handset of claim 32, wherein the gain controller is further configured for amplitude adjusting the interference-canceled signal to a predetermined amplitude value.

35. The mobile handset of claim 32, wherein the gain controller comprises a receiving element configured for receiving either the digital signal or the interference-canceled signal.

36. The mobile handset of claim 35, wherein the gain controller further comprises a selector configured for selecting either an amplitude adjusted digital signal produced from the digital signal or the amplitude adjusted interference-canceled signal for producing either a selected amplitude adjusted digital signal or a selected amplitude adjusted interference-canceled signal.

37. The mobile handset of claim 36, wherein the selector is further configured for receiving a bypass signal used by the selector to select either the amplitude adjusted digital signal or the amplitude adjusted interference-canceled signal.

38. The mobile handset of claim 36, wherein the receiver is further configured for processing the selected amplitude adjusted digital signal or the selected amplitude adjusted interference-canceled signal, and wherein the gain controller is further configured to provide either the selected amplitude adjusted digital signal or the selected amplitude adjusted interference-canceled signal to the receiver.

39. The mobile handset of claim 32, wherein the gain controller comprises memory configured for storing a previous gain value of the amplitude adjusted interference-canceled signal.

40. The mobile handset of claim 39, wherein the gain controller further comprises a memory location for storing a previous gain value of a lookup table.

41. The mobile handset of claim 40, wherein the gain controller comprises a comparator configured for receiving a bypass signal used by the comparator to retrieve the previous gain value.

42. The mobile handset of claim 41, wherein the gain controller is further configured for restoring the gain value of the interference-canceled signal to the previous gain value in response to a change in the bypass signal.

43. The mobile handset of claim 32, wherein the gain controller comprises a selector configured for receiving a bypass signal used by the selector to specify whether the amplitude adjusted interference-canceled signal or the amplitude adjusted digital signal is transferred to the receiver.

44. The mobile handset of claim 32, wherein the gain controller comprises a comparator configured for receiving a reset signal used by the comparator for deleting a previous gain value.

45. The mobile handset of claim 44, wherein the reset signal used by the comparator is configured to specify an initial gain value.

46. The mobile handset of claim 45, wherein the initial gain value is a fixed value.

47. The mobile handset of claim 45, wherein the initial gain value is determined from energy of an interfering signal.

48. A gain controller circuit for use with an interference canceller, comprising:

a receiving element configured for receiving an interference-canceled signal; and

a scaling element configured for amplitude adjusting the interference-canceled signal for producing an amplitude adjusted interference canceled signal.

49. The gain controller circuit of claim 48, wherein the receiving element is further configured for receiving either an input signal or the interference-canceled signal.

50. The gain controller circuit of claim 48, further comprising a selector configured for selecting either an amplitude adjusted input signal or the amplitude adjusted interference-canceled signal as an output signal of the gain controller circuit.

51. The gain controller circuit of claim 50, further configurable with a receiver to provide the output signal to the receiver.

52. A method, comprising:

providing for receiving a first digital signal;

providing for adjusting amplitude of the first digital signal in response to receiving the first digital signal;

providing for receiving a second digital signal; and

providing for bypassing the first digital signal from amplitude adjustment in response to receiving the second digital signal.

53. The method of claim 52, further comprising providing for selecting the first digital signal as an input signal to a receiver in response to adjusting.

54. The method of claim 52, further comprising providing for selecting the second digital signal as an input signal to a receiver in response to bypassing.

55. The method of claim 52, further comprising providing for storing a gain value corresponding to the first digital signal in memory in response to adjusting.

56. The method of claim 52, further comprising providing for receiving a bypass signal, wherein the bypass signal is used to initiate bypassing the first digital signal.

57. The method of claim 56, further comprising providing for bypassing the second digital signal in response to a change in the bypass signal.

58. The method of claim 57, further comprising providing for retrieving a previous gain value of the first digital signal from memory in response to bypassing the second digital signal.

59. The method of claim 58, further comprising providing for multiplying the first digital signal by a restored said previous gain value in response to retrieving.

60. The method of claim 58, further comprising providing for deleting the previous gain value in response to receiving a reset signal.

61. The method of claim 60, further comprising providing for configuring the reset signal used by the comparator to specify an initial gain value.

62. The method of claim 61, wherein the initial gain value is a fixed value.

63. The method of claim 61, wherein the initial gain value is determined from energy of an interfering signal.

103. A digital computer system programmed to perform the method of claim 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, or 74.

104. A computer-readable medium storing a computer program implementing the method of claim 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, or 74.

64. A method, comprising:

providing for receiving an analog signal;

providing for converting the analog signal into a digital signal;

providing for substantially canceling one or more interfering components from the digital signal to generate an interference-canceled signal;

providing for adjusting amplitude of the interference-canceled signal in response to substantially canceling the one or more interfering components to generate an amplitude adjusted interference-canceled signal.

65. The method of claim 64, further comprising:

providing for receiving a bypass signal; and

providing for interrupting said adjusting in response to receiving the bypass signal.

66. The method of claim 65, further comprising providing for amplitude adjusting the digital signal in response to receiving the bypass signal to generate an amplitude adjusted digital signal.

67. The method of claim 66, further comprising providing for conveying the amplitude adjusted digital signal to a receiver in response to adjusting the amplitude of the digital signal.

68. The method of claim 65, further comprising providing for storing a gain value of the amplitude adjusted said interference-canceled signal in response to receiving the bypass signal.

69. The method of claim 64, further comprising providing for conveying the amplitude adjusted interference-canceled signal to a receiver in response to adjusting the amplitude of the interference-canceled signal.

70. A method, comprising:

providing for receiving either an interference-canceled signal or an input signal for producing either a received interference-canceled signal or a received input signal; and

providing for amplitude adjusting of either the received interference-canceled signal or the received input signal to produce either an amplitude adjusted input signal or an amplitude adjusted interference-canceled signal; and

providing for transferring either of the amplitude adjusted input signal or the amplitude adjusted interference-canceled signal to a receiver.

71. The method of claim 70, wherein said providing for amplitude adjusting comprises providing either the amplitude adjusted input signal or the amplitude adjusted interference-canceled signal with substantially a predetermined amplitude value.

72. The method of claim 70, wherein said providing for amplitude adjusting comprises providing for applying a gain multiplier to either the interference-canceled signal or the input signal.

73. The method of claim 71, further comprising providing for receiving a bypass signal, wherein the bypass signal is used to store a gain value of the amplitude adjusted interference-canceled signal.

74. The method of claim 73, further comprising providing for retrieving a previous gain value of the amplitude adjusted interference-canceled signal in response to a change in the bypass signal.

75. A system, comprising:

means for receiving a first digital signal;

means for amplitude adjustment of the first digital signal in response to receiving the first digital signal;

means for receiving a second digital; and

means for bypassing the first digital signal from amplitude adjustment in response to receiving the second digital signal.

76. The system of claim 75, further comprising means for selecting the first digital signal as an input signal to a receiver in response to amplitude adjustment.

77. The system of claim 75, further comprising means for selecting the second digital signal as an input signal to a receiver in response to bypassing.

78. The system of claim 75, further comprising means for storing a gain value corresponding to the first digital signal in memory in response to amplitude adjustment.

79. The system of claim 75, further comprising means for receiving a bypass signal, wherein the bypass signal is used to initiate bypassing the first digital signal.

80. The system of claim 79, further comprising means for bypassing the second digital signal in response to a change in the bypass signal.

81. The system of claim 80, further comprising means for retrieving a previous gain value of the first digital signal from memory in response to bypassing the second digital signal.

82. The system of claim 81, further comprising means for substantially restoring the first digital signal to substantially the previous amplitude in response to retrieving the previous gain value.

83. The system of claim 82, further comprising means for deleting the previous gain value in response to receiving a reset signal.

84. The system of claim 82, wherein the reset signal used by the comparator is configured to specify an initial gain value.

85. The system of claim 83, wherein the initial gain value is a fixed value.

86. The system of claim 83, wherein the initial gain value is determined from energy of an interfering signal.

87. A system, comprising:

means for receiving an analog signal;

means for converting the analog signal into a digital signal;

means for substantially canceling one or more interfering components from the digital signal to generate an interference-canceled signal;

means for amplitude adjusting the interference-canceled signal in response to substantially canceling the one or more interfering components to generate an amplitude adjusted interference-canceled signal.

88. The system of claim 87, further comprising:

means for receiving a bypass signal; and

means for forgoing said amplitude adjusting in response to receiving the bypass signal.

89. The system of claim 88, further comprising means for amplitude adjusting the digital signal in response to receiving the bypass signal to generate an amplitude adjusted digital signal.

90. The system of claim 89, further comprising means for providing the amplitude adjusted digital signal to a receiver in response to amplitude adjusting the digital signal.

91. The system of claim 88, further comprising means for storing a gain value of the amplitude adjusted interference-canceled signal in response to receiving the bypass signal.

92. The system of claim 87, further comprising means for providing the amplitude adjusted interference-canceled signal to a receiver in response to amplitude adjusting the interference-canceled signal.

93. A system, comprising:

means for receiving either an interference-canceled signal or an input signal to produce either a received interference-canceled signal or a received input signal; and

means for amplitude adjusting either the received interference-canceled signal or the received input signal.

94. The system of claim 93, wherein said means for amplitude adjusting comprises means for amplitude adjusting either the received interference-canceled signal or the received input signal to a predetermined value to provide either an amplitude adjusted input signal or an amplitude adjusted interference-canceled signal.

95. The system of claim 93, wherein said means for amplitude adjusting comprises means for applying a gain multiplier to either the received interference-canceled signal or the received input signal.

96. The system of claim 94, further comprising means for providing either of the amplitude adjusted input signal or the amplitude adjusted interference-canceled signal to a mobile handset receiver.

97. The system of claim 94, further comprising means for receiving a bypass signal, wherein the bypass signal is used to store a gain value of the amplitude adjusted interference-canceled signal.

98. The system of claim 97, further comprising means for retrieving a previous gain value of the amplitude adjusted interference-canceled signal in response to a change in the bypass signal.

99. The system of claim 98, further comprising means for deleting the previous gain value in response to receiving a reset signal.

100. The system of claim 99, wherein the reset signal used by the comparator is configured to specify an initial gain value.

101. The system of claim 100, wherein the initial gain value is a fixed value.

102. The system of claim 100, wherein the initial gain value is determined from energy of an interfering signal.