Method and apparatus for continuously controlling the dynamic range from an analog-to-digital converter

• US 7,522,885 B2
• Filed: 11/21/2005
• Issued: 04/21/2009
• Est. Priority Date: 10/11/2001
• Status: Active Grant

• Current Assignee: WSOU Investments, LLC (WSOU Holdings, LLC)
• Original Assignee: Nokia Corporation
• Inventors: Vepsalainen, Jussi, Parssinen, Aarno, Seppinen, Pauli
• Primary Examiner(s): Urban; Edward
• Assistant Examiner(s): Haroon; Adeel
• Application Number:
  US11/285,541
• Publication Number:
  US 20060079191A1
• Time in Patent Office: 1,247 Days
• Field of Search: 455 6711- 6714, 4552261-2264, 455/232.1, 455/138, 455/139, 455/239.1, 375/245, 375/350, 341/155, 341/164
• US Class Current: 455/67.11
• CPC Class Codes: H03G 3/3068 Circuits generating control signals for both R.F. and I.F. stages
• CPC Class Codes: H04B 1/10 Means associated with receiver for limiting or suppressing noise or interference
• CPC Class Codes: H04B 1/109 by improving strong signal performance of the receiver when strong unwanted signals are present at the receiver input
• CPC Class Codes: H04B 1/16 Circuits

Abstract

A method for continuously determining the required dynamic range for an analog-to-digital converter by determining the received signal strength and using this received signal strength value in combination with the overall dynamic range for the ADC and the target resolution of the ADC to decode a radio channel in the absence of interference, wherein the target resolution is also related to the type of decoding to be performed subsequent to analog-to-digital conversion. The method allows for a reduction in power consumption associated with the ADC, especially when the incoming signal is received with few interfering radio channels and with a relatively high signal strength. The present method can be combined with gain control and analog alert detection.

Claims

1. An apparatus comprising:

an analog-to-digital converter configured to convert at an operating resolution a signal associated with a radio channel into a digital output signal;

a detector in communication with a signal associated with the digital output signal configured to measure a received signal parameter of said radio channel; and

control logic configured to determine the operating resolution based on a full-scale resolution of the analog-to-digital converter, a target resolution, and said received signal parameter, wherein the target resolution is the resolution necessary to decode said radio channel assuming no interference from potentially interfering radio channels.

2. The apparatus as defined in claim 1, wherein the control logic is configured to repetitively determine the operating resolution.

3. The apparatus as defined in claim 2, wherein the control logic is configured to determine the operating resolution to be said full-scale resolution of the analog-to-digital converter less said received signal parameter of said radio channel plus said target resolution.

4. The apparatus as defined in claim 1, wherein the control logic is configured to repetitively determine the operating resolution if the received signal parameter is outside of limits specified for the measurement of said received signal parameter.

5. The apparatus as defined in claim 4, wherein the control logic is configured to determine if said signal as sensed at a test node is changing faster than a predetermined amount, and if true is configured to modify the repetitive determination of the operating resolution.

6. The apparatus of claim 5, wherein the test node is at the output of the analog-to-digital converter.

7. The apparatus of claim 4, wherein said limits are based upon a threshold value.

8. The apparatus of claim 4, wherein said limits are based on a predetermined threshold value for said received signal parameter.

9. The apparatus of claim 4, wherein the control logic is configured to repetitively update the measured received signal parameter if the received signal parameter is within said limits.

10. The apparatus as defined in claim 1, further comprising at least one amplifier configured to amplify said signal associated with said radio channel prior to presenting the signal to the analog-to-digital converter.

11. The apparatus as defined in claim 10, wherein a second detector is configured to measure said digital output signal of the analog-to-digital converter.

12. The apparatus as defined in claim 11, wherein said signal associated with said radio channel is a signal in a radio frequency domain, wherein said at least one amplifier includes a radio frequency amplifier for amplifying said signal while in the radio frequency domain.

13. The apparatus of claim 12, wherein the radio frequency amplifier has an adjustable gain and wherein said control logic is configured to adjust said adjustable gain at least based on said digital output signal of said analog-to-digital converter.

14. The apparatus of claim 10, wherein each of said at least one amplifier has an adjustable gain and wherein said control logic is configured to adjust said adjustable gain based on at least said output signal of said analog-to-digital converter.

15. The apparatus of claim 14, wherein the gain of said at least one amplifier is adjustable based on at least said output signal of said analog-to-digital converter, a fading margin and the full-scale resolution of the analog-to-digital converter.

16. The apparatus of claim 14, wherein the control logic is configured to determine if the signal associated with said radio channel as sensed at a test node is changing faster than a predetermined amount over a period of time, and if true, said control logic is configured to modify the adjusting of the gain of at least one of said at least one amplifier.

17. The apparatus of claim 16, wherein the test node is at an output of one of said at least one amplifier or the output of the analog-to-digital converter.

18. The apparatus of claim 10, wherein the control logic is configured to adjust a gain of said at least one amplifier responsive to the digital output signal of said analog-to-digital converter.

19. The apparatus of claim 18, wherein the control logic is configured to adjust the gain of said at least one amplifier by comparison of said digital output signal with a value at least based on said full-scale resolution and another value.

20. The apparatus of claim 19, wherein said another value is at least based upon a fading margin.

21. The apparatus of claim 1, wherein the measured received signal parameter is based on an average of measurements of said received signal parameter.

22. The apparatus as defined in claim 1, wherein said signal associated with said radio channel is a signal in a radio frequency domain, said apparatus further comprising a radio frequency amplifier configured to amplify said signal while in the radio frequency domain.

23. The apparatus of claim 22, wherein said radio frequency amplifier has an adjustable gain and wherein said control logic is configured to adjust said adjustable gain.

24. The apparatus of claim 1, wherein said detector is configured to average the measured received signal parameter of said radio channel.

25. The apparatus of claim 1, wherein said radio channel is a code division multiple access channel conveying a spread spectrum transmission.

26. The apparatus of claim 25, wherein said code division multiple access channel is a wideband code division multiple access channel.

27. The apparatus of claim 25, wherein the detector measures the power of a received code channel after despreading the transmission of said radio channel.

28. The apparatus of claim 25, wherein the target resolution is a number of bits required to decode received information in a received code channel after despreading the transmission of said radio channel.

29. The apparatus of claim 1, comprising a detector configured to estimate a signal-to-interference ratio and wherein the control logic is configured to determine the operating resolution at least based upon said estimated signal-to-interference ratio.

30. The apparatus of claim 29, wherein the control logic is configured to determine if the estimated signal-to-interference ratio is smaller than an acceptable signal-interference-ratio and wherein the determined operating resolution is a number of bits and is increased by at least one bit if said determination is made.

31. The apparatus of claim 30, wherein the increase in the operating resolution is based upon a predetermined number.

32. The apparatus of claim 1, further comprising a radio frequency amplifier configured to amplify a signal while in the radio frequency domain, and a mixer for receipt of the output of the radio frequency amplifier so as to produce said signal associated with a radio channel.

33. The apparatus of claim 32, wherein the apparatus is configured to measure the output of the analog-to-digital converter and wherein the control logic is configured to adjust the gain of the radio frequency amplifier at least when the measured output of the analog-to-digital converter is greater than a first predetermined value or is less than a second value.

34. The apparatus of claim 33, wherein said second value is at least based upon a second predetermined value.

35. The apparatus of claim 1, wherein the signal associated with a radio channel is a code division multiple access signal.

36. The apparatus of claim 1, wherein said received signal parameter is a received signal strength of said radio channel.

37. The apparatus of claim 36, wherein said detector is a power detector.

38. The apparatus of claim 1, wherein said received signal parameter is a signal-to-interference ratio of said radio channel.

39. The apparatus of claim 1, wherein said received signal parameter includes a received power of a code division multiple access channel conveying a spread spectrum transmission.

40. The apparatus of claim 39, wherein said target resolution is at least based on a code channel power.

41. The apparatus of claim 1, wherein said target resolution is at least based on a code channel power of a code division multiple access channel conveying a spread spectrum transmission.

42. The apparatus of claim 1, wherein the apparatus is configured for use in a cellular communication system.

43. The apparatus as defined in claim 1, wherein said detector in communication with said signal associated with said digital output signal is configured so that the measuring of said received signal parameter is such that the detector is configured to determine a first signal parameter based on a signal associated with the digital output signal after filtering and despreading and a second signal parameter based on a signal associated with the digital output signal prior to said filtering, and further wherein said control logic is configured to determine the operating resolution based on said full-scale resolution of the analog-to-digital converter, the target resolution, and said first and second parameters.

44. An apparatus as defined in claim 43, wherein said radio channel is a code division multiple access channel conveying a spread spectrum transmission.

45. The apparatus as defined in claim 43, wherein the target resolution is the number of bits required to decode received information in a received code channel after despreading the transmission of said radio channel.

46. A radio receiver comprising:

an apparatus according to claim 1; and

a decoder in communication with said digital output signal so as to decode the radio channel.

47. The radio receiver as defined in claim 46, wherein the control logic is configured to repetitively determine the operating resolution.

48. A radio receiver as defined in claim 47, wherein the control logic is configured to determine the operating resolution to be said full-scale resolution of the analog-to-digital converter less the received signal parameter of said radio channel plus said target resolution.

49. A radio receiver as defined in claim 46, wherein the control logic is configured to repetitively determine the operating resolution if the received signal parameter is outside of limits specified for the measurement of said received signal parameter.

50. A radio receiver as defined in claim 49, wherein the control logic is configured to determine if the signal associated with said radio channel is changing faster than a predetermined amount, and if true, is configured to modify the repetitive determination of the operating resolution.

51. A radio receiver as defined in claim 46, further comprising at least one amplifier configured to amplify said signal associated with said radio channel prior to presenting the signal to the analog-to-digital converter.

52. A radio receiver as defined in claim 51, wherein said signal associated with said radio channel is a signal in a radio frequency domain, wherein a first amplifier is configured to amplify said signal after said signal has passed through a mixer, and a second amplifier is a radio frequency amplifier configured to amplify said signal while in the radio frequency domain prior to presenting said signal to said mixer.

53. A control module comprising:

a control logic configured to receive a detected value of a signal parameter based on a signal associated with a digital output signal of an analog-to-digital converter and configured to determine an operating resolution of said analog-to-digital converter based on the value of the signal parameter, a full-scale resolution of the analog-to-digital converter, and a target resolution indicative of a resolution necessary to decode a radio channel assuming no interference from potentially interfering radio channels.

54. The control module of claim 53, wherein the control logic is configured to repetitively receive said detected value and to repetitively determine said operating resolution.

55. The control module of claim 53, wherein the control logic is further configured to receive a signal indicative of an output of at least one amplifier associated with the generation of said detected value, and further configured to generate a signal for adjusting a gain of said at least one amplifier.

56. The control module of claim 55, wherein the control logic is configured to generate a signal for adjusting a gain of said at least one amplifier so as to reduce said operating resolution of said analog-to-digital converter.

57. The control module of claim 53, wherein said radio channel is a code division multiple access channel conveying a spread spectrum transmission.

58. The control module of claim 57, wherein the detected value is a value of a received code channel after despreading the transmission of said radio channel.

59. The control module of claim 57, wherein the target resolution is a number of bits required to decode received information in a received code channel after despreading the transmission of said radio channel.

60. The control module of claim 53, wherein said detected value is a signal strength of said radio channel.

61. The control module of claim 53, wherein said detected value is a signal-to-interference ratio of said radio channel.

62. The control module of claim 53, wherein said detected value includes a power of a code division multiple access channel conveying a spread spectrum transmission.

63. The control module as defined in claim 53, wherein said detector in communication with said signal associated with said digital output signal is configured so that the measuring of said received signal parameter is such that the detector is configured to determine a first signal parameter based on a signal associated with the digital output signal after filtering and despreading and a second signal parameter based on a signal associated with the digital output signal prior to said filtering, and further wherein said control logic is configured to determine the operating resolution based on said full-scale resolution of the analog-to-digital converter, the target resolution, and said first and second parameters.

64. The control module as defined in claim 63, wherein said radio channel is a code division multiple access channel conveying a spread spectrum transmission.

65. The control module as defined in claim 63, wherein the target resolution is the number of bits required to decode received information in a received code channel after despreading the transmission of said radio channel.

66. A method comprising:

performing an analog to digital conversion at an operating resolution of a signal associated with a radio channel into a digital output signal by an analog-to-digital converter;

measuring a received signal parameter of said radio channel based on a signal associated with said digital output signal; and

determining the operating resolution based on a full-scale resolution, a target resolution, and said received signal parameter, wherein the target resolution is a resolution necessary to decode said radio channel assuming no interference from potentially interfering radio channels.

67. The method of claim 66, wherein the determining of the operating resolution is performed repetitively.

68. The method of claim 67, further comprising modifying the repetitive determination of the operating resolution when a signal associated with said radio channel is changing faster than a predetermined amount.

69. The method of claim 66, wherein the operating resolution is the full-scale resolution less said received signal parameter of said radio channel plus said target resolution.

70. The method of claim 66, wherein the determining of the operating resolution is performed repetitively if the received signal parameter is outside of limits specified for the measurements of received signal parameter.

71. The method of claim 70, wherein said limits are based on a predetermined threshold value of said received signal parameter.

72. The method of claim 66, further comprising amplifying said signal associated with said radio channel prior to converting the signal into a digital output signal.

73. The method of claim 72, wherein the amplifying has an adjustable gain that is adjusted so as to reduce the determined operating resolution.

74. The method of claim 73, wherein the adjustable gain is adjusted by comparing said digital output signal with a value at least based on said full-scale resolution and another value.

75. The method of claim 74, wherein said another value is at least based upon a fading margin.

76. The method of claim 66, wherein said signal associated with said radio channel is a signal in a radio frequency domain, said method further comprising amplifying said signal while in the radio frequency domain.

77. The method of claim 76, wherein the amplifying has an adjustable gain that is adjusted so as to reduce the determined operating resolution.

78. The method of claim 66, wherein the measuring of said received signal parameter of said radio channel is based on an average of measurements of said received signal parameter.

79. The method of claim 66, wherein said received signal parameter is a signal-to-interference ratio of said radio channel.

80. The method of claim 66, wherein said received signal parameter includes a received power of a code division multiple access channel conveying a spread spectrum transmission.

81. The method of claim 80, wherein said target resolution is at least based on a code channel power.

82. The method of claim 66, wherein said target resolution is at least based on a code channel power of a code division multiple access channel conveying a spread spectrum transmission.

83. The method according to claim 66, wherein the measuring of said received signal parameter determines a first signal parameter based on a signal associated with the digital output signal after filtering and despreading and a second signal parameter based on a signal associated with the digital output signal prior to said filtering, and further wherein the determining the operating resolution is based on said full-scale resolution of the analog-to-digital converter, the target resolution, and said first and second parameters.

84. The method as defined in claim 83, wherein said radio channel is a code division multiple access channel conveying a spread spectrum transmission.

85. The method as defined in claim 83, wherein the target resolution is the number of bits required to decode received information in a received code channel after despreading the transmission of said radio channel.

86. An apparatus comprising:

means for converting at an operating resolution a signal associated with a radio channel into a digital output signal;

means for measuring a received signal parameter of said radio channel based on a signal associated with the digital output signal; and

means for determining the operating resolution based on a full-scale resolution of the analog-to-digital converter, a target resolution, and said received signal parameter, wherein the target resolution is the resolution necessary to decode said radio channel assuming no interference from potentially interfering radio channels.

87. The apparatus of claim 86, wherein the means for determining the operating resolution repetitively determines said operating resolution.

88. The apparatus of claim 86, wherein the received signal parameter is a received signal strength of said radio channel.