Apparatus and method for dynamic diversity based upon receiver-side assessment of link quality

• US 7,146,134 B2
• Filed: 04/04/2002
• Issued: 12/05/2006
• Est. Priority Date: 02/09/2002
• Status: Active Grant

• Current Assignee: DSP Group Incorporated (Synaptics Incorporated)
• Original Assignee: DSP Group Incorporated (Synaptics Incorporated)
• Inventors: Butenhoff, Michael E, Moon, Jaekyun, Kim, Younggyun, Brickner, Barrett J, Edwards, Paul C
• Primary Examiner(s): BEAMER, TEMICA M
• Application Number:
  US10/117,456
• Publication Number:
  US 20030153358A1
• Time in Patent Office: 1,706 Days
• Field of Search: 455/575.6, 455347-351, 455/101, 455/114.1, 455/115.1, 455/226.1, 455/67.11, 455/67.13, 455/562.1, 343/701, 343/702
• US Class Current: 455/67.11
• CPC Class Codes: H04B 7/0811 during preamble or gap period
• CPC Class Codes: H04B 7/0814 based on current reception conditions, e.g. switching to different antenna when signal level is below threshold
• CPC Class Codes: H04L 1/0001 Systems modifying transmission characteristics according to link quality, e.g. power backoff adaptive data allocation for multicarrier modulation H04L5/0044; controlling transmission power for radio systems H04W52/04
• CPC Class Codes: H04L 1/0015 characterised by the adaptation strategy
• CPC Class Codes: H04L 1/206 for modulated signals

Abstract

An apparatus for dynamic diversity signal reception based upon receiver-side link quality assessments includes two or more antennae. At least one switch is connected to the two or more antennae. A dynamic diversity controller is connected to the at least one switch. The dynamic diversity controller includes a link quality assessor to assess link quality and generate a link characterization value. A diversity configuration selector, responsive to the link characterization value, selectively activates the at least one switch to implement a dynamic diversity configuration. The link quality assessor includes a signal strength analyzer, a modem detector, and/or a MAC layer analyzer to assess the received signal and generate the link characterization value.

Claims

1. An apparatus for dynamic diversity signal reception based upon receiver-side link quality assessment, comprising:

two or more antennae;

at least one switch connected to said two or more antennae; and

a dynamic diversity control module connected to said at least one switch, said dynamic diversity control module including

a link quality assessor to assess a received signal and generate a link characterization value, and

a diversity configuration selector, responsive to said link characterization value, to selectively activate said at least one switch to implement a dynamic diversity configuration to switch between a switched diversity mode and a full diversity mode.

2. The apparatus of claim 1 wherein said link quality assessor processes said received signal as time-domain samples.

3. The apparatus of claim 1 wherein said link quality assessor processes said received signal as frequency-domain samples.

4. The apparatus of claim 1 wherein said link quality assessor processes said received signal as frequency-domain samples, said link quality assessor including N fixed frequency bins, wherein the k-th symbol transmission occupies the (k modulo N)-th frequency bin.

5. The apparatus of claim 1 wherein said link quality assessor includes a signal strength analyzer.

6. The apparatus of claim 1 wherein said link quality assessor measures orthogonal frequency division multiplexing (OFDM) coherence bandwidth to produce a delay spread estimate.

7. The apparatus of claim 1 wherein said link quality assessor measures orthogonal frequency division multiplexing coherence bandwidth from a frequency correlation function to produce a delay spread estimate.

8. The apparatus of claim 1 wherein said link quality assessor measures orthogonal frequency division multiplexing coherence bandwidth from an overall deviation of frequency response from an average value to produce a delay spread estimate.

9. The apparatus of claim 1 wherein said link quality assessor measures the accumulated differences of adjacent tones to produce a delay spread estimate.

10. The apparatus of claim 1 wherein said link quality assessor observes the number of sub-carriers whose signal strength falls below a threshold to produce a delay spread estimate.

12. The apparatus of claim 1 wherein said link quality assessor includes a modem detector to measure internal Viterbi detector parameters.

13. The apparatus of claim 1 wherein said link quality assessor includes a modem detector to identify disagreement between surviving signal paths in a Viterbi detector.

17. The apparatus of claim 1 wherein said diversity configuration selector generates control signals for said at least one switch to selectively implement the switched diversity mode and the full diversity mode.

18. The apparatus of claim 1 wherein said diversity configuration selector generates control signals for said at least one switch to selectively transition from no diversity to the full diversity mode.

19. The apparatus of claim 1 wherein said diversity configuration selector receives a receiver-side link quality measure and a receive signal strength indicator from said link quality assessor.

20. The apparatus of claim 1 wherein only one antenna is turned on during signal listen periods.

21. The apparatus of claim 1 wherein said two antennae are turned on automatically at the beginning of each received packet.

22. The apparatus of claim 1 wherein diversity configuration selection is made at the end of a preamble period of each received packet.

23. The apparatus of claim 1 wherein link quality assessment is based on examination of beacon packets released by a WLAN access point.

24. The apparatus of claim 1 wherein link quality assessment is based on examination of acknowledgment packets released by a WLAN transmitter.

52. The apparatus of claim 1, wherein the link quality assessor includes a modem detector to measure soft decisions captured at the input of a Viterbi detector, measure internal parameters of the Viterbi detector, or identify disagreement between surviving signal paths in the Viterbi detector.

53. The apparatus of claim 1, wherein the link quality assessor includes a MAC layer analyzer to examine MAC layer parameters to assess link quality.

54. The apparatus of claim 53, wherein the MAC layer analyzer uses a MAC analysis that examines Wireless Local Area Network (WLAN) retry sub-fields in a MAC header.

11. An apparatus for dynamic diversity signal reception based upon receiver-side link quality assessment, comprising:

two or more antennas;

a link quality assessor to assess a received signal; and

a diversity configuration selector to selectively activate one of a plurality of diversity antenna configurations based on the assessment, wherein said link quality assessor includes a modem detector to measure soft decisions captured at the input of a Viterbi detector, measure internal parameters of the Viterbi detector, or identify disagreement between surviving signal paths in the Viterbi detector.

55. The apparatus of claim 11, wherein the modem detector measures magnitudes of the soft decisions.

14. An apparatus for dynamic diversity signal reception based upon receiver-side link quality assessment, comprising:

two or more antennas;

a link quality assessor to assess a received signal; and

a diversity configuration selector to selectively activate one of a plurality of diversity antenna configurations based on the assessment, wherein said link quality assessor includes a MAC layer analyzer to examine MAC layer parameters to assess link quality.

15. The apparatus of claim 14, wherein said MAC analysis examines both Wireless Local Area Network (WLAN) retry sub-fields in a MAC header and a CRC check result.

16. The apparatus of claim 14 wherein said link quality assessor includes a modem detector that examines physical (PHY) layer parameters.

56. The apparatus of claim 14, wherein the MAC layer analyzer uses a MAC analysis that examines Wireless Local Area Network (WLAN) retry sub-fields in a MAC header.

25. An apparatus for dynamic diversity signal reception based upon receiver-side link quality assessments, comprising:

two antennae;

a single switch connected to one of said two antennae; and

a dynamic diversity control module connected to said single switch, said dynamic diversity control module including;

a link quality assessor to assess link information received from said two antennae and generate a link characterization value, and

a diversity configuration selector, responsive to said link characterization value, to selectively activate said switch to implement a dynamic diversity configuration to switch between a switched diversity mode and a full diversity mode.

26. The apparatus of claim 25 wherein said dynamic diversity control module turns power on and off for the entire radio frequency and analog signal paths.

57. The apparatus of claim 25, wherein the link quality assessor includes a modem detector to measure soft decisions captured at the input of a Viterbi detector, measure internal parameters of the Viterbi detector, or identify disagreement between surviving signal paths in the Viterbi detector.

58. The apparatus of claim 25, wherein the link quality assessor includes a MAC layer analyzer to examine MAC layer parameters to assess link quality, wherein the MAC layer analyzer uses a MAC analysis that examines Wireless Local Area Network (WLAN) retry sub-fields in a MAC header.

27. An apparatus to facilitate dynamic diversity signal reception, comprising:

a bus;

a control circuit connected to said bus;

input and output devices connected to said bus to route received signal information and transmit a control signal; and

a dynamic diversity control module connected to said bus, said dynamic diversity control module including a link quality assessor and a diversity configuration selector responsive to the link quality assessor to switch between a switched diversity mode and a full diversity mode.

28. The apparatus of claim 27 wherein said link quality assessor includes a signal strength analyzer to process said received signal information and generate a link characterization value that is processed by said diversity configuration selector to generate a control signal to facilitate dynamic diversity signal reception.

29. The apparatus of claim 27 wherein said link quality assessor includes a modem detector to process said received signal information and generate a link characterization value that is processed by said diversity configuration selector to generate a control signal to facilitate dynamic diversity signal reception.

30. The apparatus of claim 27 wherein said link quality assessor includes a medium access control (MAC) layer analyzer to process said received signal information and generate a link characterization value that is processed by said diversity configuration selector to generate a control signal to facilitate dynamic diversity signal reception.

31. The apparatus of claim 27 wherein said diversity configuration selector facilitates selective transitions from no diversity to full diversity configurations.

59. The apparatus of claim 27, wherein the link quality assessor includes a modem detector to measure soft decisions captured at the input of a Viterbi detector, measure internal parameters of the Viterbi detector, or identify disagreement between surviving signal paths in the Viterbi detector.

60. The apparatus of claim 27, wherein the link quality assessor includes a MAC layer analyzer to examine MAC layer parameters to assess link quality, wherein the MAC layer analyzer uses a MAC analysis that examines Wireless Local Area Network (WLAN) retry sub-fields in a MAC header.

32. A method of dynamic diversity selection based upon receiver-side link quality assessments, comprising:

receiving a wireless signal at a wireless mobile device;

assessing link quality using a technique selected from a signal strength analysis, a modem detection analysis, and a medium access control (MAC) analysis; and

switching between a switched diversity mode and a full diversity mode antenna diversity configuration based upon the assessed link quality.

33. The method of claim 32 wherein assessing includes assessing link quality using a signal strength analysis.

34. The method of claim 32 wherein assessing includes assessing link quality by measuring orthogonal frequency division multiplexing coherence bandwidth.

35. The method of claim 32 wherein assessing includes measuring orthogonal frequency division multiplexing coherence bandwidth from a frequency correlation function.

36. The method of claim 32 wherein assessing includes measuring orthogonal frequency division multiplexing coherence bandwidth from an overall deviation of frequency response from an average value.

37. The apparatus of claim 32 wherein assessing includes measuring the accumulated differences of adjacent tones.

38. The apparatus of claim 32 wherein assessing includes observing the number of subcarriers whose signal strength falls below a threshold.

39. The method of claim 32 wherein assessing includes assessing link quality using a modem detection analysis measuring soft decisions captured at the input of a Viterbi detector.

41. The method of claim 32 wherein assessing includes assessing link quality using a modem detection analysis identifying disagreement between surviving signal paths in a Viterbi detector.

44. The method of claim 32 wherein assessing includes assessing link quality using a MAC analysis that examines MAC parameters and a modem detection analysis that examines physical (PHY) layer parameters.

45. The method of claim 32 wherein selecting includes choosing a full diversity mode when said link quality falls below a full diversity mode threshold value.

46. The method of claim 45 wherein selecting includes identifying when said link quality rises above a full diversity mode transition threshold value.

47. The method of claim 46 further comprising identifying the larger of a first antenna receive signal strength indicator and a second antenna receive signal strength indicator.

48. The method of claim 47 further comprising selecting a first antenna single static connection configuration when said first antenna receive signal strength indicator is larger than said second antenna receive signal strength indicator.

49. The method of claim 48 further comprising maintaining said first antenna single static connection configuration while a first antenna receiver-side link quality measure value is above a threshold value.

50. The method of claim 47 further comprising selecting a second antenna single static connection configuration when said second antenna receive signal strength indicator is larger than said first antenna receive signal strength indicator.

51. The method of claim 50 further comprising maintaining said second antenna single static connection configuration while a second antenna receiver-side link quality measure value is above a threshold value.

61. The method of claim 32, wherein assessing includes assessing link quality using a modem detection analysis to measure soft decisions captured at the input of a Viterbi detector, measure internal parameters of the Viterbi detector, or identify disagreement between surviving signal paths in the Viterbi detector.

62. The method of claim 32, wherein assessing includes assessing link quality using a MAC layer analysis to examine MAC layer parameters to assess link quality, wherein the MAC layer analysis examines Wireless Local Area Network (WLAN) retry sub-fields in a MAC header.

63. The method of claim 39, wherein the modem detection analysis measures magnitudes of the soft decisions.

40. A method of dynamic diversity selection based upon receiver-side link quality assessments, comprising:

receiving a wireless signal at a wireless mobile device;

assessing link quality using a modem detection analysis; and

selecting an antenna diversity configuration based upon said assessing, wherein assessing includes assessing link quality using the modem detection analysis to measure internal Viterbi detector parameters, measure soft decisions captured at the input of a Viterbi detector, or identify disagreement between surviving signal paths in a Viterbi detector.

64. The method of claim 40, wherein the modem detection analysis measures magnitudes of the soft decisions.

42. A method of dynamic diversity selection based upon receiver-side link quality assessments, comprising:

receiving a wireless signal at a wireless mobile device;

assessing link quality using a medium access control (MAC) analysis; and

selecting an antenna diversity configuration based upon said assessing, wherein assessing includes assessing link quality using the MAC analysis to examine MAC layer parameters to assess link quality.

43. The method of claim 42 wherein the MAC analysis examines both Wireless Local Area Network (WLAN) retry sub-fields in a MAC header and a CRC check result.

65. The method of claim 42, wherein the MAC layer analysis examines Wireless Local Area Network (WLAN) retry sub-fields in a MAC header.