Rate adaptation in wireless systems

• US 7,864,678 B1
• Filed: 12/11/2003
• Issued: 01/04/2011
• Est. Priority Date: 08/12/2003
• Status: Active Grant

• Current Assignee: Marvell Asia Pte Limited (Marvell Technology Group Limited)
• Original Assignee: Marvell International Limited (Marvell Technology Group Limited)
• Inventors: Sampath, Hemanth, Narasimhan, Ravi
• Primary Examiner(s): Pham; Chi H.
• Assistant Examiner(s): HOM, SHICK C
• Application Number:
  US10/734,440
• Time in Patent Office: 2,581 Days
• Field of Search: None
• US Class Current: 370/232
• CPC Class Codes: H04W 28/22 Negotiating communication rate
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks

Abstract

A transceiver in an ad hoc network may use a rate adaptation module to select an optimal data rate for a given wireless environment. The rate adaptation module may use a measured RSSI (Received Signal Strength Indicator) from a receive section and a retry count from a transmit section to determine the optimal data rate.

Claims

1. A method performed by at least one device of a communication system, the method comprising:

determining a signal quality value from received packets transmitted at a first data transmission rate;

determining a packet loss indicator value from transmitted packets transmitted at a second different data transmission rate;

selecting a third different data transmission rate in response to the signal quality value determined from the received packets transmitted at the first data transmission rate and the packet loss indicator value determined from the transmitted packets transmitted at the second different data transmission rate, wherein the selecting includes selecting the third different data transmission rate from a plurality of available data transmission rates, and each of the plurality of available data transmission rates is different from the first data transmission rate and the second different data transmission rate;

transmitting packets at the third different data transmission rate; and

generating a confidence value for each of a plurality of available data transmission rates using the signal quality value and the packet loss indicator value.

2. The method of claim 1, wherein the signal quality value is selected from an RSSI (Received Signal Strength Indicator) value, an SNR (signal to noise ratio) value, an SINR (signal to interference noise ratio) value, and a SQM (signal quality measure) value, the SQM value comprising a mean of the SNRs across all of a plurality of tones.

3. The method of claim 1, wherein the packet loss indicator value is selected from a retry counter value, a bit-error update value, a packet error update value, a symbol error update value, and a CRC (Cyclic Redundancy Check) indicator value.

4. The method of claim 1, further comprising:

generating an adjustment value for the signal quality value from the packet loss indicator value.

5. The method of claim 4, wherein the signal quality value comprises an RSSI value.

6. The method of claim 5, further comprising:

generating an average received signal strength indicator (RSSI_avg) value, and

wherein the adjustment value comprises a Δ

_RSSI value, the Δ

_RSSI value comprising an adjustment to the RSSI_avg value.

7. The method of claim 6, wherein said generating the confidence value comprises solving the equation:

Confidence[j]=RSSI_avg−

RSSI_TH[j]−

Δ

_RSSI,

where RSSI_TH[j] comprises a nominal received signal strength value associated with a data transmission rate [j] in a table.

8. The method of claim 7, wherein said selecting the third different data transmission rate comprises selecting a data transmission rate associated with a positive confidence value.

9. The method of claim 7, wherein said selecting the third different data transmission rate comprises selecting a data transmission rate associated with a lowest positive confidence value.

10. The method of claim 4, further comprising:

updating the adjustment value in response to the packet loss indicator value indicating a maximum failure value corresponding to an excessive number of failed packet transmissions.

11. The method of claim 4, further comprising:

updating the adjustment value in response to the packet loss indicator value indicating a maximum success value corresponding to an excessive number of success packet transmissions.

12. The method of claim 1, further comprising:

increasing a transmit power for transmitting packets in response to the selected data transmission rate falling below a first threshold data transmission rate; and

decreasing the transmit power in response to the selected data transmission rate exceeding a second threshold data transmission rate.

13. The method of claim 12, wherein the second threshold data transmission rate is greater than the first threshold data transmission rate.

14. The method of claim 1, further comprising:

decreasing the selected data transmission rate in response to the packet loss indicator value increasing.

15. The method of claim 14, wherein said decreasing comprises decreasing the selected data transmission rate in response to data transmission rate values in a table indexed by available data transmission rates and packet loss indicator values.

16. The method of claim 1, further comprising:

selecting a fourth data transmission rate value directly from the packet loss indicator value in response to the signal quality value falling below a minimum signal quality value.

67. The method of claim 1, wherein the transmitted packets and received packets comply with one of the IEEE 802.11 family of specifications.

17. An apparatus comprising:

a transceiver including;

a transmit section operative to transmit packets at a first data transmission rate and to determine a packet loss indicator value;

a receive section operative to receive packets at a second different data transmission rate and to determine a signal quality value from said received packets; and

a rate selector operative to select a third different data transmission rate in response to the signal quality value determined from the packets received at the second different data transmission rate and the packet loss indicator value determined from the packets transmitted at the first data transmission rate, wherein the rate selector selects the third different data transmission rate from a plurality of available data transmission rates, and each of the plurality of available data transmission rates is different from the first data transmission rate and the second different data transmission rate, wherein the rate selector is further operative to generate a confidence value for each of a plurality of available data transmission rates using the signal quality value and the packet loss indicator value.

18. The apparatus of claim 17, wherein the signal quality value is selected from an RSSI (Received Signal Strength Indicator) value, an SNR (signal to noise ratio) value, an SINR (signal to interference noise ratio) value, and a SQM (signal quality measure) value, the SQM value comprising a mean of the SNRs across all of a plurality of tones.

19. The apparatus of claim 17, wherein the packet loss indicator value is selected from a retry counter value, a bit-error update value, a packet error update value, a symbol error update value, and a CRC (Cyclic Redundancy Check) indicator value.

20. The apparatus of claim 17, further comprising:

a table including the plurality of available data transmission rates, each available data transmission rate associated with a nominal signal quality value.

21. The apparatus of claim 17, further comprising:

a retry processor operative to generate an adjustment value for the signal quality value from the packet loss indicator value.

22. The apparatus of claim 21, wherein the signal quality value comprises an RSSI value.

23. The apparatus of claim 22, further comprising a filter to generate an average received signal strength indicator (RSSI_avg) value, and

wherein the adjustment value comprises a Δ

_RSSI value, the Δ

_RSSI value comprising an adjustment to the RSSI_avg value.

24. The apparatus of claim 23, wherein the rate selector is further operative to generate the confidence value by solving the equation:

Confidence[j]=RSSI_avg−

RSSI_TH[j]−

Δ

_RSSI,

where RSSI_TH[j] comprises a nominal received signal strength value associated with a data transmission rate [j] in a table.

25. The apparatus of claim 24, wherein the rate selector is operative to select a third different data transmission rate associated with a positive confidence value.

26. The apparatus of claim 24, wherein the rate selector is operative to select a third different data transmission rate associated with a lowest positive confidence value.

27. The apparatus of claim 21, further comprising a state machine operative to monitor the packet loss indicator value and determine whether a current data transmission rate causes an excessive number of failed packet transmissions or an excessive number of successful packet transmissions.

28. The apparatus of claim 27, wherein the rate selector is further operative to update the adjustment value in response to an output of the state machine indicating that the current data transmission rate causes an excessive number of failed packet transmissions or an excessive number of successful packet transmissions.

29. The apparatus of claim 17, further comprising:

a power adaptor operative to increasing a transmit power of the transmit section in response to the selected data transmission rate falling below a first threshold data transmission rate and to decrease the transmit power in response to the selected data transmission rate exceeding a second threshold data transmission rate.

30. The apparatus of claim 29, wherein the second threshold data transmission rate is greater than the first threshold data transmission rate.

31. The apparatus of claim 17, wherein the rate selector is further operative to decrease the selected data transmission rate in response to the packet loss indicator value increasing.

32. The apparatus of claim 31, further comprising a table indexed by available data transmission rates and packet loss indicator values, and

wherein the rate selector is operative to decrease the selected data transmission rate in response to data transmission rate values in said table.

33. The apparatus of claim 17, wherein the rate selector is further operative to select a fourth data transmission rate value directly from the packet loss indicator value in response to the signal quality value falling below a minimum signal quality value.

68. The apparatus of claim 17, wherein the packets are transmitted and received in compliance with one of the IEEE 802.11 family of specifications.

34. An apparatus comprising:

a transceiver including;

a transmit section including;

means for transmitting packets at a first data transmission rate, and

means for determining a packet loss indicator value from the transmitted packets; and

a receive section including;

means for receiving packets at a second different data transmission rate, and

means for determining a signal quality value from the received packets;

means for selecting a third different data transmission rate in response to the signal quality value determined from the received packets received at the second different data transmission rate and the packet loss indicator value determined from the transmitted packets transmitted at the first data transmission rate, wherein the selecting includes selecting the third different data transmission rate from a plurality of available data transmission rates, and each of the plurality of available data transmission rates is different from the first data transmission rate and the second different data transmission rate; and

means for generating a confidence value for each of a plurality of available data transmission rates using the signal quality value and the packet loss indicator value.

35. The apparatus of claim 34, wherein the signal quality value is selected from an RSSI (Received Signal Strength Indicator) value, an SNR (signal to noise ratio) value, an SINR (signal to interference noise ratio) value, and a SQM (signal quality measure) value, the SQM value comprising a mean of the SNRs across all of a plurality of tones.

36. The apparatus of claim 34, wherein the packet loss indicator value is selected from a retry counter value, a bit-error update value, a packet error update value, a symbol error update value, and a CRC (Cyclic Redundancy Check) indicator value.

37. The apparatus of claim 34, further comprising:

a table including the plurality of available data transmission rates, each available data transmission rate associated with a nominal signal quality value.

38. The apparatus of claim 34, further comprising:

means for generating an adjustment value for the signal quality value from the packet loss indicator value.

39. The apparatus of claim 38, wherein the signal quality value comprises an RSSI value.

40. The apparatus of claim 39, further comprising:

means for generating an average received signal strength indicator (RSSI_avg) value, and

wherein the adjustment value comprises a Δ

_RSSI value, the Δ

_RSSI value comprising an adjustment to the RSSI_avg value.

41. The apparatus of claim 40, further comprising:

means for generating the confidence value by solving the equation;

Confidence[j]=RSSI_avg−

RSSI_TH[j]−

Δ

_RSSI,

where RSSI_TH[j] comprises a nominal received signal strength value associated with a data transmission rate [j] in a table.

42. The apparatus of claim 41, further comprising:

means for selecting a third different data transmission rate associated with a positive confidence value.

43. The apparatus of claim 41, further comprising:

means for selecting a third different data transmission rate associated with a lowest positive confidence value.

44. The apparatus of claim 38, further comprising:

means for monitoring the packet loss indicator value; and

means for determining whether a current data transmission rate causes an excessive number of failed packet transmissions or an excessive number of successful packet transmissions.

45. The apparatus of claim 34, further comprising:

means for updating the adjustment value in response to the current data transmission rate causing an excessive number of failed packet transmissions or an excessive number of successful packet transmissions.

46. The apparatus of claim 34, further comprising:

means for increasing a transmit power of the transmit section in response to the selected data transmission rate falling below a first threshold data transmission rate and to decrease the transmit power in response to the selected data transmission rate exceeding a second threshold data transmission rate.

47. The apparatus of claim 46, wherein the second threshold data transmission rate is greater than the first threshold data transmission rate.

48. The apparatus of claim 34, further comprising:

means for decreasing the selected data transmission rate in response to the packet loss indicator value increasing.

49. The apparatus of claim 48, further comprising:

a table indexed by available data transmission rates and packet loss indicator values; and

means for decreasing the selected data transmission rate in response to data transmission rate values in said table.

50. The apparatus of claim 34, further comprising:

selecting a fourth data transmission rate value directly from the packet loss indicator value in response to the signal quality value falling below a minimum signal quality value.

69. The apparatus of claim 34, wherein the packets are transmitted and received in compliance with one of the IEEE 802.11 family of specifications.

51. A non-transitory computer-readable medium having instructions stored thereon, which, when executed by a processor, causes the processor to perform operations comprising:

determining a signal quality value from received packets transmitted at a first data transmission rate;

determining a packet loss indicator value from transmitted packets transmitted at a second different data transmission rate;

selecting a third different data transmission rate in response to the signal quality value determined from the received packets transmitted at the first data transmission rate and the packet loss indicator value determined from the transmitted packets transmitted at the second different data transmission rate, wherein the selecting includes selecting the third different data transmission rate from a plurality of available data transmission rates, and each of the plurality of available data transmission rates is different from the first data transmission rate and the second different data transmission rate;

transmitting packets at the third different data transmission rate; and

generating a confidence value for each of a plurality of available data transmission rates using the signal quality value and the packet loss indicator value.

52. The computer-readable medium of claim 51 wherein the signal quality value is selected from an RSSI (Received Signal Strength Indicator) value, an SNR (signal to noise ratio) value, an SINR (signal to interference noise ratio) value, and a SQM (signal quality measure) value, the SQM value comprising a mean of the SNRs across all of a plurality of tones.

53. The computer-readable medium of claim 51, wherein the packet loss indicator value is selected from a retry counter value, a bit-error update value, a packet error update value, a symbol error update value, and a CRC (Cyclic Redundancy Check) indicator value.

54. The computer-readable medium of claim 51, further comprising:

generating an adjustment value for the signal quality value from the packet loss indicator value.

55. The computer-readable medium of claim 54, wherein the signal quality value comprises an RSSI value.

56. The computer-readable medium of claim 55, further comprising:

generating an average received signal strength indicator (RSSI_avg) value, and

wherein the adjustment value comprises a Δ

_RSSI value, the Δ

_RSSI value comprising an adjustment to the RSSI_avg value.

57. The computer-readable medium of claim 56, wherein said generating the confidence value comprises solving the equation:

Confidence[j]=RSSI_avg−

RSSI_TH[j]−

Δ

_RSSI,

where RSSI_TH[j] comprises a nominal received signal strength value associated with a data transmission rate [j] in a table.

58. The computer-readable medium of claim 57 wherein said selecting the third different data transmission rate comprises selecting a data transmission rate associated with a positive confidence value.

59. The computer-readable medium of claim 57, wherein said selecting the third different data transmission rate comprises selecting a data transmission rate associated with a lowest positive confidence value.

60. The computer-readable medium of claim 54, further comprising:

updating the adjustment value in response to the packet loss indicator value indicating a maximum failure value corresponding to an excessive number of failed packet transmissions.

61. The computer-readable medium of claim 54, further comprising:

updating the adjustment value in response to the packet loss indicator value indicating a maximum success value corresponding to an excessive number of success packet transmissions.

62. The computer-readable medium of claim 51, further comprising:

increasing a transmit power for transmitting packets in response to the selected data transmission rate falling below a first threshold data transmission rate; and

decreasing the transmit power in response to the selected data transmission rate exceeding a second threshold data transmission rate.

63. The computer-readable medium of claim 62, wherein the second threshold data transmission rate is greater than the first threshold data transmission rate.

64. The computer-readable medium of claim 51, further comprising:

decreasing the selected data transmission rate in response to the packet loss indicator value increasing.

65. The computer-readable medium of claim 64, wherein said decreasing comprises decreasing the selected data transmission rate in response to data transmission rate values in a table indexed by available data transmission rates and packet loss indicator values.

66. The computer-readable medium of claim 51, further comprising:

selecting a fourth data transmission rate value directly from the packet loss indicator value in response to the signal quality value falling below a minimum signal quality value.

70. The computer-readable medium of claim 51, wherein the transmitted packets and received packets comply with one of the IEEE 802.11 family of specifications.