Mode selection for data transmission in wireless communication channels based on statistical parameters

• US 6,760,882 B1
• Filed: 09/19/2000
• Issued: 07/06/2004
• Est. Priority Date: 09/19/2000
• Status: Expired due to Term

• Current Assignee: Apple Inc.
• Original Assignee: Intel Corporation
• Inventors: Gesbert, David J., Catreux, Severine E., Heath, Robert W. Jr., Paulraj, Arogyaswami J., Sebastian, Peroor K.
• Primary Examiner(s): MOISE, EMMANUEL LIONEL
• Application Number:
  US09/665,149
• Time in Patent Office: 1,386 Days
• Field of Search: 714/774, 714/704, 714/708, 714/748, 714/751, 370/252, 370/345, 370/206, 375/261, 375/259, 375/267, 455/102, 455/67.11, 455/67.13
• US Class Current: 714/774
• 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 1/0002 by adapting the transmission rate
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0016 involving special memory structures, e.g. look-up tables
• CPC Class Codes: H04L 1/0021 in which the algorithm uses adaptive thresholds
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 1/0033 arrangements specific to the transmitter
• CPC Class Codes: H04L 1/06 using space diversity
• CPC Class Codes: H04L 1/20 using signal quality detector

Abstract

A method and communication system for selecting a mode for encoding data for transmission in a wireless communication channel between a transmit unit and a receive unit. The data is initially transmitted in an initial mode and the selection of the subsequent mode is based on a selection of first-order and second-order statistical parameters of short-term and long-term quality parameters. Suitable short-term quality parameters include signal-to-interference and noise ratio (SINR), signal-to-noise ratio (SNR), power level and suitable long-term quality parameters include error rates such as bit error rate (BER) and packet error rate (PER). The method of the invention can be employed in Multiple Input Multiple Output (MIMO), Multiple Input Single Output (MISO), Single Input Single Output (SISO) and Single Input Multiple Output (SIMO) communication systems to make subsequent mode selection faster and more efficient. Furthermore the method can be used in communication systems employing various transmission protocols including OFDMA, FDMA, CDMA, TDMA.

Claims

1. A method for selecting a mode for encoding data for transmission in a wireless communication channel between a transmit unit and a receive unit, said method comprising:

a) transmitting said data encoded in an initial mode from said transmit unit to said receive unit;

b) sampling at least one quality parameter of said data received by said receive unit;

c) computing a first-order statistical parameter of said at least one quality parameter;

d) computing a second-order statistical parameter of said at least one quality parameter; and

e) selecting a subsequent mode for encoding said data based on said first-order statistical parameter and said second-order statistical parameter.

2. The method of claim 1, wherein said at least one quality parameter comprises a short-term quality parameter and said method further comprises setting a first sampling window during which said short-term quality parameter is sampled.

3. The method of claim 2, wherein said wireless communication channel has a coherence time and said first sampling window is set based on said coherence time.

4. The method of claim 2, wherein said subsequent mode is applied after a delay time, and said first sampling window is set based on said delay time.

5. The method of claim 2, wherein said second-order statistical parameter is a variance of said short-term quality parameter, said variance being computed over a variance computation time and said first sampling window being set on the order of said variance computation time.

6. The method of claim 2, wherein said short-term quality parameter is selected from the group consisting of signal-to-interference and noise ratio, signal-to-noise ratio and power level.

7. The method of claim 1, wherein said at least one quality parameter comprises a long-term quality parameter and said method further comprises setting a second sampling window during which said long-term quality parameter is sampled.

8. The method of claim 7, wherein said first-order statistical parameter is a mean of said long-term quality parameter, said mean being computed over a mean computation time and said second sampling window being set on the order of said mean computation time.

9. The method of claim 7, wherein said long-term quality parameter comprises an error rate of said data at said receive unit.

10. The method of claim 9, wherein said error rate is computed over an error rate computation time, and said second sampling window is set on the order of said error rate computation time.

11. The method of claim 9, wherein said error rate is selected from the group consisting of bit error rate and packet error rate.

12. The method of claim 1, wherein said first-order statistical parameter is a mean of said at least one quality parameter.

13. The method of claim 1, wherein said second-order statistical parameter is a variance of said at least one quality parameter.

14. The method of claim 13, wherein said data is transmitted at more than one frequency and said variance is a frequency variance.

15. The method of claim 13, wherein said data is transmitted in a multi-carrier scheme and said variance is a frequency variance.

16. The method of claim 13, wherein said variance is a temporal variance.

17. The method of claim 1, wherein said initial mode is selected from a set of modes related to said at least one quality parameter.

18. The method of claim 1, wherein said subsequent mode is selected to maximize a communication parameter.

19. The method of claim 18, wherein said communication parameter is selected from the group consisting of bit error rate, packet error rate, data capacity, signal quality, spectral efficiency and throughput.

20. The method of claim 1, further comprising communicating said subsequent mode to said transmit unit.

21. The method of claim 1, wherein at least one of said transmit unit and said receive unit are multiple input and multiple output units.

22. The method of claim 1, wherein said transmitting step is performed in accordance with a transmission technique selected from the group consisting of OFDMA, FDMA, CDMA, TDMA.

23. A method for selecting a mode from a set of modes for encoding data for transmission in a wireless communication channel between a transmit unit and a receive unit, said method comprising:

a) transmitting said data encoded in an initial mode selected from said set of modes from said transmit unit to said receive unit;

b) sampling a short-term quality parameter of said data received by said receive unit;

c) computing a statistical parameter of said short-term quality parameter;

d) selecting a subsequent mode from said set of modes for encoding said data based on said short-term statistical parameter;

e) sampling a long-term quality parameter of said data received by said receive unit; and

f) adjusting said subsequent mode selection in step d) based on said long-term quality parameter.

24. The method of claim 23, wherein said long-term quality parameter is an error rate selected from the group consisting of bit error rate and packet error rate.

25. The method of claim 23, further comprising setting a first sampling window during which said short-term quality parameter is sampled and setting a second sampling window during which said long-term quality parameter is sampled.

26. The method of claim 25, wherein said long-term quality parameter is an error rate and is computed over an error rate computation time, and said second sampling window is set on the order of said error rate computation time.

27. The method of claim 25, wherein said short-term quality parameter is selected from the group consisting of signal-to-interference and noise ratio, signal-to-noise ratio and power level.

28. The method of claim 23, wherein said set of modes is arranged in a lookup table and ordered by said short-term quality parameter.

29. The method of claim 28, wherein said adjusting comprises modifying said lookup table based on said long-term quality parameter.

30. The method of claim 23, wherein said statistical parameter comprises at least one statistical parameter selected from the group consisting of first-order statistical parameters and second-order statistical parameters.

31. A system for assigning a subsequent mode for encoding data for transmission in a wireless communication channel, said system comprising:

a) a transmit unit having a transmit processing block for encoding said data in a mode;

b) a receive unit for receiving said data transmitted from said transmit unit, said receive unit having;

1) a statistics computation block for sampling at least one quality parameter of said data and computing a first-order statistical parameter of said at least one quality parameter and a second-order statistical parameter of said at least one quality parameter;

2) a mode selection block for assigning said subsequent mode based on said first-order statistical parameter and said second-order statistical parameter.

32. The system of claim 31, further comprising at least one database containing a set of modes from which said mode and said subsequent mode are selected.

33. The system of claim 32, wherein said at least one database comprises a first database in said transmit unit and a second database in said receive unit.

34. The system of claim 31, further comprising a feedback mechanism for communicating said subsequent mode between said receive unit and said transmit unit.

35. A method comprising:

sampling at least one quality parameter of data received via a wireless communication channel from a remote transmitter, said data encoded according to initial mode;

computing at least a first-order and second-order statistical parameter of said at least one quality parameter; and

selecting a subsequent mode for encoding said data based, at least in part, on the computed at least first-order and said second-order statistical parameters.

36. A method according to claim 35, wherein the at least one quality parameter comprises a short-term quality parameter and said method further comprises setting a first sampling window during which said short-term quality parameter is sampled.

37. A method according to claim 36, wherein said wireless communication channel has a coherence time, and wherein said first sampling window is set based, at least in part, on the coherence time of the communication channel.

38. A method according to claim 36, wherein the subsequent mode is applied after a delay time, and the first sampling window is set based, at least in part, on this delay time.

39. A method according to claim 36, wherein the second-order statistical parameter is a variance of the short-term quality parameter, wherein the variance is computed over a variance computation time and the first sampling window is set on the order of the variance computation time.

40. A method according to claim 35, wherein the quality parameter represents one or more of a signal-to-interference and noise ratio (SINR), signal-to-noise ratio (SNR), power level, and received signal strength indicator (RSSI).

41. A method according to claim 35, wherein the quality parameter comprises a long-term quality parameter, the method further comprising:

setting a second sampling window during which the long-term quality parameter is sampled.

42. A method according to claim 41, where the first-order statistical parameter is a statistical mean of the long term quality parameter, the mean being computed over a mean computation time, and wherein the second sampling window is set to satisfy at least the mean computation time.

43. A method according to claim 42, wherein the long-term quality parameter is an error rate associated with the received data.

44. A method according to claim 35, wherein the first-order statistical parameter is a statistical mean of said at least one quality parameter.

45. A method according to claim 35, wherein the first-order statistical parameter is computed from a first quality parameter, while the second-order statistical parameter is computed from a second quality parameter.

46. A method according to claim 45, wherein the first quality parameter is determined over a period of time which differs from that in which the second quality parameter is determined.

47. A method according to claim 35, wherein the subsequent mode is selected from a pre-determined set of modes.

48. A method according to claim 47, wherein the selected subsequent mode is communicated to the transmitter for use in encoding a subsequent transmission of data.

49. A method according to claim 35, wherein the selected subsequent mode is communicated to the transmitter for use in encoding a subsequent transmission of data.

50. An apparatus comprising:

a receiver, coupled with one or more antenna(e), to sample at least one quality parameter of data encoded according to an initial mode from a remote transmitter via a wireless communication channel; and

a quality parameter computation block, responsive to the sampled quality parameter(s), to compute at least a first-order statistical parameter and a second-order statistical parameter from the sampled quality parameter(s), from which a subsequent mode for encoding data is selected based, at least in part, on the first-order statistical quality parameter and the second-order statistical quality parameter.

51. An apparatus according to claim 50, further comprising:

a mode selection block, responsive to the quality parameter computation block, to receive an indication of the at least first-order statistical parameter and the second-order statistical parameter from the quality parameter computation block, and to select a subsequent mode for encoding data based, at least in part, on the received indications.

52. An apparatus according to claim 51, further comprising:

a transmitter, responsive to the mode selection block, to receive an indication denoting the selected subsequent mode, and to communicate a representation of the indication to the remote transmitter.

53. An apparatus according to claim 50, wherein the first-order statistical parameter is obtained from a first quality parameter sampled over a first sample period, while the second-order statistical parameter is obtained from a second quality parameter sampled over a second sample period.

54. An apparatus according to claim 53, wherein first quality parameter is a error rate, and the first-order statistical parameter is a mean of the error rate.

55. An apparatus according to claim 53, wherein the second quality parameter is one or more of a signal-to-interference and noise ratio (SINR), a signal-to-noise ratio (SNR), a power level, and a received signal strength indication (RSSI).

56. An apparatus according to claim 55, wherein the second-order statistical parameter is a variance.

57. An apparatus according to claim 56, wherein the first sample period is greater than the second sample period.

58. A system comprising:

one or more dipole antenna(e); and

a receiver, responsive to the one or more dipole antenna(e), to sample at least one quality parameter of data encoded according to an initial mode from a remote transmitter via a wireless communication channel, to compute at least a first-order statistical parameter and a second-order statistical parameter from the sampled quality parameter(s), from which a subsequent mode for encoding data is selected based, at least in part, on the first-order statistical quality parameter and the second-order statistical quality parameter.

59. A system according to claim 58, the receiver comprising:

a quality parameter computation block, responsive to the sampled quality parameter(s), to compute at least a first-order statistical parameter and a second-order statistical parameter from the sampled quality parameter(s), from which a subsequent mode for encoding data is selected based, at least in part, on the first-order statistical quality parameter and the second-order statistical quality parameter.

60. A system according to claim 59, the receiver further comprising:

a mode selection block, responsive to the quality parameter computation block, to receive an indication of the at least first-order statistical parameter and the second-order statistical parameter from the quality parameter computation block, and to select a subsequent mode for encoding data based, at least in part, on the received indications.

61. A system according to claim 60, further comprising:

a transmitter, responsive to the mode selection block, to receive an indication denoting the select subsequent mode, and to generate a communication signal for transmission to the remote transmitter.