Method and apparatus for signal quality loss compensation in multiplexing transmission systems

• US 20070008943A1
• Filed: 05/26/2005
• Published: 01/11/2007
• Est. Priority Date: 05/26/2005
• Status: Active Grant

• Current Assignee: Unwired Planet LLC (JP Morgan Chase & Co)
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Cheng, Jung-fu, Molnar, Karl, Grant, Stephen, Ramesh, Rajaram, Wang, Yi-Pin
• Granted Patent: US 9,130,706 B2
• Time in Patent Office: Days
• US Class Current: 370/342
• CPC Class Codes: H04B 17/309 Measuring or estimating channel quality parameters
• CPC Class Codes: H04B 7/061 using feedback from receiving side
• CPC Class Codes: H04B 7/0678 using different spreading codes between antennas code allocation H04J13/16
• CPC Class Codes: H04B 7/0691 using subgroups of transmit antennas
• CPC Class Codes: H04B 7/0697 using spatial multiplexing
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• 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
• CPC Class Codes: H04L 5/0057 Physical resource allocation for CQI
• CPC Class Codes: H04W 24/10 Scheduling measurement reports ; Arrangements for measurement reports

Abstract

A wireless communication receiver receiving a multiplexed signal comprising two or more signal streams calculates a received signal quality for the multiplexed signal as a function of stream-specific received signal qualities, determines one or more loss parameters indicative of variations in the stream-specific received signal qualities, and generates quality feedback based on such information. In turn, a transmitter controls the selection of one or more transmission parameters of the multiplexed signal based on the quality feedback, such that its transmit link adaptations account for the losses in received signal quality at the receiver arising from the variations in the stream-specific received signal qualities. The quality feedback may include calculated loss values, or parameter/penalties that permit loss calculation, and the method applies to both code multiplexing and spatial multiplexing.

Claims

1. A method of compensating for losses in received signal quality experienced by a receiver receiving a multiplexed signal comprising two or more signal streams, the method comprising selecting a transmit coding rate for the multiplexed signal based at least in part on estimating coding rate-dependent signal quality losses arising at the receiver due to variations in stream-specific received signal qualities for the multiplexed signal at the receiver.

2. The method of claim 1, wherein estimating coding rate-dependent signal quality losses arising at the receiver due to variations in stream-specific received signal qualities for the multiplexed signal at the receiver comprises estimating coding rate-dependent signal quality losses for the multiplexed signal corresponding to a number of defined coding rates, determining effective received signal qualities for the multiplexed signal based on the coding rate-dependent signal quality losses, and selecting an appropriate coding rate for the multiplexed signal based on comparing the effective received signal qualities to signal quality thresholds defined for the defined coding rates.

3. A method of compensating for losses in received signal quality experienced by a receiver receiving a multiplexed signal comprising two or more signal streams, the method comprising:

calculating a received signal quality for the multiplexed signal as a function of stream-specific received signal qualities determined for the two or more signal streams of the multiplexed signal;

determining a loss in received signal quality as a function of variations in the stream-specific received signal qualities; and

controlling one or more transmission parameters of the multiplexed signal as a function of the received signal quality and the loss in received signal quality.

4. The method of claim 3, wherein controlling one or more transmission parameters of the multiplexed signal as a function of the received signal quality and the loss in received signal quality comprises generating an effective received signal quality for the multiplexed signal as a function of the received signal quality and the loss, and selecting one or more transmission parameters to be used for transmitting the multiplexed signal based on the effective received signal quality.

5. The method of claim 3, wherein controlling one or more transmission parameters of the multiplexed signal as a function of the received signal quality and the loss in received signal quality generally comprises selecting at least one of a modulation format and a coding rate to be used for the transmitting the multiplexed signal based on the received signal quality of the multiplexed signal as reduced by the loss.

6. The method of claim 3, wherein calculating a received signal quality for the multiplexed signal as a function of stream-specific received signal qualities determined for the two or more signal streams of the multiplexed signal comprises calculating a mode-specific received signal quality for the multiplexed signal for each of one or more multiplexing modes available for transmitting the multiplexed signal.

7. The method of claim 6, wherein determining a loss in received signal quality as a function of variations in the stream-specific received signal qualities comprises, for each mode-specific received signal quality, determining rate-specific signal quality losses for each coding rate available for transmitting the multiplexed signal.

8. The method of claim 7, wherein controlling one or more transmission parameters of the multiplexed signal as a function of the received signal quality and the loss in received signal quality comprises determining a highest achievable coding rate for each multiplexing mode based on the mode-specific received signal quality and the corresponding rate-specific signal quality losses, and setting the coding rate of the multiplexed signal based on comparing the highest achievable coding rates.

9. A method of feeding back received signal quality information from a receiver receiving a multiplexed signal comprising two or more signal streams, the method comprising:

calculating a received signal quality for the multiplexed signal as a function of stream-specific received signal qualities determined for the multiplexed signal;

determining a loss parameter for the received signal quality as a function of variations in the stream-specific received signal qualities; and

generating received signal quality information for feedback based on the received signal quality and the loss parameter.

10. The method of claim 9, wherein calculating a received signal quality for the multiplexed signal as a function of stream-specific received signal qualities determined for the multiplexed signal comprises calculating a mode-specific received signal quality for each of one or more multiplexing modes defined for the multiplexed signal.

11. The method of claim 10, wherein determining a loss parameter for the received signal quality as a function of variations in the stream-specific received signal qualities comprises, for each mode-specific received signal quality, determining one or more coding rate-dependent loss parameters.

12. The method of claim 9, wherein calculating a received signal quality for the multiplexed signal as a function of stream-specific received signal qualities determined for the multiplexed signal comprises calculating a Channel Quality Indicator (CQI) value for each of one or more multiplexing modes associated with the multiplexed signal, and wherein determining a loss parameter for the received signal quality as a function of variations in the stream-specific received signal qualities comprises determining one or more coding rate-dependent loss parameters for each CQI, such that the received signal quality information comprises mode-specific CQI values and corresponding coding rate-dependent loss parameters.

13. The method of claim 9, wherein the multiplexed signal comprises a spatially multiplexed signal transmitted from a different number of transmit antennas in each of one or more spatial multiplexing modes, and wherein calculating a received signal quality for the multiplexed signal as a function of stream-specific received signal qualities determined for the multiplexed signal comprises calculating a received signal quality for a best set of transmit antennas in each spatial multiplexing mode.

14. The method of claim 13, wherein determining a loss parameter for the received signal quality as a function of variations in the stream-specific received signal qualities comprises, for each spatial multiplexing mode, determining one or more coding rate-dependent loss parameters.

15. The method of claim 9, wherein generating received signal quality information for feedback based on the received signal quality and the loss parameter comprises generating the received signal quality information as the received signal quality, or a quantized version thereof, and the loss parameter.

16. The method of claim 9, wherein generating received signal quality information for feedback based on the received signal quality and the loss parameter comprises generating the received signal quality information as an effective received signal quality calculated as a function of the received signal quality and the loss parameter.

17. The method of claim 9, wherein calculating a received signal quality for the multiplexed signal as a function of stream-specific received signal qualities determined for the multiplexed signal comprises calculating an average signal quality from the stream-specific received signal qualities.

18. The method of claim 17, wherein determining a loss parameter for the received signal quality as a function of variations in the stream-specific received signal qualities comprises determining a maximum spread of the variations in the stream-specific signal qualities, such that the received signal quality information indicates the average received signal quality and the maximum spread.

19. The method of claim 17, wherein determining a loss parameter for the received signal quality as a function of variations in the stream-specific received signal qualities comprises determining a variation statistic characterizing the variations in the stream-specific signal qualities, such that the received signal quality information indicates the average received signal quality and the variation statistic.

20. The method of claim 19, wherein the variation statistic comprises one or more of a variance of the stream-specific received signal qualities, a standard deviation of the stream-specific received signal qualities, and a maximum spread of the stream-specific received signal qualities.

21. The method of claim 9, wherein determining a loss parameter for the received signal quality as a function of variations in the stream-specific received signal qualities comprises expressing effective losses in the received signal quality arising from the variations in the stream-specific received signal as loss functions of multiplexed signal coding rate, and generating the loss parameter as a set of parameters corresponding to a best-fitting one of the loss functions.

22. The method of claim 9, wherein determining a loss parameter for the received signal quality as a function of variations in the stream-specific received signal qualities comprises determining a loss value representing an effective reduction in the received signal quality arising because of the variations in the stream-specific received signal qualities.

23. The method of claim 22, wherein determining a loss value representing an effective reduction in the received signal quality comprises determining the loss value from a loss equation or data table maintained at the receiver that models signal quality loss as one or more coding rate-dependent functions of the received signal quality of the multiplexed signal.

24. The method of claim 9, wherein calculating a received signal quality for the multiplexed signal as a function of stream-specific received signal qualities determined for the multiplexed signal comprises determining a set of best transmit antennas for each of one or more spatial multiplexing modes associated with the multiplexed signal, and calculating a channel quality indicator value for each spatial multiplexing mode based on the stream-specific received signal qualities of the multiplexed signal corresponding to the best set of transmit antennas.

25. The method of claim 9, wherein determining a loss parameter for the received signal quality as a function of variations in the stream-specific received signal qualities comprises determining one or more loss parameters for each spatial multiplexing mode using the variations in the stream-specific received signal qualities corresponding to the best set of antennas for that spatial multiplexing mode, and wherein generating received signal quality information for feedback based on the received signal quality and the loss parameter comprises generating the received signal quality information as the channel quality indicators and corresponding loss parameters calculated for the spatial multiplexing modes.

26. The method of claim 9, wherein the receiver comprises a Wideband Code Division Multiple Access (W-CDMA) receiver, and wherein the multiplexed signal comprises a spatially multiplexed High Speed Downlink Shared Channel (HS-DSCH) signal, and wherein the received signal quality information comprises a Channel Quality Indicator (CQI) value and one or more coding rate-dependent loss parameters, for each of one or more spatial multiplexing modes associated with the spatially multiplexed HS-DSCH signal.

27. A method of compensating for losses in received signal quality experienced by a receiver receiving a multiplexed signal comprising two or more signal streams, the method comprising:

receiving a received signal quality for the multiplexed signal and a loss parameter indicative of variations in stream-specific received signal qualities of the multiplexed signal; and

controlling the selection of one or more transmission parameters of the multiplexed signal as a function of the received signal quality and the loss parameter.

28. The method of claim 27, wherein receiving a received signal quality for the multiplexed signal and a loss parameter indicative of variations in stream-specific received signal qualities of the multiplexed signal comprises receiving a received signal quality and a loss parameter for each of one or more multiplexing modes associated with the multiplexed signal.

29. The method of claim 28, wherein controlling the selection of one or more transmission parameters of the multiplexed signal as a function of the received signal quality and the loss parameter comprises calculating coding rate-dependent signal quality losses for the multiplexed signal in each multiplexing mode based on the loss parameter received for that multiplexing mode, identifying a highest coding rate supportable in each multiplexing mode based on the coding-rate-dependent signal quality losses calculated for that multiplexing mode, and selecting a multiplexing mode and coding rate to use for the multiplexed signal based on comparing the highest coding rates between the multiplexing modes.

30. The method of claim 27, wherein receiving a received signal quality for the multiplexed signal and a loss parameter indicative of variations in stream-specific received signal qualities of the multiplexed signal comprises receiving mode-specific received signal qualities and corresponding mode-specific loss parameters for each of one or more multiplexing modes associated with the multiplexed signal.

31. The method of claim 30, wherein each mode-specific received signal quality comprises a received signal quality indicator calculated as a function of the stream-specific received signal qualities for the multiplexed signal for the corresponding multiplexing mode, and wherein each corresponding loss parameter indicates the variations in those stream-specific received signal qualities.

32. The method of claim 31, wherein controlling the selection of one or more transmission parameters of the multiplexed signal as a function of the received signal quality and the loss parameter comprises determining effective received signal qualities in each multiplexing mode based on the mode-specific received signal quality indicator and a number of coding rate-dependent signal quality losses calculated from the mode-specific loss parameter and coding-rate dependent signal quality loss modeling information, and selecting one of the multiplexing modes and coding rates based on comparing the effective received signal qualities to coding-rate dependent signal quality thresholds.

33. The method of claim 27, wherein the loss parameter comprises a statistical value indicating the variations in the stream-specific received signal qualities, and wherein controlling the selection of one or more transmission parameters of the multiplexed signal as a function of the received signal quality and the loss parameter comprises calculating a loss value from the loss parameter, calculating an effective received signal quality from the loss value and the received signal quality, and controlling the selection of the one or more transmission parameters based on the effective received signal quality.

34. The method of claim 33, wherein the statistical value comprises a maximum spread of the stream-specific received signal qualities, a standard deviation of the stream-specific received signal qualities, or a variance of the stream-specific received signal qualities.

35. The method of claim 27, wherein the loss parameter comprises a parameter set identifying a loss curve or function that models signal quality losses as a function of variations in the stream-specific received signal qualities, and wherein controlling the selection of one or more transmission parameters of the multiplexed signal as a function of the received signal quality and the loss parameter comprises calculating a loss value from the identified loss curve or function, calculating an effective received signal quality from the loss value and the received signal quality, and controlling the selection of the one or more transmission parameters based on the effective received signal quality.

36. A multiplexing transmitter for use in a wireless communication network comprising:

radio transmission circuits configured to transmit a multiplexed signal comprising two or more signal streams from the multiplexing transmitter to a remote receiver;

one or more interface circuits configured to receive feedback from the remote receiver comprising a received signal quality for the multiplexed signal and a loss parameter indicative of variations in stream-specific received signal qualities of the multiplexed signal; and

a control circuit configured to control the selection of one or more transmission parameters of the multiplexed signal as a function of the received signal quality and the loss parameter.

37. The multiplexing transmitter of claim 36, wherein the control circuit includes or is associated with a calculation circuit that is configured to determine an effective received signal quality for the remote receiver based on estimating a loss in received signal quality arising at the remote receiver from the variations in the stream-specific received signal qualities of the multiplexed signal.

38. The multiplexing transmitter of claim 36, wherein the received signal quality and the loss parameter comprise a received signal quality and a loss parameter for each of one or more multiplexing modes associated with the multiplexed signal.

39. The multiplexing transmitter of claim 38, wherein the control circuit is configured to control the selection of the one or more transmission parameters of the multiplexed signal by calculating coding rate-dependent signal quality losses for the multiplexed signal in each multiplexing mode based on the loss parameter received for that multiplexing mode, identifying a highest coding rate supportable in each multiplexing mode based on the coding-rate-dependent signal quality losses calculated for that multiplexing mode, and selecting a multiplexing mode and coding rate to use for the multiplexed signal based on comparing the highest coding rates between the multiplexing modes.

40. The multiplexing transmitter of claim 36, wherein the received signal quality and the loss parameter received as feedback comprise mode-specific received signal qualities and corresponding mode-specific loss parameters for each of one or more multiplexing modes associated with the multiplexed signal.

41. The multiplexing transmitter of claim 40, wherein each mode-specific received signal quality comprises a received signal quality indicator calculated as a function of the stream-specific received signal qualities for the multiplexed signal for the corresponding multiplexing mode, and wherein each corresponding loss parameter indicates the variations in those stream-specific received signal qualities.

42. The multiplexing transmitter of claim 41, wherein the control circuit is configured to control the selection of one or more transmission parameters of the multiplexed signal as a function of the received signal quality and the loss parameter by determining effective received signal qualities in each multiplexing mode based on the mode-specific received signal quality indicator and a number of coding rate-dependent signal quality losses calculated from the mode-specific loss parameter and coding-rate dependent signal quality loss modeling information, and selecting one of the multiplexing modes and coding rates based on comparing the effective received signal qualities to coding-rate dependent signal quality thresholds.

43. The multiplexing transmitter of claim 36, wherein the loss parameter comprises a statistical value indicating the variations in the stream-specific received signal qualities, and wherein the control circuit is configured to control the selection of one or more transmission parameters of the multiplexed signal as a function of the received signal quality and the loss parameter by calculating a loss value from the loss parameter, calculating an effective received signal quality from the loss value and the received signal quality, and controlling the selection of the one or more transmission parameters based on the effective received signal quality.

44. The multiplexing transmitter of claim 43, wherein the statistical value comprises a maximum spread of the stream-specific received signal qualities, a standard deviation of the stream-specific received signal qualities, or a variance of the stream-specific received signal qualities.

45. The multiplexing transmitter of claim 36, wherein the loss parameter comprises a parameter set identifying a loss curve or function that models signal quality losses as a function of variations in the stream-specific received signal qualities, and wherein the control circuit is configured to control the selection of one or more transmission parameters of the multiplexed signal as a function of the received signal quality and the loss parameter by calculating a loss value from the identified loss curve or function, calculating an effective received signal quality from the loss value and the received signal quality, and controlling the selection of the one or more transmission parameters based on the effective received signal quality.

46. A wireless communication receiver configured to receive a multiplexed signal comprising two or more signal streams, said wireless communication receiver comprising one or more processing circuits configured to:

calculate a received signal quality for the multiplexed signal as a function of stream-specific received signal qualities determined for the multiplexed signal;

determine a loss parameter for the received signal quality as a function of variations in the stream-specific received signal qualities; and

generate received signal quality information for feedback based on the received signal quality and the loss parameter.

47. The receiver of claim 46, wherein the one or more processing circuits are configured to calculate the received signal quality as a mode-specific received signal quality for each of one or more multiplexing modes defined for the multiplexed signal.

48. The receiver of claim 47, wherein the one or more processing circuits are configured to determine the loss parameter as one or more coding rate-dependent loss parameters for each mode-specific received signal quality, based on the variations in the stream-specific received signal qualities of the multiplexed signal in the corresponding multiplexing mode.

49. The receiver of claim 48, wherein the multiplexed signal comprises a spatially multiplexed signal transmitted from a different number of transmit antennas in each multiplexing mode, and wherein the one or more processing circuits are configured to calculate the mode-specific received signal qualities by calculating the received signal quality for a best set of transmit antennas in each multiplexing mode.

50. The receiver of claim 46, wherein the one or more processing circuits are configured to generate the received signal quality information as the received signal quality, or a quantized version thereof, and the loss parameter.

51. The receiver of claim 46, wherein the one or more processing circuits are configured to generate the received signal quality information as an effective received signal quality calculated as a function of the received signal quality and the loss parameter.

52. The receiver of claim 46, wherein the one or more processing circuits are configured to calculate the received signal quality for the multiplexed signal as a function of stream-specific received signal qualities determined for the multiplexed signal by calculating an average signal quality from the stream-specific received signal qualities.

53. The receiver of claim 52, wherein the one or more processing circuits are configured to determine a loss parameter for the received signal quality as a function of variations in the stream-specific received signal qualities by determining a maximum spread of the variations in the stream-specific signal qualities, such that the received signal quality information indicates the average received signal quality and the maximum spread.

54. The receiver of claim 52, wherein the one or more processing circuits are configured to determine a loss parameter for the received signal quality as a function of variations in the stream-specific received signal qualities by determining a variation statistic characterizing the variations in the stream-specific signal qualities, such that the received signal quality information indicates the average received signal quality and the variation statistic.

55. The receiver of claim 46, wherein the one or more processing circuits are configured to determine a loss parameter for the received signal quality as a function of variations in the stream-specific received signal qualities by expressing effective losses in the received signal quality arising from the variations in the stream-specific received signal as loss functions of multiplexed signal coding rate, and generating the loss parameter as a set of parameters corresponding to a best-fitting one of the loss functions.

56. The receiver of claim 46, wherein the one or more processing circuits are configured to determine a loss parameter for the received signal quality as a function of variations in the stream-specific received signal qualities by determining a loss value representing an effective reduction in the received signal quality arising because of the variations in the stream-specific received signal qualities.

57. The receiver of claim 56, wherein the one or more processing circuits are configured to determine a loss value representing an effective reduction in the received signal quality by determining the loss value from a loss equation or data table maintained at the receiver that models signal quality loss as one or more coding rate-dependent functions of the received signal quality of the multiplexed signal.

58. The receiver of claim 46, wherein the one or more processing circuits are configured to determine a loss parameter for the received signal quality as a function of variations in the stream-specific received signal qualities by determining a set of best transmit antennas for each of one or more spatial multiplexing modes associated with the multiplexed signal, and determining a loss parameter for each spatial multiplexing mode using the variations in the stream-specific received signal qualities corresponding to a best set of antennas for that spatial multiplexing mode.

59. The receiver of claim 58, wherein the one or more processing circuits are configured to generate the received signal quality information as individual channel quality indicators corresponding to respective ones of the best transmit antennas for each spatial multiplexing mode, and as corresponding loss parameters for each spatial multiplexing mode.

60. The receiver of claim 46, wherein the receiver comprises a Wideband Code Division Multiple Access (W-CDMA) receiver, and wherein the multiplexed signal comprises a spatially multiplexed High Speed Downlink Shared Channel (HS-DSCH) signal, and wherein the received signal quality information comprises a Channel Quality Indicator (CQI) value and one or more coding rate-dependent loss parameters, for each of one or more spatial multiplexing modes associated with the spatially multiplexed HS-DSCH signal.