Physical layer metrics to support adaptive station-dependent channel state information feedback rate in multi-user communication systems

• US 8,811,200 B2
• Filed: 09/17/2010
• Issued: 08/19/2014
• Est. Priority Date: 09/22/2009
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Breit, Gregory Alan, Vermani, Sameer, Abraham, Santosh Paul, Sampath, Hemanth
• Primary Examiner(s): Pham, Chi
• Assistant Examiner(s): HOM, SHICK C
• Application Number:
  US12/884,854
• Publication Number:
  US 20110069629A1
• Time in Patent Office: 1,432 Days
• Field of Search: None
• US Class Current: 370/252
• CPC Class Codes: H04B 17/24 with feedback of measurements to the transmitter
• CPC Class Codes: H04B 17/336 Signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR]
• CPC Class Codes: H04B 7/0626 Channel coefficients, e.g. channel state information [CSI]
• CPC Class Codes: H04L 1/0027 Scheduling of signalling, e.g. occurrence thereof
• CPC Class Codes: H04L 25/0202 Channel estimation

Abstract

Certain aspects of the present disclosure present physical layer metrics for supporting adaptive station-dependent channel state information feedback rate in multi-user communication systems. For certain aspects, the physical layer metrics may be calculated at the stations and communicated to the AP. For certain aspects, the metrics may be calculated at an access point utilizing information about channel characteristics of stations available at the access point.

Claims

1. A method to support an adaptive user dependent channel state information (CSI) feedback rate in a multi-user wireless communication system, performed by a first apparatus, comprising:

receiving a current channel estimate;

calculating a metric based at least on the current channel estimate and a recent channel estimate communicated to a second apparatus; and

comparing the metric with a threshold for deciding if a CSI update is to be sent to the second apparatus.

2. The method of claim 1, further comprising:

receiving a request message from the second apparatus; and

in response to the request message, transmitting the metric to the second apparatus.

3. The method of claim 1, wherein the second apparatus comprises an access point.

4. The method of claim 1, wherein the threshold is based on a signal to noise ratio (SNR) of a channel used by the first apparatus.

5. The method of claim 4, further comprising:

transmitting the logical value to the second apparatus.

41. The method of claim 1, wherein the metric is calculated according to the following:

42. The method of claim 1, wherein the metric is calculated according to the following:

43. The method of claim 1, wherein the metric is calculated according to the following:

6. An apparatus that supports an adaptive user dependent channel state information (CSI) feedback rate in a multi-user wireless communication system, comprising:

an estimator configured to obtain a current channel estimate;

a circuit configured to calculate a metric based at least on the current channel estimate and a recent channel estimate communicated to another apparatus; and

another circuit configured to compare the metric with a threshold for deciding if a CSI update is to be sent to the other apparatus.

7. The apparatus of claim 6, further comprising:

a receiver configured to receive a request message from the other apparatus; and

a transmitter configured to transmit, in response to the request message, the metric to the other apparatus.

8. The apparatus of claim 6, wherein the other apparatus comprises an access point.

9. The apparatus of claim 6, wherein the threshold is based on a signal to noise ratio (SNR) of a channel used by the apparatus.

10. The apparatus of claim 9, wherein the transmitter is also configured to transmit the logical value to the other apparatus.

11. An apparatus that supports an adaptive user dependent channel state information (CSI) feedback rate in a multi-user wireless communication system, comprising:

means for obtaining a current channel estimate;

means for calculating a metric based at least on the current channel estimate and a recent channel estimate communicated to another apparatus; and

means for comparing the metric with a threshold for deciding if a CSI update is to be sent to the other apparatus.

12. The apparatus of claim 11, further comprising:

means for receiving a request message from the other apparatus; and

means for transmitting, in response to the request message, the metric to the other apparatus.

13. The apparatus of claim 11, wherein the other apparatus comprises an access point.

14. The apparatus of claim 11, wherein the threshold is based on a signal to noise ratio (SNR) of a channel used by the apparatus.

15. The apparatus of claim 14, further comprising:

means for transmitting the logical value to the other apparatus.

16. A computer-program product to support an adaptive user dependent channel state information (CSI) feedback rate in a multi-user wireless communication system, comprising a non-transitory computer-readable medium comprising instructions executable to:

obtain a current channel estimate;

calculate a metric based at least on the current channel estimate and a recent channel estimate communicated to an apparatus; and

compare the metric with a threshold for deciding if a CSI update is to sent to the apparatus.

17. A wireless node that supports an adaptive user dependent channel state information (CSI) feedback rate in a multi-user wireless communication system, comprising:

at least one antenna;

an estimator configured to obtain a current channel estimate;

a circuit configured to calculate a metric based at least on the current channel estimate and a recent channel estimate communicated to an access point; and

another circuit to compare the metric with a threshold for deciding if a CSI update is to be sent to the access point.

18. A method to support an adaptive user dependent channel state information (CSI) feedback rate in a multi-user wireless communication system, comprising:

receiving a current channel estimate and a recent channel estimate from an apparatus;

calculating a metric based at least on the current channel estimate and the recent channel estimate; and

comparing the metric with a threshold for deciding if a request for a CSI update is to be sent to the apparatus.

19. The method of claim 18, wherein the apparatus comprises an access point.

20. The method of claim 18, wherein deciding to request the CSI update is based at least on the metric and time elapsed since a most recent CSI update.

21. The method of claim 18, wherein the threshold is based on a signal to noise ratio (SNR) of a channel.

22. The method of claim 21, wherein deciding if a request for the CSI update is to be sent to the apparatus comprises:

deciding if the CSI request is to be sent to the apparatus based at least on the logical value and time elapsed since a most recent CSI update.

23. The method of claim 18, further comprising:

transmitting, to the apparatus based on the decision, the request for the CSI update.

24. The method of claim 23, wherein the request for the CSI update comprises at least one of a training request message or a channel sounding message.

25. An apparatus that supports an adaptive user dependent channel state information (CSI) feedback rate in a multi-user wireless communication system, comprising:

a receiver configured to obtain a current channel estimate and a recent channel estimate from another apparatus;

a circuit configured to calculate a metric based at least on the current channel estimate and the recent channel estimate; and

another circuit to compare the metric with a threshold to decide if a request for a CSI update is to be sent to the other apparatus.

26. The apparatus of claim 25, comprising an access point.

27. The apparatus of claim 25, wherein deciding to request the CSI update is based at least on the metric and time elapsed since a most recent CSI update.

28. The apparatus of claim 25, wherein the threshold is based on a signal to noise ratio (SNR) of a channel used by the apparatus.

29. The apparatus of claim 28, wherein the other circuit is also configured to:

decide if the request for the channel state information update is to be sent to the other apparatus based at least on the logical value and time elapsed since the last CSI update.

30. The apparatus of claim 25, further comprising:

a transmitter configured to transmit, to the other apparatus based on the decision, the request for the CSI update.

31. The apparatus of claim 30, wherein the request for the CSI update comprises at least one of a training request message or a channel sounding message.

32. An apparatus that supports an adaptive user dependent channel state information (CSI) feedback rate in a multi-user wireless communication system, comprising:

means for obtaining a current channel estimate and a recent channel estimate from another apparatus;

means for calculating a metric based at least on the current channel estimate and the recent channel estimate; and

means for comparing the metric with a threshold for deciding if a request for a CSI update is to be sent to the other apparatus.

33. The apparatus of claim 32, comprising access point.

34. The apparatus of claim 32, wherein deciding to request the CSI update is based at least on the metric and time elapsed since a most recent CSI update.

35. The apparatus of claim 32, wherein the threshold is based on a signal to noise ratio (SNR) of a channel used by the apparatus.

36. The apparatus of claim 35, wherein the means for deciding if a channel state information request is to be sent to the other apparatus comprises:

means for deciding if the request for the CSI update is to be sent to the other apparatus based at least on the logical value and time elapsed since a most recent CSI update.

37. The apparatus of claim 32, further comprising:

means for transmitting, to the other apparatus based on the decision, a request for the CSI update.

38. The apparatus of claim 37, wherein the request for the CSI update comprises at least one of a training request message or a channel sounding message.

39. A computer-program product that supports an adaptive user dependent channel state information (CSI) feedback rate in a multi-user wireless communication system, comprising a non-transitory computer-readable medium comprising instructions executable to:

obtain a current channel estimate and a recent channel estimate from an apparatus;

calculate a metric based at least on the current channel estimate and the recent channel estimate; and

compare the metric with a threshold for deciding if a request for a CSI update is to be sent to the apparatus.

40. An access point that supports an adaptive user dependent channel state information (CSI) feedback rate in a multi-user wireless communication system, comprising:

at least one antenna;

a receiver configured to obtain via the at least one antenna a current channel estimate and a recent channel estimate from a wireless node;

a circuit configured to calculate a metric based at least on the current channel estimate and the recent channel estimate; and

another circuit configured to compare the metric with a threshold to decide if a request for a CSI update is to be sent to the wireless node.