MULTI-RESOLUTION BEAMFORMING IN MIMO SYSTEMS

• US 20090232240A1
• Filed: 03/16/2009
• Published: 09/17/2009
• Est. Priority Date: 03/17/2008
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Lakkis, Ismail
• Granted Patent: US 9,100,068 B2
• Time in Patent Office: Days
• US Class Current: 375/260
• CPC Class Codes: H04B 7/0417 Feedback systems
• CPC Class Codes: H04B 7/0491 using two or more sectors, i.e. sector diversity
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/0628 Diversity capabilities
• CPC Class Codes: H04B 7/0634 Antenna weights or vector/matrix coefficients

Abstract

Certain aspects of the present disclosure relate to methods for beamforming that achieve beamforming optimality criterions. Some proposed beamforming techniques are based on antenna directions with multiple resolutions.

Claims

1. A method for wireless communications, comprising:

receiving training signals transmitted from a device using a first set of transmit directions;

deriving, from the first set of transmit directions, a preferred transmit direction; and

providing, as feedback to the device, an indication of the preferred transmit direction to the device, wherein the feedback is provided by sweeping through a second set of transmit directions.

2. The method of claim 1, further comprising:

exchanging with the device, before each data session, information about a number of one or more beamforming levels to be used for that data session.

3. The method of claim 1, further comprising:

receiving information regarding beamforming capabilities of the device from a PNC, during or after association with the PNC.

4. The method of claim 1, wherein receiving training signals transmitted from the device comprises receiving each training signal that was transmitted from one transmit direction using all receive directions.

5. The method of claim 1, wherein receiving training signals from the device comprises receiving all training signals transmitted from the set of transmit directions using one receive direction and repeating this procedure for all receive directions.

6. The method of claim 1, wherein at least a part of each training signal is based on Golay sequences.

7. An apparatus for wireless communications, comprising:

a receiver for receiving training signals transmitted from a device using a first set of transmit directions;

a circuit for deriving, from the first set of transmit directions, a preferred transmit direction; and

a circuit for providing, as feedback to the device, an indication of the preferred transmit direction to the device, wherein the feedback is provided by sweeping through a second set of transmit directions.

8. The apparatus of claim 7, further comprising:

a circuit for exchanging with the device, before each data session, information about a number of one or more beamforming levels to be used for that data session.

9. The apparatus of claim 7, further comprising:

a receiver for receiving information regarding beamforming capabilities of the device from a PNC, during or after association with the PNC.

10. The apparatus of claim 7, wherein the receiver for receiving training signals transmitted from the device comprises a circuit for receiving each training signal that was transmitted from one transmit direction using all receive directions.

11. The apparatus of claim 7, wherein the receiver for receiving training signals from the device comprises a circuit for receiving all training signals transmitted from the set of transmit directions using one receive direction and repeating this procedure for all receive directions.

12. The apparatus of claim 7, wherein at least a part of each training signal is based on Golay sequences.

13. An apparatus for wireless communications, comprising:

means for receiving training signals transmitted from a device using a first set of transmit directions;

means for deriving, from the first set of transmit directions, a preferred transmit direction; and

means for providing, as feedback to the device, an indication of the preferred transmit direction to the device, wherein the feedback is provided by sweeping through a second set of transmit directions.

14. The apparatus of claim 13, further comprising:

means for exchanging with the device, before each data session, information about a number of one or more beamforming levels to be used for that data session.

15. The apparatus of claim 13, further comprising:

means for receiving information regarding beamforming capabilities of the device from a PNC, during or after association with the PNC.

16. The apparatus of claim 13, wherein the means for receiving training signals transmitted from the device comprises means for receiving each training signal that was transmitted from one transmit direction using all receive directions.

17. The apparatus of claim 13, wherein the means for receiving training signals from the device comprises means for receiving all training signals transmitted from the set of transmit directions using one receive direction and repeating this procedure for all receive directions.

18. The apparatus of claim 13, wherein at least a part of each training signal is based on Golay sequences.

19. A computer-program product for wireless communications, comprising a computer readable medium encoded with instructions executable to:

receive training signals transmitted from a device using a first set of transmit directions;

derive, from the first set of transmit directions, a preferred transmit direction; and

provide, as feedback to the device, an indication of the preferred transmit direction to the device, wherein the feedback is provided by sweeping through a second set of transmit directions.

20. An access point, comprising:

at least one antenna;

a receiver for receiving via the at least one antenna training signals transmitted from a device using a first set of transmit directions;

a circuit for deriving, from the first set of transmit directions, a preferred transmit direction; and

a circuit for providing, as feedback to the device, an indication of the preferred transmit direction to the device, wherein the feedback is provided by sweeping through a second set of transmit directions.

21. A method for wireless communications, comprising:

transmitting training signals to a device using a first set of transmit directions;

receiving, from the device, an indication of at least one first preferred transmit direction derived from the first set of transmit directions;

transmitting training signals to the device using a second set of transmit directions, wherein the second set of transmit directions is derived from the at least one first preferred transmit direction;

receiving, from the device, an indication of at least one second preferred transmit direction derived from the second set of transmit directions; and

using the at least one second transmit preferred direction to communicate with the device.

22. The method of claim 21, further comprising:

exchanging with the device, before each data session, information about a number of one or more beamforming levels to be used for that data session.

23. The method of claim 22, wherein the second set of transmit directions is derived from the at least one first preferred transmit direction if the number of beamforming levels is greater than one.

24. The method of claim 23, further comprising:

deriving at least a third set of transmit directions from the at least one second preferred transmit direction; and

receiving, from the device, an indication of at least a third preferred transmit direction derived from at least the third set of transmit directions; and

wherein at least the third set of transmit directions is derived from the at least one second preferred transmit direction if the number of beamforming levels is greater than two.

25. The method of claim 21, further comprising:

transmitting beamforming capability information to the device, wherein the beamforming capability information comprises a maximum number of supported beamforming levels, a number of transmit directions in the first set of transmit directions, and a number of receive directions in a first set of receive directions.

26. The method of claim 21, wherein the at least one first preferred transmit direction is derived from the first set of transmit directions based on a first signal-quality metric, and wherein the at least one second preferred transmit direction is derived from the second set of transmit directions based on a second signal-quality metric.

27. The method of claim 21, further comprising:

forming at least one cluster of transmit directions by grouping transmit directions from the second set of transmit directions, wherein each cluster comprises one preferred transmit direction from the second set of transmit directions; and

providing, as feedback to the device, information that includes a number of clusters, a number of transmit directions that belong to the second set of transmit directions in each cluster, codeword identifiers of transmit directions that belong to the second set of transmit directions in each cluster, and information about which transmit direction belong to which cluster.

28. The method of claim 27, further comprising:

transmitting a plurality of tracking packets using a transmit direction within a cluster of transmit directions; and

receiving information about a preferred pair of direction; and

wherein the plurality of tracking packets were transmitted at a lower rate than the training signals.

29. The method of claim 21, wherein at least a part of each training signal is based on Golay sequences.

30. An apparatus for wireless communications, comprising:

a circuit for transmitting training signals to a device using a first set of transmit directions;

a circuit for receiving, from the device, an indication of at least one first preferred transmit direction derived from the first set of transmit directions;

a circuit for transmitting training signals to the device using a second set of transmit directions, wherein the second set of transmit directions is derived from the at least one first preferred transmit direction;

a circuit for receiving, from the device, an indication of at least one second preferred transmit direction derived from the second set of transmit directions; and

a circuit for using the at least one second transmit preferred direction to communicate with the device.

31. The apparatus of claim 30, further comprising:

a circuit for exchanging with the device, before each data session, information about a number of one or more beamforming levels to be used for that data session.

32. The apparatus of claim 31, wherein the second set of transmit directions is derived from the at least one first preferred transmit direction if the number of beamforming levels is greater than one.

33. The apparatus of claim 32, further comprising:

a circuit for deriving at least a third set of transmit directions from the at least one second preferred transmit direction; and

a receiver for receiving, from the device, an indication of at least a third preferred transmit direction derived from at least the third set of transmit directions; and

wherein at least the third set of transmit directions is derived from the at least one second preferred transmit direction if the number of beamforming levels is greater than two.

34. The apparatus of claim 30, further comprising:

a circuit for transmitting beamforming capability information to the device, wherein the beamforming capability information comprises a maximum number of supported beamforming levels, a number of transmit directions in the first set of transmit directions, and a number of receive directions in a first set of receive directions.

35. The apparatus of claim 30, wherein the at least one first preferred transmit direction is derived from the first set of transmit directions based on a first signal-quality metric, and wherein the at least one second preferred transmit direction is derived from the second set of transmit directions based on a second signal-quality metric.

36. The apparatus of claim 30, further comprising:

a circuit for forming at least one cluster of transmit directions by grouping transmit directions from the second set of transmit directions, wherein each cluster comprises one preferred transmit direction from the second set of transmit directions; and

a circuit for providing, as feedback to the device, information that includes a number of clusters, a number of transmit directions that belong to the second set of transmit directions in each cluster, codeword identifiers of transmit directions that belong to the second set of transmit directions in each cluster, and information about which transmit direction belong to which cluster.

37. The apparatus of claim 36, further comprising:

a circuit for transmitting a plurality of tracking packets using a transmit direction within a cluster of transmit directions; and

a circuit for receiving information about a preferred pair of direction; and

wherein the plurality of tracking packets were transmitted at a lower rate than the training signals.

38. The apparatus of claim 30, wherein at least a part of each training signal is based on Golay sequences.

39. An apparatus for wireless communications, comprising:

means for transmitting training signals to a device using a first set of transmit directions;

means for receiving, from the device, an indication of at least one first preferred transmit direction derived from the first set of transmit directions;

means for transmitting training signals to the device using a second set of transmit directions, wherein the second set of transmit directions is derived from the at least one first preferred transmit direction;

means for receiving, from the device, an indication of at least one second preferred transmit direction derived from the second set of transmit directions; and

means for using the at least one second transmit preferred direction to communicate with the device.

40. The apparatus of claim 39, further comprising:

means for exchanging with the device, before each data session, information about a number of one or more beamforming levels to be used for that data session.

41. The apparatus of claim 40, wherein the second set of transmit directions is derived from the at least one first preferred transmit direction if the number of beamforming levels is greater than one.

42. The apparatus of claim 41, further comprising:

means for deriving at least a third set of transmit directions from the at least one second preferred transmit direction; and

means for receiving, from the device, an indication of at least a third preferred transmit direction derived from at least the third set of transmit directions; and

wherein at least the third set of transmit directions is derived from the at least one second preferred transmit direction if the number of beamforming levels is greater than two.

43. The apparatus of claim 39, further comprising:

means for transmitting beamforming capability information to the device, wherein the beamforming capability information comprises a maximum number of supported beamforming levels, a number of transmit directions in the first set of transmit directions, and a number of receive directions in a first set of receive directions.

44. The apparatus of claim 39, wherein the at least one first preferred transmit direction is derived from the first set of transmit directions based on a first signal-quality metric, and wherein the at least one second preferred transmit direction is derived from the second set of transmit directions based on a second signal-quality metric.

45. The apparatus of claim 39, further comprising:

means for forming at least one cluster of transmit directions by grouping transmit directions from the second set of transmit directions, wherein each cluster comprises one preferred transmit direction from the second set of transmit directions; and

means for providing, as feedback to the device, information that includes a number of clusters, a number of transmit directions that belong to the second set of transmit directions in each cluster, codeword identifiers of transmit directions that belong to the second set of transmit directions in each cluster, and information about which transmit direction belong to which cluster.

46. The apparatus of claim 45, further comprising:

means for transmitting a plurality of tracking packets using a transmit direction within a cluster of transmit directions; and

means for receiving information about a preferred pair of direction; and

wherein the plurality of tracking packets were transmitted at a lower rate than the training signals.

47. The apparatus of claim 39, wherein at least a part of each training signal is based on Golay sequences.

48. A computer-program product for wireless communications, comprising a computer readable medium encoded with instructions executable to:

transmit training signals to a device using a first set of transmit directions;

receive, from the device, an indication of at least one first preferred transmit direction derived from the first set of transmit directions;

transmit training signals to the device using a second set of transmit directions, wherein the second set of transmit directions is derived from the at least one first preferred transmit direction;

receive, from the device, an indication of at least one second preferred transmit direction derived from the second set of transmit directions; and

use the at least one second transmit preferred direction to communicate with the device.

49. An access point, comprising:

at least one antenna;

a circuit for transmitting via the at least one antenna training signals to a device using a first set of transmit directions;

a circuit for receiving via the at least one antenna, from the device, an indication of at least one first preferred transmit direction derived from the first set of transmit directions;

a circuit for transmitting via the at least one antenna training signals to the device using a second set of transmit directions, wherein the second set of transmit directions is derived from the at least one first preferred transmit direction;

a circuit for receiving via the at least one antenna, from the device, an indication of at least one second preferred transmit direction derived from the second set of transmit directions; and

a circuit for using the at least one second transmit preferred direction to communicate with the device.

50. A method for wireless communications, comprising:

receiving training signals transmitted from a device using a set of sectors;

deriving, from the set of sectors, at least one preferred sector;

providing, as feedback to the device, an indication of the at least one preferred sector to the device, wherein the feedback is provided by sweeping through a set of transmit directions related to sectors;

receiving training signals transmitted from the device using at least one set of beams, wherein the at least one set of beams is derived from the at least one preferred sector;

deriving, from the at least one set of beams, at least one preferred beam; and

providing, as feedback to the device, an indication of the at least one preferred beam to the device, wherein the feedback is provided by using the at least one preferred sector; and

wherein a sector is an antenna pattern covering a region of space, and wherein a beam is an antenna pattern covering a region in space smaller than the region in space covered by the sector.

51. An apparatus for wireless communications, comprising:

a circuit for receiving training signals transmitted from a device using a set of sectors;

a circuit for deriving, from the set of sectors, at least one preferred sector;

a circuit for providing, as feedback to the device, an indication of the at least one preferred sector to the device, wherein the feedback is provided by sweeping through a set of transmit directions related to sectors;

a circuit for receiving training signals transmitted from the device using at least one set of beams, wherein the at least one set of beams is derived from the at least one preferred sector;

a circuit for deriving, from the at least one set of beams, at least one preferred beam; and

a circuit for providing, as feedback to the device, an indication of the at least one preferred beam to the device, wherein the feedback is provided by using the at least one preferred sector; and

wherein a sector is an antenna pattern covering a region of space, and wherein a beam is an antenna pattern covering a region in space smaller than the region in space covered by the sector.

52. An apparatus for wireless communications, comprising:

means for receiving training signals transmitted from a device using a set of sectors;

means for deriving, from the set of sectors, at least one preferred sector;

means for providing, as feedback to the device, an indication of the at least one preferred sector to the device, wherein the feedback is provided by sweeping through a set of transmit directions related to sectors;

means for receiving training signals transmitted from the device using at least one set of beams, wherein the at least one set of beams is derived from the at least one preferred sector;

means for deriving, from the at least one set of beams, at least one preferred beam; and

means for providing, as feedback to the device, an indication of the at least one preferred beam to the device, wherein the feedback is provided by using the at least one preferred sector; and

wherein a sector is an antenna pattern covering a region of space, and wherein a beam is an antenna pattern covering a region in space smaller than the region in space covered by the sector.

53. A method for wireless communications, comprising:

transmitting training signals to a device using a set of sectors;

receiving, from the device, an indication of at least one preferred sector derived from the set of sectors;

transmitting training signals to the device using at least one set of beams, wherein the at least one set of beams is derived from the at least one preferred sector;

receiving, from the device, an indication of at least one preferred beam derived from the at least one set of beams; and

using the at least one preferred beam to communicate with the device; and

wherein a sector is an antenna pattern covering a region of space, and wherein a beam is an antenna pattern covering a region in space smaller than the region in space covered by the sector.

54. An apparatus for wireless communications, comprising:

a circuit for transmitting training signals to a device using a set of sectors;

a circuit for receiving, from the device, an indication of at least one preferred sector derived from the set of sectors;

a circuit for transmitting training signals to the device using at least one set of beams, wherein the at least one set of beams is derived from the at least one preferred sector;

a circuit for receiving, from the device, an indication of at least one preferred beam derived from the at least one set of beams; and

a circuit for using the at least one preferred beam to communicate with the device; and

wherein a sector is an antenna pattern covering a region of space, and wherein a beam is an antenna pattern covering a region in space smaller than the region in space covered by the sector.

55. An apparatus for wireless communications, comprising:

means for transmitting training signals to a device using a set of sectors;

means for receiving, from the device, an indication of at least one preferred sector derived from the set of sectors;

means for transmitting training signals to the device using at least one set of beams, wherein the at least one set of beams is derived from the at least one preferred sector;

means for receiving, from the device, an indication of at least one preferred beam derived from the at least one set of beams; and

means for using the at least one preferred beam to communicate with the device; and

wherein a sector is an antenna pattern covering a region of space, and wherein a beam is an antenna pattern covering a region in space smaller than the region in space covered by the sector.