Codebook and feedback design for high order MIMO

• US 9,397,738 B2
• Filed: 05/16/2013
• Issued: 07/19/2016
• Est. Priority Date: 05/17/2012
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Xu, Hao, Geirhofer, Stefan, Gaal, Peter, Chen, Wanshi, Wei, Yongbin
• Primary Examiner(s): Washburn, Daniel
• Assistant Examiner(s): HUGHES, EBONI N
• Application Number:
  US13/895,772
• Publication Number:
  US 20130308714A1
• Time in Patent Office: 1,160 Days
• Field of Search: 375/260, 375/267, 370/252, 370328-329
• US Class Current: 1/1
• CPC Class Codes: H04B 7/0417 Feedback systems
• CPC Class Codes: H04B 7/0456 Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
• CPC Class Codes: H04B 7/0639 Using selective indices, e.g. of a codebook, e.g. pre-distortion matrix index [PMI] or for beam selection
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver

Abstract

Aspects of the present disclosure relate to techniques that may be utilized in networks with base stations and/or mobile devices that use large number of antennas or multi-dimensional arrays of antennas. According to certain aspects, a method for wireless communications is provided. The method may be performed, for example, by a base station and generally includes mapping N physical antennas arranged in at least two dimensions to K virtual antennas, wherein K is less than N, transmitting reference signals (RS) via the K virtual antennas, and receiving, from a user equipment, feedback based on the RS transmitted on the K virtual antennas.

Claims

1. A method for wireless communications by a base station, comprising:

mapping N physical antennas arranged in at least two dimensions to K virtual antennas, wherein K is less than N, and wherein the mapping comprises spatial sampling in both vertical and horizontal directions;

transmitting reference signals (RS) via the K virtual antennas; and

receiving, from a user equipment (UE), feedback based on the RS transmitted on the K virtual antennas, wherein a timeline for UE feedback reporting is dependent on a number of transmit antennas of the base station.

2. The method of claim 1, wherein the mapping comprises:

applying joint virtual antenna mapping in horizontal and vertical dimensions.

3. The method of claim 1, wherein the mapping is based on at least one of precoding vector mapping or continuous phase mapping.

4. The method of claim 1, wherein the mapping from physical antennas to virtual antennas is periodically changed to beamform in different directions in both azimuth and elevation.

5. The method of claim 4, further comprising signaling the UE of periodic updates to the mapping.

6. The method of claim 4, further comprising selecting a preferred beam forming direction based on multiple reports corresponding to different mappings.

7. The method of claim 1, further comprising configuring the UE to report measurements corresponding to different mappings in different subframes.

8. The method of claim 1, further comprising configuring different spatial sampling frequencies.

9. The method of claim 1, further comprising configuring different spatial sampling rate for horizontal and vertical dimensions.

10. The method of claim 1, wherein, within each subband, each physical resource block (PRB) contains a different virtual antenna port and can have different beamforming.

11. The method of claim 1, wherein, across subbands, the same sets of antenna ports and beamforming is repeated.

12. The method of claim 1, wherein, a number of antenna ports is limited such that one antenna port is present only once per coherence bandwidth.

13. The method of claim 1, wherein antenna ports are evenly distributed to span at least one of physical or virtual antennas within each coherence bandwidth.

14. The method of claim 1, wherein antenna ports are evenly distributed across available bandwidth.

15. The method of claim 1, wherein frequency cycling and time cycling are used jointly to change the mapping.

16. The method of claim 1, wherein code domain reuse is used for antenna ports to allow multiplexing of multiple RS ports on the same physical resources.

17. The method of claim 1, wherein:

the N physical antennas are arranged in a 2-dimensional array; and

at least one of a center row or center column of the antenna array is used for RS transmission.

18. The method of claim 1, wherein the UE utilizes a common structure for vertical and horizontal measurement reporting.

19. The method of claim 1, wherein the UE provides beamforming feedback for vertical and horizontal dimensions separately.

20. The method of claim 1, wherein the UE provides beamforming feedback for vertical and horizontal dimensions jointly.

21. The method of claim 1, wherein the UE provides feedback for one dimension as a difference relative to another dimension.

22. The method of claim 1, wherein, if the UE reports rank 1 on both horizontal and vertical directions, the base station beamforms jointly from both directions.

23. The method of claim 1, wherein:

a dual codebook structure decouples horizontal and vertical components.

24. The method of claim 1, wherein:

the base station receives one horizontal and one vertical precoding matrix indicator (PMI), respectively; and

the base station combines this feedback to determine beamforming using an antenna array of the N physical antennas arranged in a 2-dimensional array.

25. The method of claim 1, further comprising:

utilizing a joint codebook design for 2-dimensions for beamforming.

26. The method of claim 1, wherein different codebook designs for a vertical array and a horizontal array are used.

27. The method of claim 1, wherein the spatial sampling comprises selecting at least one of a center row or center column from the N physical antennas arranged in at least two dimensions.

28. A method for wireless communications by a user equipment (UE), comprising:

receiving information regarding mapping of N physical antennas of a base station arranged in at least two dimensions to K virtual antennas, wherein K is less than N, and wherein the mapping comprises spatial sampling in both vertical and horizontal directions;

receiving reference signals (RS) transmitted from the base station via the K virtual antennas; and

transmitting, to the base station, feedback based on the RS, wherein a timeline for transmitting the feedback is dependent on a number of transmit antennas of the base station.

29. The method of claim 28, wherein the information regarding mapping comprises:

information regarding applying joint virtual antenna mapping in horizontal and vertical dimensions.

30. The method of claim 28, wherein the mapping is based on at least one of precoding vector mapping or continuous phase mapping.

31. The method of claim 28, wherein the mapping from physical antennas to virtual antennas is periodically changed to beamform in different directions in both azimuth and elevation.

32. The method of claim 31, further comprising receiving signaling of periodic updates to the mapping.

33. The method of claim 31, further comprising transmitting multiple feedback reports corresponding to different mappings.

34. The method of claim 28, wherein the UE is configured to report measurements corresponding to different mappings in different subframes.

35. The method of claim 28, further comprising receiving information regarding different spatial sampling frequencies.

36. The method of claim 28, further comprising receiving information regarding different sampling rate for horizontal and vertical dimensions.

37. The method of claim 28, wherein, within each subband, each physical resource block (PRB) contains a different virtual antenna port and can have different beamforming.

38. The method of claim 28, wherein, across subbands, the same sets of antenna ports and beamforming is repeated.

39. The method of claim 28, wherein, a number of antenna ports is limited such that one antenna port is present only once per coherence bandwidth.

40. The method of claim 28, wherein antenna ports are evenly distributed to span at least one of physical or virtual antennas within each coherence bandwidth.

41. The method of claim 28, wherein antenna ports are evenly distributed across available bandwidth.

42. The method of claim 28, wherein frequency cycling and time cycling are used jointly to change the mapping.

43. The method of claim 28, wherein code domain reuse is used for antenna ports to allow multiplexing of multiple RS ports on the same physical resources.

44. The method of claim 28, wherein:

the N physical antennas are arranged in a 2-dimensional array; and

at least one of a center row or center column of the antenna array is used for RS transmission.

45. The method of claim 28, wherein the UE utilizes a common structure for vertical and horizontal measurement reporting.

46. The method of claim 28, wherein:

a dual codebook structure decouples horizontal and vertical components.

47. The method of claim 46, wherein transmitting the feedback comprises:

transmitting at least one horizontal precoding matrix indicator (PMI) and one vertical PMI.

48. The method of claim 28, wherein transmitting the feedback comprises transmitting beamforming feedback for vertical and horizontal dimensions separately.

49. The method of claim 28, wherein transmitting the feedback comprises transmitting beamforming feedback for vertical and horizontal dimensions jointly.

50. The method of claim 28, wherein transmitting the feedback comprises transmitting feedback for one dimension as a difference relative to another dimension.

51. The method of claim 28, wherein the spatial sampling comprises selecting at least one of a center row or center column from the N physical antennas arranged in at least two dimensions.

52. An apparatus for wireless communications by a base station, comprising:

means for mapping N physical antennas arranged in at least two dimensions to K virtual antennas, wherein K is less than N, and wherein the mapping comprises spatial sampling in both vertical and horizontal directions;

means for transmitting reference signals (RS) via the K virtual antennas; and

means for receiving, from a user equipment (UE), feedback based on the RS transmitted on the K virtual antennas, wherein a timeline for UE feedback reporting is dependent on a number of transmit antennas of the base station.

53. The apparatus of claim 52, wherein the means for mapping comprises:

means for applying joint virtual antenna mapping in horizontal and vertical dimensions.

54. The apparatus of claim 52, wherein the means for mapping applies at least one of precoding vector mapping or continuous phase mapping.

55. The apparatus of claim 52, wherein mapping from physical antennas to virtual antennas is periodically changed to beamform in different directions in both azimuth and elevation.

56. The apparatus of claim 55, further comprising means for signaling the UE of periodic updates to the mapping.

57. The apparatus of claim 52, wherein the spatial sampling comprises selecting at least one of a center row or center column from the N physical antennas arranged in at least two dimensions.

58. An apparatus for wireless communications by a user equipment (UE), comprising:

means for receiving information regarding mapping of N physical antennas of a base station arranged in at least two dimensions to K virtual antennas, wherein K is less than N, and wherein the mapping comprises spatial sampling in both vertical and horizontal directions;

means for receiving reference signals (RS) transmitted from the base station via the K virtual antennas; and

means for transmitting, to the base station, feedback based on the RS,

wherein a timeline for transmitting the feedback is dependent on a number of transmit antennas of the base station.

59. The apparatus of claim 58, wherein the information regarding mapping comprises:

information regarding applying joint virtual antenna mapping in horizontal and vertical dimensions.

60. The apparatus of claim 58, wherein the mapping is based on at least one of precoding vector mapping or continuous phase mapping.

61. The apparatus of claim 58, wherein the mapping from physical antennas to virtual antennas is periodically changed to beamform in different directions in both azimuth and elevation.

62. The apparatus of claim 61, further comprising receiving signaling of periodic updates to the mapping.

63. The apparatus of claim 58, wherein the spatial sampling comprises selecting at least one of a center row or center column from the N physical antennas arranged in at least two dimensions.

64. An apparatus for wireless communications by a base station, comprising:

at least one processor configured to map N physical antennas arranged in at least two dimensions to K virtual antennas, wherein K is less than N, and wherein the map comprises spatial sampling in both vertical and horizontal directions, transmit reference signals (RS) via the K virtual antennas, and receive from a user equipment (UE), feedback based on the RS transmitted on the K virtual antennas, wherein a timeline for UE feedback reporting is dependent on a number of transmit antennas of the base station; and

a memory coupled with the at least one processor.

65. The apparatus of claim 64, wherein the spatial sampling comprises selecting at least one of a center row or center column from the N physical antennas arranged in at least two dimensions.

66. An apparatus for wireless communications by a user equipment (UE), comprising:

at least one processor configured to receive information regarding mapping of N physical antennas of a base station arranged in at least two dimensions to K virtual antennas, wherein K is less than N, and wherein the mapping comprises spatial sampling in both vertical and horizontal directions, receive reference signals (RS) transmitted from the base station via the K virtual antennas, and transmit, to the base station, feedback based on the RS, wherein a timeline for transmitting the feedback is dependent on a number of transmit antennas of the base station; and

a memory coupled with the at least one processor.

67. The apparatus of claim 66, wherein the spatial sampling comprises selecting at least one of a center row or center column from the N physical antennas arranged in at least two dimensions.

68. A non-transitory computer readable medium for wireless communications by a base station the non-transitory computer readable medium having instructions stored thereon for:

mapping N physical antennas arranged in at least two dimensions to K virtual antennas, wherein K is less than N, and wherein the mapping comprises spatial sampling in both vertical and horizontal directions;

transmitting reference signals (RS) via the K virtual antennas; and

receiving, from a user equipment (UE), feedback based on the RS transmitted on the K virtual antennas, wherein a timeline for UE feedback reporting is dependent on a number of transmit antennas of the base station.

69. A non-transitory computer readable medium for wireless communications by a user equipment (UE), the non-transitory computer readable medium having instructions stored thereon for:

receiving information regarding mapping of N physical antennas of a base station arranged in at least two dimensions to K virtual antennas, wherein K is less than N, and wherein the mapping comprises spatial sampling in both vertical and horizontal directions;

receiving reference signals (RS) transmitted from the base station via the K virtual antennas; and

transmitting, to the base station, feedback based on the RS,

wherein a timeline for transmitting the feedback is dependent on a number of transmit antennas of the base station.