LTE/LTE-A UPLINK CARRIER AGGREGATION USING UNLICENSED SPECTRUM

• US 20140362780A1
• Filed: 12/04/2013
• Published: 12/11/2014
• Est. Priority Date: 06/11/2013
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Malladi, Durga Prasad, Bhushan, Naga, Luo, Tao, Wei, Yongbin
• Granted Patent: US 9,883,404 B2
• Time in Patent Office: Days
• US Class Current: 370/329
• CPC Class Codes: H04L 27/0006 Assessment of spectral gaps suitable for allocating digitally modulated signals, e.g. for carrier allocation in cognitive radio for spectrum sharing between different networks H04W16/14
• CPC Class Codes: H04L 5/001 the frequencies being arranged in component carriers
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/0092 Indication of how the channel is divided
• CPC Class Codes: H04L 5/14 Two-way operation using the same type of signal, i.e. duplex
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 72/20 Control channels or signalling for resource management
• CPC Class Codes: H04W 72/542 using measured or perceived quality
• CPC Class Codes: H04W 74/0808 using carrier sensing, e.g. carrier sense multiple access [CSMA]

Abstract

Methods, systems, and apparatuses are described for wireless communications. In one method, an uplink grant may be received over a licensed spectrum. A clear channel assessment (CCA) may be performed in response to the uplink grant to determine availability of an unlicensed spectrum. The CCA may be performed prior to a transmission associated with the uplink grant. In another method, scheduling information may be received over a licensed spectrum. An uplink grant may be transmitted over the licensed spectrum. The uplink grant may be based at least in part on the scheduling information. The uplink grant may be configured to trigger a CCA to determine availability of an unlicensed spectrum prior to a transmission associated with the uplink grant.

Claims

1. A method for wireless communications, comprising:

receiving an uplink grant over a licensed spectrum; and

performing clear channel assessment (CCA) in response to the uplink grant to determine availability of an unlicensed spectrum, the CCA being performed prior to a transmission associated with the uplink grant.

2. The method of claim 1, further comprising:

transmitting data using the unlicensed spectrum when a determination is made that the unlicensed spectrum is available; and

disregarding the uplink grant when a determination is made that the unlicensed spectrum is not available.

3. The method of claim 1, further comprising:

transmitting data using the unlicensed spectrum when a determination is made that the unlicensed spectrum is available; and

transmitting signaling using the licensed spectrum indicating unavailability of the unlicensed spectrum when a determination is made that the unlicensed spectrum is not available.

4. The method of claim 1, further comprising:

transmitting data using the unlicensed spectrum when a determination is made that the unlicensed spectrum is available; and

transmitting data using the licensed spectrum when a determination is made that the unlicensed spectrum is not available.

5. The method of claim 4, wherein:

transmitting data using the unlicensed spectrum comprises transmitting data during a first subset of subframes indicated by the uplink grant; and

transmitting data using the licensed spectrum comprises transmitting data during a second subset of subframes indicated by the uplink grant.

6. The method of claim 5, wherein each of the first and second subsets of subframes is specified in terms of one or more of a number of subframes in the subset, a time interval between successive subframes in the subset, and an initial offset between a time of reception of the uplink grant and a first occurrence of a subframe in the subset.

7. The method of claim 5, wherein the first subset of subframes includes the second subset of subframes.

8. The method of claim 5, wherein the first and second subset of subframes start in a same subframe.

9. The method of claim 5, wherein:

the first subset of subframes starts in a first subframe; and

the second subset of subframes starts in a second subframe delayed from the first subframe.

10. The method of claim 1, wherein:

the uplink grant comprises a prioritized sequence of uplink grants, each uplink grant in the prioritized sequence being associated with a respective component carrier; and

performing CCA to determine availability of the unlicensed spectrum comprises;

performing CCA on at least one of the component carriers associated with the prioritized sequence of uplink grants to determine availability; and

identifying one of the component carriers found to be available for use in transmitting data.

11. The method of claim 10, wherein:

the component carriers corresponding to a subset of the uplink grants in the prioritized sequence are found to be available; and

identifying the one component carrier for use in transmitting data comprises selecting from the component carriers found to be available the one that corresponds to the uplink grant with a highest priority in the subset.

12. The method of claim 10, wherein each uplink grant in the prioritized sequence further comprises one or more of:

a set of physical resource blocks (PRBs) for the respective component carrier; and

a subset of subframes for which the uplink grant is applicable.

13. The method of claim 12, wherein the subset of subframes is specified in terms of one or more of a number of subframes in the subset, a time interval between successive subframes in the subset, and an initial offset between a time of reception of the uplink grant and a first occurrence of a subframe in the subset.

14. The method of claim 10, wherein a parameter in an uplink grant in the prioritized sequence is determined implicitly from a respective parameter in another uplink grant in the prioritized sequence.

15. The method of claim 10, wherein an implicit relationship between parameters in different uplink grants of the prioritized sequence is specified at least in part through radio resource control (RRC) signaling.

16. The method of claim 1, further comprising:

receiving over the licensed spectrum, an indication of a maximum uplink data rate over the unlicensed spectrum for a set of PRBs; and

performing CCA in a subframe in response to the indication, the CCA being performed to determine availability of a component carrier for the set of PRBs in the unlicensed spectrum to transmit data in a next subframe.

17. The method of claim 16, further comprising:

transmitting data using the unlicensed spectrum when a determination is made that the component carrier for the set of PRBs in the unlicensed spectrum is available; and

performing CCA in the next subframe when a determination is made that the component carrier for the set of PRBs in the unlicensed spectrum is not available.

18. The method of claim 16, further comprising:

transmitting data using the unlicensed spectrum when a determination is made that the component carrier for the set of PRBs in the unlicensed spectrum is available; and

transmitting data using the licensed spectrum when a determination is made that the component carrier for the set of PRBs in the unlicensed spectrum is not available.

19. The method of claim 16, wherein the same set of PRBs are assigned to each of a plurality of users on the uplink of the unlicensed spectrum.

20. The method of claim 19, wherein data transmitted from the plurality of users assigned the same set of PRBs is decoded using successive interference cancellation (SIC).

21. The method of claim 19, wherein the plurality of users assigned the same set of PRBs are assigned orthogonal demodulation reference signals (DM-RS) sequences.

22. The method of claim 21, wherein each of the plurality of users is assigned a distinct scrambling code.

23. The method of claim 16, wherein when a determination is made that the component carrier for the set of PRBs in the unlicensed spectrum is available, the method further comprises:

transmitting one or more of uplink data, uplink control signals, and uplink reference signals according to one or both of an assigned orthogonal DM-RS sequence and an assigned scrambling code.

24. The method of claim 23, further comprising:

transmitting, along with the one or more of the uplink data, the uplink control signals, and the uplink reference signals, a signal indicating one or more of a transmit format selection, a Hybrid Automatic Repeat Request identifier (HARQ-ID), and a HARQ redundancy version (RV).

25. The method of claim 1, further comprising:

transmitting one or more of a scheduling request, a buffer status report, and a power headroom report for a base station to schedule the uplink grant.

26. The method of claim 25, wherein the power headroom report indicates a power headroom associated with the licensed spectrum and a power headroom associated with the unlicensed spectrum.

27. The method of claim 1, further comprising:

identifying a change from a modulation coding scheme (MCS) indicated by the uplink grant; and

transmitting a message over a set of resource elements within PRBs allocated by the uplink grant, the message indicating the identified change in MCS.

28. The method of claim 1, wherein the uplink grant allocates PRBs for uplink transmission without allocating MCS for uplink transmission, the method further comprising:

determining the MCS for uplink transmission upon receiving the uplink grant; and

transmitting a message over a set of resource elements within the PRBs allocated for uplink transmission, the message indicating the MCS determined for uplink transmission.

29. An apparatus for wireless communications, comprising:

a processor;

memory in electronic communication with the processor; and

instructions stored in the memory, the instructions being executable by the processor to;

receive an uplink grant over a licensed spectrum; and

perform clear channel assessment (CCA) in response to the uplink grant to determine availability of an unlicensed spectrum, the CCA being performed prior to a transmission associated with the uplink grant.

30. The apparatus of claim 29, wherein the instructions are executable by the processor to:

transmit data using the unlicensed spectrum when a determination is made that the unlicensed spectrum is available; and

disregard the uplink grant when a determination is made that the unlicensed spectrum is not available.

31. The apparatus of claim 29, wherein the instructions are executable by the processor to:

transmit data using the unlicensed spectrum when a determination is made that the unlicensed spectrum is available; and

transmit signaling using the licensed spectrum indicating unavailability of the unlicensed spectrum when a determination is made that the unlicensed spectrum is not available.

32. The apparatus of claim 29, wherein the instructions are executable by the processor to:

transmit data using the unlicensed spectrum when a determination is made that the unlicensed spectrum is available; and

transmit data using the licensed spectrum when a determination is made that the unlicensed spectrum is not available.

33. The apparatus of claim 32, wherein:

the instructions executable by the processor to transmit data using the unlicensed spectrum comprise instructions executable by the processor to transmit data during a first subset of subframes indicated by the uplink grant; and

the instructions executable by the processor to transmit data using the licensed spectrum comprise instructions executable by the processor to transmit data during a second subset of subframes indicated by the uplink grant.

34. The apparatus of claim 33, wherein each of the first and second subsets of subframes is specified in terms of one or more of a number of subframes in the subset, a time interval between successive subframes in the subset, and an initial offset between a time of reception of the uplink grant and a first occurrence of a subframe in the subset.

35. The apparatus of claim 33, wherein:

the first subset of subframes starts in a first subframe; and

the second subset of subframes starts in a second subframe delayed from the first subframe.

36. The apparatus of claim 29, wherein:

the uplink grant comprises a prioritized sequence of uplink grants, each uplink grant in the prioritized sequence being associated with a respective component carrier; and

the instructions executable by the processor to perform CCA to determine availability of the unlicensed spectrum comprise instructions executable by the processor to;

perform CCA on at least one of the component carriers associated with the prioritized sequence of uplink grants to determine availability; and

identify one of the component carriers found to be available for use in transmitting data.

37. The apparatus of claim 36, wherein each uplink grant in the prioritized sequence further comprises one or more of:

a set of physical resource blocks (PRBs) for the respective component carrier; and

a subset of subframes for which the uplink grant is applicable.

38. The apparatus of claim 37, wherein the subset of subframes is specified in terms of one or more of a number of subframes in the subset, a time interval between successive subframes in the subset, and an initial offset between a time of reception of the uplink grant and a first occurrence of a subframe in the subset.

39. The apparatus of claim 36, wherein an implicit relationship between parameters in different uplink grants of the prioritized sequence is specified at least in part through radio resource control (RRC) signaling.

40. The apparatus of claim 29, wherein the instructions are executable by the processor to:

receive over the licensed spectrum, an indication of a maximum uplink data rate over the unlicensed spectrum for a set of PRBs; and

perform CCA in a subframe in response to the indication, the CCA being performed to determine availability of a component carrier for the set of PRBs in the unlicensed spectrum to transmit data in a next subframe.

41. The apparatus of claim 40, wherein the instructions are executable by the processor to:

transmit data using the unlicensed spectrum when a determination is made that the component carrier for the set of PRBs in the unlicensed spectrum is available; and

perform CCA in the next subframe when a determination is made that the component carrier for the set of PRBs in the unlicensed spectrum is not available.

42. The apparatus of claim 40, wherein the instructions are executable by the processor to:

transmit data using the unlicensed spectrum when a determination is made that the component carrier for the set of PRBs in the unlicensed spectrum is available; and

transmit data using the licensed spectrum when a determination is made that the component carrier for the set of PRBs in the unlicensed spectrum is not available.

43. The apparatus of claim 40, wherein the same set of PRBs are assigned to each of a plurality of users on the uplink of the unlicensed spectrum.

44. The apparatus of claim 43, wherein data transmitted from the plurality of users assigned the same set of PRBs is decoded using successive interference cancellation (SIC).

45. The apparatus of claim 43, wherein the plurality of users assigned the same set of PRBs are assigned orthogonal demodulation reference signals (DM-RS) sequences.

46. The apparatus of claim 45, wherein each of the plurality of users is assigned a distinct scrambling code.

47. The apparatus of claim 40, wherein when a determination is made that the component carrier for the set of PRBs in the unlicensed spectrum is available, the instructions are executable by the processor to:

transmit one or more of uplink data, uplink control signals, and uplink reference signals according to one or both of an assigned orthogonal DM-RS sequence and an assigned scrambling code.

48. The apparatus of claim 47, wherein the instructions are executable by the processor to:

transmit, along with the one or more of the uplink data, the uplink control signals, and the uplink reference signals, a signal indicating one or more of a transmit format selection, a Hybrid Automatic Repeat Request identifier (HARQ-ID), and a HARQ redundancy version (RV).

49. The apparatus of claim 29, wherein the instructions are executable by the processor to:

transmit one or more of a scheduling request, a buffer status report, and a power headroom report for a base station to schedule the uplink grant.

50. The apparatus of claim 29, wherein:

the uplink grant allocates PRBs for uplink transmission without allocating a modulation coding scheme (MCS) for uplink transmission; and

the instructions are executable by the processor to;

determine the MCS for uplink transmission upon receiving the uplink grant; and

transmit a message over a set of resource elements within the PRBs allocated for uplink transmission, the message indicating the MCS determined for uplink transmission.

51. An apparatus for wireless communications, comprising:

means for receiving an uplink grant over a licensed spectrum; and

means for performing clear channel assessment (CCA) in response to the uplink grant to determine availability of an unlicensed spectrum, the CCA being performed prior to a transmission associated with the uplink grant.

52. The apparatus of claim 51, further comprising:

means for transmitting data using the unlicensed spectrum when a determination is made that the unlicensed spectrum is available; and

means for disregarding the uplink grant when a determination is made that the unlicensed spectrum is not available.

53. The apparatus of claim 51, further comprising:

means for transmitting data using the unlicensed spectrum when a determination is made that the unlicensed spectrum is available; and

means for transmitting signaling using the licensed spectrum indicating unavailability of the unlicensed spectrum when a determination is made that the unlicensed spectrum is not available.

54. The apparatus of claim 51, further comprising:

means for transmitting data using the unlicensed spectrum when a determination is made that the unlicensed spectrum is available; and

means for transmitting data using the licensed spectrum when a determination is made that the unlicensed spectrum is not available.

55. A computer program product for wireless communications, the computer program product comprising a non-transitory computer-readable medium storing instructions executable by a processor to:

receive an uplink grant over a licensed spectrum; and

perform clear channel assessment (CCA) in response to the uplink grant to determine availability of an unlicensed spectrum, the CCA being performed prior to a transmission associated with the uplink grant.

56. The computer program product of claim 55, wherein the instructions are executable by the processor to:

transmit data using the unlicensed spectrum when a determination is made that the unlicensed spectrum is available; and

disregard the uplink grant when a determination is made that the unlicensed spectrum is not available.

57. The computer program product of claim 55, wherein the instructions are executable by the processor to:

transmit data using the unlicensed spectrum when a determination is made that the unlicensed spectrum is available; and

transmit signaling using the licensed spectrum indicating unavailability of the unlicensed spectrum when a determination is made that the unlicensed spectrum is not available.

58. The computer program product of claim 55, wherein the instructions are executable by the processor to:

transmit data using the unlicensed spectrum when a determination is made that the unlicensed spectrum is available; and

transmit data using the licensed spectrum when a determination is made that the unlicensed spectrum is not available.

59. A method for wireless communications, comprising:

receiving scheduling information over a licensed spectrum; and

transmitting an uplink grant over the licensed spectrum, the uplink grant being based at least in part on the scheduling information, and the uplink grant being configured to trigger a clear channel assessment (CCA) to determine availability of an unlicensed spectrum prior to a transmission associated with the uplink grant.

60. The method of claim 59, further comprising:

receiving data over the unlicensed spectrum when a determination is made that the unlicensed spectrum is available; and

receiving data over the licensed spectrum when a determination is made that the unlicensed spectrum is not available.

61. The method of claim 60, wherein:

receiving data over the unlicensed spectrum comprises receiving data transmitted over a first subset of subframes indicated by the uplink grant; and

receiving data over the licensed spectrum comprises receiving data transmitted over a second subset of subframes indicated by the uplink grant.

62. The method of claim 61, wherein the first subset of subframes includes the second subset of subframes.

63. The method of claim 61, wherein the first and second subsets of subframes start in a same subframe.

64. The method of claim 61, wherein:

the first subset of subframes starts in a first subframe; and

the second subset of subframes starts in a second subframe delayed from the first subframe.

65. The method of claim 64, further comprising:

releasing resources in the licensed spectrum associated with the transmission of data over the second subset of subframes when data transmitted over the first subset of subframes is received.

66. The method of claim 59, wherein the scheduling information comprises one or more of:

a scheduling request;

a buffer status report; and

a power headroom report indicating a power headroom associated with the licensed spectrum and a power headroom associated with the unlicensed spectrum.

67. The method of claim 59, further comprising:

assigning a same set of physical resource blocks (PRBs) to a plurality of users on the uplink of the unlicensed spectrum based at least in part on the transmitted uplink grant;

receiving uplink data from the plurality of users using the assigned PRBs; and

decoding the uplink data using a successive interference cancellation (SIC).

68. The method of claim 67, further comprising:

assigning one or both of an orthogonal demodulation reference signals (DM-RS) sequence and a scrambling code to each of the plurality of users for transmission of the uplink data.

69. The method of claim 67, further comprising:

receiving from each of the plurality of users, along with the uplink data, a signal indicating one or more of a transmit format selection, a Hybrid Automatic Repeat Request identifier (HARQ-ID), and a HARQ redundancy version (RV).

70. An apparatus for wireless communications, comprising:

a processor;

memory in electronic communication with the processor; and

instructions stored in the memory, the instructions being executable by the processor to;

receive scheduling information over a licensed spectrum; and

transmit an uplink grant over the licensed spectrum, the uplink grant being based at least in part on the scheduling information, and the uplink grant being configured to trigger a clear channel assessment (CCA) to determine availability of an unlicensed spectrum prior to a transmission associated with the uplink grant.

71. The apparatus of claim 70, wherein the instructions are executable by the processor to:

receive data over the unlicensed spectrum when a determination is made that the unlicensed spectrum is available; and

receive data over the licensed spectrum when a determination is made that the unlicensed spectrum is not available.

72. The apparatus of claim 71, wherein:

the instructions executable by the processor to receive data over the unlicensed spectrum comprise instructions executable by the processor to receive data transmitted over a first subset of subframes indicated by the uplink grant; and

the instructions executable by the processor to receive data over the licensed spectrum comprise instructions executable by the processor to receive data transmitted over a second subset of subframes indicated by the uplink grant.

73. The apparatus of claim 70, wherein the scheduling information comprises one or more of:

a scheduling request;

a buffer status report; and

a power headroom report indicating a power headroom associated with the licensed spectrum and a power headroom associated with the unlicensed spectrum.

74. An apparatus for wireless communications, comprising:

means for receiving scheduling information over a licensed spectrum; and

means for transmitting an uplink grant over the licensed spectrum, the uplink grant being based at least in part on the scheduling information, and the uplink grant being configured to trigger a clear channel assessment (CCA) to determine availability of an unlicensed spectrum prior to a transmission associated with the uplink grant.

75. The apparatus of claim 74, further comprising:

means for receiving data over the unlicensed spectrum when a determination is made that the unlicensed spectrum is available; and

means for receiving data over the licensed spectrum when a determination is made that the unlicensed spectrum is not available.

76. The apparatus of claim 75, wherein:

means for receiving data over the unlicensed spectrum comprises receiving data transmitted over a first subset of subframes indicated by the uplink grant; and

means for receiving data over the licensed spectrum comprises receiving data transmitted over a second subset of subframes indicated by the uplink grant.

77. A computer program product for wireless communications, the computer program product comprising a non-transitory computer-readable medium storing instructions executable by a processor to:

receive scheduling information over a licensed spectrum; and

transmit an uplink grant over the licensed spectrum, the uplink grant being based at least in part on the scheduling information, and the uplink grant being configured to trigger a clear channel assessment (CCA) to determine availability of an unlicensed spectrum prior to a transmission associated with the uplink grant.

78. The computer program product of claim 77, wherein the instructions are executable by the processor to:

receive data over the unlicensed spectrum when a determination is made that the unlicensed spectrum is available; and

receive data over the licensed spectrum when a determination is made that the unlicensed spectrum is not available.

79. The computer program product of claim 78, wherein:

the instructions executable by the processor to receive data over the unlicensed spectrum comprise instructions executable by the processor to receive data transmitted over a first subset of subframes indicated by the uplink grant; and

the instructions executable by the processor to receive data over the licensed spectrum comprise instructions executable by the processor to receive data transmitted over a second subset of subframes indicated by the uplink grant.