Listen before talk techniques in shared millimeter wave radio frequency spectrum

1. A method for wireless communication at a user equipment (UE), comprising:

receiving an uplink grant from a base station that indicates uplink resources for transmission of uplink data from the UE to the base station in a shared millimeter wave (mmW) radio frequency spectrum band;

determining a duration of a listen-before-talk (LBT) procedure, wherein the duration of the LBT procedure is synchronized with a frame boundary, a slot boundary, or a symbol boundary of a frame structure used for communications between the UE and the base station;

performing, responsive to receiving the uplink grant, the LBT procedure to determine that the shared mmW radio frequency spectrum band is available for the transmission of the uplink data, wherein the LBT procedure is a clear channel assessment (CCA) check using energy detection (ED) for a duration of a CCA observation time based in part on a random number that is selected for a number of CCA slots to measure channel energy; and

transmitting, based at least in part on the shared mmW radio frequency spectrum band being available for the transmission of the uplink data, the uplink data to the base station using the uplink resources indicated in the uplink grant.

2. The method of claim 1 , further comprising:

receiving, from the base station, an indication of the duration of the LBT procedure.

3. The method of claim 2 , wherein the receiving the indication of the duration of the LBT procedure comprises receiving the random number from the base station.

4. The method of claim 2 , wherein the indication of the duration of the LBT procedure is included in the uplink grant or transmitted together with the uplink grant.

5. The method of claim 2 , wherein the indication of the duration of the LBT procedure further indicates an offset value, and wherein the LBT procedure is initiated after a time period associated with the offset value.

6. The method of claim 1 , wherein the uplink grant is a short control signaling transmission that is exempt from the LBT procedure.

7. The method of claim 1 , further comprising:

abandoning the transmitting of the uplink data based at least in part on the shared mmW radio frequency spectrum band being unavailable for the transmission of the uplink data.

8. The method of claim 1 , wherein the uplink grant is received from the base station during a downlink transmission from the base station in a previous channel occupancy time (COT) or transmission opportunity (TxOP).

9. The method of claim 8 , wherein the uplink grant further indicates an ending time of the previous COT or TxOP, and wherein the UE initiates the LBT procedure after the ending time of the previous COT or TxOP.

10. The method of claim 8 , wherein at least a portion of the duration of the LBT procedure overlaps with a portion of the previous COT or TxOP.

11. The method of claim 10 , wherein the previous COT or TxOP includes a transmission for a different UE.

12. The method of claim 1 , wherein one or more of the uplink grant or transmission of the uplink data are transmitted via a beamformed transmission beam.

13. A method for wireless communication at a base station, comprising:

allocating uplink resources to a user equipment (UE) for an uplink transmission of uplink data from the UE to the base station in a shared millimeter wave (mmW) radio frequency spectrum band;

transmitting an uplink grant to the UE indicating the uplink resources;

determining a duration of a listen-before-talk (LBT) procedure, wherein the duration of the LBT procedure is synchronized with a frame boundary, a slot boundary, or a symbol boundary of a frame structure used for communications between the UE and the base station; and

monitoring for the uplink transmission from the UE using the uplink resources indicated in the uplink grant, wherein the UE is to perform the LBT procedure prior to the uplink transmission, and wherein the LBT procedure is a clear channel assessment (CCA) check using energy detection (ED) for a duration of a CCA observation time based in part on a random number that is selected for a number of CCA slots to measure channel energy.

14. The method of claim 13 , further comprising:

transmitting, to the UE, an indication of the duration of the LBT procedure.

15. The method of claim 14 , wherein the method further comprises:

randomly selecting the random number for the CCA, and

providing the random number to the UE as the indication of the duration of the LBT procedure.

16. The method of claim 14 , wherein the indication of the duration of the LBT procedure is included in the uplink grant or transmitted together with the uplink grant.

17. The method of claim 14 , wherein the UE is a first UE, and wherein the method further comprises:

determining that a second uplink transmission of a second UE has a second duration that is less than the duration of the LBT procedure of the first UE;

scheduling the second uplink transmission of the second UE within the duration of the LBT procedure of the first UE; and

transmitting a second uplink grant to the second UE.

18. The method of claim 17 , further comprising:

determining an offset value between the uplink grant and a start of the LBT procedure at the first UE based at least in part on a duration of the second uplink transmission of the second UE; and

indicating the offset value to the first UE.

19. The method of claim 17 , wherein the second UE is selected based at least in part on a cross-UE interference between transmission beams of the first UE and the second UE being below a threshold value.

20. The method of claim 13 , further comprising:

transmitting a second uplink grant to a different UE during the duration of the LBT procedure.

21. The method of claim 13 , wherein the uplink grant is a short control signaling transmission that is exempt from the LBT procedure.

22. The method of claim 13 , wherein the monitoring comprises:

determining that the uplink transmission is not received; and

reusing the granted resource for transmission or reception for one or more different UEs.

23. The method of claim 13 , wherein the uplink grant is transmitted to the UE during a downlink transmission of a previous channel occupancy time (COT) or transmission opportunity (TxOP).

24. The method of claim 23 , wherein the uplink grant further indicates an ending time of the previous COT or TxOP, and wherein the UE initiates the LBT procedure after the ending time of the previous COT or TxOP.

25. The method of claim 23 , wherein at least a portion of the duration of the LBT procedure overlaps with a portion of the previous COT or TxOP.

26. The method of claim 23 , wherein the uplink grant is transmitted from the base station before an end of the downlink transmission of downlink shared channel data.

27. The method of claim 13 , wherein one or more of the uplink grant or uplink transmission are transmitted via a beamformed transmission beam.

28. An apparatus for wireless communication at a user equipment (UE), comprising:

a processor,

memory coupled with the processor; and

instructions stored in the memory and executable by the processor to cause the apparatus to:

receive an uplink grant from a base station that indicates uplink resources for transmission of uplink data from the UE to the base station in a shared millimeter wave (mmW) radio frequency spectrum band;

determine a duration of a listen-before-talk (LBT) procedure, wherein the duration of the LBT procedure is synchronized with a frame boundary, a slot boundary, or a symbol boundary of a frame structure used for communications between the UE and the base station;

perform, responsive to receiving the uplink grant, the LBT procedure to determine that the shared mmW radio frequency spectrum band is available for the transmission of the uplink data, wherein the LBT procedure is a clear channel assessment (CCA) check using energy detection (ED) for a duration of a CCA observation time based in part on a random number that is selected for a number of CCA slots to measure channel energy; and

transmit, based at least in part on the shared mmW radio frequency spectrum band being available for the transmission of the uplink data, the uplink data to the base station using the uplink resources indicated in the uplink grant.

29. The apparatus of claim 28 , wherein the instructions are further executable by the processor to cause the apparatus to:

receive, from the base station, an indication of the duration of the LBT procedure.

30. The apparatus of claim 29 , wherein the receiving the indication of the duration of the LBT procedure comprises receiving the random number from the base station.

31. The apparatus of claim 29 , wherein the indication of the duration of the LBT procedure is included in the uplink grant or transmitted together with the uplink grant.

32. The apparatus of claim 29 , wherein the indication of the duration of the LBT procedure further indicates an offset value, and wherein the LBT procedure is initiated after a time period associated with the offset value.

33. The apparatus of claim 28 , wherein the uplink grant is a short control signaling transmission that is exempt from the LBT procedure.

34. The apparatus of claim 28 , wherein the instructions are further executable by the processor to cause the apparatus to:

abandon the transmitting of the uplink data based at least in part on the shared mmW radio frequency spectrum band being unavailable for the transmission of the uplink data.

35. The apparatus of claim 28 , wherein the uplink grant is received from the base station during a downlink transmission from the base station in a previous channel occupancy time (COT) or transmission opportunity (TxOP).

36. The apparatus of claim 35 , wherein the uplink grant further indicates an ending time of the previous COT or TxOP, and wherein the UE initiates the LBT procedure after the ending time of the previous COT or TxOP.

37. The apparatus of claim 35 , wherein at least a portion of the duration of the LBT procedure overlaps with a portion of the previous COT or TxOP.

38. The apparatus of claim 37 , wherein the previous COT or TxOP includes a transmission for a different UE.

39. The apparatus of claim 28 , wherein one or more of the uplink grant or transmission of the uplink data are transmitted via a beamformed transmission beam.

40. An apparatus for wireless communication at a base station, comprising:

a processor,

memory coupled with the processor; and

instructions stored in the memory and executable by the processor to cause the apparatus to:

allocate uplink resources to a user equipment (UE) for an uplink transmission of uplink data from the UE to the base station in a shared millimeter wave (mmW) radio frequency spectrum band;

transmit an uplink grant to the UE indicating the uplink resources;

determine a duration of a listen-before-talk (LBT) procedure, wherein the duration of the LBT procedure is synchronized with a frame boundary, a slot boundary, or a symbol boundary of a frame structure used for communications between the UE and the base station; and

monitor for the uplink transmission from the UE using the uplink resources indicated in the uplink grant, wherein the UE is to perform the LBT procedure prior to the uplink transmission, and wherein the LBT procedure is a clear channel assessment (CCA) check using energy detection (ED) for a duration of a CCA observation time based in part on a random number that is selected for a number of CCA slots to measure channel energy.

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

transmit, to the UE, an indication of the duration of the LBT procedure.

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

randomly select the random number for the CCA procedure; and

provide the random number to the UE as the indication of the duration of the LBT procedure.

43. The apparatus of claim 41 , wherein the indication of the duration of the LBT procedure is included in the uplink grant or transmitted together with the uplink grant.

44. The apparatus of claim 41 , wherein the UE is a first UE, and wherein the instructions are further executable by the processor to cause the apparatus to:

determine that a second uplink transmission of a second UE has a second duration that is less than the duration of the LBT procedure of the first UE;

schedule the second uplink transmission of the second UE within the duration of the LBT procedure of the first UE; and

transmit a second uplink grant to the second UE.

45. The apparatus of claim 44 , wherein the instructions are further executable by the processor to cause the apparatus to:

determine an offset value between the uplink grant and a start of the LBT procedure at the first UE based at least in part on a duration of the second uplink transmission of the second UE; and

indicate the offset value to the first UE.

46. The apparatus of claim 44 , wherein the second UE is selected based at least in part on a cross-UE interference between transmission beams of the first UE and the second UE being below a threshold value.

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

transmit a second uplink grant to a different UE during the duration of the LBT procedure.

48. The apparatus of claim 40 , wherein the uplink grant is a short control signaling transmission that is exempt from the LBT procedure.

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

determine that the uplink transmission is not received; and

reuse the granted resource for transmission or reception for one or more different UEs.

50. The apparatus of claim 40 , wherein the uplink grant is transmitted to the UE during a downlink transmission of a previous channel occupancy time (COT) or transmission opportunity (TxOP).

51. The apparatus of claim 50 , wherein the uplink grant further indicates an ending time of the previous COT or TxOP, and wherein the UE initiates the LBT procedure after the ending time of the previous COT or TxOP.

52. The apparatus of claim 50 , wherein the uplink grant is transmitted from the base station before an end of the downlink transmission of downlink shared channel data.

53. The apparatus of claim 40 , wherein at least a portion of the duration of the LBT procedure overlaps with a portion of the previous COT or TxOP.

54. The apparatus of claim 40 , wherein one or more of the uplink grant or uplink transmission are transmitted via a beamformed transmission beam.

55. An apparatus for wireless communication at a user equipment (UE), comprising:

means for receiving an uplink grant from a base station that indicates uplink resources for transmission of uplink data from the UE to the base station in a shared millimeter wave (mmW) radio frequency spectrum band;

means for determining a duration of a listen-before-talk (LBT) procedure, wherein the duration of the LBT procedure is synchronized with a frame boundary, a slot boundary, or a symbol boundary of a frame structure used for communications between the UE and the base station;

means for performing, responsive to receiving the uplink grant, the LBT procedure to determine that the shared mmW radio frequency spectrum band is available for the transmission of the uplink data, wherein the LBT procedure is a clear channel assessment (CCA) check using energy detection (ED) for a duration of a CCA observation time based in part on a random number that is selected for a number of CCA slots to measure channel energy; and

means for transmitting, based at least in part on the shared mmW radio frequency spectrum band being available for the transmission of the uplink data, the uplink data to the base station using the uplink resources indicated in the uplink grant.

56. An apparatus for wireless communication at a base station, comprising:

means for allocating uplink resources to a user equipment (UE) for an uplink transmission of uplink data from the UE to the base station in a shared millimeter wave (mmW) radio frequency spectrum band;

means for transmitting an uplink grant to the UE indicating the uplink resources;

means for determining a duration of a listen-before-talk (LBT) procedure, wherein the duration of the LBT procedure is synchronized with a frame boundary, a slot boundary, or a symbol boundary of a frame structure used for communications between the UE and the base station; and

means for monitoring for the uplink transmission from the UE using the uplink resources indicated in the uplink grant, wherein the UE is to perform the LBT procedure prior to the uplink transmission, and wherein the LBT procedure is a clear channel assessment (CCA) check using energy detection (ED) for a duration of a CCA observation time based in part on a random number that is selected for a number of CCA slots to measure channel energy.

57. A non-transitory computer-readable medium storing code for wireless communication at a user equipment (UE), the code comprising instructions executable by a processor to:

receive an uplink grant from a base station that indicates uplink resources for transmission of uplink data from the UE to the base station in a shared millimeter wave (mmW) radio frequency spectrum band;

determine a duration of a listen-before-talk (LBT) procedure, wherein the duration of the LBT procedure is synchronized with a frame boundary, a slot boundary, or a symbol boundary of a frame structure used for communications between the UE and the base station;

perform, responsive to receiving the uplink grant, the LBT procedure to determine that the shared mmW radio frequency spectrum band is available for the transmission of the uplink data, wherein the LBT procedure is a clear channel assessment (CCA) check using energy detection (ED) for a duration of a CCA observation time based in part on a random number that is selected for a number of CCA slots to measure channel energy; and

transmit, based at least in part on the shared mmW radio frequency spectrum band being available for the transmission of the uplink data, the uplink data to the base station using the uplink resources indicated in the uplink grant.

58. A non-transitory computer-readable medium storing code for wireless communication at a base station, the code comprising instructions executable by a processor to:

allocate uplink resources to a user equipment (UE) for an uplink transmission of uplink data from the UE to the base station in a shared millimeter wave (mmW) radio frequency spectrum band;

transmit an uplink grant to the UE indicating the uplink resources;

determine a duration of a listen-before-talk (LBT) procedure, wherein the duration of the LBT procedure is synchronized with a frame boundary, a slot boundary, or a symbol boundary of a frame structure used for communications between the UE and the base station; and

monitor for the uplink transmission from the UE using the uplink resources indicated in the uplink grant, wherein the UE is to perform the LBT procedure prior to the uplink transmission, and wherein the LBT procedure is a clear channel assessment (CCA) check using energy detection (ED) for a duration of a CCA observation time based in part on a random number that is selected for a number of CCA slots to measure channel energy.