SEARCH SPACE CONFIGURATIONS FOR RANDOM ACCESS MESSAGING

• US 20190327767A1
• Filed: 02/22/2019
• Published: 10/24/2019
• Est. Priority Date: 04/18/2018
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Islam, Muhammad Nazmul, Sadiq, Bilal, Abedini, Navid, Lee, Heechoon, Luo, Tao
• Granted Patent: US 11,974,321 B2
• Time in Patent Office: Days
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04B 7/0695 using beam selection
• CPC Class Codes: H04B 7/088 using beam selection
• CPC Class Codes: H04L 27/2602 Signal structure
• CPC Class Codes: H04L 27/26025 Numerology, i.e. varying one or more of symbol duration, subcarrier spacing, Fourier transform size, sampling rate or down-clocking allocating sub-channels of the transmission path H04L5/003
• CPC Class Codes: H04L 27/2666 Acquisition of further OFDM parameters, e.g. bandwidth, subcarrier spacing, or guard interval length
• CPC Class Codes: H04L 5/0051 of dedicated pilots, i.e. pilots destined for a single user or terminal
• CPC Class Codes: H04L 5/0094 Indication of how sub-channels of the path are allocated
• CPC Class Codes: H04W 24/08 Testing, supervising or monitoring using real traffic
• CPC Class Codes: H04W 56/001 Synchronization between nodes
• CPC Class Codes: H04W 72/046 the resource being in the space domain, e.g. beams
• CPC Class Codes: H04W 72/23 in the downlink direction of a wireless link, i.e. towards a terminal
• CPC Class Codes: H04W 74/0833 Random access procedures, e.g. with 4-step access
• CPC Class Codes: H04W 80/02 Data link layer protocols

Abstract

Methods, systems, and devices for wireless communications are described. In some systems, a user equipment (UE) may perform a random access (RACH) procedure based on a selected synchronization signal block (SSB). During this RACH procedure, a base station may transmit physical downlink control channel (PDCCH) messages for UE RACH message handling. To receive PDCCH signaling for RACH Messages 2, 3, or 4 (Msg 2/3/4), the UE may identify a set of time resources used by the base station for transmitting SSBs that are not quasi-co-located (QCL) with the selected SSB. The UE may identify a Msg 2/3/4 search space that does not overlap with this identified set of resources, and may monitor this identified search space. The search space may correspond to a modified remaining minimum system information (RMSI) search space indicated by the base station, or a valid RMSI search space not indicated by the base station.

Claims

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

transmitting, to a base station, a first random access (RACH) message based at least in part on a synchronization signal block (SSB) received by the UE on a first receive beam;

identifying a set of time resources used by the base station for transmission of one or more other SSBs from the base station;

identifying a search space for receiving a physical downlink control channel (PDCCH) message based at least in part on the first RACH message, wherein the identified search space comprises time resources that are different from the identified set of time resources; and

monitoring for the PDCCH message in the identified search space.

2. The method of claim 1, wherein the PDCCH message comprises a PDCCH grant for a RACH message 2 (Msg2) transmission, a PDCCH grant for a RACH message 3 (Msg3) transmission, a PDCCH grant for a RACH message 4 (Msg4) transmission, or a combination thereof.

3. The method of claim 1, wherein the one or more other SSBs are received by the UE on receive beams that are different from the first receive beam.

4. The method of claim 1, further comprising:

identifying a remaining minimum system information (RMSI) search space corresponding to the SSB and configured via a physical broadcast channel (PBCH) configuration.

5. The method of claim 4, wherein identifying the search space further comprises:

removing time resources from the identified RMSI search space that overlap with the identified set of time resources, wherein the identified search space comprises remaining time resources of the identified RMSI search space.

6. The method of claim 5, wherein removing the time resources for the identified RMSI search space comprises:

altering a slot-level periodicity of the identified RMSI search space, wherein the identified search space comprises same symbol index locations as the identified RMSI search space but with the altered slot-level periodicity of the identified RMSI search space.

7. The method of claim 4, wherein identifying the search space further comprises:

determining to implement a default search space based at least in part on an RMSI transmission from the base station; and

identifying monitoring occasions for monitoring for the PDCCH message based at least in part on monitoring occasions of the RMSI search space.

8. The method of claim 1, wherein identifying the search space further comprises:

identifying a remaining minimum system information (RMSI) search space with time resources non-overlapping with the identified set of time resources, wherein the identified search space comprises the identified RMSI search space.

9. The method of claim 1, further comprising:

receiving, from the base station, an indication of a set of time resources for the search space; and

removing time resources of the identified set of time resources from the indicated set of time resources for the search space, wherein the identified search space comprises remaining time resources of the indicated set of time resources for the search space.

10. The method of claim 9, wherein:

the indication of the set of time resources for the search space comprises a time window for the search space; and

a subset of slots of the time window comprise the identified search space.

11. The method of claim 10, wherein the subset of slots comprises each slot of the time window.

12. The method of claim 1, wherein identifying the search space further comprises:

identifying a start of the search space based at least in part on transmitting the first RACH message; and

identifying an end of the search space based at least in part on a response timer.

13. The method of claim 12, wherein the response timer comprises a random access response (RAR) window, a contention resolution timer, or a combination thereof.

14. The method of claim 1, further comprising:

receiving the SSB from the base station, wherein the first RACH message is transmitted in a RACH occasion corresponding to the SSB.

15. The method of claim 1, further comprising:

selecting the first receive beam, wherein the identified search space is monitored using the selected first receive beam during the time resources that are different from the identified set of time resources;

selecting a second receive beam different from the selected first receive beam; and

monitoring for at least one SSB of the one or more other SSBs using the selected second receive beam during the identified set of time resources.

16. The method of claim 15, further comprising:

receiving the at least one SSB of the one or more other SSBs from the base station based at least in part on the time resources for the identified search space not overlapping with the identified set of time resources.

17. The method of claim 1, further comprising:

receiving the PDCCH message in control channel elements (CCEs) of the identified search space based at least in part on the monitoring.

18. The method of claim 1, wherein the one or more other SSBs comprise one or more SSBs actually transmitted by the base station.

19. The method of claim 18, further comprising:

receiving, from the base station, an indication of the one or more SSBs actually transmitted by the base station in remaining minimum system information (RMSI), other system information (OSI), a radio resource control (RRC) message, a medium access control (MAC) control element (CE), a handover message, or a combination thereof.

20. The method of claim 1, wherein locations of the one or more other SSBs are fixed.

21. A method for wireless communications at a base station, comprising:

receiving, from a user equipment (UE), a first random access (RACH) message based at least in part on a synchronization signal block (SSB) received by the UE on a first receive beam;

identifying a set of time resources used for transmission of one or more other SSBs by the base station;

identifying a search space for the UE to receive a physical downlink control channel (PDCCH) message based at least in part on the first RACH message, wherein the identified search space comprises time resources that are different from the identified set of time resources;

mapping the PDCCH message to control channel elements (CCEs) within the identified search space; and

transmitting, to the UE, the PDCCH message according to the mapping.

22. The method of claim 21, wherein the PDCCH message comprises a PDCCH grant for a RACH message 2 (Msg2) transmission, a PDCCH grant for a RACH message 3 (Msg3) transmission, a PDCCH grant for a RACH message 4 (Msg4) transmission, or a combination thereof.

23. The method of claim 21, wherein the one or more other SSBs are received by the UE on receive beams that are different from the first receive beam.

24. The method of claim 21, further comprising:

identifying a remaining minimum system information (RMSI) search space corresponding to the SSB and configured via a physical broadcast channel (PBCH) configuration.

25. The method of claim 24, wherein identifying the search space further comprises:

removing time resources from the identified RMSI search space that overlap with the identified set of time resources, wherein the identified search space comprises remaining time resources of the identified RMSI search space.

26. The method of claim 25, wherein removing the time resources for the identified RMSI search space comprises:

altering a slot-level periodicity of the identified RMSI search space, wherein the identified search space comprises same symbol index locations as the identified RMSI search space but with the altered slot-level periodicity of the identified RMSI search space.

27. The method of claim 21, wherein identifying the search space further comprises:

identifying a remaining minimum system information (RMSI) search space with time resources non-overlapping with the identified set of time resources, wherein the identified search space comprises the identified RMSI search space.

28. The method of claim 21, further comprising:

transmitting, to the UE, an indication of a set of time resources for the search space; and

removing time resources of the identified set of time resources from the indicated set of time resources for the search space, wherein the identified search space comprises remaining time resources of the indicated set of time resources for the search space.

29. The method of claim 28, wherein:

the indication of the set of time resources for the search space comprises a time window for the search space; and

a subset of slots of the time window comprise the identified search space.

30. The method of claim 29, wherein the subset of slots comprises each slot of the time window.

31. The method of claim 21, further comprising:

transmitting, to the UE, the SSB, wherein the first RACH message is received in a RACH occasion corresponding to the SSB.

32. An apparatus for wireless communications at a user equipment (UE), comprising:

means for transmitting, to a base station, a first random access (RACH) message based at least in part on a synchronization signal block (SSB) received by the UE on a first receive beam;

means for identifying a set of time resources used by the base station for transmission of one or more other SSBs from the base station;

means for identifying a search space for receiving a physical downlink control channel (PDCCH) message based at least in part on the first RACH message, wherein the identified search space comprises time resources that are different from the identified set of time resources; and

means for monitoring for the PDCCH message in the identified search space.

33. An apparatus for wireless communications at a base station, comprising:

means for receiving, from a user equipment (UE), a first random access (RACH) message based at least in part on a synchronization signal block (SSB) received by the UE on a first receive beam;

means for identifying a set of time resources used for transmission of one or more other SSBs by the base station;

means for identifying a search space for the UE to receive a physical downlink control channel (PDCCH) message based at least in part on the first RACH message, wherein the identified search space comprises time resources that are different from the identified set of time resources;

means for mapping the PDCCH message to control channel elements (CCEs) within the identified search space; and

means for transmitting, to the UE, the PDCCH message according to the mapping.

34. An apparatus for wireless communications at a user equipment (UE), comprising:

a processor;

memory in electronic communication with the processor; and

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

transmit, to a base station, a first random access (RACH) message based at least in part on a synchronization signal block (SSB) received by the UE on a first receive beam;

identify a set of time resources used by the base station for transmission of one or more other SSBs from the base station;

identify a search space for receiving a physical downlink control channel (PDCCH) message based at least in part on the first RACH message, wherein the identified search space comprises time resources that are different from the identified set of time resources; and

monitor for the PDCCH message in the identified search space.

35. The apparatus of claim 34, wherein the PDCCH message comprises a PDCCH grant for a RACH message 2 (Msg2) transmission, a PDCCH grant for a RACH message 3 (Msg3) transmission, a PDCCH grant for a RACH message 4 (Msg4) transmission, or a combination thereof.

36. The apparatus of claim 34, wherein the one or more other SSBs are received by the UE on receive beams that are different from the first receive beam.

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

identify a remaining minimum system information (RMSI) search space corresponding to the SSB and configured via a physical broadcast channel (PBCH) configuration.

38. The apparatus of claim 37, wherein the instructions to identify the search space further are executable by the processor to cause the apparatus to:

remove time resources from the identified RMSI search space that overlap with the identified set of time resources, wherein the identified search space comprises remaining time resources of the identified RMSI search space.

39. The apparatus of claim 38, wherein the instructions to remove the time resources for the identified RMSI search space are executable by the processor to cause the apparatus to:

alter a slot-level periodicity of the identified RMSI search space, wherein the identified search space comprises same symbol index locations as the identified RMSI search space but with the altered slot-level periodicity of the identified RMSI search space.

40. The apparatus of claim 37, wherein the instructions to identify the search space further are executable by the processor to cause the apparatus to:

determine to implement a default search space based at least in part on an RMSI transmission from the base station; and

identify monitoring occasions for monitoring for the PDCCH message based at least in part on monitoring occasions of the RMSI search space.

41. The apparatus of claim 34, wherein the instructions to identify the search space further are executable by the processor to cause the apparatus to:

identify a remaining minimum system information (RMSI) search space with time resources non-overlapping with the identified set of time resources, wherein the identified search space comprises the identified RMSI search space.

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

receive, from the base station, an indication of a set of time resources for the search space; and

remove time resources of the identified set of time resources from the indicated set of time resources for the search space, wherein the identified search space comprises remaining time resources of the indicated set of time resources for the search space.

43. The apparatus of claim 42, wherein:

the indication of the set of time resources for the search space comprises a time window for the search space; and

a subset of slots of the time window comprise the identified search space.

44. The apparatus of claim 43, wherein the subset of slots comprises each slot of the time window.

45. The apparatus of claim 34, wherein the instructions to identify the search space further are executable by the processor to cause the apparatus to:

identify a start of the search space based at least in part on transmitting the first RACH message; and

identify an end of the search space based at least in part on a response timer.

46. The apparatus of claim 45, wherein the response timer comprises a random access response (RAR) window, a contention resolution timer, or a combination thereof.

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

receive the SSB from the base station, wherein the first RACH message is transmitted in a RACH occasion corresponding to the SSB.

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

select the first receive beam, wherein the identified search space is monitored using the selected first receive beam during the time resources that are different from the identified set of time resources;

select a second receive beam different from the selected first receive beam; and

monitor for at least one SSB of the one or more other SSBs using the selected second receive beam during the identified set of time resources.

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

receive the at least one SSB of the one or more other SSBs from the base station based at least in part on the time resources for the identified search space not overlapping with the identified set of time resources.

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

receive the PDCCH message in control channel elements (CCEs) of the identified search space based at least in part on the monitoring.

51. The apparatus of claim 34, wherein the one or more other SSBs comprise one or more SSBs actually transmitted by the base station.

52. The apparatus of claim 51, wherein the instructions are further executable by the processor to cause the apparatus to:

receive, from the base station, an indication of the one or more SSBs actually transmitted by the base station in remaining minimum system information (RMSI), other system information (OSI), a radio resource control (RRC) message, a medium access control (MAC) control element (CE), a handover message, or a combination thereof.

53. The apparatus of claim 34, wherein locations of the one or more other SSBs are fixed.

54. An apparatus for wireless communications at a base station, comprising:

a processor;

memory in electronic communication with the processor; and

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

receive, from a user equipment (UE), a first random access (RACH) message based at least in part on a synchronization signal block (SSB) received by the UE on a first receive beam;

identify a set of time resources used for transmission of one or more other SSBs by the base station;

identify a search space for the UE to receive a physical downlink control channel (PDCCH) message based at least in part on the first RACH message, wherein the identified search space comprises time resources that are different from the identified set of time resources;

map the PDCCH message to control channel elements (CCEs) within the identified search space; and

transmit, to the UE, the PDCCH message according to the mapping.

55. The apparatus of claim 54, wherein the PDCCH message comprises a PDCCH grant for a RACH message 2 (Msg2) transmission, a PDCCH grant for a RACH message 3 (Msg3) transmission, a PDCCH grant for a RACH message 4 (Msg4) transmission, or a combination thereof.

56. The apparatus of claim 54, wherein the one or more other SSBs are received by the UE on receive beams that are different from the first receive beam.

57. The apparatus of claim 54, wherein the instructions are further executable by the processor to cause the apparatus to:

identify a remaining minimum system information (RMSI) search space corresponding to the SSB and configured via a physical broadcast channel (PBCH) configuration.

58. The apparatus of claim 57, wherein the instructions to identify the search space further are executable by the processor to cause the apparatus to:

remove time resources from the identified RMSI search space that overlap with the identified set of time resources, wherein the identified search space comprises remaining time resources of the identified RMSI search space.

59. The apparatus of claim 58, wherein the instructions to remove the time resources for the identified RMSI search space are executable by the processor to cause the apparatus to:

alter a slot-level periodicity of the identified RMSI search space, wherein the identified search space comprises same symbol index locations as the identified RMSI search space but with the altered slot-level periodicity of the identified RMSI search space.

60. The apparatus of claim 54, wherein the instructions to identify the search space further are executable by the processor to cause the apparatus to:

identify a remaining minimum system information (RMSI) search space with time resources non-overlapping with the identified set of time resources, wherein the identified search space comprises the identified RMSI search space.

61. The apparatus of claim 54, wherein the instructions are further executable by the processor to cause the apparatus to:

transmit, to the UE, an indication of a set of time resources for the search space; and

remove time resources of the identified set of time resources from the indicated set of time resources for the search space, wherein the identified search space comprises remaining time resources of the indicated set of time resources for the search space.

62. The apparatus of claim 61, wherein:

the indication of the set of time resources for the search space comprises a time window for the search space; and

a subset of slots of the time window comprise the identified search space.

63. The apparatus of claim 62, wherein the subset of slots comprises each slot of the time window.

64. The apparatus of claim 54, wherein the instructions are further executable by the processor to cause the apparatus to:

transmit, to the UE, the SSB, wherein the first RACH message is received in a RACH occasion corresponding to the SSB.

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

transmit, to a base station, a first random access (RACH) message based at least in part on a synchronization signal block (SSB) received by the UE on a first receive beam;

identify a set of time resources used by the base station for transmission of one or more other SSBs from the base station;

identify a search space for receiving a physical downlink control channel (PDCCH) message based at least in part on the first RACH message, wherein the identified search space comprises time resources that are different from the identified set of time resources; and

monitor for the PDCCH message in the identified search space.

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

receive, from a user equipment (UE), a first random access (RACH) message based at least in part on a synchronization signal block (SSB) received by the UE on a first receive beam;

identify a set of time resources used for transmission of one or more other SSBs by the base station;

identify a search space for the UE to receive a physical downlink control channel (PDCCH) message based at least in part on the first RACH message, wherein the identified search space comprises time resources that are different from the identified set of time resources;

map the PDCCH message to control channel elements (CCEs) within the identified search space; and

transmit, to the UE, the PDCCH message according to the mapping.