COVERAGE ENHANCEMENT MODE SWITCHING FOR WIRELESS COMMUNICATIONS USING SHARED RADIO FREQUENCY SPECTRUM

• US 20180269962A1
• Filed: 03/12/2018
• Published: 09/20/2018
• Est. Priority Date: 03/14/2017
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Liu, Chih-Hao, Yerramalli, Srinivas, Kadous, Tamer
• Granted Patent: US 10,411,795 B2
• Time in Patent Office: Days
• CPC Class Codes: H01Q 1/246 specially adapted for base stations
• CPC Class Codes: H04B 7/0491 using two or more sectors, i.e. sector diversity
• CPC Class Codes: H04B 7/0689 using different transmission schemes, at least one of them being a diversity transmission scheme
• CPC Class Codes: H04B 7/2606 Arrangements for base station coverage control, e.g. by using relays in tunnels
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 16/24 Cell structures
• CPC Class Codes: H04W 36/06 Reselecting a communication resource in the serving access point
• CPC Class Codes: H04W 36/305 Handover due to radio link failure control signalling for hand-off failure H04W36/0079
• CPC Class Codes: H04W 4/70 Services for machine-to-machine communication [M2M] or machine type communication [MTC]
• CPC Class Codes: H04W 48/18 Selecting a network or a communication service
• CPC Class Codes: H04W 72/541 using the level of interference
• CPC Class Codes: H04W 74/08 Non-scheduled access, e.g. ALOHA hybrid access H04W74/02
• CPC Class Codes: H04W 8/005 Discovery of network devices, e.g. terminals
• CPC Class Codes: H04W 88/04 adapted for relaying to or from another terminal or user
• CPC Class Codes: H04W 88/06 adapted for operation in multiple networks or having at least two operational modes, e.g. multi-mode terminals

Abstract

Described techniques provide for switching a user equipment (UE) between different coverage enhancement (CE) modes, such as between a non-CE mode and a CE mode. A UE may determine that a CE mode switch is to be performed and may initiate the mode switching. The UE may compare signal qualities of signals from one or more base stations against one or more threshold values and determine that a switch from a CE mode to a non-CE mode, or from a non-CE to CE mode, is to be performed. In some cases, a UE may be in idle mode and switch between CE modes, or may perform a cell reselection to a different base station. In other cases, a UE may be in connected mode and may declare a radio link failure to initiate a mode switch. A base station may initiate mode switching based on radio link monitoring of UEs.

Claims

1. A method for wireless communication, comprising:

establishing a connection with a base station according to a non-coverage enhancement (non-CE) mode;

monitoring a channel quality of a radio link with the base station; and

switching from the non-CE mode to a coverage enhancement (CE) mode based at least in part on the channel quality of the radio link being below a threshold value for a first time period.

2. The method of claim 1, further comprising:

determining, subsequent to the switching, that the channel quality of the radio link is above the threshold value for a second time period; and

switching, responsive to the determining, from the CE mode to the non-CE mode.

3. The method of claim 2, wherein the non-CE mode is preferred over the CE mode, and wherein the second time period is selected to be shorter than the first time period.

4. The method of claim 2, wherein

the monitoring the channel quality comprises monitoring a first reference signal associated with non-CE mode transmissions, and

the determining that the channel quality of the radio link is above the threshold value comprises monitoring a second reference signal associated with CE mode transmissions.

5. The method of claim 1, further comprising:

determining, subsequent to the switching, that the channel quality of the radio link is below a cell reselection threshold; and

measuring a signal quality of one or more neighboring base stations.

6. The method of claim 5, wherein the measuring the signal quality comprises:

measuring a first signal quality of one or more non-CE mode reference signals of the neighboring base stations; and

measuring a second signal quality of one or more CE mode reference signals of the neighboring base stations.

7. The method of claim 6, further comprising:

determining to perform a reselection procedure to establish a non-CE mode connection with a first neighboring base station based at least in part on the first signal quality exceeding the channel quality of the radio link by a first offset value;

or

determining to perform a reselection procedure to establish a CE mode connection with the first neighboring base station based at least in part on the second signal quality exceeding the channel quality of the radio link by a second offset value.

8. The method of claim 7, wherein the second offset value is less than the first offset value.

9. The method of claim 1, wherein the switching comprises:

determining a radio link failure (RLF) has occurred; and

transmitting a random access request using random access resources associated with the CE mode to establish the CE mode connection.

10. The method of claim 1, wherein the switching comprises:

transmitting a radio link failure (RLF) indication to the base station; and

receiving a reconfiguration message from the base station to switch from the non-CE mode to the CE mode.

11. The method of claim 10, further comprising:

initiating, subsequent to the transmitting the RLF indication, a reconfiguration timer; and

transmitting, responsive to an expiration of the reconfiguration timer, a random access request using random access resources associated with the CE mode to establish the CE mode connection.

12. The method of claim 10, wherein the RLF indication is transmitted in an uplink feedback transmission associated with a downlink transmission from the base station.

13. The method of claim 10, wherein the RLF indication is transmitted in a random access transmission using random access resources associated with the CE mode.

14. The method of claim 1, further comprising:

receiving a paging message from the base station;

identifying a first subset of random access resources for non-CE mode random access transmission and a second subset of random access resources for CE mode random access transmissions;

selecting the first subset of random access resources or the second subset of random access resources for transmission of a random access request responsive to the paging message, based at least in part on whether the CE mode or the non-CE mode is to be used for transmissions; and

transmitting the random access request to the base station using the selected random access resources.

15. A method for wireless communication, comprising:

establishing a connection with a base station according to a non-coverage enhancement (non-CE) mode;

providing the base station with an indication of a channel quality of a radio link with the base station;

receiving an indication from the base station to reestablish the connection using a coverage enhancement (CE) mode based at least in part on the indication of the channel quality of the radio link.

16. The method of claim 15, wherein the receiving comprises:

receiving a radio resource control (RRC) reconfiguration message to reconfigure the connection using the CE mode; and

transmitting a RRC reconfiguration complete message to the base station upon completion of the RRC reconfiguration.

17. The method of claim 15, wherein the providing the base station with the indication of the channel quality comprises:

providing a measurement report to the base station that includes measurements associated with one or more of non-CE mode transmissions or CE mode transmissions of the base station.

18. The method of claim 17, wherein the measurement report is provided to the base station periodically or based on a trigger received from the base station.

19. The method of claim 17, wherein the measurement report includes both CE mode measurements based at least in part on a first measurement window associated with CE mode transmissions and non-CE mode measurements based at least in part on a second measurement window associated with non-CE mode transmissions.

20. The method of claim 17, wherein the non-CE mode measurements have an associated first threshold value for switching from the non-CE mode to the CE mode, and the CE mode measurements have an associated second threshold value for switching from the CE mode to the non-CE mode.

21. The method of claim 15, further comprising:

receiving an uplink grant to transmit an uplink transmission using the CE mode that is transmitted using both non-CE and CE control resources; and

transmitting a RRC reconfiguration complete message to the base station.

22. The method of claim 15, wherein the receiving comprises:

receiving a radio resource control (RRC) reconfiguration message to establish a new connection with the base station using the CE mode; and

initiating the new connection using the CE mode responsive to the RRC reconfiguration message.

23. A method for wireless communication, comprising:

establishing a first connection with a first base station according to a coverage enhancement (CE) mode or a non-CE mode;

providing the first base station with an indication of a channel quality of a radio link with the first base station and one or more channel quality measurements for one or more neighboring base stations, the one or more neighboring base stations including a second base station; and

receiving a handover command from the base station to establish a second connection with the second base station, the handover command indicating a CE mode or non-CE mode for the second connection.

24. The method of claim 23, further comprising:

transmitting a random access request to the second base station based at least in part on the handover command using random access resources selected, based at least in part on the indication of CE mode or non-CE mode for the second connection, from CE mode random access resources or non-CE mode random access resources.

25. The method of claim 24, further comprising:

receiving a random access response and uplink resource grant on a control channel associated with the respective CE mode transmissions or non-CE mode transmissions.

26. The method of claim 23, further comprising:

providing a measurement report to the first base station that includes measurements associated with one or more of non-CE mode transmissions or CE mode transmissions of the first base station and one or more neighboring base stations.

27. The method of claim 26, wherein the measurement report is provided to the first base station periodically or based on a trigger received from the base station.

28. The method of claim 26, wherein the non-CE mode measurements have an associated first threshold value for switching from the non-CE mode to the CE mode, and the CE mode measurements have an associated second threshold value for switching from the CE mode to the non-CE mode.

29. A method for wireless communication, comprising:

establishing, at a base station, a connection with a user equipment (UE) according to a non-coverage enhancement (non-CE) mode;

receiving, from the UE, an indication of a channel quality of a radio link between the UE and the base station;

determining that the channel quality of the radio link is below a threshold value; and

transmitting an indication to the UE to reestablish the connection using a coverage enhancement (CE) mode based at least in part on the determining.

30. The method of claim 29, wherein the transmitting comprises:

transmitting a radio resource control (RRC) reconfiguration message to reconfigure the connection using the CE mode; and

receiving a RRC reconfiguration complete message from the UE upon completion of the RRC reconfiguration.

31. The method of claim 29, wherein the receiving the indication of the channel quality comprises:

receiving a measurement report that includes measurements associated with one or more of non-CE mode transmissions or CE mode transmissions of the base station.

32. The method of claim 31, wherein the measurement report is provided to the base station periodically or based on a trigger transmitted from the base station.

33. The method of claim 31, wherein the measurement report includes both CE mode measurements based at least in part on a first measurement window associated with CE mode transmissions and non-CE mode measurements based at least in part on a second measurement window associated with non-CE mode transmissions.

34. The method of claim 31, wherein the non-CE mode measurements have an associated first threshold value for switching from the non-CE mode to the CE mode, and the CE mode measurements have an associated second threshold value for switching from the CE mode to the non-CE mode.

35. The method of claim 29, further comprising:

transmitting an uplink grant for an uplink transmission using the CE mode, wherein the uplink grant is transmitted using both non-CE and CE control resources until a RRC reconfiguration complete message is received from the UE.

36. The method of claim 29, wherein the transmitting comprises:

transmitting a radio resource control (RRC) reconfiguration message to the UE to establish a new connection with the base station using the CE mode.

37. A method for wireless communication, comprising:

establishing, at a first base station, a first connection with a user equipment (UE) according to a coverage enhancement (CE) mode or a non-CE mode;

receiving, from the UE, an indication of a channel quality of a radio link with the first base station and one or more channel quality measurements for one or more neighboring base stations, the one or more neighboring base stations including a second base station;

determining that the channel quality of the radio link is below a threshold value; and

transmitting a handover command to the UE to establish a second connection with the second base station, the handover command indicating a CE mode or non-CE mode for the second connection.

38. The method of claim 37, further comprising:

determining, based at least in part on the one or more channel quality measurements for the one or more neighboring base stations, whether to indicate the CE mode or non-CE mode for the second connection.

39. An apparatus for wireless communication, comprising:

means for establishing a connection with a base station according to a non-coverage enhancement (non-CE) mode;

means for monitoring a channel quality of a radio link with the base station; and

means for switching from the non-CE mode to a CE mode based at least in part on the channel quality of the radio link being below a threshold value for a first time period.

40. An apparatus for wireless communication, comprising:

means for establishing a connection with a base station according to a non-coverage enhancement (non-CE) mode;

means for providing the base station with an indication of a channel quality of a radio link with the base station; and

means for receiving an indication from the base station to reestablish the connection using a coverage enhancement (CE) mode based at least in part on the indication of the channel quality of the radio link.

41. An apparatus for wireless communication, comprising:

means for establishing a first connection with a first base station according to a coverage enhancement (CE) mode or a non-CE mode;

means for providing the first base station with an indication of a channel quality of a radio link with the first base station and one or more channel quality measurements for one or more neighboring base stations, the one or more neighboring base stations including a second base station; and

means for receiving a handover command from the base station to establish a second connection with the second base station, the handover command indicating a CE mode or non-CE mode for the second connection.

42. An apparatus for wireless communication, comprising:

means for establishing, at a base station, a connection with a user equipment (UE) according to a non-coverage enhancement (non-CE) mode;

means for receiving, from the UE, an indication of a channel quality of a radio link between the UE and the base station;

means for determining that the channel quality of the radio link is below a threshold value; and

means for transmitting an indication to the UE to reestablish the connection using a coverage enhancement (CE) mode based at least in part on the determining.

43. An apparatus for wireless communication, comprising:

means for establishing, at a first base station, a first connection with a user equipment (UE) according to a coverage enhancement (CE) mode or a non-CE mode;

means for receiving, from the UE, an indication of a channel quality of a radio link with the first base station and one or more channel quality measurements for one or more neighboring base stations, the one or more neighboring base stations including a second base station;

means for determining that the channel quality of the radio link is below a threshold value; and

means for transmitting a handover command to the UE to establish a second connection with the second base station, the handover command indicating a CE mode or non-CE mode for the second connection.

44. An apparatus for wireless communication, in a system comprising:

a processor;

memory in electronic communication with the processor; and

instructions stored in the memory and operable, when executed by the processor, to cause the apparatus to;

establish a connection with a base station according to a non-coverage enhancement (non-CE) mode;

monitor a channel quality of a radio link with the base station; and

switch from the non-CE mode to a CE mode based at least in part on the channel quality of the radio link being below a threshold value for a first time period.

45. The method of claim 44, wherein the instructions are further operable to cause the apparatus to:

determine, subsequent to the switching, that the channel quality of the radio link is above the threshold value for a second time period; and

switch, responsive to the determining, from the CE mode to the non-CE mode.

46. The method of claim 44, wherein the instructions are further operable to cause the apparatus to:

determine, subsequent to the switching, that the channel quality of the radio link is below a cell reselection threshold; and

measure a signal quality of one or more neighboring base stations.

47. The method of claim 46, wherein the instructions are further operable to cause the apparatus to:

measure a first signal quality of one or more non-CE mode reference signals of the neighboring base stations; and

measure a second signal quality of one or more CE mode reference signals of the neighboring base stations.

48. The method of claim 47, wherein the instructions are further operable to cause the apparatus to:

determine to perform a reselection procedure to establish a non-CE mode connection with a first neighboring base station based at least in part on the first signal quality exceeding the channel quality of the radio link by a first offset value;

or

determine to perform a reselection procedure to establish a CE mode connection with the first neighboring base station based at least in part on the second signal quality exceeding the channel quality of the radio link by a second offset value.

49. The method of claim 44, wherein the instructions are further operable to cause the apparatus to:

determine a radio link failure (RLF) has occurred; and

transmit a random access request using random access resources associated with the CE mode to establish the CE mode connection.

50. The method of claim 44, wherein the instructions are further operable to cause the apparatus to:

receive a paging message from the base station;

identify a first subset of random access resources for non-CE mode random access transmission and a second subset of random access resources for CE mode random access transmissions; and

select the first subset of random access resources or the second subset of random access resources for transmission of a random access request responsive to the paging message, based at least in part on whether the CE mode or the non-CE mode is to be used for transmissions; and

transmit the random access request to the base station using the selected random access resources.

51. An apparatus for wireless communication, in a system comprising:

a processor;

memory in electronic communication with the processor; and

instructions stored in the memory and operable, when executed by the processor, to cause the apparatus to;

establish a connection with a base station according to a non-coverage enhancement (non-CE) mode;

provide the base station with an indication of a channel quality of a radio link with the base station; and

receive an indication from the base station to reestablish the connection using a coverage enhancement (CE) mode based at least in part on the indication of the channel quality of the radio link.

52. The method of claim 51, wherein the instructions are further operable to cause the apparatus to:

receive a radio resource control (RRC) reconfiguration message to reconfigure the connection using the CE mode; and

transmit a RRC reconfiguration complete message to the base station upon completion of the RRC reconfiguration.

53. The method of claim 51, wherein the instructions are further operable to cause the apparatus to:

provide a measurement report to the base station that includes measurements associated with one or more of non-CE mode transmissions or CE mode transmissions of the base station.

54. The method of claim 53, wherein the non-CE mode measurements have an associated first threshold value for switching from the non-CE mode to the CE mode, and the CE mode measurements have an associated second threshold value for switching from the CE mode to the non-CE mode.

55. The method of claim 51, wherein the instructions are further operable to cause the apparatus to:

receive an uplink grant to transmit an uplink transmission using the CE mode that is transmitted using both non-CE and CE control resources; and

transmit a RRC reconfiguration complete message to the base station.

56. The method of claim 51, wherein the instructions are further operable to cause the apparatus to:

receive a radio resource control (RRC) reconfiguration message to establish a new connection with the base station using the CE mode; and

initiate the new connection using the CE mode responsive to the RRC reconfiguration message.

57. An apparatus for wireless communication, in a system comprising:

a processor;

memory in electronic communication with the processor; and

instructions stored in the memory and operable, when executed by the processor, to cause the apparatus to;

establish a first connection with a first base station according to a coverage enhancement (CE) mode or a non-CE mode;

provide the first base station with an indication of a channel quality of a radio link with the first base station and one or more channel quality measurements for one or more neighboring base stations, the one or more neighboring base stations including a second base station; and

receive a handover command from the base station to establish a second connection with the second base station, the handover command indicating a CE mode or non-CE mode for the second connection.

58. The method of claim 57, wherein the instructions are further operable to cause the apparatus to:

transmit a random access request to the second base station based at least in part on the handover command using random access resources selected, based at least in part on the indication of CE mode or non-CE mode for the second connection, from CE mode random access resources or non-CE mode random access resources.

59. The method of claim 58, wherein the instructions are further operable to cause the apparatus to:

receive a random access response and uplink resource grant on a control channel associated with the respective CE mode transmissions or non-CE mode transmissions.

60. An apparatus for wireless communication, in a system comprising:

a processor;

memory in electronic communication with the processor; and

instructions stored in the memory and operable, when executed by the processor, to cause the apparatus to;

establish, at a base station, a connection with a user equipment (UE) according to a non-coverage enhancement (non-CE) mode;

receive, from the UE, an indication of a channel quality of a radio link between the UE and the base station;

determine that the channel quality of the radio link is below a threshold value; and

transmit an indication to the UE to reestablish the connection using a coverage enhancement (CE) mode based at least in part on the determining.

61. An apparatus for wireless communication, in a system comprising:

a processor;

memory in electronic communication with the processor; and

instructions stored in the memory and operable, when executed by the processor, to cause the apparatus to;

establish, at a first base station, a first connection with a user equipment (UE) according to a coverage enhancement (CE) mode or a non-CE mode;

receive, from the UE, an indication of a channel quality of a radio link with the first base station and one or more channel quality measurements for one or more neighboring base stations, the one or more neighboring base stations including a second base station;

determine that the channel quality of the radio link is below a threshold value; and

transmit a handover command to the UE to establish a second connection with the second base station, the handover command indicating a CE mode or non-CE mode for the second connection.

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

establish a connection with a base station according to a non-coverage enhancement (non-CE) mode;

monitor a channel quality of a radio link with the base station; and

switch from the non-CE mode to a CE mode based at least in part on the channel quality of the radio link being below a threshold value for a first time period.

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

establish a connection with a base station according to a non-coverage enhancement (non-CE) mode;

provide the base station with an indication of a channel quality of a radio link with the base station; and

receive an indication from the base station to reestablish the connection using a coverage enhancement (CE) mode based at least in part on the indication of the channel quality of the radio link.

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

establish a first connection with a first base station according to a coverage enhancement (CE) mode or a non-CE mode;

provide the first base station with an indication of a channel quality of a radio link with the first base station and one or more channel quality measurements for one or more neighboring base stations, the one or more neighboring base stations including a second base station; and

receive a handover command from the base station to establish a second connection with the second base station, the handover command indicating a CE mode or non-CE mode for the second connection.

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

establish, at a base station, a connection with a user equipment (UE) according to a non-coverage enhancement (non-CE) mode;

receive, from the UE, an indication of a channel quality of a radio link between the UE and the base station;

determine that the channel quality of the radio link is below a threshold value; and

transmit an indication to the UE to reestablish the connection using a coverage enhancement (CE) mode based at least in part on the determining.

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

establish, at a first base station, a first connection with a user equipment (UE) according to a coverage enhancement (CE) mode or a non-CE mode;

receive, from the UE, an indication of a channel quality of a radio link with the first base station and one or more channel quality measurements for one or more neighboring base stations, the one or more neighboring base stations including a second base station;

determine that the channel quality of the radio link is below a threshold value; and

transmit a handover command to the UE to establish a second connection with the second base station, the handover command indicating a CE mode or non-CE mode for the second connection.