METHODS AND APPARATUS FOR RADIO LINK MONITORING IN NEW CARRIER TYPE (NCT) IN A LONG TERM EVOLUTION (LTE) SYSTEM

• US 20140043988A1
• Filed: 02/07/2013
• Published: 02/13/2014
• Est. Priority Date: 08/09/2012
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Chen, Wanshi, Luo, Tao, Xu, Hao, Gaal, Peter
• Granted Patent: US 8,976,698 B2
• Time in Patent Office: Days
• US Class Current: 370/252
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements

Abstract

Certain aspects provide methods and apparatus for performing radio link monitoring (RLM) based on channel state information reference signals (CSI-RSs). Such RLM may be performed for certain carriers, such as New Carrier Type (NCT) in a Long Term Evolution (LTE) system, for example, in which reference signals conventionally used for RLM (e.g., common reference signals (CRSs) in LTE Rel-8/9/10) are not available in every subframe. Radio link failure (RLF) may be declared based on the RLM. One example method generally includes determining at least one of a first set of CSI-RS resources for use in channel estimation to perform RLM measurements or a second set of CSI-RS resources for use in interference estimation to perform the RLM measurements and performing the RLM measurements based on the one or more determined sets of CSI-RS resources. Certain aspects provide methods and apparatus for performing radio resource management (RRM) based on CSI-RSs.

Claims

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

determining at least one of a first set of channel state information reference signal (CSI-RS) resources for use in channel estimation to perform radio link monitoring (RLM) measurements or a second set of CSI-RS resources for use in interference estimation to perform the RLM measurements; and

performing the RLM measurements based on the one or more determined sets of CSI-RS resources.

2. The method of claim 1, wherein at least one or more portions of the first set of CSI-RS resources are received in a downlink (DL) subframe using a new carrier type (NCT) in which common reference signals (CRSs) are not transmitted in at least a subset of DL subframes.

3. The method of claim 1, further comprising determining a third set of CSI-RS resources for use in channel estimation to generate channel state information (CSI) feedback or for use in coordinated multipoint (CoMP) set management.

4. The method of claim 3, wherein the first and third sets of CSI-RS resources at least partially overlap.

5. The method of claim 4, wherein the first set of CSI-RS resources includes at least a subset of a portion of the third set of CSI-RS resources used for performing channel estimation for the CSI feedback.

6. The method of claim 4, wherein the first set of CSI-RS resources is determined based on the third set of CSI-RS resources and wherein the first set of CSI-RS resources corresponds to a subset of the third set of CSI-RS resources associated with at least one of a reduced number of antenna ports or a reduced number of subframes carrying CSI-RS.

7. The method of claim 1, further comprising determining a third set of CSI-RS resources for use in interference estimation to generate channel state information (CSI) feedback.

8. The method of claim 7, wherein the second and third sets of CSI-RS resources are separately indicated to the UE.

9. The method of claim 7, wherein the second and third sets of CSI-RS resources at least partially overlap.

10. The method of claim 7, wherein the second set of CSI-RS resources includes at least a subset of a portion of the third set of CSI-RS resources used for performing interference estimation for the CSI feedback.

11. The method of claim 7, wherein one or more portions of the second set of CSI-RS resources have at least one of different antenna ports or periodicity from one or more portions of the third set of CSI-RS resources used for performing interference estimation for the CSI feedback.

12. The method of claim 1, further comprising declaring a radio link failure (RLF) based on the RLM measurements and on performance of a corresponding control channel or a shared data channel.

13. The method of claim 12, wherein the control channel comprises a distributed enhanced physical downlink control channel (ePDCCH) or a localized ePDCCH.

14. The method of claim 12, wherein at least one of the first or second set of CSI-RS resources is based on one or more bandwidth portions associated with the control channel or the shared data channel.

15. The method of claim 14, wherein the one or more bandwidth portions are explicitly or implicitly signaled.

16. The method of claim 1, wherein performing the RLM measurements further comprises performing the RLM measurements based on a set of resources different than the first and second sets of CSI-RS resources.

17. The method of claim 16, wherein the set of resources different than the first and second sets of CSI-RS resources comprises at least one of primary synchronization signal (PSS)-based resources, secondary synchronization signal (SSS)-based resources, common reference signal (CRS) resources, or a third set of CSI-RS resources different than the first and second sets of CSI-RS resources.

18. The method of claim 17, wherein at least one of the first or second set of CSI-RS resources is associated with a different cell identifier than the third set of CSI-RS resources.

19. The method of claim 16, wherein performing the RLM measurements comprises selecting between or mathematically combining a first radio link quality measured based on the one or more determined sets of CSI-RS resources and a second radio link quality measured based on the set of resources different than the first and second sets of CSI-RS resources.

20. The method of claim 19, wherein the selecting comprises favoring maintenance of a radio link over declaration of a radio link failure (RLF).

21. The method of claim 1, wherein a bandwidth of the first or second set of CSI-RS resources is a fraction of a system bandwidth.

22. An apparatus for wireless communications, comprising:

a processing system configured to;

determine at least one of a first set of channel state information reference signal (CSI-RS) resources for use in channel estimation to perform radio link monitoring (RLM) measurements or a second set of CSI-RS resources for use in interference estimation to perform the RLM measurements; and

perform the RLM measurements based on the one or more determined sets of CSI-RS resources.

23. The apparatus of claim 22, wherein at least one or more portions of the first set of CSI-RS resources are received in a downlink (DL) subframe using a new carrier type (NCT) in which common reference signals (CRSs) are not transmitted in at least a subset of DL subframes.

24. The apparatus of claim 22, wherein the processing system is further configured to determine a third set of CSI-RS resources for use in channel estimation to generate channel state information (CSI) feedback or for use in coordinated multipoint (CoMP) set management.

25. The apparatus of claim 24, wherein the first and third sets of CSI-RS resources at least partially overlap.

26. The apparatus of claim 25, wherein the first set of CSI-RS resources includes at least a subset of a portion of the third set of CSI-RS resources used for performing channel estimation for the CSI feedback.

27. The apparatus of claim 25, wherein the first set of CSI-RS resources is determined based on the third set of CSI-RS resources and wherein the first set of CSI-RS resources corresponds to a subset of the third set of CSI-RS resources associated with at least one of a reduced number of antenna ports or a reduced number of subframes carrying CSI-RS.

28. The apparatus of claim 22, wherein the processing system is further configured to determine a third set of CSI-RS resources for use in interference estimation to generate channel state information (CSI) feedback.

29. The apparatus of claim 28, wherein the second and third sets of CSI-RS resources are separately indicated to the apparatus.

30. The apparatus of claim 28, wherein the second and third sets of CSI-RS resources at least partially overlap.

31. The apparatus of claim 28, wherein the second set of CSI-RS resources includes at least a subset of a portion of the third set of CSI-RS resources used for performing interference estimation for the CSI feedback.

32. The apparatus of claim 28, wherein one or more portions of the second set of CSI-RS resources have at least one of different antenna ports or periodicity from one or more portions of the third set of CSI-RS resources used for performing interference estimation for the CSI feedback.

33. The apparatus of claim 22, wherein the processing system is further configured to declare a radio link failure (RLF) based on the RLM measurements and on performance of a corresponding control channel or a shared data channel.

34. The apparatus of claim 33, wherein the control channel comprises a distributed enhanced physical downlink control channel (ePDCCH) or a localized ePDCCH.

35. The apparatus of claim 33, wherein at least one of the first or second set of CSI-RS resources is based on one or more bandwidth portions associated with the control channel or the shared data channel.

36. The apparatus of claim 35, wherein the one or more bandwidth portions are explicitly or implicitly signaled.

37. The apparatus of claim 22, wherein the processing system is further configured to perform the RLM measurements by performing the RLM measurements based on a set of resources different than the first and second sets of CSI-RS resources.

38. The apparatus of claim 37, wherein the set of resources different than the first and second sets of CSI-RS resources comprises at least one of primary synchronization signal (PSS)-based resources, secondary synchronization signal (SSS)-based resources, common reference signal (CRS) resources, or a third set of CSI-RS resources different than the first and second sets of CSI-RS resources.

39. The apparatus of claim 38, wherein at least one of the first or second set of CSI-RS resources is associated with a different cell identifier than the third set of CSI-RS resources.

40. The apparatus of claim 37, wherein the processing system is configured to perform the RLM measurements by selecting between or mathematically combining a first radio link quality measured based on the one or more determined sets of CSI-RS resources and a second radio link quality measured based on the set of resources different than the first and second sets of CSI-RS resources.

41. The apparatus of claim 40, wherein the selecting comprises favoring maintenance of a radio link over declaration of a radio link failure (RLF).

42. The apparatus of claim 22, wherein a bandwidth of the first or second set of CSI-RS resources is a fraction of a system bandwidth.

43. An apparatus for wireless communications, comprising:

means for determining at least one of a first set of channel state information reference signal (CSI-RS) resources for use in channel estimation to perform radio link monitoring (RLM) measurements or a second set of CSI-RS resources for use in interference estimation to perform the RLM measurements; and

means for performing the RLM measurements based on the one or more determined sets of CSI-RS resources.

44. A computer program product for wireless communications by a user equipment (UE), comprising:

a computer-readable medium comprising code for;

determining at least one of a first set of channel state information reference signal (CSI-RS) resources for use in channel estimation to perform radio link monitoring (RLM) measurements or a second set of CSI-RS resources for use in interference estimation to perform the RLM measurements; and

performing the RLM measurements based on the one or more determined sets of CSI-RS resources.

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

determining at least one of a first set of channel state information reference signal (CSI-RS) resources for use in channel estimation to perform radio resource management (RRM) measurements or a second set of CSI-RS resources for use in interference estimation to perform the RRM measurements; and

performing the RRM measurements based on the one or more determined sets of CSI-RS resources.

46. The method of claim 45, wherein the RRM measurements include at least one of reference signal received power (RSRP) or reference signal received quality (RSRQ) measurements.

47. An apparatus for wireless communications, comprising:

a processing system configured to;

determine at least one of a first set of channel state information reference signal (CSI-RS) resources for use in channel estimation to perform radio resource management (RRM) measurements or a second set of CSI-RS resources for use in interference estimation to perform the RRM measurements; and

perform the RRM measurements based on the one or more determined sets of CSI-RS resources.

48. The apparatus of claim 47, wherein the RRM measurements include at least one of reference signal received power (RSRP) or reference signal received quality (RSRQ) measurements.

49. An apparatus for wireless communications, comprising:

means for determining at least one of a first set of channel state information reference signal (CSI-RS) resources for use in channel estimation to perform radio resource management (RRM) measurements or a second set of CSI-RS resources for use in interference estimation to perform the RRM measurements; and

means for performing the RRM measurements based on the one or more determined sets of CSI-RS resources.

50. The apparatus of claim 49, wherein the RRM measurements include at least one of reference signal received power (RSRP) or reference signal received quality (RSRQ) measurements.

51. A computer program product for wireless communications by a user equipment (UE), comprising:

a computer-readable medium comprising code for;

determining at least one of a first set of channel state information reference signal (CSI-RS) resources for use in channel estimation to perform radio resource management (RRM) measurements or a second set of CSI-RS resources for use in interference estimation to perform the RRM measurements; and

performing the RRM measurements based on the one or more determined sets of CSI-RS resources.

52. The computer program product of claim 51, wherein the RRM measurements include at least one of reference signal received power (RSRP) or reference signal received quality (RSRQ) measurements.