METHOD AND APPARATUS FOR IDENTIFYING INTERFERENCE TYPE IN TIME DIVISION DUPLEX SYSTEMS

• US 20140177486A1
• Filed: 12/21/2012
• Published: 06/26/2014
• Est. Priority Date: 12/21/2012
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: Blackberry Limited
• Inventors: WANG, Yiping, WENG, Jianfeng, LI, Jun
• Granted Patent: US 9,768,929 B2
• Time in Patent Office: Days
• US Class Current: 370/280
• CPC Class Codes: H04L 1/1607 Details of the supervisory signal
• CPC Class Codes: H04L 1/20 using signal quality detector
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• CPC Class Codes: H04W 52/244 Interferences in heterogeneous networks, e.g. among macro and femto or pico cells or other sector / system interference [OSI]

Abstract

Methods and apparatus at an evolved Node B (eNB) and user equipment (UE) in cells operating in time division duplex with a first configuration and having a neighbor cell eNB operating in time division duplex with a second configuration, the methods and apparatus: identifying potential eNB-to-eNB; UE-to-UE; eNB-to-UE; and UE-to-eNB interference. Further methods and apparatus to report interference including enumerated interference types to neighbor cell eNBs. Further, methods and apparatus for interference mitigation.

Claims

1. A method at an evolved Node B (eNB) for a cell operating in time division duplex with a first configuration and having a neighbor cell eNB operating in time division duplex with a second configuration, the method comprising:

identifying whether a subframe has a potential for eNB-to-eNB interference;

correlating a received signal with a locally generated cell specific reference signal according to an identifier for the neighbor cell eNB; and

determining that eNB-to-eNB interference exists in the subframe if results of the correlating exceed a threshold.

2. The method of claim 1, wherein the evolved Node B has no information about the second configuration.

3. The method of claim 2, wherein the identifying finds whether the subframe in the first configuration is an uplink subframe and whether any other configurations have a downlink subframe.

4. The method of claim 1, wherein the evolved Node B has knowledge of the second configuration of the neighbor cell.

5. The method of claim 4, wherein the identifying finds whether the subframe in the first configuration is an uplink subframe and whether the second configuration is a downlink subframe.

6. The method of claim 4, wherein the knowledge of the second configuration is received over a backhaul from the neighbor cell eNB.

7. The method of claim 6, wherein the knowledge of the second configuration is received in an information element dedicated to exchanging time division duplex configurations.

8. The method of claim 1, wherein the identifier for the neighbor cell eNB is received over a backhaul from the neighbor cell eNB.

9. The method of claim 1, wherein the identifier for the neighbor cell eNB is reported by a user equipment served by the eNB and able to receive signals from the neighbor cell.

10. The method of claim 1, wherein the identifier is determined by the eNB by shutting down downlink transmission from the eNB periodically to listen for any neighbor cell eNBs.

11. The method of claim 10, wherein the shutting down is in subframes 0 or 5.

12. The method of claim 10, wherein the period for shutting down downlink transmission is randomly selected.

13. The method of claim 1, further comprising reporting eNB-to-eNB interference to the neighbor cell.

14. The method of claim 13, wherein the reporting uses an interference overload indicator information element.

15. The method of claim 14, wherein the interference overload indicator information element includes an enumerated list of interference types.

16. The method of claim 1, wherein the eNB only schedules user equipments close to a cell center if eNB-to-eNB interference exists.

17. The method of claim 1, wherein the eNB initiates a frequency reuse plan with the neighbor cell eNB.

18. The method of claim 17, wherein the frequency reuse is done in subframes in which eNB-to-eNB interference potentially exists.

19. An evolved Node B (eNB) for a cell and operating in time division duplex with a first configuration and having a neighbor cell eNB operating in time division duplex with a second configuration, the evolved Node B comprising:

a processor; and

a communications subsystem,

wherein the eNB is configured to;

identify whether a subframe has a potential for eNB-to-eNB interference;

correlate a received signal with a locally generated cell specific reference signal according to an identifier for the neighbor cell eNB; and

determine that eNB-to-eNB interference exists in the subframe if results of the correlating exceed a threshold.

20-36. -36. (canceled)

37. A method at an evolved Node B (eNB) for a cell operating in time division duplex with a first configuration and having a neighbor cell eNB operating in time division duplex with a second configuration, the method comprising:

identifying whether a subframe has a potential for UE-to-UE interference;

calculating a first negative acknowledgment (NAK) rate base on a percentage of NAKs received from a user equipment in a first set of subframes;

calculating a second NAK rate base on a percentage of NAKs received from the user equipment in a second set of subframes; and

determining that UE-to-UE interference exists in the first NAK rate exceeds the second NAK rate by a threshold.

38. The method of claim 37, wherein the evolved Node B has no information about the second configuration.

39. The method of claim 38, wherein the identifying finds whether the subframe in the first configuration is a downlink subframe and whether any other configurations have an uplink subframe.

40. The method of claim 37, wherein the evolved Node B has knowledge of the second configuration.

41. The method of claim 40, wherein the identifying finds whether the subframe in the first configuration is downlink subframe and whether the second configuration is an uplink subframe.

42. The method of claim 41, wherein the knowledge of the second configuration is received over a backhaul from the neighbor cell eNB.

43. The method of claim 41, wherein the knowledge of the second configuration is received in an information element dedicated to exchanging time division duplex configurations.

44. The method of claim 37, further comprising reporting UE-to-UE interference to the neighbor cell.

45. The method of claim 44, wherein the reporting uses an interference overload indicator information element.

46. The method of claim 45, wherein the interference overload indicator information element includes an enumerated list of interference types.

47. The method of claim 37, wherein the eNB only schedules user equipments close to a cell center if UE-to-UE interference exists.

48. The method of claim 37, wherein the eNB initiates a frequency reuse plan with the neighbor cell eNB.

49. The method of claim 37, wherein the calculation the first NAK rate and the calculating the second NAK rate are done over a time duration.

50. An evolved Node B (eNB) for a cell and operating in time division duplex with a first configuration and having a neighbor cell eNB operating in time division duplex with a second configuration, the eNB comprising:

a processor; and

a communications subsystem,

wherein the eNB is configured to;

identify whether a subframe has a potential for UE-to-UE interference;

calculate a first negative acknowledgment (NAK) rate base on a percentage of NAKs received from a user equipment in a first set of subframes;

calculate a second NAK rate base on a percentage of NAKs received from the user equipment in a second set of subframes; and

determine that UE-to-UE interference exists in the first NAK rate exceeds the second NAK rate by a threshold.

51-82. -82. (canceled)