METHOD AND APPARATUS FOR INTERFERENCE REPORTING IN A N-MIMO COMMUNICATION SYSTEM

• US 20100106828A1
• Filed: 10/15/2009
• Published: 04/29/2010
• Est. Priority Date: 10/24/2008
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Bhushan, Naga, Palanki, Ravi, Gorokhov, Alexei Y.
• Granted Patent: US 8,417,252 B2
• Time in Patent Office: Days
• US Class Current: 709/224
• CPC Class Codes: H04B 17/24 with feedback of measurements to the transmitter
• CPC Class Codes: H04B 17/345 Interference values signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR] H04B17/336
• CPC Class Codes: H04J 11/0053 using co-ordinated multipoint transmission/reception co-ordinated antenna or beam-forming aspects H04B7/022
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 1/0028 Formatting
• CPC Class Codes: H04L 1/02 by diversity reception
• CPC Class Codes: H04L 2001/0092 Error control systems characterised by the topology of the transmission link
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04L 5/0035 Resource allocation in a cooperative multipoint environment
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 72/27 between access points
• CPC Class Codes: H04W 72/542 using measured or perceived quality
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Systems and methodologies are described herein that facilitate interference measurement and reporting in a network multiple-in-multiple-out (N-MIMO) communication system. As described herein, a network device can measure and report interference corresponding to network nodes outside a designated set of nodes that can cooperatively serve the device. Respective interference reports can additionally identify dominant interfering nodes, correlation between transmit antennas of respective nodes, or the like. Subsequently, respective interference reports can be combined with per-node channel information to manage coordination and scheduling across respective network nodes. As further described herein, interference from a network node can be measured by observing reference and/or synchronization signals from the network node. To aid such observation, respective non-interfering network nodes can define null pilot intervals in which transmission is silenced or otherwise reduced. As additionally described herein, loading information broadcasted by respective interfering network nodes can be identified and utilized in connection with interference calculation.

Claims

1. A method, comprising:

identifying a set of network cells operable to conduct communication with inter-site coordination;

measuring an amount of received power from respective network cells not associated with the identified set of network cells; and

reporting a measured amount of received power to one or more network cells in the identified set of network cells.

2. The method of claim 1, further comprising:

observing channel quality associated with channels corresponding to respective network cells in the identified set of network cells; and

providing one or more reports of observed channel quality to respectively corresponding network cells.

3. The method of claim 1, wherein:

the measuring comprises identifying a primary interfering network cell; and

the reporting comprises reporting an identity of the primary interfering network cell to one or more network cells in the identified set of network cells.

4. The method of claim 1, wherein:

the method further comprises identifying one or more interfering network cells respectively comprising a plurality of transmit antennas;

the measuring comprises computing correlation between respective transmit antennas of the one or more interfering network cells; and

the reporting comprises reporting information relating to a computed correlation between respective transmit antennas of one or more interfering network cells to one or more network cells in the identified set of network cells.

5. The method of claim 4, wherein the one or more interfering network cells comprise a dominant interfering network cell.

6. The method of claim 4, wherein the reporting further comprises:

determining an amount of interference nulling that is employable relative to one or more interfering network cells based on a computed correlation between respective transmit antennas of the one or more interfering network cells; and

estimating a projected rate for communication based on application of the determined amount of employable interference nulling; and

reporting the projected rate to one or more network cells in the identified set of network cells.

7. The method of claim 4, wherein the reporting further comprises:

identifying a plurality of associated receive antennas;

determining an amount of receiver interference nulling that is employable relative to one or more interfering network cells via the plurality of associated receive antennas; and

reporting the determined amount of receiver interference nulling to one or more network cells in the identified set of network cells.

8. The method of claim 7, wherein the reporting the determined amount of receiver interference nulling comprises:

estimating a projected rate for communication based on application of the determined amount of receiver interference nulling; and

reporting the projected rate to one or more network cells in the identified set of network cells.

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

estimating a projected rate for communication based on the measured amount of received power; and

reporting the projected rate to one or more network cells in the identified set of network cells.

10. The method of claim 1, wherein the reporting comprises reporting a measured amount of received power to one or more network cells using Layer 1 (L1) signaling.

11. The method of claim 1, wherein the reporting comprises reporting a measured amount of received power to one or more network cells using Layer 3 (L3) signaling.

12. The method of claim 1, wherein the measuring comprises measuring an amount of received power associated with one or more of reference signals or synchronization signals broadcasted from respective network cells not associated with the identified set of network cells.

13. The method of claim 12, wherein the measuring further comprises:

identifying a loading indicator within at least one of a reference signal or synchronization signal broadcasted from a network cell;

determining loading of the network cell based at least in part on the loading indicator; and

estimating interference caused by the network cell as a function of loading of the network cell.

14. The method of claim 13, wherein the identifying a loading indicator comprises identifying a loading indicator within a preamble of a reference signal or a synchronization signal.

15. The method of claim 1, wherein the measuring comprises measuring an amount of received power associated with at least one of reference signaling, a primary synchronization signal (PSS), a secondary synchronization signal (SSS), or Low Reuse Preamble (LRP) signaling communicated by respective network cells not associated with the identified set of network cells.

16. A wireless communications apparatus, comprising:

a memory that stores data relating to a set of serving network nodes operable to conduct communication with inter-node coordination; and

a processor configured to measure an amount of received power from respective network nodes not associated with the set of serving network nodes and to report a measured amount of received power to one or more serving network nodes.

17. The wireless communications apparatus of claim 16, wherein the processor is further configured to analyze quality of channels corresponding to respective serving network nodes and to providing one or more reports of analyzed channel quality to respectively corresponding serving network nodes.

18. The wireless communications apparatus of claim 16, wherein:

the memory further stores data relating to one or more interfering network nodes, the one or more interfering network nodes respectively comprising a plurality of transmit antennas; and

the processor is further configured to compute correlation between respective transmit antennas of the one or more interfering network nodes and to report respective computed correlations between transmit antennas of respective interfering network nodes to one or more serving network nodes.

19. The wireless communications apparatus of claim 18, wherein the one or more interfering network nodes comprise a dominant interfering network node.

20. The wireless communications apparatus of claim 18, wherein the processor is further configured to determine an amount of interference nulling that is employable relative to one or more interfering network nodes based on respective computed correlations between transmit antennas of respective interfering network nodes, to estimate a projected rate for communication associated with application of the determined amount of employable interference nulling, and to report the projected rate to one or more serving network nodes.

21. The wireless communications apparatus of claim 18, wherein:

the memory further stores data relating to a plurality of associated receive antennas; and

the processor is further configured to determine an amount of receiver interference nulling that is employable relative to one or more interfering network nodes via the plurality of associated receive antennas and to report the determined amount of receiver interference nulling to one or more serving network nodes.

22. The wireless communications apparatus of claim 21, wherein the processor is further configured to estimate a projected communication rate based on application of the determined amount of receiver interference nulling and to report the determined amount of receiver interference nulling implicitly at least in part by reporting the projected communication rate to one or more serving network nodes.

23. The wireless communications apparatus of claim 16, wherein the processor is further configured to report a measured amount of received power to one or more serving network nodes using at least one of Layer 1 (L1) signaling or Layer 3 (L3) signaling.

24. The wireless communications apparatus of claim 16, wherein the processor is further configured to measure an amount of received power from a network node not associated with the set of serving network nodes based on at least one of reference signals or synchronization signals broadcasted from the network node.

25. The wireless communications apparatus of claim 24, wherein the processor is further configured to identify a loading indicator provided within at least one of a reference signal or a synchronization signal broadcasted by a network node, to determining loading of the network node according to the loading indicator, and to estimate interference caused by the network node as a function of loading of the network node.

26. The wireless communications apparatus of claim 24, wherein the loading indicator is provided within a preamble of a reference signal or a synchronization signal.

27. The wireless communications apparatus of claim 16, wherein the processor is further configured to measure an amount of received power from a network node based at least in part on at least one of reference signaling, a primary synchronization signal (PSS), a secondary synchronization signal (SSS), or Low Reuse Preamble (LRP) signaling communicated by the network node and detected by the wireless communications apparatus.

28. An apparatus, comprising:

means for identifying a set of associated network nodes operable to perform at least one of uplink communication or downlink communication using inter-node coordination; and

means for reporting an amount of received power corresponding to respective network nodes not associated with the set of associated network nodes.

29. The apparatus of claim 28, further comprising:

means for observing channel quality associated with channels corresponding to respective associated network nodes; and

means for providing one or more reports of observed channel quality to respectively corresponding associated network nodes.

30. The apparatus of claim 28, wherein:

the apparatus further comprises means for identifying one or more interfering network nodes having a plurality of transmit antennas; and

the means for reporting comprises means for reporting correlation between respective transmit antennas of the one or more interfering network nodes to respective associated network nodes.

31. The apparatus of claim 30, wherein the means for reporting further comprises:

means for determining an employable amount of interference nulling relative to respective interfering network nodes based on computed correlations between transmit antennas of the respective interfering network nodes;

means for estimating a projected communication rate associated with application of the employable amount of interference nulling; and

means for reporting the projected communication rate to one or more associated network nodes.

32. The apparatus of claim 30, wherein the means for reporting further comprises:

means for identifying a plurality of associated receive antennas;

means for determining an employable amount of receiver interference nulling relative to respective interfering network nodes via the plurality of associated receive antennas;

means for estimating a projected communication rate associated with application of the determined amount of receiver interference nulling; and

means for reporting the projected communication rate to one or more associated network nodes.

33. The apparatus of claim 28, wherein the means for reporting comprises means for providing one or more reports to an associated network node using at least one of Layer 1 (L1) signaling or Layer 3 (L3) signaling.

34. The apparatus of claim 28, further comprising means for measuring an amount of received power corresponding to a network node based on at least one of reference signals or synchronization signals broadcasted from the network node.

35. The apparatus of claim 34, wherein the means for measuring comprises:

means for identifying a loading indicator within at least one of a reference signal or a synchronization signal broadcasted from the network node;

means for determining loading of the network node based on the loading indicator; and

means for estimating interference caused by the network node as a function of loading of the network node.

36. The apparatus of claim 34, wherein the means for measuring comprises means for measuring an amount of received power corresponding to a network node based on at least one of reference signaling, a primary synchronization signal (PSS), a secondary synchronization signal (SSS), or Low Reuse Preamble (LRP) signaling communicated by the network node.

37. A computer program product, comprising:

a computer-readable medium, comprising;

code for causing a computer to identify a set of associated network nodes operable to perform at least one of uplink communication or downlink communication using inter-node coordination; and

code for causing a computer to report an amount of received power corresponding to respective network nodes not associated with the set of associated network nodes.

38. The computer program product of claim 37, wherein the computer-readable medium further comprises:

code for causing a computer to observe channel quality associated with channels corresponding to respective associated network nodes; and

code for causing a computer to provide one or more reports of observed channel quality to respectively corresponding associated network nodes.

39. The computer program product of claim 37, wherein:

the computer-readable medium further comprises code for causing a computer to identify one or more interfering network nodes having a plurality of transmit antennas; and

code for causing a computer to report comprises code for causing a computer to report correlation between respective transmit antennas of the one or more interfering network nodes to respective associated network nodes.

40. The computer program product of claim 37, wherein the code for causing a computer to report comprises code for causing a computer to provide one or more reports to an associated network node using at least one of Layer 1 (L1) signaling or Layer 3 (L3) signaling.

41. The computer program product of claim 37, wherein the computer-readable medium further comprises code for causing a computer to measure an amount of received power corresponding to a network node based on at least one of reference signals or synchronization signals broadcasted from the network node.

42. The computer program product of claim 41, wherein the code for causing a computer to measure comprises:

code for causing a computer to determine loading of the network node based at least in part on a loading indicator provided within a reference signal or a synchronization signal broadcasted from the network node; and

code for causing a computer to estimate interference caused by the network node as a function of loading of the network node.

43. The computer program product of claim 41, wherein the code for causing a computer to measure comprises code for causing a computer to measure an amount of received power corresponding to a network node based on at least one of reference signaling, a primary synchronization signal (PSS), a secondary synchronization signal (SSS), or Low Reuse Preamble (LRP) signaling communicated by the network node.

44. A method, comprising:

defining an interference reporting schedule for one or more associated user equipment units (UEs);

scheduling respective null pilot intervals within the interference reporting schedule; and

conducting limited transmission upon occurrence of a scheduled null pilot interval within the interference reporting schedule.

45. The method of claim 44, wherein the conducting limited transmission comprises silencing transmission upon occurrence of a scheduled null pilot interval.

46. The method of claim 44, wherein the conducting limited transmission comprises reducing transmit power by a predefined power backoff value upon occurrence of a scheduled null pilot interval.

47. The method of claim 44, further comprising:

obtaining an interference report from a UE subsequent to occurrence of a null pilot interval; and

selecting a coordination strategy to be utilized across respective network nodes for communication with the UE based at least in part on the interference report.

48. A wireless communications apparatus, comprising:

a memory that stores data relating to one or more user devices and an interference reporting schedule associated with the one or more user devices; and

a processor configured to define respective null pilot intervals within the interference reporting schedule such that limiting is performed for communication occurring substantially simultaneously with the respective null pilot intervals.

49. The wireless communications apparatus of claim 48, wherein the processor is further configured to silence respective transmissions occurring substantially simultaneously with the respective null pilot intervals.

50. The wireless communications apparatus of claim 48, wherein the processor is further configured to reduce transmit power of respective transmissions occurring substantially simultaneously with the respective null pilot intervals.

51. The wireless communications apparatus of claim 48, wherein the processor is further configured to receive interference feedback from a user device upon completion of a null pilot interval and to select a coordination strategy to be utilized between the wireless communications apparatus and one or more cooperative network cells for communication with the user device based on the interference feedback.

52. An apparatus, comprising:

means for defining an interference reporting schedule for respective associated user devices, wherein the interference reporting schedule includes one or more null pilots; and

means for performing at least one of transmit silencing or transmit power backoff upon occurrence of respective null pilots in the interference reporting schedule.

53. The apparatus of claim 52, further comprising:

means for receiving interference feedback from a user device subsequent to occurrence of a null pilot; and

means for selecting a coordination strategy to be utilized among respective cooperative network nodes for communication with the user device based at least in part on the interference feedback.

54. A computer program product, comprising:

a computer-readable medium, comprising;

code for causing a computer to define an interference reporting schedule for respective associated user equipment units (UEs), wherein the interference reporting schedule includes one or more null pilots; and

code for causing a computer to conduct at least one of transmit silencing or transmit power backoff upon occurrence of respective null pilots in the interference reporting schedule.

55. The computer program product of claim 54, wherein the computer-readable medium further comprises:

code for causing a computer to receive interference feedback from a UE subsequent to occurrence of a null pilot; and

code for causing a computer to select an inter-node coordination strategy to be utilized for communication with the UE based on the interference feedback.