Method and apparatus for interference reporting in a N-MIMO communication system

• US 9,426,670 B2
• Filed: 03/20/2013
• Issued: 08/23/2016
• Est. Priority Date: 10/24/2008
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Palanki, Ravi, Gorokhov, Alexei Y., Bhushan, Naga
• Primary Examiner(s): Maung, Nay A
• Assistant Examiner(s): PEREZ, ANGELICA
• Application Number:
  US13/847,709
• Publication Number:
  US 20130219055A1
• Time in Patent Office: 1,252 Days
• Field of Search: 455/67.11, 455/522, 455/450, 455/452.11, 455/422.1, 455/448, 370/329, 370/328, 370/334
• US Class Current: 1/1
• 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:

determining an interference reporting schedule for a user equipment in relation to a serving set of network cells;

scheduling null pilot intervals for the serving set of network cells based on the interference reporting schedule, wherein the scheduled null pilot intervals comprise at least one null pilot interval associated with limited transmission by a plurality of network cells of the serving set of network cells;

conducting the limited transmission during the at least one null pilot interval, the limited transmission comprising one of silencing transmission during the at least one null pilot interval or reducing transmit power by a power backoff value during the at least one null pilot interval;

receiving a combined interference report from the user equipment comprising an indication of channel conditions measured by the user equipment during the at least one null pilot interval, wherein the measured channel conditions comprise interference associated with one or more network cells not within the plurality of network cells; and

scheduling a communication by one or more network cells of the serving set of network cells to the user equipment based at least in part on the received combined interference report.

2. The method of claim 1, further comprising selecting a transmission scheme for the communication to the user equipment, wherein the selected transmission scheme comprises one or more of joint transmission, coordinated silencing, or coordinated beamforming.

3. The method of claim 1, wherein the combined interference report comprises information relating to an achievable channel quality for the one or more network cells of the serving set of network cells under different coordination schemes.

4. The method of claim 1, wherein the combined interference report comprises information relating to a frequency bandwidth or to one or more frequency sub-bands of a corresponding communication system.

5. The method of claim 1, wherein the communication is further based on a mobility of the user equipment or an antenna correlation of the user equipment.

6. The method of claim 1, further comprising:

identifying a primary interfering network cell among the network cells not within the plurality of network cells of the serving set of network cells; and

determining a correlation of transmit antennas of the primary interfering network cell,

wherein the communication is based at least in part on the determined correlation.

7. The method of claim 1, wherein the combined interference report comprises channel information associated with downlink channels of the one or more network cells of the serving set of network cells, and wherein the scheduling of the communication is based at least in part on the reported channel information associated with the downlink channels.

8. The method of claim 1, wherein the combined interference report comprises an amount of received power associated with one or more of reference signals or synchronization signals from the one or more network cells not within the plurality of network cells of the serving set of network cells, and wherein the scheduling of the communication is based at least in part on the reported amount of received power of the one or more of reference signals or synchronization signals.

9. A method comprising:

measuring, by a user equipment associated with a serving set of network cells, channel conditions during a null pilot interval scheduled in accordance with an interference reporting schedule for the serving set of network cells, wherein a plurality of network cells of the serving set of network cells silence or reduce transmit power of transmissions that occur during the scheduled null pilot interval;

sending, to a network cell of the serving set of network cells, a combined interference report comprising an indication of the channel conditions measured by the user equipment during the at least one null pilot interval, wherein the measured channel conditions comprise interference associated with one or more network cells not within the plurality of network cells; and

receiving communications from one or more network cells of the serving set of network cells, wherein the received communications are based at least in part on the combined interference report.

10. The method of claim 9, further comprising:

determining an achievable channel quality associated with channels corresponding to respective network cells in the serving set of network cells; and

providing the achievable channel quality with the combined interference report.

11. The method of claim 9, wherein:

the measuring comprises identifying a primary interfering network cell; and

the combined interference report comprises an identity of the primary interfering network cell.

12. The method of claim 9, further comprising:

identifying one or more interfering network cells comprising a plurality of transmit antennas,

wherein the measuring comprises computing a correlation between respective transmit antennas of the one or more interfering network cells.

13. The method of claim 12, wherein the one or more interfering network cells comprise a primary interfering network cell.

14. The method of claim 12, wherein the combined interference report comprises information relating to the computed correlation between the respective transmit antennas of the one or more interfering network cells.

15. The method of claim 12, further comprising:

determining an amount of interference nulling for application relative to the one or more interfering network cells based on the computed correlation between the 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 interference nulling,

wherein the combined interference report comprises the estimated projected rate.

16. The method of claim 12, further comprising:

determining an amount of receiver interference nulling for application relative to the one or more interfering network cells via a plurality of receive antennas,

wherein the combined interference report comprises the determined amount of receiver interference nulling.

17. The method of claim 9, wherein the measuring comprises measuring an amount of received power associated with one or more of reference signals or synchronization signals from the one or more network cells not within the plurality of network cells of the serving set of network cells.

18. The method of claim 9, wherein the measuring further comprises:

identifying a loading indicator within at least one of a reference signal or synchronization signal from a network cell not within the plurality of network cells of the serving set of network cells;

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.

19. The method of claim 18, wherein the identifying the loading indicator comprises identifying the loading indicator within a preamble of the reference signal or the synchronization signal.

20. The method of claim 9, 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 the one or more network cells not within the plurality of network cells of the serving set of network cells.

57. The method of claim 9, further comprising:

measuring channel conditions corresponding to network cells in the serving set of network cells; and

providing information corresponding to the measured channel conditions associated with the network cells in the serving set of network cells with the combined interference report.

61. The method of claim 10, wherein the provided achievable channel quality for the respective network cells in the serving set of network cells relates to at least one coordination scheme utilizing the one or more network cells of the serving set of network cells.

62. The method of claim 61, wherein the at least one coordination scheme comprises one or more of coordinated silencing, coordinated beamforming, or joint transmission.

21. A communications device comprising:

at least one processor configured to;

determine an interference reporting schedule for a user equipment in relation to a serving set of network cells;

schedule null pilot intervals for the serving set of network cells based on the interference reporting schedule, wherein the scheduled null pilot intervals comprise at least one null pilot interval associated with limited transmission by a plurality of network cells of the serving set of network cells;

conduct the limited transmission during the at least one null pilot interval, the limited transmission comprising one of silencing transmission during the at least one scheduled null pilot interval or reducing transmit power by a power backoff value during the at least one null pilot interval;

receive a combined interference report from the user equipment comprising an indication of channel conditions measured by the user equipment during the at least one null pilot interval, wherein the measured channel conditions comprise interference associated with one or more network cells not within the plurality of network cells; and

schedule a communication by one or more network cells of the serving set of network cells to the user equipment based at least in part on the received combined interference report.

22. The communications device of claim 21, wherein the at least one processor is further configured to select a transmission scheme for the communication to the user equipment, and wherein the selected transmission scheme comprises one or more of joint transmission, coordinated silencing, or coordinated beamforming.

23. The communications device of claim 21, wherein the combined interference report comprises information relating to an achievable channel quality for the one or more network cells under one or more coordination schemes.

24. The communications device of claim 21, wherein the combined interference report comprises information relating to a frequency bandwidth or to one or more frequency sub-bands of a corresponding communication system.

25. The communications device of claim 21, wherein the communication is further based on a mobility of the user equipment or an antenna correlation of the user equipment.

26. The communications device of claim 21, wherein the at least one processor is further configured to:

identify a primary interfering network cell among the network cells not within the plurality of network cells of the serving set of network cells; and

determine a correlation of transmit antennas of the primary interfering network cell; and

schedule the communication based at least in part on the determined correlation.

27. The communications device of claim 21, wherein the combined interference report comprises channel information associated with downlink channels of the one or more network cells of the serving set of network cells, and wherein the at least one processor is further configured to schedule the communication based at least in part on the reported channel information associated with the downlink channels.

28. The communications device of claim 21, wherein the combined interference report comprises an amount of received power associated with one or more of reference signals or synchronization signals from the one or more network cells not within the plurality of network cells of the serving set of network cells and wherein the at least one processor is further configured to schedule the communication based at least in part on the reported amount of received power of the one or more of reference signals or synchronization signals.

29. A communications device comprising:

at least one processor configured to;

measure, by a user equipment associated with a serving set of network cells, channel conditions during a null pilot interval scheduled in accordance with an interference reporting schedule for the serving set of network cells, wherein a plurality of network cells of the serving set of network cells silence or reduce transmit power of transmissions that occur during the scheduled null pilot interval;

send, to a network cell of the serving set of network cells, a combined interference report comprising an indication of the channel conditions measured by the user equipment during the at least one null pilot interval, wherein the measured channel conditions comprise interference associated with one or more network cells not within the plurality of network cells; and

receive communications from one or more network cells of the serving set of network cells, wherein the received communications are based at least in part on the combined interference report.

30. The communications device of claim 29, wherein the at least one processor is further configured to:

determine an achievable channel quality associated with channels corresponding to respective network cells in the serving set of network cells; and

provide the achievable channel quality with the combined interference report.

31. The communications device of claim 29, wherein the at least one processor is further configured to identify a primary interfering network cell, and wherein the combined interference report comprises an identity of the primary interfering network cell.

32. The communications device of claim 29, wherein the at least one processor is further configured to identify one or more interfering network cells comprising a plurality of transmit antennas, and wherein the measuring comprises computing a correlation between respective transmit antennas of the one or more interfering network cells.

33. The communications device of claim 32, wherein the one or more interfering network cells comprise a primary interfering network cell.

34. The communications device of claim 32, wherein the combined interference report comprises information relating to the computed correlation between the respective transmit antennas of the one or more interfering network cells.

35. The communications device of claim 32, wherein the at least one processor is further configured to:

determine an amount of interference nulling for application relative to the one or more interfering network cells based on the computed correlation between the respective transmit antennas of the one or more interfering network cells;

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

send, with the combined interference report, the estimated projected rate.

36. The communications device of claim 32, wherein the at least one processor is further configured to determine an amount of receiver interference nulling for application relative to the one or more interfering network cells via a plurality of receive antennas, and send, with the combined interference report, the determined amount of receiver interference nulling.

37. The communications device of claim 29, wherein the at least one processor is further configured to measure an amount of received power associated with one or more of reference signals or synchronization signals from the one or more network cells not within the plurality of network cells of the serving set of network cells.

38. The communications device of claim 29, wherein the at least one processor is further configured to:

identify a loading indicator within at least one of a reference signal or synchronization signal from a network cell not within the plurality of network cells of the serving set of network cells;

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

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

39. The communications device of claim 38, wherein the at least one processor is further configured to identify the loading indicator within a preamble of the reference signal or the synchronization signal.

40. The communications device of claim 29, wherein the at least one processor is further configured to measure 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 the one or more network cells not within the plurality of network cells of the serving set of network cells.

58. The communications device of claim 29, wherein the at least one processor is further configured to:

measure channel conditions corresponding to network cells in the serving set of network cells; and

provide information corresponding to the measured channel conditions associated with the network cells in the serving set of network cells with the combined interference report.

41. A communications device comprising:

means for determining an interference reporting schedule for a user equipment in relation to a serving set of network cells;

means for scheduling null pilot intervals for the serving set of network cells based on the interference reporting schedule, wherein the scheduled null pilot intervals comprise at least one null pilot interval associated with limited transmission by a plurality of network cells of the serving set of network cells;

means for conducting the limited transmission during the at least one null pilot interval, the limited transmission comprising one of silencing transmission during the at least one null pilot interval or reducing transmit power by a power backoff value during the at least one null pilot interval;

means for receiving a combined interference report from the user equipment comprising an indication of channel conditions measured by the user equipment during the at least one null pilot interval, wherein the measured channel conditions comprise interference associated with one or more network cells not within the plurality of network cells; and

means for scheduling a communication by one or more network cells of the serving set of network cells to the user equipment based at least in part on the received combined interference report.

42. The communications device of claim 41, wherein the means for scheduling the communication identifies a primary interfering network cell among the network cells not within the plurality of network cells of the set of network cells, determines a correlation of transmit antennas of the primary interfering network cell, and schedules the communication based at least in part on the determined correlation.

43. The communications device of claim 41, wherein the combined interference report comprises channel information associated with downlink channels of the one or more network cells of the serving set of network cells, and wherein the means for scheduling the communication schedules the communication based at least in part on the reported channel information associated with the downlink channels.

44. A communications device comprising:

means for measuring, by a user equipment associated with a serving set of network cells, channel conditions during a null pilot interval scheduled in accordance with an interference reporting schedule for the serving set of network cells, wherein a plurality of network cells of the serving set of network cells silence or reduce transmit power of transmissions that occur during the scheduled null pilot interval;

means for sending, to a network cell of the serving set of network cells, a combined interference report comprising an indication of the channel conditions measured by the user equipment during the at least one null pilot interval, wherein the measured channel conditions comprise interference associated with one or more network cells not within the plurality of network cells; and

means for receiving communications from one or more network cells of the serving set of network cells, wherein the received communications are based at least in part on the combined interference report.

45. The communications device of claim 44, wherein the means for measuring determines an achievable channel quality associated with channels corresponding to respective network cells in the serving set of network cells and the means for sending the combined interference report provides the achievable channel quality with the combined interference report.

46. The communications device of claim 44, wherein the means for measuring identifies one or more interfering network cells comprising a plurality of transmit antennas and computes a correlation between respective transmit antennas of the one or more interfering network cells.

47. The communications device of claim 46, wherein the combined interference report comprises information relating to the computed correlation between the respective transmit antennas of the one or more interfering network cells.

48. The communications device of claim 46, wherein the means for measuring determines an amount of interference nulling for application relative to the one or more interfering network cells based on the computed correlation between the respective transmit antennas of the one or more interfering network cells and estimates a projected rate for communication based on application of the determined amount of interference nulling, and wherein the combined interference report comprises the estimated projected rate.

49. The communications device of claim 46, wherein the means for measuring determines an amount of receiver interference nulling for application relative to the one or more interfering network cells via a plurality of receive antennas, and wherein the combined interference report comprises the determined amount of receiver interference nulling.

59. The communications device of claim 44, wherein:

the means for measuring measures channel conditions corresponding to network cells in the serving set of network cells; and

the means for sending provides information corresponding to the measured channel conditions associated with the network cells in the serving set of network cells with the combined interference report.

50. A non-transitory computer-readable medium storing computer-executable code, comprising:

code for determining an interference reporting schedule for a user equipment in relation to a serving set of network cells;

code for scheduling null pilot intervals for the serving set of network cells based on the interference reporting schedule, wherein the scheduled null pilot intervals comprise at least one null pilot interval associated with limited transmission by a plurality of network cells of the serving set of network cells;

code for conducting the limited transmission during the at least one null pilot interval, the limited transmission comprising one of silencing transmission during the at least one null pilot interval or reducing transmit power by a power backoff value during the at least one null pilot interval;

code for receiving a combined interference report from the user equipment comprising an indication of channel conditions measured by the user equipment during the at least one null pilot interval, wherein the measured channel conditions comprise interference associated with one or more network cells not within the plurality of network cells; and

code for scheduling a communication by one or more network cells of the serving set of network cells to the user equipment based at least in part on the received combined interference report.

51. The non-transitory computer-readable medium of claim 50, wherein the non-transitory computer-readable medium further comprises:

code for identifying a primary interfering network cell among the network cells not within the plurality of network cells of the serving set of network cells;

code for determining a correlation of transmit antennas of the primary interfering network cell; and

code for scheduling the communication based at least in part on the determined correlation.

52. The non-transitory computer-readable medium of claim 50, wherein the combined interference report comprises channel information associated with downlink channels of the one or more network cells of the serving set of network cells, and wherein the scheduling the communication is based at least in part on the reported channel information associated with the downlink channels.

53. A non-transitory computer-readable medium storing computer-executable code, comprising:

code for measuring, by a user equipment associated with a serving set of network cells, channel conditions during a null pilot interval scheduled in accordance with an interference reporting schedule for the serving set of network cells, wherein a plurality of network cells of the serving set of network cells silence or reduce transmit power of transmissions that occur during the scheduled null pilot interval;

code for sending, to a network cell of the serving set of network cells, a combined interference report comprising an indication of the channel conditions measured by the user equipment during the at least one null pilot interval, wherein the measured channel conditions comprise interference associated with one or more network cells not within the plurality of network cells; and

code for receiving communications from one or more network cells of the serving set of network cells, wherein the received communications are based at least in part on the combined interference report.

54. The non-transitory computer-readable medium of claim 53, wherein the non-transitory computer-readable medium further comprises:

code for determining an achievable channel quality associated with channels corresponding to respective network cells in the serving set of network cells; and

code for providing the achievable channel quality with the combined interference report.

55. The non-transitory computer-readable medium of claim 53, wherein the non-transitory computer-readable medium further comprises code for identifying a primary interfering network cell, and wherein the combined interference report comprises an identity of the primary interfering network cell.

56. The non-transitory computer-readable medium of claim 53, wherein the non-transitory computer-readable medium further comprises:

code for identifying one or more interfering network cells comprising a plurality of transmit antennas; and

code for computing a correlation between respective transmit antennas of the one or more interfering network cells.

60. The non-transitory computer-readable medium of claim 53, wherein the non-transitory computer-readable medium further comprises:

code for measuring channel conditions corresponding to network cells in the serving set of network cells; and

code for providing information corresponding to the measured channel conditions associated with the network cells in the serving set of network cells with the combined interference report.