NODE AND METHOD FOR GENERATING BEAMFORMED FOR DOWNLINK COMMUNICATIONS

• US 20130242773A1
• Filed: 09/13/2012
• Published: 09/19/2013
• Est. Priority Date: 03/15/2012
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Wernersson, Niklas, Hammarwall, David, Bergman, Svante
• Granted Patent: US 9,236,916 B2
• Time in Patent Office: Days
• US Class Current: 370/252
• CPC Class Codes: H04B 17/24 with feedback of measurements to the transmitter
• CPC Class Codes: H04B 7/024 Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/0619 using feedback from receiving side feedback signaling for adaptive modulation/coding H04L1/0001
• CPC Class Codes: H04B 7/0626 Channel coefficients, e.g. channel state information [CSI]
• CPC Class Codes: H04B 7/063 Parameters other than those covered in groups H04B7/0623 - H04B7/0634, e.g. channel matrix rank or transmit mode selection
• CPC Class Codes: H04B 7/0632 Channel quality parameters, e.g. channel quality indicator [CQI]
• CPC Class Codes: H04B 7/0639 Using selective indices, e.g. of a codebook, e.g. pre-distortion matrix index [PMI] or for beam selection
• CPC Class Codes: H04B 7/10 Polarisation diversity; Directional diversity
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04W 72/563 of the wireless resources

Abstract

Example embodiments presented herein are directed towards an eNodeB, and method therein, for generating downlink communications in a multiple antenna system. The method comprises transmitting, to a number of user equipments, a plurality of reference signals, where each signal is beamformed in a distinct direction within at least one correlated domain (e.g., elevation and/or azimuth). The eNodeB receives at least one CSI report from a specific user equipment and determines a primary reference signal based on, for example, the at least one CSI report. The eNodeB may thereafter generate downlink communication signals for antenna element(s) and/or subelements of the multiple antenna system. The downlink communication signals are beamformed into a transmitting direction that aligns most closely with a beamforming direction of the at least one primary reference signal, as compared to any other beamforming direction of the reference signals.

Claims

1. A method, in an eNodeB, for generating downlink communications in a multiple antenna system, the eNodeB being comprised in a wireless communications network, the method comprising:

transmitting, to a plurality of user equipments, a plurality of reference signals, each reference signal being beamformed into a distinct direction within at least one correlated domain of the multiple antenna system;

receiving, from a specific user equipment, at least one Channel State Information, CSI, report for at least a subset of said plurality of reference signals;

determining at least one primary reference signal among said plurality of reference signals based on the received at least one CSI report; and

generating downlink communication signals for antenna element(s) and/or sub-elements of the multiple antenna system, wherein the downlink communication signals are beamformed into a transmitting direction that aligns most closely with a beamforming direction of the at least one primary reference signal, as compared to any other beamforming direction of reference signals comprised in the first set of reference signals.

2. The method of claim 1, wherein the at least one correlated domain is an elevation and/or azimuth domain.

3. The method of claim 1, wherein the plurality of reference signals are Channel State Information Reference Symbols, CSI-RS.

4. The method of claim 1, wherein the CSI report comprises a Precoder Matrix Indicator, PMI, a Rank Indicator, RI, and/or at least one signal quality indicator, CQI.

5. The method of claim 1, the method further comprises determining at least one candidate beamforming direction for the specific user equipment, within said at least one correlated domain of the multiple antenna system, for a subsequent data transmission.

6. The method of claim 5, wherein the determining is based, at least in part, on uplink measurements on received signals transmitted by the specific user equipment.

7. The method of claim 5, wherein the determining is based, at least in part, on a plurality of signal quality assessments, received from the specific user equipment, of beamformed signals received by the specific user equipment.

8. The method of claim 7, wherein the signal quality assessment is a reference signal received power, RSRP, a reference signal received quality, RSRQ, and/or a received signal strength indicator, RSSI.

9. The method of claim 5, wherein the receiving further comprises receiving a CSI report for a single reference signal, of said plurality of reference signals, with a beamforming direction that aligns most closely with the at least one candidate beamforming direction, as compared to any other beamforming direction of any other reference signal of said plurality of reference signals.

10. The method of claim 1, wherein the receiving further comprises receiving a plurality of CSI reports for respective reference signals of the plurality of reference signals.

11. The method of claim 10, further comprising configuring a plurality of CSI Processes and/or a CoMP Measurement Set for said specific user equipment, the CSI Processes and/or the set comprising, at least, the plurality of reference signals associated with said plurality of CSI reports.

12. The method of claim 11, wherein the determining further comprises selecting said at least one primary reference signal from said plurality of reference signals associated with said plurality of CSI reports.

13. The method of claim 5, wherein the at least one primary reference signal is selected such that a beamforming direction of said at least one primary reference signal, aligns most closely with the at least one candidate beamforming direction, as compared to any other beamforming direction of any other reference signal of said plurality of reference signals.

14. The method of claim 9, wherein the determining is further based on signal quality indicators, CQI, of the at least one CSI report.

15. The method of claim 9, wherein the at least one CSI report is a plurality of CSI reports and the at least one primary reference signal is a reference signal associated with a CSI report with a highest signal quality indicator or a corresponding highest recommended total transmission rate.

16. The method of claim 1, further comprising:

configuring said specific user equipment to measure said plurality of reference signals, and report an index identifying a recommended effective channel among a plurality of effective channels excited by said plurality of reference signals; and

receiving said index from said specific user equipment.

17. The method of claim 16, wherein the determining further comprises determining the at least one primary reference signal based on said received index.

18. The method of claim 17, wherein said index and said at least one CSI report are received in a same report from the specific user equipment, and the at least one CSI report represents said identified recommended effective channel.

19. An eNodeB, for generating downlink communications in a multiple antenna system, the eNodeB being comprised in a wireless communications network, the eNodeB comprising:

radio circuitry configured to transmit, to a plurality of user equipments, a plurality of reference signals, each reference signal being beamformed into a distinct direction within at least one correlated domain of the multiple antenna system;

the radio circuitry further configured to receive, from a specific user equipment, at least one Channel State Information, CSI, report for a first set of reference signals of said plurality of transmitted reference signals;

processing circuitry configured to determine at least one primary reference signal among said first set of reference signals; and

the processing circuitry further configured to generate downlink communication signals for antenna element(s) and/or sub-elements of the multiple antenna system, wherein the downlink communication signals are beamformed into a beamforming direction of the at least one primary reference signal, as compared to any other beamforming direction of reference signals comprised in the first set of reference signals.

20. The eNodeB of claim 19, wherein the at least one correlated domain is an elevation and/or azimuth domain.

21. The eNodeB of claim 19, wherein the plurality of reference signals are Channel State Information Reference Symbols, CSI-RS.

22. The eNodeB of claim 19, wherein the CSI report comprises a Precoder Matrix Indicator, PMI, a Rank Indicator, RI, and/or at least one signal quality indicator, CQI.

23. The eNodeB of claim 19, the processing circuitry is further configured to determine at least one candidate beamforming direction for the specific user equipment, within said at least one correlated domain of the multiple antenna system, for a subsequent data transmission.

24. The eNodeB of claim 23, wherein the processing circuitry is further configured to determine the at least one candidate beamforming direction based, at least in part, on uplink measurements on received signals transmitted by the specific user equipment.

25. The eNodeB of claim 23, wherein the processing circuitry is further configured to determine the at least one candidate beamforming direction based, at least in part, on a plurality of signal quality assessments, received from the specific user equipment, of beamformed signals received by the specific user equipment.

26. The eNodeB of claim 25, wherein the signal quality assessment is a reference signal received power, RSRP, a reference signal received quality, RSRQ, and/or a received signal strength indicator, RSSI.

27. The eNodeB of claim 23, wherein the radio circuitry is further configured to receive a CSI report for a single reference signal, of said plurality of reference signals, with a beamforming direction that aligns most closely with the at least one candidate beamforming direction, as compared to any other beamforming direction of any other reference signal of said plurality of reference signals.

28. The eNodeB of claim 19, wherein the radio circuitry is further configured to receive a plurality of CSI reports for respective reference signals of the plurality of reference signals.

29. The eNodeB of claim 28, wherein the processing circuitry is configured to configure a plurality of CSI Processes and/or a CoMP Measurement Set for said specific user equipment, the CSI Processes and/or the set comprising, at least, the plurality of reference signals associated with said plurality of CSI reports.

30. The eNodeB of claim 29, wherein the processing circuitry is configured to select said at least one primary reference signal from said plurality of reference signals associated with said plurality of CSI reports.

31. The eNodeB of claim 23, wherein the at least one primary reference signal is selected such that a beamforming direction of said at least one primary reference signal, aligns most closely with the at least one candidate beamforming direction, as compared to any other beamforming direction of any other reference signal of said plurality of reference signals.

32. The eNodeB of claim 27, wherein the processing circuitry is configured to determine the at least one candidate beamforming direction further based on signal quality indicators, CQI, of the at least one CSI report.

33. The eNodeB of claim 27, wherein the at least one CSI report is a plurality of CSI reports and the at least one primary reference signal is a reference signal associated with a CSI report with a highest signal quality indicator or a corresponding highest recommended total transmission rate.

34. The eNodeB of claim 19, wherein the processing circuitry is further configured to configure said specific user equipment to measure said plurality of reference signals, and report an index identifying a recommended effective channel among a plurality of effective channels excited by said plurality of reference signals;

and the radio circuitry is further configured to receive said index from said specific user equipment.

35. The eNodeB of claim 34, wherein the processing circuitry is further configured to determine the at least one primary reference signal based on said received index.

36. The eNodeB of claim 35, wherein said index and said at least one CSI report are received in a same report from the specific user equipment, and the at least one CSI report represents said identified recommended effective channel.

37. A method in a user equipment, for establishing beamforming for a multiple antenna system, the user equipment being comprised in a wireless communications network, the method comprising:

receiving, from an eNodeB, a plurality of reference signals, each reference signal being beamformed into a distinct direction within at least one correlated domain of the multiple antenna system;

measuring a corresponding effective channel for, at least a subset, of the plurality of reference signals;

determining a recommended effective channel, among said effective channels, based on a performance metric relating to a performance of a data transmission over a given effective channel; and

transmitting, to a wireless communication network, an index identifying said recommended effective channel

38. The method in claim 37, further comprising transmitting a CSI report for said recommended effective channel.

39. The method of claim 37, wherein the CSI report comprises a Precoder Matrix Indicator, PMI, a Rank Indicator, RI, and/or at least one signal quality indicator, CQI.

40. The method of claim 37, wherein the plurality of reference signals are Channel State Information Reference Symbols, CSI-RS.

41. The method of claim 37, wherein said performance metric is an effective received signal power.

42. The method of claim 37, wherein said performance metric is an effective data throughput.

43. A user equipment, for establishing beamforming for a multiple antenna system, the user equipment being comprised in a wireless communications network, the user equipment comprising:

radio circuitry configured to receive, from an eNodeB, a plurality of reference signals, each reference signal being beamformed into a distinct direction within at least one correlated domain of the multiple antenna system;

processing circuitry configured to measure a corresponding effective channel for, at least a subset, of the plurality of reference signals;

the processing circuitry further configured to determine a recommended effective channel, among said effective channels, based on a performance metric relating to a performance of a data transmission over a given effective channel; and

the radio circuitry further configured to transmit, to a wireless communication network, an index identifying said recommended effective channel.

44. The user equipment in claim 43, wherein the radio circuitry is further configured to transmit a CSI report for said recommended effective channel.

45. The method of claim 43, wherein the CSI report comprises a Precoder Matrix Indicator, PMI, a Rank Indicator, RI, and/or at least one signal quality indicator, CQI.

46. The user equipment of claim 43, wherein the plurality of reference signals are Channel State Information Reference Symbols, CSI-RS.

47. The user equipment of claim 43, wherein said performance metric is an effective received signal power.

48. The user equipment of claim 43, wherein said performance metric is an effective data throughput.