METHOD FOR DYNAMIC CSI FEEDBACK

• US 20160149679A1
• Filed: 03/11/2015
• Published: 05/26/2016
• Est. Priority Date: 10/10/2014
• Status: Abandoned Application

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Frenne, Mattias, Furuskog, Johan, J?ngren, George, Harrison, Mark
• Application Number:
  US14/440,960
• Publication Number:
  US 20160149679A1
• Time in Patent Office: Days
• CPC Class Codes: H04L 5/005 of common pilots, i.e. pilots destined for multiple users or terminals

Abstract

Systems and methods for providing Channel State Information (CSI) feedback in a cellular communications network are disclosed. In some embodiments, a base station of a cellular communications network disables inter-subframe channel interpolation and/or filtering of CSI-RS estimates across subframes at the wireless device and receives one or more CSI reports from the wireless device that are generated by the wireless device with inter-subframe channel interpolation and/or filtering of CSI-RS estimates across subframes disabled in response to the base station disabling inter-subframe channel interpolation and/or filtering of CSI-RS estimates across subframes at the wireless device. In this manner, CSI feedback is improved particularly in embodiments in which the base station transmits a beamformed CSI-RS resource(s) and reuses the same CSI-RS resource(s) for different beams over time.

Claims

1. A method of operation of a base station of a cellular communications network to control Channel State Information Reference Symbol, CSI-RS, based channel estimation at a wireless device, comprising:

disabling, at a wireless device, inter-subframe channel interpolation and/or filtering of CSI-RS estimates across subframes; and

receiving one or more Channel State Information, CSI, reports from the wireless device that are generated by the wireless device with disabled inter-subframe channel interpolation and/or filtering of CSI-RS estimates across subframes.

2. The method of claim 1 wherein the base station transmits a beamformed CSI-RS resource, the beamformed CSI-RS resource corresponding to a beam direction, and reuses the same CSI-RS resource for different beam directions over time.

3. The method of claim 1 wherein the wireless device utilizes two or more CSI processes for CSI reporting, and disabling inter-subframe channel interpolation and/or filtering of CSI-RS estimates across subframes comprises disabling inter-subframe channel interpolation and/or filtering of CSI-RS estimates across subframes on a per CSI process basis.

4. The method of claim 1 wherein the wireless device utilizes two or more CSI processes for CSI reporting, and disabling inter-subframe channel interpolation and/or filtering of CSI-RS estimates across subframes comprises disabling inter-subframe channel interpolation and/or filtering of CSI-RS estimates across subframes for all of the two or more CSI processes.

5. The method of claim 1 wherein disabling inter-subframe channel interpolation and/or filtering of CSI-RS estimates across subframes comprises disabling inter-subframe channel interpolation and/or filtering of CSI-RS estimates across subframes via Radio Resource Control, RRC, signaling.

6. The method of claim 5 wherein disabling inter-subframe channel interpolation and/or filtering of CSI-RS estimates across subframes via RRC signaling comprises:

sending, in an RRC information element that configures a CSI process of the wireless device, an indication that inter-subframe channel interpolation and/or filtering of CSI-RS estimates across subframes is not allowed for the CSI process of the wireless device.

7. The method of claim 1 further comprising disabling, at the wireless device, combining of CSI Interference Measurement, CSI-IM, estimates across subframes.

8. The method of claim 1 wherein disabling inter-subframe channel interpolation and/or filtering of CSI-RS estimates across subframes comprises signaling, to the wireless device an indication that inter-subframe channel interpolation and/or filtering of CSI-RS estimates across subframes is not allowed.

9. The method of claim 1 further comprising configuring the wireless device with a set of CSI-RS resources.

10. The method of claim 9 wherein receiving the one or more CSI reports from the wireless device comprises receiving CSI reports for a subset of the set of CSI-RS resources configured for the wireless device.

11. The method of claim 9 wherein configuring the wireless device with the set of CSI-RS resources comprises configuring the wireless device with the set of CSI-RS resources via Radio Resource Control, RRC, signaling.

12. The method of claim 9 wherein configuring the wireless device with the set of CSI-RS resources comprises semi-statically configuring the wireless device with the set of CSI-RS resources.

13. The method of claim 9 wherein the set of CSI-RS resources is specific to a CSI process of the wireless device.

14. The method of claim 9 wherein the base station transmits beamformed CSI-RS, and the method further comprises dynamically changing beams used on the set of CSI-RS resources configured for the wireless device, each beam corresponding to a different beam direction.

15. A base station of a cellular communications network enabled to control Channel State Information Reference Symbol, CSI-RS, based channel estimation at a wireless device comprising:

means for disabling, at a wireless device, inter-subframe channel interpolation and/or filtering of CSI-RS estimates across subframes; and

means for receiving a Channel State Information, CSI, report from the wireless device that is generated by the wireless device with inter-subframe channel interpolation and/or filtering of CSI-RS estimates across subframes disabled in response to disabling inter-subframe channel interpolation and/or filtering of CSI-RS estimates across subframes at the wireless device.

16. The base station of claim 15 wherein the base station transmits beamformed CSI-RS and reuses the same CSI-RS resources for different beams over time.

17. The base station of claim 15 wherein the base station further comprises a means for disabling averaging of CSI Interference Measurement, CSI-IM, estimates across subframes for the wireless device.

18. A base station of a cellular communications network enabled to control Channel State Information Reference Symbol, CSI-RS, based channel estimation at a wireless device comprising:

at least one transmitter;

at least one receiver;

at least one processor; and

memory storing software instructions executable by the at least one processor whereby the base station is operative to;

disable, via the at least one transmitter, inter-subframe channel interpolation and/or filtering of CSI-RS estimates across subframes at a wireless device; and

receive, via the at least one receiver, a Channel State Information, CSI, report from the wireless device that is generated by the wireless device with inter-subframe channel interpolation and/or filtering of CSI-RS estimates across subframes disabled in response to disabling inter-subframe channel interpolation and/or filtering of CSI-RS estimates across subframes at the wireless device.

19. (canceled)

20. (canceled)

21. A method of operation of a wireless device in a cellular communications network to provide Channel State Information, CSI, reporting, comprising:

receiving an indication from a base station of the cellular communications network to disable inter-subframe channel interpolation and/or filtering of Channel State Information Reference Symbol, CSI-RS, estimates across subframes;

in response, performing one or more CSI-RS measurements with inter-subframe channel interpolation and/or filtering of CSI-RS estimates across subframes disabled; and

transmitting a CSI report to the base station determined from the one or more CSI-RS measurements.

22. The method of claim 21 wherein the base station transmits a beamformed CSI-RS resource and reuses the same CSI-RS resource for different beams over time.

23. The method of claim 21 wherein the wireless device utilizes two or more CSI processes for CSI reporting, and the indication received from the base station is an indication to disable inter-subframe channel interpolation and/or filtering of CSI-RS estimates across subframes for a particular CSI process.

24. The method of claim 21 wherein the wireless device utilizes two or more CSI processes for CSI reporting, and the indication received from the base station is an indication to disable inter-subframe channel interpolation and/or filtering of CSI-RS estimates across subframes for all of the two or more CSI processes.

25. The method of claim 21 wherein receiving the indication comprises receiving the indication via Radio Resource Control, RRC, signaling.

26. The method of claim 25 wherein the wireless device utilizes two or more CSI processes for CSI reporting, the indication received from the base station is an indication to disable inter-subframe channel interpolation and/or filtering of CSI-RS estimates across subframes for a particular CSI process of the wireless device, and receiving the indication comprises receiving the indication comprised in an RRC information element that configures the particular CSI process of the wireless device.

27. The method of claim 21 further comprising:

receiving, from the base station, an indication to disable combining of CSI Interference Measurement, CSI-IM, estimates across subframes; and

in response, performing one or more CSI-IM measurements with combining of CSI-IM estimates across subframes disabled.

28. The method of claim 21 further comprising:

receiving a configuration of a set of CSI-RS resources for the wireless device.

29. The method of claim 28 wherein the CSI report is for a subset of the set of CSI-RS resources configured for the wireless device.

30. The method of claim 28 wherein receiving the configuration of the set of CSI-RS resources comprises receiving the configuration of the set of CSI-RS resources from the base station via Radio Resource Control, RRC, signaling.

31. The method of claim 28 wherein the configuration of the set of CSI-RS resources is semi-static.

32. The method of claim 28 wherein the set of CSI-RS resources is specific to a CSI process of the wireless device.

33. The method of claim 28 wherein the base station transmits beamformed CSI-RS, and beams used on the set of CSI-RS resources configured for the wireless device are dynamically changed.

34. A wireless device in a cellular communications network to provide Channel State Information, CSI, reporting, comprising:

means for receiving an indication from a base station of the cellular communications network to disable inter-subframe channel interpolation and/or filtering of Channel State Information Reference Symbol, CSI-RS, estimates across subframes;

means for performing one or more CSI-RS measurements with inter-subframe channel interpolation and/or filtering of CSI-RS estimates across subframes disabled in response to receiving the indication; and

means for transmitting a CSI report to the base station determined from the one or more CSI-RS measurements.

35. The wireless device of claim 34 wherein the base station transmits beamformed CSI-RS and reuses the same CSI-RS resources for different beams over time.

36. The wireless device of claim 34 further comprising:

means for receiving an indication to disable averaging of CSI Interference Measurement, CSI-IM, estimates across subframes from the base station; and

means for performing one or more CSI-IM measurements with averaging of CSI-IM estimates across subframes disabled in response to the indication to disable averaging of CSI-IM estimates across subframes.

37. A wireless device in a cellular communications network to provide Channel State Information, CSI, reporting, comprising:

at least one transmitter;

at least one receiver;

at least one processor; and

memory storing software instructions executable by the at least one processor whereby the wireless device is operative to;

receive, via the at least one receiver, an indication from a base station of the cellular communications network to disable inter-subframe channel interpolation and/or filtering of Channel State Information Reference Symbol, CSI-RS, estimates across subframes;

in response, perform one or more CSI-RS measurements with inter-subframe channel interpolation and/or filtering of CSI-RS estimates across subframes disabled; and

transmitting a CSI report to the base station determined from the one or more CSI-RS measurements.

38. (canceled)

39. (canceled)