Feedback reporting based on channel state information reference signal (CSI-RS) groups

Patent metadata

Field	Value
Publication number	US-9559820-B2
Application number	US-201213359154-A
Country	US
Kind code	B2
Filing date	Jan 26, 2012
Priority date	Feb 18, 2011
Publication date	Jan 31, 2017
Grant date	Jan 31, 2017

Abstract

In macro/RRH setups, channel state information reference signals (CSI-RS) and demodulation reference signals (DM-RS) may be used to decouple control and data transmission. Data transmission (e.g. for LTE Rel 10 and beyond) may be based on CSI-RS and DM-RS, while control may be received from a different set of cells or TxPs via CRS. Certain aspects of the present disclosure introduce a reporting framework, in which configuration of data-serving cells/TxPs may be carried out based on CSI-RS. In certain aspects, a new concept of CSI-RS groups, i.e., a set of CSI-RS ports that a UE considers as one group for precoding matrix indicator (PMI)/channel quality indicator (CQI)/rank indicator (RI) reporting, may be defined.

First claim

What is claimed is:

1. A method for wireless communications, the method comprising:
determining a plurality of channel state information reference signal (CSI-RS) groups for feedback reporting, each one of the plurality of CSI-RS groups comprising a set of CSI-RS ports assigned to antennas of multiple transmission points, each transmission point of the multiple transmission points comprising a cell identifier (ID);
transmitting, to a user equipment (UE), an indicator that identifies the plurality of CSI-RS groups to the UE;
transmitting, to the UE, CSI-RSs corresponding to the plurality of CSI-RS groups;
providing signaling to the UE to restrict feedback reporting to a set of the plurality of CSI-RS groups; and
receiving feedback reports, from the UE, corresponding to at least one CSI-RS group of the set of the plurality of CSI-RS groups.

2. The method of claim 1 , wherein:
at least one CSI-RS group of the plurality of CSI-RS groups corresponds to multiple transmission points.

3. The method of claim 1 , wherein the set of CSI-RS ports of different CSI-RS groups are mapped to a same set of antennas.

4. The method of claim 1 , wherein a cell specific reference signal (CRS) of the UE's serving cell is used as an additional virtual CSI-RS group.

5. The method of claim 1 , wherein each one of the plurality of CSI-RS groups is configured with a scrambling sequence corresponding to a CSI-RS group-specific virtual cell ID.

6. The method of claim 1 , wherein the feedback reporting is restricted by dynamically signaling to indicate the set of the plurality of CSI-RS groups to the UE via additional bits in a grant requesting an aperiodic feedback report or by reusing existing bits in the grant.

7. The method of claim 1 , wherein separate periodic feedback reporting instances are configured for the set of the plurality of CSI-RS groups.

8. The method of claim 1 , further comprising:
signaling the at least one CSI-RS group of the plurality of CSI-RS groups to the UE via a CSI-RS port pattern configuration.

9. The method of claim 1 , wherein the receiving comprises receiving, in different reporting instances, feedback reports that are cycled across each of the plurality of CSI-RS groups in a predefined cycling pattern.

10. The method of claim 1 , wherein different CSI-RS groups are defined for different subframe types.

11. The method of claim 1 , wherein at least one of the feedback reports is based on the set of the plurality of CSI-RS groups.

12. The method of claim 1 , further comprising signaling one or more codebooks per CSI-RS group or for different CSI-RS group combinations.

13. The method of claim 1 , wherein at least one feedback report indicates the plurality of CSI-RS groups with CSI-RSs that satisfy a received signal strength or capacity criterion.

14. The method of claim 1 , further comprising signaling a codebook with entries that are structured such that sets of one or more antenna ports are turned off.

15. The method of claim 1 , wherein the set of the plurality of CSI-RS groups is configured for reporting at least a precoding matrix indicator (PMI), a channel quality indicator (CQI), a rank indicator (RI), or a combination thereof based at least in part on feedback of signal strength indicators received from the UE for the set of the plurality of CSI-RS groups.

16. A method for wireless communications, the method comprising:
receiving an indicator that identifies a plurality of channel state information reference signal (CSI-RS) groups for feedback reporting, each one of the plurality of CSI-RS groups comprising a set of CSI-RS ports assigned to antennas of multiple transmission points, each transmission point of the multiple transmission points comprising a cell identifier (ID);
receiving CSI-RSs corresponding to the plurality of CSI-RS groups;
performing channel measurements for at least one of the plurality of CSI-RS groups;
receiving signaling to restrict feedback reporting to a set of the plurality of CSI-RS groups; and
transmitting a feedback report corresponding to at least one CSI-RS group of the set of the plurality of CSI-RS groups.

17. The method of claim 16 , wherein:
at least one CSI-RS group of the plurality of CSI-RS groups corresponds to multiple transmission points.

18. The method of claim 16 , wherein CSI-RS ports of different CSI-RS groups are mapped to a same set of antennas.

19. The method of claim 16 , wherein a cell specific reference signal (CRS) corresponding to a serving cell is used as an additional virtual CSI-RS group.

20. The method of claim 16 , wherein the feedback report comprises at least a precoding matrix indicator (PMI), a channel quality indicator (CQI), a rank indicator (RI), a received signal strength indicator, a CSI-RS group selection indicator, or a combination thereof.

21. The method of claim 16 , wherein the determining comprises receiving a CSI-RS port pattern configuration indicating the plurality of CSI-RS groups.

22. The method of claim 16 , wherein the transmitting comprises transmitting, in different reporting instances, a plurality of feedback reports that are cycled across the plurality of CSI-RS groups in a predefined cycling pattern.

23. The method of claim 16 , wherein each one of the plurality of CSI-RS groups is configured with a scrambling sequence corresponding to a CSI-RS group specific virtual cell ID.

24. The method of claim 16 , wherein different CSI-RS groups are defined for different subframe types.

25. The method of claim 16 , further comprising receiving signaling indicating at least one codebook to use per CSI-RS group or different CSI-RS group combinations.

26. The method of claim 16 , wherein at least one feedback report indicates the plurality of CSI-RS groups with CSI-RSs that satisfy a received signal strength or capacity criterion.

27. The method of claim 16 , wherein at least one feedback report indicates at least one bandwidth part from at least one CSI-RS group selected from the plurality of CSI-RS groups corresponding to CSI-RSs that satisfy a received signal strength or capacity criterion.

28. The method of claim 16 , wherein the feedback report is generated based at least in part on channel measurements separately for the plurality of CSI-RS groups.

29. The method of claim 16 , wherein the feedback report is generated based at least in part on channel measurements for different aggregations of the plurality of CSI-RS groups and wherein the feedback report is based at least in part on an aggregation of the plurality of CSI-RS groups.

30. The method of claim 16 wherein a reporting payload of the feedback report is encoded jointly across the plurality of CSI-RS groups.

31. The method of claim 16 , wherein the feedback report is based on the set of the plurality of CSI-RS groups.

32. An apparatus for wireless communications, comprising:
a memory unit; and
at least one processor coupled to the memory unit, the at least one processor being configured:
to determine a plurality of channel state information reference signal (CSI-RS) groups for feedback reporting, each one of the plurality of CSI-RS groups comprising a set of CSI-RS ports assigned to antennas of multiple transmission points, each transmission point of the multiple transmission points comprising a cell identifier (ID);
to

Assignees

• Geirhofer Stefan
• Luo Tao
• Chen Wanshi
• Gaal Peter
• Xu Hao
• Bhattad Kapil
• Ji Tingfang
• Qualcomm Inc

Inventors

• Geirhofer Stefan
• Luo Tao
• Chen Wanshi
• Gaal Peter
• Xu Hao
• Bhattad Kapil
• Ji Tingfang

Classifications

• H04L5/0048 Primary

  Allocation of pilot signals, i.e. of signals known to the receiver (allocation of control signalling H04L5/0053; use of control signalling H04L5/0091) · CPC title

• H04W24/10 Primary

  Scheduling measurement reports {; Arrangements for measurement reports} · CPC title