Method and apparatus for channel state information (CSI) reporting in a massive MIMO communications system

• US 10,277,296 B2
• Filed: 02/16/2017
• Issued: 04/30/2019
• Est. Priority Date: 02/16/2017
• Status: Active Grant

• Current Assignee: Hong Kong Applied Science And Technology Research Institute Co., Ltd.
• Original Assignee: Hong Kong Applied Science And Technology Research Institute Co., Ltd.
• Inventors: Zhang, Yuxian, Kwan, Man Wai, Tsang, Eric Kong Chau
• Primary Examiner(s): Hamza, Faruk
• Assistant Examiner(s): Haque, Abusayeed M
• Application Number:
  US15/434,115
• Publication Number:
  US 20180234149A1
• Time in Patent Office: 803 Days
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/0626 Channel coefficients, e.g. channel state information [CSI]
• CPC Class Codes: H04B 7/0632 Channel quality parameters, e.g. channel quality indicator [CQI]
• CPC Class Codes: H04B 7/0695 using beam selection
• CPC Class Codes: H04L 5/0025 Spatial division following the spatial signature of the channel
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/0094 Indication of how sub-channels of the path are allocated

Abstract

Provided is a method of base station (BS) for channel state information (CSI) acquisition in a massive multiple input/multiple output (MIMO) communication system. The method comprises the steps at the BS of sending a set of beamformed reference signals (RSs) to a user equipment (UE) and receiving from said UE an indication of a subset of said set of beamformed RSs and CSI acquired by said UE for only said subset of said set of beamformed RSs. Also provided is a further method and a user equipment (UE) for CSI acquisition. The further method comprises the steps at the UE of receiving from the BS the set of beamformed RSs; estimating a channel of each RS comprising said set of beamformed RSs; selecting a subset of said set of beamformed RSs; acquiring CSI for only said selected subset of said set of beamformed RSs; and communicating to said BS an indication of said selected subset of said set of beamformed RSs and reporting the CSI acquired for said selected subset of said set of beamformed RSs.

Claims

1. A method of channel state information (CSI) acquisition in a multiple input/multiple output (MIMO) communication system, comprising the steps at a user equipment (UE) of:

receiving from a base station (BS) a set of beamformed downlink (DL) reference signals (DL-RSs);

selecting a subset of said set of beamformed DL-RSs;

acquiring CSI for only said selected subset of said set of beamformed DL-RSs; and

communicating to said BS an indication of said selected subset of said set of beamformed DL-RSs and the CSI acquired for said selected subset of said set of beamformed DL-RSs;

wherein the step of communicating to said BS an indication of said selected subset of said set of beamformed DL-RSs comprises communicating a selected subset indication value (SSIV) derived from a number of contiguous DL-RSs forming the selected subset and an identity of a DL-RS at a starting edge of the contiguous subset with respect to an antenna port number.

2. The method of claim 1, wherein the MIMO communication system is any of a massive MIMO communication system, a large-scale antenna communication system, a very large MIMO communication system, a hyper MIMO communication system, or a full-dimension (FD) MIMO communication system.

3. The method of claim 2, wherein the step of selecting a subset of said set of beamformed DL-RSs comprises estimating each DL-RS comprising said set of beamformed DL-RSs.

4. The method of claim 1, wherein the UE receives payload data from the BS based on the CSI communicated by the UE to the BS for said selected subset of said set of beamformed DL-RSs.

5. The method of claim 1, wherein the step of estimating each DL-RS comprising said set of beamformed DL-RSs comprises measuring a parameter of each DL-RS comprising said set of beamformed DL-RSs.

6. The method of claim 5, wherein the parameter of each DL-RS to be measured comprises any one or any combination of:

received power;

signal to noise ratio;

signal to interference ratio; and

energy per bit to noise power spectral density ratio.

7. The method of claim 5, wherein the step of selecting a subset of said set of beamformed DL-RSs comprises selecting a subset of DL-RSs whose measured parameter is above a predetermined threshold value.

8. The method of claim 5, wherein the step of selecting a subset of said set of beamformed DL-RSs comprises selecting a contiguous subset of DL-RSs where a measured parameter for each RS falls within a range determined from a DL-RS whose measured signal parameter is largest.

9. The method of claim 1, wherein the SSIV is given by the equation:

10. The method of claim 1, wherein the step of acquiring CSI for only said selected subset of said set of beamformed DL-RSs further comprises acquiring at least one of a Rank Indicator (RI) or a Channel Quality Indicator (CQI).

11. The method of claim 1, wherein the set of beamformed DL-RSs received at the UE from the BS comprise beamformed CSI-RSs.

12. A user equipment (UE) for a multiple input/multiple output (MIMO) communication system, said UE comprising:

a memory; and

a processor connected to the memory configured to;

receive from a base station (BS) a set of beamformed downlink (DL) reference signals (DL-RSs);

estimate a channel of each DL-RS comprising said set of beamformed DL-RSs;

select a subset of said set of beamformed DL-RSs;

acquire CSI for only said selected subset of said set of beamformed DL-RSs; and

communicate to said BS an indication of said selected subset of said set of beamformed DL-RSs and the CSI acquired for said selected subset of said set of beamformed DL-RSs;

wherein the processor is configured to communicate said indication of said selected subset of said set of beamformed DL-RSs by communicating a selected subset indication value (SSIV) derived from a number of contiguous DL-RSs forming the selected subset and an identity of a DL-RS at a starting edge of the contiguous subset with respect to an antenna port number.

13. A method of channel state information (CSI) acquisition in a multiple input/multiple output (MIMO) communication system, comprising the steps at a base station (BS) of:

sending a set of beamformed downlink (DL) reference signals (DL-RSs) to a user equipment (UE); and

receiving from said UE an indication of a subset of said set of beamformed DL-RSs and CSI acquired by said UE for only said subset of said set of beamformed DL-RSs;

wherein the step of receiving at said BS an indication of said selected subset of said set of beamformed DL-RSs comprises receiving a selected subset indication value (SSIV) derived from a number of contiguous DL-RSs forming the selected subset and an identity of a DL-RS at a starting edge of the contiguous subset with respect to an antenna port number.

14. The method of claim 13, wherein the MIMO communication system is any of a massive MIMO communication system, a large-scale antenna communication system, a very large MIMO communication system, a hyper MIMO communication system, or a full-dimension (FD) MIMO communication system.

15. The method of claim 13, further comprising the step of, prior to the step of sending a set of beamformed DL-RSs to the UE, determining the set of beamformed DL-RSs which are to be sent to the UE.

16. The method of claim 13, wherein at the least the BS has a massive number of antennas number 100 or more.

17. The method of claim 13, wherein the BS transmits payload data to the UE based on the CSI received by the BS from the UE for said selected subset of said set of beamformed DL-RSs.

18. The method of claim 13, wherein the SSIV is given by the equation:

19. The method of claim 13, wherein the step of receiving at said BS CSI for only said selected subset of said set of beamformed DL-RSs further comprises receiving at least one of a Rank Indicator (RI) or a Channel Quality Indicator (CQI).

20. The method of claim 13, wherein the set of beamformed DL-RSs transmitted from the BS to the UE comprise beamformed CSI-RSs.

21. A base station (BS) for a multiple input/multiple output (MIMO) communication system, said BS comprising:

a memory; and

a processor connected to the memory configured to;

send a set of beamformed downlink (DL) reference signals (DL-RSs) to a user equipment (UE); and

receive from said UE an indication of a subset of said set of beamformed DL-RSs and CSI acquired by said UE for only said subset of said set of beamformed DL-RSs;

wherein the processor is configured to receive at said BS an indication of said selected subset of said set of beamformed DL-RSs by receiving a selected subset indication value (SSIV) derived from a number of contiguous DL-RSs forming the selected subset and an identity of a DL-RS at a starting edge of the contiguous subset with respect to an antenna port number.

22. A method of channel state information (CSI) acquisition in a multiple input/multiple output (MIMO) communication system, comprising the steps at a user equipment (UE) of:

receiving from a base station (BS) a set of beamformed downlink (DL) reference signals (DL-RSs);

selecting a subset of said set of beamformed DL-RSs;

acquiring CSI for only said selected subset of said set of beamformed DL-RSs; and

communicating to said BS an indication of said selected subset of said set of beamformed DL-RSs and the CSI acquired for said selected subset of said set of beamformed DL-RSs;

wherein the step of acquiring CSI for only said selected subset of said set of beamformed DL-RSs comprises finding a precoding matrix indicator (PMI) from a codebook with each codeword comprising M elements of the codeword in the codebook for all DL-RSs for each layer, where M is the cardinality of the selected subset of DL-RSs.

23. The method of claim 22, wherein the codewords for the selected subset of DL-RSs is normalized.

24. A user equipment (UE) for a multiple input/multiple output (MIMO) communication system, said UE comprising:

a memory; and

a processor connected to the memory configured to;

receive from a base station (BS) a set of beamformed downlink (DL) reference signals (DL-RSs);

estimate a channel of each DL-RS comprising said set of beamformed DL-RSs;

select a subset of said set of beamformed DL-RSs;

acquire CSI for only said selected subset of said set of beamformed DL-RSs; and

communicate to said BS an indication of said selected subset of said set of beamformed DL-RSs and the CSI acquired for said selected subset of said set of beamformed DL-RSs;

wherein the processor is configured to acquire CSI for only said selected subset of said set of beamformed DL-RSs by finding a precoding matrix indicator (PMI) from a codebook with each codeword comprising M elements of the codeword in the codebook for all DL-RSs for each layer, where M is the cardinality of the selected subset of DL-RSs.

25. A method of channel state information (CSI) acquisition in a multiple input/multiple output (MIMO) communication system, comprising the steps at a base station (BS) of:

sending a set of beamformed downlink (DL) reference signals (DL-RSs) to a user equipment (UE); and

receiving from said UE an indication of a subset of said set of beamformed DL-RSs and CSI acquired by said UE for only said subset of said set of beamformed DL-RSs;

wherein the step of receiving at said BS the CSI acquired for said selected subset of said set of beamformed DL-RSs comprises receiving a precoding matrix indicator (PMI) from a codebook with each codeword comprising M elements of the codeword in the codebook for all DL-RSs for each layer, where M is the cardinality of the selected subset of DL-RSs.

26. A base station (BS) for a multiple input/multiple output (MIMO) communication system, said BS comprising:

a memory; and

a processor connected to the memory configured to;

send a set of beamformed downlink (DL) reference signals (DL-RSs) to a user equipment (UE); and

receive from said UE an indication of a subset of said set of beamformed DL-RSs and CSI acquired by said UE for only said subset of said set of beamformed DL-RSs;

wherein the processor is configured to receive at said BS the CSI acquired for said selected subset of said set of beamformed DL-RSs by receiving a precoding matrix indicator (PMI) from a codebook with each codeword comprising M elements of the codeword in the codebook for all DL-RSs for each layer, where M is the cardinality of the selected subset of DL-RSs.

27. The method of claim 26, wherein the codewords for the selected subset of DL-RSs is normalized.