METHOD AND APPARATUS FOR FEEDING BACK CHANNEL STATE INFORMATION

• US 20120051257A1
• Filed: 06/17/2010
• Published: 03/01/2012
• Est. Priority Date: 06/18/2009
• Status: Active Grant

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Kim, Hyung Tae, Seo, Han Byul, Kim, Ki Jun
• Granted Patent: US 8,774,037 B2
• Time in Patent Office: Days
• US Class Current: 370/252
• 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 7/0621 Feedback content
• 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 7/0663 using vector or matrix manipulations

Abstract

There is disclosed a method of a user equipment feeding back channel state information in a wireless communication system, comprising receiving a reference signal from a base station; generating first channel state information by measuring the reference signal; generating second channel state information based on the first channel state information; and transmitting the first channel state information and the second channel state information to the base station. The first channel state information is channel state information of a single user single cell Multi-input Multi-Output (MIMO) mode, and the second channel state information is channel state information of a multi-user MIMO (MU-MIMO) mode or a Cooperative Multiple Points Transmission and Reception (CoMP) mode.

Claims

1. A method of a user equipment feeding back channel state information in a wireless communication system, the method comprising:

receiving a reference signal from a base station;

generating first channel state information by measuring the reference signal;

generating second channel state information based on the first channel state information; and

transmitting the first channel state information and the second channel state information to the base station, wherein the first channel state information is channel state information of a single user single cell Multi-input Multi-Output (MIMO) mode, and the second channel state information is channel state information of a multi-user MIMO (MU-MIMO) mode or a Cooperative Multiple Points Transmission and Reception (CoMP) mode.

2. The method of claim 1, wherein each of the first channel state information and the second channel state information includes a Channel Quality Indication (CQI), a Precoding Matrix Index (PMI), and a Rank Indicator (RI).

3. The method of claim 2, wherein the first channel state information includes a first PMI indicative of a first precoding matrix, the second channel state information includes a second PMI indicative of a second precoding matrix, and the second precoding matrix includes some of or all column vectors of the first precoding matrix.

4. The method of claim 3, wherein the second PMI includes information about column vectors of the first precoding matrix constituting the second precoding matrix.

5. The method of claim 3, wherein if a number of ranks indicated by the second channel state information is smaller than a number of ranks indicated by the first channel state information, the second PMI indicates column vectors, included in the second precoding matrix, from among column vectors of the first precoding matrix in a bitmap.

6. The method of claim 3, wherein if the number of ranks indicated by the second channel state information is smaller than the number of ranks indicated by the first channel state information and is a fixed value

n,

the second PMI indicates

n

column vectors selected from the first precoding matrix.

7. The method of claim 3, wherein if the number of ranks indicated by the second channel state information is smaller than the number of ranks indicated by the first channel state information, the second PMI indicates column vectors, excluded from the second precoding matrix, from among column vectors of the first precoding matrix.

8. The method of claim 3, wherein:

if the number of ranks indicated by the second channel state information is smaller than the number of ranks indicated by the first channel state information, the second PMI indicates a second precoding matrix included in a reduced codebook, and the reduced codebook includes only matrices, each of which includes only some of column vectors of the first precoding matrix.

9. The method of claim 3, wherein if column vectors constituting the second precoding matrix have a linear combination of column vectors of the first precoding matrix, the second PMI includes a coefficient for each of the column vectors of the first precoding matrix.

10. The method of claim 3, wherein:

if the number of ranks indicated by the second channel state information is greater than the number of ranks indicated by the first channel state information, the second PMI indicates a second precoding matrix included in a reduced codebook, and the reduced codebook includes only matrices, each including all column vectors of the first precoding matrix in a codebook which is determined according to the number of ranks indicated by the second channel state information.

11. A method of a user equipment feeding back channel state information in a multi-carrier system, the method comprising:

receiving a reference signal from a base station through first carrier and second carrier;

generating first channel state information for the first carrier by measuring the reference signal;

generating second channel state information for the second carrier based on the first channel state information; and

transmitting the first channel state information and the second channel state information to the base station, wherein the first carrier and the second carrier are contiguous carriers in frequency domain.

12. The method of claim 11, wherein the first channel state information includes a first PMI indicative of a first precoding matrix, the second channel state information includes a second PMI indicative of a second precoding matrix, and the second precoding matrix includes some of or all column vectors of the first precoding matrix.

13. The method of claim 12, wherein the second PMI includes information about column vectors of the first precoding matrix constituting the second precoding matrix.

14. A user equipment, comprising:

a Radio Frequency (RF) unit configured to transmit or receive a radio signal; and

a processor connected to the RF unit, wherein the processor receives a reference signal from a base station, generates first channel state information by measuring the reference signal, generates second channel state information based on the first channel state information, and transmits the first channel state information and the second channel state information to the base station, and the first channel state information is channel state information of a single user single cell MIMO mode, and the second channel state information is channel state information of an MU-MIMO) mode or a CoMP mode.