Method and apparatus for transmitting and receiving downlink channel state information in a mobile communication system

Patent metadata

Field	Value
Publication number	US-10390352-B2
Application number	US-201214349875-A
Country	US
Kind code	B2
Filing date	Oct 5, 2012
Priority date	Oct 7, 2011
Publication date	Aug 20, 2019
Grant date	Aug 20, 2019

Abstract

Disclosed is a method and apparatus for transmitting channel state information (CSI) by a user equipment in a mobile communication system. The method includes receiving a CSI-reference signal (CSI-RS) for measuring a state of a downlink channel and a CSI feedback-related configuration from a base station (BS); determining a channel quality indication (CQI) for at least one transmission point and control information for determining a CQI for multiple transmission points, based on the received CSI-RS and CSI feedback-related configuration; and transmitting the determined CQI for the at least one transmission point and control information to the BS.

First claim

The invention claimed is:

1. A method for transmitting channel state information (CSI) by a user equipment (UE) in a mobile communication system, the method comprising:
receiving a CSI-reference signal (CSI-RS) used for measuring a downlink channel and configuration information related to a CSI feedback from a base station (BS);
determining channel quality indicators (CQIs) of at least two cells involved in a joint transmission and control information related to a CQI for the joint transmission of the at least two cells, based on the CSI-RS and the configuration information related to the CSI feedback; and
transmitting feedback information comprising the determined CQIs and the control information to the BS,
wherein the control information comprises a relative value indicating a difference between a data rate receivable by the UE when the at least two cells simultaneously transmit and a data rate corresponding to a greatest CQI among the determined CQIs.

2. The method of claim 1 , wherein the relative value is determined by a following equation,
Δ CQI =CQI JT −max(CQI 1 , . . . ,CQI N )

where Δ CQI denotes the relative value, N is a number of the at least two cells involved in the joint transmission, CQI JT denotes the data rate receivable by the UE when the at least two cells simultaneously transmit, and max(CQI 1 , . . . CQI N ) denotes the greatest CQI among the determined CQIs.

3. The method of claim 1 , wherein the feedback information further comprises rank indicators (RIs) and precoding matrix indicators (PMIs) for the each of the at least two cells, and
wherein the RIs and the PMIs are determined based on the CSI-RS and the configuration information related to the CSI feedback.

4. The method of claim 1 , wherein the configuration information related to CSI feedback comprises at least one of first information indicating whether the UE receives coordinated multi-point (CoMP) signals and second information indicating whether the UE transmits CSI feedback for the joint transmission of the at least two cells.

5. A method for receiving channel state information (CSI) by a base station (BS) in a mobile communication system, the method comprising:
transmitting, to a user equipment (UE), a CSI-reference signal (CSI-RS) used for measuring a downlink channel and configuration information related to a CSI feedback;
receiving, from the UE, feedback information, which is determined based on the CSI-RS and the configuration information related to the CSI feedback, comprising determined channel quality indicators (CQIs) and control information related to a CQI for a joint transmission of at least two cells; and
obtaining a data rate receivable by the UE when the at least two cells simultaneously transmit, based on the determined CQIs and the control information,
wherein the control information comprises a relative value indicating a difference between the data rate receivable by the UE when the at least two cells simultaneously transmit and a data rate corresponding to a greatest CQI among the determined CQIs.

6. The method of claim 5 , wherein the relative value is determined by a following equation,
Δ CQI =CQI JT −max(CQI 1 , . . . ,CQI N )

where Δ CQI denotes the relative value, N is a number of the at least two cells involved in the joint transmission, CQI JT denotes the data rate receivable by the UE when the at least two cells simultaneously transmit, and max(CQI 1 , . . . CQI N ) denotes the greatest CQI among the at least two CQIs for each of the at least two cells.

7. The method of claim 5 , wherein the feedback information further comprises rank indicators (RIs) and precoding matrix indicators (PMIs) for the each of the at least two cells, and
wherein the RIs and the PMIs are determined based on the CSI-RS and the configuration information related to the CSI feedback.

8. The method of claim 7 , wherein an RI for the at least two cells is determined based on a smallest RI of the RIs for the each of the at least two cells.

9. The method of claim 8 , further comprising combining precoding matrices comprising combining partial columns from precoding matrices indicated by the PMIs for the each of the at least two cells based on the determined RI when the RIs for the each of the at least two cells are different.

10. An apparatus for transmitting channel state information (CSI) by a user equipment (UE) in a mobile communication system, the apparatus comprising:
a receiver configured to receive a CSI-reference signal (CSI-RS) use for measuring a downlink channel and a configuration information related to a CSI feedback from a base station (BS);
a controller configured to determine channel quality indicators (CQIs) of at least two cells involved in a joint transmission and control information related to a CQI for the joint transmission of the at least two cells, based on the CSI-RS and the configuration information related to the CSI feedback; and
a transmitter for transmitting feedback information comprising the determined CQIs and the control information to the BS,
wherein the control information comprises a relative value indicating a difference between a data rate receivable by the UE when the at least two cells simultaneously transmit and a data rate corresponding to a greatest CQI among the determined CQIs.

11. The apparatus of claim 10 wherein the relative value is determined by a following equation,
Δ CQI =CQI JT −max(CQI 1 , . . . ,CQI N )

where Δ CQI denotes the relative value, N is a number of the at least two cells involved in the joint transmission, CQI JT denotes the data rate receivable by the UE when the at least two cells simultaneously transmit, and max(CQI 1 , CQI N ) denotes the greatest CQI among the determined CQIs.

12. The apparatus of claim 10 , wherein the feedback information further comprises rank indicators (RIs) and precoding matrix indicators (PMIs) for the each of the at least two cells, and
wherein the RIs and the PMIs are determined based on the CSI-RS and the configuration information related to the CSI feedback.

13. An apparatus for receiving channel state information (CSI) by a base station (BS) in a mobile communication system, the apparatus comprising:
a transmitter configured to transmit, to a user equipment (UE), a CSI-reference signal (CSI-RS) used for measuring a downlink channel and configuration information related to a CSI feedback;
a receiver configured to receive, from the UE, feedback information, which is determined based on the CSI-RS and the configuration information related to the CSI feedback, comprising determined channel quality indicators (CQIs) and control information related to a CQI for a joint transmission of at least two cells; and
a controller configured to obtain a data rate receivable by the UE when the at least two cells simultaneously transmit, based on the determined CQIs and the control information,
wherein the control information comprises a relative value indicating a difference between the data rate receivable by the UE when the at least two cells simultaneously transmit and a data rate corresponding to a greatest CQI among the determined CQIs.

14. The apparatus of claim 13 , wherein the relative value is determined by a following equation,
Δ CQI =CQI JT −max(CQI 1 , . . . ,CQI N )

where Δ CQI denotes the relative value, N is a number of the at least two cells involved in the joint transmission, CQI JT denotes the data rate receivable by the UE when the at least two cells simultaneously transmit, and max(CQI 1 , CQI N ) denotes the greatest CQI among the at least two CQIs for each of the at least two cells.

Assignees

• Samsung Electronics Co Ltd

Inventors

• Kim Youn-Sun
• Kim Ki-Il
• Lee Ju-Ho
• Lee Hyo-Jin
• Cho Joon-Young
• Choi Seung-Hoon

Classifications

• H04W72/542 Primary

  using measured or perceived quality · CPC title

• H04W72/23

  in the downlink direction of a wireless link, i.e. towards a terminal · CPC title

• H04B7/024

  Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems · CPC title

• H04B7/063

  Parameters other than those covered in groups H04B7/0623 - H04B7/0634, e.g. channel matrix rank or transmit mode selection · CPC title

• H04B7/0639

  Using selective indices, e.g. of a codebook, e.g. pre-distortion matrix index [PMI] or for beam selection · CPC title