Method and apparatus for reporting channel state information in wireless communication system
The present invention relates to a wireless communication system and, more specifically, to a method and an apparatus for reporting channel state information (CSI). Particularly, the method comprises the steps of: receiving a reference signal (RS) from a base station; and reporting, to the base station, the CSI generated by using the RS, wherein the CSI is measured on the basis of a specific CSI-RS set among a plurality of CSI-RS sets, beamforming weight vectors in a vertical domain which are set differently for each of horizontal domain antenna ports to which the same beamforming weight vectors in a vertical domain is applied.
1. A method of reporting channel state information (CSI), which is reported by a user equipment in a wireless communication system, the method comprising:
receiving a reference signal from a base station; and
reporting the CSI generated using the reference signal to the base station,
wherein the CSI is measured based on a specific channel state information-reference signal CSI-RS set among a plurality of CSI-RS sets,
wherein each of the plurality of CSI-RS sets is configured with a vertical domain beamforming weight vector differently configured for each of the plurality of CSI-RS sets,
wherein each of the plurality of CSI-RS sets includes a plurality of CSI-reference signals, and
wherein the plurality of CSI-reference signals are generated from for a plurality of horizontal domain antenna ports to which an identical vertical domain beamforming weight vector is applied.
2. The method of claim 1 ,
wherein the specific CSI-RS set is configured by combining vertical domain antenna ports selected from each of the plurality of CSI-RS sets with each other, and
wherein the vertical domain antenna ports have an identical horizontal domain antenna port index.
3. The method of claim 1 ,
wherein the specific CSI-RS set is configured in a manner of combining vertical domain antenna ports selected for each of the plurality of CSI-RS sets with each other, and
wherein the vertical domain antenna ports have an index preferred by the user equipment in a predefined codebook.
4. The method of claim 1 , wherein the CSI comprises channel state information measured for each of the plurality of CSI-RS sets and channel state information measured by combining specific vertical domain antenna ports among the plurality of CSI-RS sets.
5. The method of claim 4 , wherein, if the CSI is measured by combining a plurality of vertical domain antenna ports, the CSI comprises a single precoding matrix index (PMI).
6. The method of claim 1 , wherein the CSI comprises an average CSI for all CSI-RS ports associated with the plurality of CSI-RS sets and a channel quality indicator (CQI) for each of the plurality of CSI-RS sets.
7. The method of claim 1 , wherein the specific CSI-RS set is configured by antenna ports precoded using a vertical beamforming weight vector.
8. The method of claim 7 , wherein the precoded antenna ports correspond to one of UE-specific antenna ports or cell-specific antenna ports.
9. The method of claim 7 , wherein the CSI comprises at least one selected from a group consisting of an index of a preferred antenna port, index strength of an antenna port, strength of all measured antenna ports and information on a precoding used for a combination of antenna ports.
10. The method of claim 1 , wherein the plurality of CSI-RS sets are configured via Radio Resource Control (RRC) signaling from the base station.
11. A user equipment reporting channel state information (CSI) in a wireless communication system, comprising:
a radio frequency unit; and
a processor, the processor configured to receive a reference signal from a base station, the processor configured to report the CSI generated using the reference signal to the base station,
wherein the CSI is measured based on a specific channel state information-reference signal (CSI-RS) set among a plurality of CSI-RS sets,
wherein each of the plurality of CSI-RS sets is configured with a vertical domain beamforming weight vector differently configured for each of the plurality of CSI-RS sets,
wherein each of the plurality of CSI-RS sets includes a plurality of CSI-reference signals, and
wherein the plurality of CSI-reference signals are generated from a plurality of horizontal domain antenna ports to which an identical vertical domain beamforming weight vector is applied.