Method for feeding back channel state information in wireless communication system and apparatus therefor
The present invention relates to a method for receiving a reference CSI configuration information and a following CSI configuration information which is configured to report a same RI (Rank Indicator) as the reference CSI configuration information, receiving a first precoding codebook subset information for the reference CSI configuration information and a second precoding codebook subset information for the following CSI configuration information, set of RIs according to the second precoding codebook subset information is same as set of RIs according to the first precoding codebook subset information, and transmitting CSI determined based on at least one of the first precoding codebook subset information and the second preceding codebook subset information.
1. A method for receiving Channel State Information (CSI) from a user equipment (UE) by a base station (BS) in a wireless access system, the method comprising:
transmitting a precoder codebook subset restriction for a reference CSI process, wherein a set of restricted Rank Indicators (RIs) for the reference CSI process is given by the precoder codebook subset restriction for the reference CSI process;
transmitting a precoder codebook subset restriction for a CSI process which is not identical to the precoder codebook subset restriction for the reference CSI process, wherein a set of restricted RIs for the CSI process is given by the precoder codebook subset restriction for the CSI process; and
receiving the CSI from the UE based on the precoder codebook subset restriction for the CSI process,
wherein an RI based on the CSI process is set to one of the set of restricted RIs for the CSI process,
wherein an RI based on the reference CSI process is set to one of the set of restricted RIs for the reference CSI process, and
wherein, if the RI based on the reference CSI process is not included in the set of restricted RIs for the CSI process, the RI based on the CSI process is set to the closest value with regard to the RI based on the reference CSI process.
2. The method of claim 1 , wherein the precoder codebook subset restrictions are configured as a bitmap parameter.
3. The method of claim 1 , wherein the precoder codebook subset restrictions for the CSI process and the reference CSI process are transmitted via RRC (Radio Resource Control) signaling.
4. The method of claim 1 , wherein the CSI includes at least one of an RI, a PMI (Precoding Matrix Indicator), and a CQI (Channel Quality Indicator).
5. A base station (BS) configured for receiving Channel State Information (CSI) in a wireless access system, the BS comprising:
a transceiver; and
a processor configured to control the transceiver to:
transmit a precoder codebook subset restriction for a reference CSI process, wherein a set of restricted Rank Indicators (RIs) for the reference CSI process is identified by the precoder codebook subset restriction for the reference CSI process;
transmit a precoder codebook subset restriction for a CSI process which is not identical to the precoder codebook subset restriction for the reference CSI process, wherein a set of restricted RIs for the CSI process is identified by the precoder codebook subset restriction for the CSI process; and
receive the CSI from a user equipment (UE) based on the precoder codebook subset restriction for the CSI process,
wherein an RI based on the CSI process is set to one of the set of restricted RIs for the CSI process,
wherein an RI based on the reference CSI process is set to one of the set of restricted RIs for the reference CSI process, and
wherein, if the RI based on the reference CSI process is not included in the set of restricted RIs for the CSI process, the RI based on the CSI process is set to the closest value with regard to the RI based on the reference CSI process.
6. The BS of claim 5 , wherein the precoder codebook subset restrictions are configured as a bitmap parameter.
7. The BS of claim 5 , wherein the precoder codebook subset restrictions for the CSI process and the reference CSI process are transmitted via RRC (Radio Resource Control) signaling.
8. The BS of claim 5 , wherein the CSI includes at least one of an RI, a PMI (Precoding Matrix Indicator), and a CQI (Channel Quality Indicator).