Method for feeding back channel state information in wireless communication system and apparatus therefor

A method for receiving CSI (Channel State Information) by a base station in a wireless access system, the method transmitting configuration information including a first codebook subset restriction of a first CSI process and a second codebook subset restriction of a second CSI process;

• and
• receiving the CSI including a RI (Rank Indicator) periodically, based on at least one of the first codebook subset restriction information and the second codebook subset restriction information,
• wherein a RI of the second CSI process is the same as a most recently reported RI of the first CSI process,
• wherein the first codebook subset restriction and the second codebook subset restriction are configured independently,
• wherein the RI of the second CSI process is restricted to a second RI value set with the second codebook subset restriction, and
• wherein the second RI value set with the second codebook subset restriction is always the same as a first RI value set with the first codebook subset restriction.

A user equipment for transmitting CSI (Channel State Information) in a wireless access system, the user equipment comprising:

• a RF (Radio Frequency) module;
• and
• a processor that controls the RF module to:
• receive configuration information including a first codebook subset restriction of a first CSI process and a second codebook subset restriction of a second CSI process;
• and
• transmit the CSI including a RI (Rank Indicator) periodically, based on at least one of the first codebook subset restriction and the second codebook subset restriction,
• wherein a RI of the second CSI process is the same as a most recently reported RI of the first CSI process,
• wherein the first codebook subset restriction and the second codebook subset restriction are configured independently,
• wherein the RI of the second CSI process is restricted to a second RI value set with the second codebook subset restriction, and
• wherein the second RI value set with the second codebook subset restriction is always the same as a first RI value set with the first codebook subset restriction.

A base station for receiving CSI (Channel State Information) in a wireless access system, the base station comprising:

• a RF (Radio Frequency) module;
• and
• a processor that controls the RF module to:
• transmit configuration information including a first codebook subset restriction information of a first CSI process and a second codebook subset restriction information of a second CSI process;
• and
• receive the CSI including a RI (Rank Indicator) periodically, based on at least one of the first codebook subset restriction information and the second codebook subset restriction information,
• wherein a RI of the second CSI process is the same as a most recently reported RI of the first CSI process,
• wherein the first codebook subset restriction and the second codebook subset restriction are configured independently,
• wherein the RI of the second CSI process is restricted to a second RI value set with the second codebook subset restriction, and
• wherein the second RI value set with the second codebook subset restriction is always the same as a first RI value set with the first codebook subset restriction.