Method and apparatus for transmitting channel state information in wireless communication system

A user equipment (UE) which is configured with a first cell group and a second cell group, comprising:

• a transceiver which transmits or receives a radio signal;
• and
• a processor, connected with the transceiver,
• wherein the processor is configured to:
• select a first cell included in the first cell group and a second cell included in the second cell group,
• wherein the first cell is a cell on an activated carrier with a lowest cell index in the first cell group and the second cell is another cell on another activated carrier with a lowest cell index in the second cell group,
• generate first CSI for the first cell and second CSI for the second cell, and
• control the transceiver to transmit the first CSI or the second CSI, whichever has a higher priority,
• wherein a CSI having a lower cell index between the first CSI and the second CSI has the higher priority,
• wherein cells in each of the first cell group and the second cell group have a same CSI transmission period or multiples of the CSI transmission period, and
• wherein when the first CSI and the second CSI have a same priority, a CSI having a higher process identifier (ID) between the first CSI and the second CSI has the higher priority.