Method and apparatus for operating pdcp layer processing qos in wireless communication system

A method by a terminal in a wireless communication system, the method comprising:

• receiving, via a radio resource control (RRC) signaling from a base station in the wireless communication system, first information configuring one or more channel state information reference signal (CSI-RS) resources;
• receiving, on a serving cell from the base station, a medium access control (M AC) control element (CE) indicating activation or deactivation of the one or more CSI-RS resources of the serving cell for at least one channel state information (CSI) process configured for the terminal;
• identifying the activation or deactivation of the one or more CSI-RS resources of the serving cell for the at least one CSI process based on the received MAC CE;
• and
• receiving at least one CSI-RS via at least one activated CSI-RS resource of the one or more CSI-RS resources based on the identifying,
• wherein the MAC CE includes at least one CSI-RS command, each of which corresponds to one CSI process related to at least one CSI-RS resource,
• wherein the at least one CSI-RS command is included in the MAC CE in an ascending order of a CSI process ID, and
• wherein a CSI-RS command includes a plurality of bits, each of which indicates an activation/deactivation status of a corresponding CSI-RS resource for a CSI process.