Device and method for changing primary cell in wireless communication system

A method comprising:

• receiving a random access preamble;
• transmitting receiving a random access response;
• receiving a message including a radio resource control (RRC) setup request;
• transmitting a message including a RRC setup;
• configuring a primary cell (PCell) of the terminal among cells of the base station;
• configuring a secondary cell (SCell) of the terminal among the cells of the base station;
• and
• transmitting an indication to change the PCell from a first cell to a second cell to the terminal.

A terminal comprising:

• a transceiver;
• and
• a processor coupled with the transceiver,
• wherein the processor is configured to:
• transmit a random access preamble;
• receive a random access response;
• transmit a message including a radio resource control (RRC) setup request;
• receive a message including a RRC setup,
• perform a procedure for configuring a primary cell (PCell);
• perform a procedure for adding a secondary cell (SCell);
• receive an indication to change the PCell from a first cell to a second cell, and
• based on the second cell being in inactive state or an active bandwidth part (BWP) of the terminal being dormant in the second cell, change the PCell to a third cell different from the second cell or change the PCell to the second cell after switching the active BWP.