Method for configuring and transmitting key

A method by a second base station in a wireless communication system where a terminal communicates with a first base station associated with a primary cell (PCell), and the second base station associated with one or more secondary cells (SCells) only, the method comprising:

• receiving, from the first base station, a first message, for adding at least one SCell associated with the second base station for the terminal, including second security information based on which a second communication between the second base station and the terminal is performed on the at least one SCell, the second security information being determined by the first base station which is different from first security information based on which a first communication between the first base station and the terminal is performed;
• determining a primary SCell (PSCell) from the at least one SCell;
• and
• transmitting, to the first base station in response to receiving the first message, a second message including configuration information for the at least one SCell, the configuration information including information on the PSCell.

A first base station in a wireless communication system where a terminal communicates with the first base station associated with a primary cell (PCell), and a second base station associated with one or more secondary cells (SCells) only, the first base station comprising:

• a transceiver configured to transmit and receive signals;
• and
• a controller configured to:
• determine second security information which is different from first security information based on which a first communication between the first base station and the terminal is performed,
• transmit, via the transceiver to the second base station, a first message for adding at least one SCell associated with the second base station for the terminal, the first message including the second security information based on which a second communication between the second base station and the terminal is performed on the at least one SCell, and
• receive, via the transceiver from the second base station in response to transmitting the first message, a second message including configuration information for the at least one SCell,
• wherein the configuration information includes information on a primary SCell (PSCell) of the at least one SCell, and
• wherein the PSCell is determined by the second base station from the at least one SCell.

A second base station in a wireless communication system where a terminal communicates with a first base station associated with a primary cell (PCell), and the second base station associated with one or more secondary cells (SCells) only, the second base station comprising:

• a transceiver configured to transmit and receive signals;
• and
• a controller configured to:
• receive, via the transceiver from the first base station, a first message, for adding at least one SCell associated with the second base station for the terminal, including second security information based on which a second communication between the second base station and the terminal is performed on the at least one SCell, the second security information being determined by the first base station which is different from first security information based on which a first communication between the first base station and the terminal is performed,
• determine a primary SCell (PSCell) from the at least one SCell, and
• transmit, via the transceiver to the first base station in response to receiving the first message, a second message including configuration information for the at least one SCell, the configuration information including information on the PSCell.