1. A method by a terminal, the method comprising:receiving, from a base station, a radio resource control (RRC) message, the RRC message including information on respective time alignment timer (TAT)s of at least two timing advance group (TAG)s and configuration information on a random access channel (RACH) for a secondary cell (SCell);
transmitting, to the base station, a random access preamble based on the configuration information on the RACH for the SCell;
receiving, from the base station, a random access response including timing advance information based on a transmission of the random access preamble;
receiving, from the base station, a medium access control (MAC) control element including an identity of a TAG including the SCell, and a timing advance command (TAC) for the TAG including the SCell;
applying the TAC to the TAG including the SCell if the MAC control element is received; and
starting a TAT associated with the TAG including the SCell based on the information on the respective TATs of at least two TAGs if the MAC control element is received,
wherein the TAT associated with the TAG is used to control how long the terminal considers at least one cell included in the TAG to be uplink aligned.