Patent ID: 8774112

Claim:
A method for performing a random access procedure to a base station at a User Equipment (UE) in a mobile communication system using carrier aggregation in which communication is performed using a plurality of component carriers, the method comprising: transmitting a first random access preamble to the base station through a first uplink component carrier (UL CC) from among a plurality of UL CCs; receiving a first random access response message including a backoff indicator as a response to the first random access preamble through a first downlink component carrier (DL CC) corresponding to the first UL CC; applying a backoff period to the first UL CC in consideration of the backoff indicator received through the first random access response message; and transmitting a second random access preamble to the base station through a second UL CC to which a backoff period is not applied from among the plurality of UL CCs even during the backoff period of the first UL CC.