Patent ID: 8885589

Claim:
A method of transmitting a sounding reference signal (SRS) by a user equipment in a wireless communication system, the method comprising: receiving a radio resource control (RRC) message for configuring at least one second component carrier (CC) in addition to a first CC configured in the user equipment; receiving a medium access control (MAC) message for activating the at least one second CC other than the first CC, the MAC message including a bitmap for indicating the at least one second CC to be activated; activating the at least one second CC based on the bitmap; receiving a physical downlink control channel (PDCCH) including a carrier indicator field (CIF) and a SRS field via the first CC, the CIF indicating a CC of the at least one second CC and the SRS field indicating whether to transmit the SRS via the CC indicated by the CIF; and transmitting the SRS on an uplink subframe via the CC indicated by the CIF, when the SRS field is enabled, wherein the CC indicated by the CIF is one of the activated at least one second CC based on the bitmap included in the MAC message.