A method of receiving a sounding reference signal (SRS). The method includes transmitting, to a user equipment, a radio resource control (RRC) message transmitting, to the user equipment, a medium access control (MAC) message, the MAC message including a bitmap for indicating at least one second CC to be activated and the at least one second CC being activated based on the bitmap; transmitting, to the user equipment, a physical downlink control channel (PDCCH) including a carrier indicator field (CIF) and an SRS field via the first CC, the CIF indicating a CC of the at least one second CC and the SRS field indicating whether the user equipment has to transmit the SRS via the CC indicated by the CIF; and receiving, from the user equipment, the SRS on an uplink subframe via the CC indicated by the CIF, when the SRS field is enabled.