A multiple carrier technology may also be referred to as a carrier aggregation technology. Unlike the conventional method of using a single carrier in an uplink and a downlink in a general wireless communication system, the multiple carrier technology corresponds to a technology of physically grouping multiple carriers in a frequency domain in order to support an extended bandwidth, so as to produce an effect of logically using a frequency bandwidth having a large band.
Meanwhile, a Transmit Power Control Command (or transmission power control command) for controlling an uplink transmission power of a user equipment may be provided to the user equipment through a downlink control channel transmitted from a base station.