1. A method for monitoring a control channel in a multiple carrier system, the method comprising:if an aggregation of carriers is configured and if a carrier indicator field (CIF) is configured, monitoring a plurality of downlink control channels within a plurality of UE-specific search spaces of a first carrier; and
receiving downlink control information (DCI) on at least one of the plurality of the downlink control channels, which is successfully decoded, via the first carrier,
wherein a start point for each of the plurality of UE-specific search spaces is determined based on the CIF, and
wherein the DCI includes scheduling information on either a downlink channel or an uplink channel in a second carrier.