The present disclosure relates to transmission and reception of data in a wireless communication system, the wireless communication system supporting aggregation of a plurality of component carriers and an additional carrier accessible by a listen before talk approach. In particular, monitoring is performed of a search space on a cross-scheduling component carrier for detecting downlink control information having a carrier identification field indicating the cross-scheduling component carrier as well as for detecting downlink control information with the carrier identification field indicating the additional carrier, wherein the search space is specified by a subset of resources, associated with carrier identification of the cross-scheduling component carrier but is not associated with carrier identification of the additional carrier. Then data are transmitted or received on the carriers in accordance with the received downlink control information.