A dedicated control information format for use in a mobile communication system capable of using an aggregation of component carriers in downlink, wherein the dedicated control information format comprises: a resource assignment field for indicating assigned downlink resources within a sub-frame of one of the component carriers in the downlink, and a carrier indicator field for indicating on which component carrier the downlink resources are assigned, and for further indicating the number of OFDM symbols used for control signaling within the sub-frame on the component carrier on which downlink resources are assigned by the dedicated control information, characterized in that the range of numbers of OFDM symbols used for control signaling that can be indicated by the bits of the carrier indicator field covers only a selected subset of the total range of numbers of OFDM symbols that can be used for control signaling, and wherein the subset of the range of numbers of OFDM symbols used for control signaling that can be indicated by the carrier indicatorfield is depending on at least one of: - interference conditions and power level on the assigned downlink component carrier, - the channel quality on the assigned downlink component carrier, - the bandwidth of the assigned downlink component carrier, - status of a load balancing function for the downlink component carriers, - the type of the assigned downlink component carrier, - the number of OFDM symbols used for control signaling on the component carrier on which the dedicated control information is transmitted, and - the number of downlink ACK/NACKs to be signaled on the assigned component carrier. a resource assignment field for indicating assigned downlink resources within a sub-frame of one of the component carriers in the downlink, and a carrier indicator field for indicating on which component carrier the downlink resources are assigned, and for further indicating the number of OFDM symbols used for control signaling within the sub-frame on the component carrier on which downlink resources are assigned by the dedicated control information, characterized in that the range of numbers of OFDM symbols used for control signaling that can be indicated by the bits of the carrier indicator field covers only a selected subset of the total range of numbers of OFDM symbols that can be used for control signaling, and wherein the subset of the range of numbers of OFDM symbols used for control signaling that can be indicated by the carrier indicatorfield is depending on at least one of: - interference conditions and power level on the assigned downlink component carrier, - the channel quality on the assigned downlink component carrier, - the bandwidth of the assigned downlink component carrier, - status of a load balancing function for the downlink component carriers, - the type of the assigned downlink component carrier, - the number of OFDM symbols used for control signaling on the component carrier on which the dedicated control information is transmitted, and - the number of downlink ACK/NACKs to be signaled on the assigned component carrier. - interference conditions and power level on the assigned downlink component carrier, - the channel quality on the assigned downlink component carrier, - the bandwidth of the assigned downlink component carrier, - status of a load balancing function for the downlink component carriers, - the type of the assigned downlink component carrier, - the number of OFDM symbols used for control signaling on the component carrier on which the dedicated control information is transmitted, and - the number of downlink ACK/NACKs to be signaled on the assigned component carrier.