A wireless device may receive at least one message comprising configuration parameters of a plurality of cells being in a cross-carrier scheduling group comprising a first cell and a second cell. The first cell identified by a first cell identifier may employ a first number of bits. The configuration parameters may indicate that the second cell is a cross-carrier scheduling cell for the first cell. The configuration parameters may comprise the first cell identifier and a first cell indicator field. The first cell indicator field may employ a second number of bits. The wireless device may receive downlink control information via a control channel of the second cell for a packet transmitted via the first cell. The downlink control information may comprise the first cell indicator field identifying the first cell. The wireless device may receive the packet on the first cell via radio resources identified by the downlink control information.