A wireless device receives one or more messages from a base station. The one or more messages comprise configuration parameters of a cell. The configuration parameters indicate: a plurality of slot format combinations of the cell; a channel occupancy time (COT) radio network temporary identifier (RNTI); and an index of a field in a downlink control information (DCI) for the cell. The DCI scrambled by the COT-RNTI is received. A COT structure, for the cell, is determined based on one of the plurality of slot format combinations indicated by the field in the DCI associated with the index. A transport block is transmitted, via the cell, on uplink resources according to the COT structure.