A wireless device receives configuration parameters indicating a plurality of a channel occupancy time (COT) lengths of a cell and a position parameter for a COT of the cell. The wireless device receives downlink control information (DCI) comprising a plurality of fields. The position parameter indicates a position of a field, of the plurality of fields. The field indicates a COT length, of the plurality of COT lengths. The wireless device transmits a transport block via uplink resources of the COT with the COT length.