A wireless device receives message(s) comprising configuration parameters of one or more secondary cells. The wireless device receives an activation/deactivation media access control control element (A/D MAC CE). If the number of the one or more secondary cells is seven or less and the one or more secondary cells are each configured with a cell index having a value from one to seven, then the A/D MAC CE is of a fixed size of one octet and the A/D MAC CE is identified by a first subheader comprising a first logical channel identifier (LCID). Otherwise the A/D MAC CE is of a fixed size of four octets and the A/D MAC CE is identified by a second subheader comprising a second LCID different from the first LCID. At least one secondary cell of the one or more secondary cells is activating or deactivating according to the A/D MAC CE.