A wireless device receives message(s) configuring transmissions of sounding reference signals on a secondary cell in a secondary cell group. The wireless device receives an activation command to activate the secondary cell. The wireless device transmits the sounding reference signals if the secondary cell is activated, a timing advance command is applied to the secondary cell group, and a time alignment timer for the secondary cell group is running. The wireless device is configured to not transmit the sounding reference signals on the secondary cell during the period between receiving the activation command and applying the timing advance command.