Reducing interference from devices at extraordinary altitudes

A method of reducing interference in a mobile communication system caused by a first user equipment, UE, device operating in a cell at a significantly higher altitude than other UE devices in the cell so as to cause interference, the method comprising:

• detecting that the first UE device is operating at an altitude considered by the mobile communication system to be an extraordinary altitude;
• and
• reducing interference caused at a non-serving base station of the mobile communication system by the first UE device operating at the extraordinary altitude by controlling the operation of the first UE device,
• wherein in the method:
• a base station serving the first UE device in the cell determines, using a radio link between the first UE device and the serving base station, that an altitude of the first UE device exceeds a threshold and having determined that the altitude of the first UE device exceeds the threshold configures the first UE device to report altitude measurements of the first UE device, the reported altitude measurements being used by the serving base station to detect that the first UE device is operating at an altitude considered by the mobile communication system to be an extraordinary altitude.