The present invention provides a method of operating a user equipment, UE device in communication with a non-terrestrial communication system comprising a plurality of transmission points, the method comprising in the UE device triggering a transmission of a measurement report dependent on a measurement by the UE device of a received signal parameter (1) of a signal received from a transmission point of the system and a comparison of the measured parameter with a threshold (2), the threshold varying according to a predetermined function dependent on an expected position of the UE device with respect to the transmission point.