A mechanism is provided for performing timing adjustment within a wireless communication system for a moving vehicle. The wireless communication system has an antenna system for communicating with a further antenna system, and communication control circuitry for performing a sign-on procedure to seek to establish a communication link with the further antenna system. During the sign-on procedure, the communication control circuitry issues via the antenna system a connection setup signal for receipt by the further antenna within an identified timing window. The wireless communication system also has location specifying circuitry for identifying a current location of the wireless communication system, and distance computation circuitry for obtaining location information specifying a location of the further antenna system, and for determining a separation distance between the antenna system and the further antenna system. The communication control circuitry is arranged to issue the connection setup signal at a default time unless the separation distance exceeds a setup threshold distance that indicates that use of the default time would prevent the connection setup signal being received within the identified timing window. In that event, the control circuitry instead applies a timing advance in order to issue the connection setup signal prior to the default time so as to cause the connection setup signal to be received by the further antenna system within the identified timing window. This facilitates successful establishment of a communication link even in situations where the separation distance between the antenna system and the further antenna system exceeds that supported by modern telecommunications Standards.