A communication system for facilitating control over a function of a vehicle (102) comprises a base station (104) positioned in the vehicle (102) and a mobile communication unit (122). The base station (104) comprises a first transmitter for transmitting a signal to the mobile communication unit (122) and a first receiver for receiving a signal from the mobile communication unit (122). The base station (104) is further configured to cause the mobile communication unit (122) to operate in accordance with a limited-response duty cycle.