Patent attributes
A secure vehicle access system comprises a vehicle and a key associated with the vehicle. The key comprises: a radio frequency, RF, key transceiver configured to: broadcast at least one signal; and listen for an acknowledgement message from the vehicle. The vehicle comprises: a radio frequency, RF, vehicle transceiver configured to: listen for the at least one broadcast signal from the key; and in response thereto, transmit an acknowledgement message back to the key to establish a communication link between the vehicle and the key. The key further comprises a ranging circuit configured to perform a distance determination between the vehicle and the key, following the establishment of the communication link, to determine whether to allow access to the vehicle.