ULTRA-WIDEBAND BASED VEHICLE ACCESS SYSTEM AND COMMUNICATION PROTOCOL FOR LOCALIZATION OF A TARGET DEVICE

摘要

A vehicle access system having a plurality of system nodes arranged throughout a vehicle is disclosed. The vehicle access system employs a communication protocol which utilizes two way ranging (TWR) and time distance of arrival (TDoA) localization processes to determine a position of a target portable device. The communication protocol selects the optimal combination of TWR and TDoA estimations, depending on a number of system nodes that are in communication range of the target portable device, to provide the greatest accuracy with the best power efficiency at the target portable device. Particularly, the communication protocol minimizes the number of messages sent and received by the target portable device, thereby improving the power efficiency thereof. Furthermore, the communication protocol schedules messages between the system nodes and target portable device so as to minimize the wake time of the target portable device, thereby further improving the power efficiency thereof.