An Empirical Study of RF Link for Wireless Automotive Passive Entry System

The wireless systems in automotive applications increase for security and comfort considerations. As the structure of the car involves many metallic frames, the channel of the RF signal is tricky to model. As a consequence,the developers need efficient and accurate means of characterization to develop these systems. This study proposes a full characterization of a RF link between a transmitter (badge) and a receiver (integrated in the structure of the car). As the design of a car is relevant with a multi-scale analysis, the needs can vary from a car to another one: we propose a strategy based on the development of generic wireless modules to cut the development costs. Therefore, the medium of propagation influence is intensively characterized to develop matched strategies for secured data propagation. First, an empirical analysis describes on the radio channel characterization for the car access systems. Then, the received field is measured in 2D around the vehicle for different various parameters (vehicle frame, antennas relative heights, badge and receiver´s position and relative distance). The free radio frequency of 434 MHz is chosen for this study.