Empirical path loss model for 2.4 GHz IEEE 802.15.4 wireless networks in compact cars

Wireless sensor systems are becoming increasingly attractive as a means to flexibly extend sensing capabilities towards more intelligent cars. Wireless sensors can reduce cabling costs and weight, allow for cheaper customization, and allow retrofitting new functionality into older vehicles. The communication system design for these wireless sensor systems requires models for radio propagation in cars. In this paper we present a novel empirical path loss model for the 2.4 GHz based IEEE 802.15.4 radio channel. Our model is based on extensive measurements in two compact cars. We have extracted model parameters for two types of wireless links, those between sensors in the car and those towards sensors on the outside of the car. We have calibrated the model parameters for both path loss and shadow fading to fit our measurements.