Measurement based Shadow Fading Model for Vehicle-to-Vehicle Network Simulations

The Vehicle-to-Vehicle (V2V) propagation channel has significant implications on the design and performance of novel communication protocols for Vehicular Ad Hoc Networks (VANETs). Extensive research efforts have been made to develop V2V channel models to be implemented in advanced VANET system simulators for performance evaluation. The impact of shadowing caused by other vehicles has, however, largely been neglected in most of the models, as well as in the system simulations. In this paper we present a simple shadow fading model targeting system simulations based on real world measurements performed in urban and highway scenarios. The measurement data is separated for the situations line-of-sight (LOS), obstructed line-of-sight (OLOS) by vehicles, and non line-of-sight (NLOS) by buildings with the help of video information available during measurements. It is observed that vehicles obstructing the LOS induce an additional attenuation of about 10 dB in the received signal power. We use a Markov chain based state transition diagram to model transitions from LOS to obstructed LOS and present an example of state transition intensities for a real traffic mobility model. We also provide a simple recipe, to incorporate our shadow fading model in VANET network simulators and provide simulation results which show performance degradation due to OLOS.