Interference modelling and SNR threshold study for use in vehicular safety messaging simulation

The DSRC safety messaging system was initially proposed for emergencies and vehicle safety applications; having a high reliability is a major design factor. Due to the fact that the DSRC system has different data rates according to its modulation and coding schemes, a minimum SNR threshold for different data rates is required for successful message transmission. This paper provides the different SNR ratios for the varying data rates used in the current DSRC IEEE802.11p standard. More specifically, our model and simulations focus directly on how the SNR for various data rates using repetition based protocols decreases with distance and with added interfering terminals. We have also explored the effects of changing packet length and are shown to have negligible effects for the minimum SNR levels. Additionally, we propose an interference model that uses the distance between vehicles and the transmission power based on the minimum SNR values obtained in this paper and simulated the probability of successful transmission for different data rates. This allows us to solve for the optimal data rate for use in DSRC safety messaging systems. The simulation traffic model used is the well known SUMO traffic model, and we simulated for both highway and urban traffic scenarios while taking hidden terminals into account.