A model for power contributions from diffraction around a truck in vehicle-to-vehicle communications

Channel modeling studies in vehicle-to-vehicle (V2V) communications have shown that larger road users act as blocking objects for the communication of surrounding vehicles, dramatically altering the statistical properties of the wireless channel. Without a strong line-of-sight component, packet delivery depends on other propagation mechanisms that are statistically more likely to add destructively so that the signal falls below the noise threshold of the receiver. An analytical model to understand dominant propagation mechanisms in these scenarios is a very powerful tool to predict system performance for important safety scenarios, facilitating both application development and vehicle antenna design. In this paper we present an analytical model for the power contributions from diffraction around a truck. The model is later verified using real life channel measurements from a rural road scenario. A general conclusion is that the channel between the vehicles is highly sensitive to lateral position, and even longitudinal position in the vicinity immediately behind the truck. Finally we conclude that non line-of-sight communication in rural environments is possible using only diffraction as a propagation mechanism, and that antenna diversity significantly increases communication reliability.