Effect of minimum headway distance on connectivity of VANETs

The knowledge of vehicle headway distribution is essential for estimating the probability of connectivity in vehicle ad hoc networks. We consider the distribution of vehicles in a single lane, taking into account that consecutive vehicles have to maintain a minimum safe distance between them. It is shown that the account of safe distance improves the agreement between vehicles theoretical spacing distribution and empirical data in single lane traffic. We study how this minimum distance affects the connectivity probability in light traffic conditions. We show that the headway distribution of single lane traffic in the free flow conditions is better modeled using a shifted exponential model which takes into account the safe distance between vehicles. We also show that neglecting this effect will result in overestimating the connectivity in vehicular ad hoc networks, therefore, underestimating the communication range needed to establish the network with a given connectivity probability. The effect is stronger for shorter transmission range.