Dynamie topology characteristics of VANETs in fading channels

Identifying the properties of the topology is critical to the development of the protocols for vehicular ad-hoc networks (VANETs). In VANETs, the propagation of radio waves in outside environment is easily affected by some obstacles like buildings. Therefore, the approach to model transmission ranges based on the geometric disk model is unscientific, especially in urban environments. The topology characteristics of VANETs taking into account the channel randomness are studied with complex networks in this paper. We assess the topology characteristics in the case of various vehicular densities and path loss exponent. The evaluated metrics are the degree, the clustering coefficient, and the global efficiency. It turns out that not only vehicular densities but also path loss exponents have an important effect on topology characteristics. By comparing the results obtained with the geometric disk model to those of fading channels models, we conclude that more optimistic but less reliable results on connectivity for VANETs are brought forth due to the ignorance of influences by obstacles.