Vehicular Ad hoc wireless NETworks (VANETs) are a particularly challenging class of Mobile Ad hoc wireless NETworks (MANETs) that are currently attracting the extensive attention of research in the field of wireless networking as well as automotive industries. ANETs exhibits stronger challenges than that in other general MANETs. Infrastructure-free environments and higher dynamic network topology cause frequent network partition. Moreover, vehicular ad hoc wireless networks is often deployed by the constraint of roadways where trees, buildings and other assorted obstacles influence the practical transmission effects as compared to generic open fields.