Abstract
Wireless telecommunication technologies are flattering the foremost structure of information transmission, and considered one of the majority active research area. Ad hoc Networks for vehicles communications (VANET) emerged as a detachment of the Mobile Ad hoc Network (MANET), but they are at variance from MANET by their architecture, challenges, characteristics and applications. VANET believed to be a considerable approach to the ITS (Intelligent Transportation System). It is pioneered to support driving system, advance safety requirements and driving comfort in the direction of creating protected, self organized and intelligent driving environment. Incorporation of vehicular Ad hoc network and cellular network results in a heterogeneous wireless network (HWN) architecture, where gateway nodes are necessitated in VANET to link with the cellular network for data communication. This paper investigates the recent integration of VANET and cellular networks, and classifies the various approaches.