Hybrid sensor and vehicular networks: a survey

In recent years, vehicular networks have been attracting considerable attention of research communities, and they are considered as the most prominent component of Intelligent Transportation System (ITS). However, owing to the high mobility of vehicles and sparse deployment of the roadside units, vehicular networks cannot ensure a permanent connectivity between vehicles. Furthermore, pure VANETs (Vehicular Ad hoc Networks) cannot guarantee timely detection of dangerous road conditions. To overcome these issues, WSNs (Wireless Sensor Networks) have been integrated in VANETs to form a hybrid vehicular environment which benefits from the advantages of each one of them. This leads the emergence of new networks, called Hybrid Sensor and Vehicular Networks (HSVNs), where sensor nodes are deployed along the two sides of a road to assist VANET in order to provide better performance. In this paper, we outline the background and the main features of vehicular networks, and we survey the state of the art of routing and communication protocols of networks presented in the three categories, namely VANETs, WSNs and HSVNs.