Routing in Vehicular Ad Hoc Networks: towards Road-Connectivity Based Routing

Abstract

The proliferation of wireless technologies has inspired researchers from both academia and automotive industry to integrate advanced capabilities to the vehicles and provide new services and mobile applications. In particular, vehicular networks have emerged as a novel class of Mobile Ad Hoc Networks (MANETs) formed between moving vehicles equipped with wireless devices. Based on multi-hop communications, these self-organizing networks enable data exchanges among nearby vehicles and between vehicles and the road side infrastructure. Driven by the transportation safety and efficiency issues, Vehicle-to-Vehicle (V2V) and Vehicle-to-Infrastructure (V2I) communications are attracting considerable attention in providing Intelligent Transportation Systems (ITS). In this context, a variety of services are offered to road users for improving their security and comfort. These emerging applications include among others safety applications for traffic monitoring and collision prevention, road information services, and infotainment and so on. However, unlike other ad hoc networks, Vehicular ad hoc Networks (VANETs) have their unique characteristics which give rise to many challenging issues. One of the most salient features is the high mobility of vehicles resulting in dynamic topology changes. Accordingly, data routing remains a key networking issue that needs to be addressed in order to support the emerging applications. Over the last decades, many efforts have been concerted to design efficient routing protocols after recognizing the inefficiency of traditional MANET protocols to meet the requirements of vehicular environments. This chapter presents an analysis of the routing problem in vehicular ad hoc networks. First, it discusses the main characteristics and challenges of VANETs that distinguish them from the traditional MANETs. Then, it reviews the most relevant routing strategies proposed in the research community highlighting their advantages and disadvantages. Based on these considerations, we introduce a new class of geographic routing protocols called RCBR, Road Connectivity-based Routing for vehicular networks. The proposed approach exploits information about road connectivity and vehicles distribution to find stable routes and reduce the probability of links breakage. Simulations results are used to show how traffic awareness combined with a spatial knowledge of the environment can optimize the routing decisions in high dynamic networks.