Vehicular Ad Hoc Networks (VANETs) are appropriate networks that can be applied for intelligent transportation systems. Three important challenges in VANETs are studied in this chapter. The first challenge is to defend against attackers. Because of the lack of a coordination unit in a VANET, vehicles should cooperate together and monitor each other in order to enhance security performance of the VANET. As the second challenge in VANETs, scalability is a critical issue for a network designer. Clustering is one solution for the scalability problem and is vital for efficient resource consumption and load balancing in large scale VANETs. On the other hand, due to the high-rate topology changes and high variability in vehicles density, transmission range of a vehicle is an important issue for forwarding and receiving messages. In this chapter, we study the clustering algorithms, the solutions appropriate to increase connectivity, and the algorithms that can detect attackers in a VANET.
Efficient Resource Discovery in Mobile Ad Hoc Networks