Chapter 1 INTRODUCTION 1.1 Background Vehicular ad hoc networks (VANETs) are self-configuring networks where the nodes are vehicles (equipped with onboard computers), elements of roadside infrastructure, sensors, and pedestrian personal devices. Wi-Fi (IEEE 802.11-based) technologies are used for deploying such kind of networks. At present, the IEEE group is completing the IEEE 802.11p and IEEE 1609 final drafts, which are known as “Standard Wireless Access in Vehicular Environments”(WAVE), specifically designed for VANETs. This technology presents the opportunity to develop powerful car systems capable of gathering, processing, and distributing information. For example, a driver assistance system could collect accurate and up-to-date data about the surrounding environment, detect potentially dangerous situations, and notify the driver. In VANETs, the Wi-Fi limitations in coverage and capacity of the channel, the high mobility of the nodes, and the presence of obstacles generate packet loss, frequent topology changes, and network fragmentation. Thus, a great deal of effort is dedicated to offer new medium access control access strategies and to design efficient routing protocols. In turn, in such kind of networks, routing is a challenging task since there is no central entity in charge of finding the routing paths among the nodes. Different routing strategies have been defined based on prior ad hoc network architectures by targeting the specific VANET needs of scenarios and applications. These protocols can be grouped into topology based (proactive, e.g., destinationsequenced distance-vector and optimized link state routing (OLSR), reactive, e.g., ad hoc On demand distance vector (AODV) and dynamic source routing (DSR), carryand- forwarding, etc.), position based (e.g., greedy perimeter stateless routing (GPSR) and greedy perimeter coordinator routing), cluster based (e.g., clustering for open IVC network and location-based routing algorithm with cluster-based flooding), and broadcasting (e.g., ROADCOMM and history enhanced vector based tracing detection) protocols .
Most of the VANET applications critically rely on routing protocols. Thus, an optimal routing strategy that makes better use of resources is crucial to deploy efficient VANETs that actually work in volatile networks. Finding well-suited parameter configurations of existing mobile ad hoc network (MANET) protocols is a way of improving their performance, even making the difference between a network that does work or does not, e.g., networks with high routing load suffer from congestion and cannot ensure timely and reliable delivery of messages. The DBR protocol to address the short coming of position based and map based approach. In this protocol real time...