Opportunistic Networking in Delay Tolerant Vehicular Ad Hoc Networks

Vehicular Area Networking (VANET) is an emerging technology to support a class of applications involving communications between vehicles, and vehicles and the environment. Activity in this area includes development of the Dedicated Short Range Communication (DSRC) protocol aimed at enabling vehicles to exchange safety information to enhance awareness of the vehicle beyond the line of sight, and to enhance safety features such as active braking and collision warning. While safety is the primary driver for development, additional applications emerge as potential users of this technology that are more general in nature. Real-time traffic and route updates, traffic monitoring, remote diagnostics, general purpose Internet access and in-car entertainment are examples that require data collection and dissemination analogous to the wired Internet. However, DSRC and related short-range communications technology would appear to be insufficient for these scenarios. In this chapter, we describe, how and under what conditions it is feasible, and in fact desirable, to use short range communications. We describe a network formed over moving vehicles implemented by short-range communication and thereby analyze factors that affect the design and performance. Observations reveal intermittent connectivity between vehicles traveling on the roadway in opposite directions that hinders applications. Techniques adapted from related research in computer networks provide solutions for enabling networking in a fragmented network of moving vehicles. We elaborate and demonstrate analytically the application of techniques that enable networking through short-range communication.

Mobility and Traffic Model Analysis for Vehicular Ad-hoc Networks

Vehicular Ad Hoc Networks represent a specialized application of Mobile Ad Hoc Networks. Here the mobile nodes move in lanes and their mobility can be modeled based on realistic traffic scenarios. To meet the above challenge the goal of defining the mobility model for vehicular ad hoc network along with a realistic traffic pattern is an important research area. Vehicular mobility is characterized by acceleration, deceleration, possibility of different lanes and intelligent driving patterns. Also a modeling of traffic is necessary to evaluate a vehicular ad hoc network in a highway environment. The traffic model has to take into account the driver behavior in order to take decisions of when to overtake, change lanes, accelerate and decelerate. To overcome the limitation of traditional mobility models and mimic traffic models, many traffic model based simulators like CORSIM, PARAMICS and MOVE have been proposed. In this chapter we provide taxonomy of mobility models and analyze their implications. To study the impact of mobility model on routing protocol for vehicular motion of nodes we analyze the performance of mobility models with suitable metrics and study their correlation with routing protocol. We also discuss the fundamentals of traffic engineering and provide an insight into traffic dynamics with the Intelligent Driver Model along with its lane changing behavior.

Clustering, Connectivity, and Monitoring Challenges in Vehicular Ad hoc Networks

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.

Survey of Routing Protocols in Vehicular Ad Hoc Networks

The chapter provides a survey of routing protocols in vehicular ad hoc networks. The routing protocols fall into two major categories of topology-based and position-based routing. The chapter discusses the advantages and disadvantages of these routing protocols, explores the motivation behind their design and trace the evolution of these routing protocols. Finally, it concludes the chapter by pointing out some open issues and possible direction of future research related to VANET routing.

Reliable Routing Protocols in VANETs

One of the notoriously difficult problems in vehicular ad-hoc networks is to ensure that established paths do not break before the end of data transmission. This is a difficult problem because the network topology is changing constantly and the routing links are inherently unstable. This chapter reviews several routing protocols which are designed for vehicular network environment. Currently, there are five major types of routing protocols based on the metrics used for routing: 1) flooding based routing, 2) mobility based routing, 3) infrastructure based routing, 4) geographic position based routing, and 5) probability model based routing. We give a survey of each type of routing method. Since probability theory is an ideal tool to describe the dynamics of vehicles, we present one probability model based routing method as a detailed example.

Information Sharing in VANETs

This chapter looks at a vehicular ad hoc network (VANET) as a peer-to-peer network, where mobile users may request information contents as well as provide them to other nodes, and it addresses the major technical issues that emerge when dealing with information sharing in VANETs. After briefly reviewing some proposals appeared in the literature on application and network protocols for data exchange in VANETs, the chapter focuses on a possible application for data sharing between vehicular users, which exploits the pull-based approach. It then highlights the main challenges in such a scenario and introduces some mechanisms that can be applied to solve two major issues in content sharing: content query propagation and content caching. A comparison among the schemes presented for query propagation, as well as between the mechanisms introduced for data caching, is shown through simulation results derived using the network simulator ns2. Finally, future challenges and emerging research topics for content sharing and dissemination in VANETs are outlined.

The Role of Communication Technologies in Vehicular Applications

Vehicular networks attract a lot of attention in the research world. Novel vehicular applications need a suitable communication channel in order to extend in-vehicle capabilities and, be aware of surrounding events. However, these networks present some peculiarities, such as high mobility or specific topologies. These features affect the performance of applications; hence, more effort should be directed to identify the final necessities of the network. Few works deal with application requirements that should be considered when vehicular services are designed. In this chapter this gap is filled, proposing an analysis of application requirements mapped with suitable communication technologies for physical/MAC and network layers. This study contains key factors that must be taken into account not only at the design stage of the vehicular network, but also when applications are evaluated.

Analyzing IEEE 802.11g and IEEE 802.16e Technologies for Single-Hop Inter-Vehicle Communication

This chapter analyzes two prominent technologies, IEEE 802.11g (WiFi) and IEEE 802.16e (WiMAX), for single-hop inter-vehicular communication (SIVC). We begin our analysis by comparing the physical and MAC layers of both standards. Following this, we simulate two scenarios, one with IEEE 802.11g and the other with IEEE 802.16e, in a single-hop inter-vehicular communication network. In both scenarios, the Location-Based Routing Algorithm with Cluster-Based Flooding (LORA-CBF) was employed to create a hierarchical vehicular organization that acts as a cluster-head with its corresponding member nodes. The simulation scenarios consist of five different node sizes of 20, 40, 60, 80 and 100 vehicles, respectively. We propose a novel simulation model that is suitable for mesh topologies in WiMAX networks and provide preliminary results in terms of delay, load and throughput for single-hop inter-vehicle communication.

Infrastructures in Vehicular Communications

Vehicular communication is regarded as a backbone for the development of intelligent transportation system (ITS). Recently vehicular communication has attracted researchers from both academia and industry all over the world, notably, in the United States of America, Japan and European Union. The rapid advances in wireless technologies provide opportunities to utilize them in vehicular communication in advanced road safety applications. The most important feature of vehicular communication is to improve the road traffic safety, efficiency, comfort and quality of everyday road travel. Networking in particular and communication in general are important rudiments in the development of ITS. Generally, in vehicular communication, the information exchange occurs among vehicles not only in an ad-hoc based vehicle-to-vehicle networking but also in a vehicle-to-infrastructure with possible intermediate infrastructure-to-infrastructure networking. Therefore, the infrastructure plays major role in order to realize the full potential of vehicular communications. This chapter provides an in-depth survey of the infrastructures and technologies that are recently proposed as part of future ITS developments as well as tested for vehicular communications in mobile environment. Specifically, we provide an in-depth analysis of wireless technology-applications such as ad-hoc networking and wireless local area network (WLAN), dedicated short-range communication (DSRC), cellular technology and NOTICE Architecture, and compare their characteristics in terms of their abilities to support vehicular communications for development of ITS.

Safety and Commercial Applications

Applications in Vehicular Networks are the main motive for all researchers and vehicle manufactures to design new protocols; technologies and implementations that allow a specific type of applications. The chapter starts with different classifications of Applications in Vehicular Ad-Hoc Network (VANET). Then, it gives a background on Applications in VANET. Then, it discusses different categories of applications in details starting with different types of safety application and commercial applications. It compares between communications in high and low safety application. Then, it describes in details monitoring, service applications and a view on entertainment applications. Finally, it will explain the requirements for real-time applications. At the end, the chapter gives some case studies for applications.