Michele C. Weigle

Vehicular Networks: From Theory to Practice

In spite of their importance and potential societal impact, there is currently no comprehensive source of information about vehicular ad hoc networks (VANETs). Cohesively integrating the state of the art in this emerging field, Vehicular Networks: From Theory to Practice elucidates many issues involved in vehicular networking, including traffic engineering, human factors studies, and novel computer science research. Divided into six broad sections, the book begins with an overview of traffic engineering issues, such as traffic monitoring and traffic flow modeling. It then introduces governmental and industrial efforts in the United States and Europe to set standards and perform field tests on the feasibility of vehicular networks. After highlighting innovative applications enabled by vehicular networks, the book discusses several networking-related issues, including routing and localization. The following section focuses on simulation, which is currently the primary method for evaluating vehicular networking systems. The final part explores the extent and impact of driver distraction with in-vehicle displays. Encompassing both introductory and advanced concepts, this guide covers the various areas that impact the design of applications for vehicular networks. It details key research challenges, offers guidance on developing future standards, and supplies valuable information on existing experimental studies.

Providing VANET security through active position detection

Vehicle position is one of the most valuable pieces of information in a Vehicular Ad hoc Network (VANET). The main contribution of this work is a novel approach to enhancing position security in VANETs. We achieve local security by enlisting the help of on-board radar to detect neighboring vehicles and to confirm their announced coordinates. Local security is extended to achieve global security by using preset position-based groups to create a communication network and by using a dynamic challenging mechanism to confirm remote position information. Our solution is predicated on the widely accepted assumption that the vast majority of vehicles are honest and behave responsibly. Extensive simulations confirm the quality of the proposed solution by measuring how fast compromised vehicles can be detected under various conditions.

Stochastic models for generating synthetic HTTP source traffic

New source-level models for aggregated HTTP traffic and a design for their integration with the TCP transport layer are built and validated using two large-scale collections of TCP/IP packet header traces. An implementation of the models and the design in the ns network simulator can be used to generate web traffic in network simulations

Security challenges in vehicular cloud computing

In a series of recent papers, Prof. Olariu and his co-workers have promoted the vision of vehicular clouds (VCs), a nontrivial extension, along several dimensions, of conventional cloud computing. In a VC, underutilized vehicular resources including computing power, storage, and Internet connectivity can be shared between drivers or rented out over the Internet to various customers. Clearly, if the VC concept is to see a wide adoption and to have significant societal impact, security and privacy issues need to be addressed. The main contribution of this work is to identify and analyze a number of security challenges and potential privacy threats in VCs. Although security issues have received attention in cloud computing and vehicular networks, we identify security challenges that are specific to VCs, e.g., challenges of authentication of high-mobility vehicles, scalability and single interface, tangled identities and locations, and the complexity of establishing trust relationships among multiple players caused by intermittent short-range communications. Additionally, we provide a security scheme that addresses several of the challenges discussed.

CASCADE: Cluster-Based Accurate Syntactic Compression of Aggregated Data in VANETs

We present a method for accurate aggregation of highway traffic information in vehicular ad hoc networks (VANETs). Highway congestion notification applications need to disseminate information about traffic conditions to distant vehicles. In dense traffic, aggregation is needed to allow a single frame to carry information about a large number of vehicles. Our technique, CASCADE, uses compression to provide aggregation without losing accuracy. We show that CASCADE makes efficient use of the wireless channel while providing each vehicle with data that is highly accurate, represents a large area in front of the vehicle, and can be combined with aggregated data from other vehicles to further extend the covered area.

Providing location security in vehicular Ad Hoc networks

It is fair to say that most, if not all, VANET applications rely on accurate location information. It is therefore imperative to provide mechanisms that ensure the integrity, availability, and confidentiality of location information. In this article we present a number of location security mechanisms specifically designed for VANETs. Proposed mechanisms for location integrity range from the use of onboard radar devices and GPS to simpler methods that rely on information fusion. We also address ways to enhance the availability of location information by selecting and maintaining stable routing paths. Finally, we discuss a mechanism that promotes location confidentiality through encryption/decryption and access control using geographical information. Our location information security mechanisms meet the requirements of the Confidentiality, Integrity, and Availability (CIA) information security model.

Highway mobility and vehicular ad-hoc networks in ns-3

The study of vehicular ad-hoc networks (VANETs) requires efficient and accurate simulation tools. As the mobility of vehicles and driver behavior can be affected by network messages, these tools must include a vehicle mobility model integrated with a quality network simulator. We present the first implementation of a well-known vehicle mobility model to ns-3, the next generation of the popular ns-2 networking simulator. Vehicle mobility and network communication are integrated through events. User-created event handlers can send network messages or alter vehicle mobility each time a network message is received and each time vehicle mobility is updated by the model. To aid in creating simulations, we have implemented a straight highway model that manages vehicle mobility, while allowing for various user customizations. We show that the results of our implementation of the mobility model matches that of the models author and provide and example of using our implementation in ns-3.

TDMA cluster-based MAC for VANETs (TC-MAC)

One of the challenges for Vehicular Ad-hoc Networks (VANETs) is the design of the Medium Access Control (MAC) protocol. When exchanging messages between vehicles, there are network issues that must be addressed, including the hidden terminal problem, high density, high node mobility, and data rate limitations. A cluster-based MAC scheme is needed in VANETs to overcome the lack of specialized hardware for infrastructure and the mobility to support network stability and channel utilization. This paper presents a MAC algorithm for vehicular ad-hoc networks using a new method for TDMA slot reservation based on clustering of vehicles. Our algorithm aims to decrease collisions and packet drops in the channel, as well as provide fairness in sharing the wireless medium and minimizing the effect of hidden terminals.

p-IVG: Probabilistic Inter-Vehicle Geocast for Dense Vehicular Networks

In this paper, we study the effect of dense vehicular networks on data dissemination. When using intelligent broadcast- ing techniques, such as Inter-Vehicle Geocast, we have discovered the spatial broadcast storm problem in which multiple vehicles will be chosen to re-broadcast frames at nearly the same time, resulting in channel contention and collisions. We present a probabilistic version of IVG (p-IVG) to address this problem. In p-IVG, which vehicles re-broadcast frames is probabilistic depending upon the traffic density surrounding the vehicles. We show that p-IVG solves the spatial broadcast storm problem and that using p-IVG results in improved reception rates, lower channel contention, and most importantly, faster dissemination of data to distant vehicles than IVG. I. INTRODUCTION

Dynamic Adaptation of Joint Transmission Power and Contention Window in VANET

In this paper, we propose an algorithm for joint adaptation of transmission power and contention window to improve the performance of vehicular network in a cross layer approach. The high mobility of vehicles in vehicular communica- tion results in the change in topology of the Vehicular Ad-hoc Network (VANET) dynamically, and the communication link between two vehicles might remain active only for short duration of time. In order for VANET to make a connection for long time and to mitigate adverse effects due to high and fixed transmission power, the proposed algorithm adapts transmission power dynamically based on estimated local traffic density. In addition to that, the prioritization of messages according to their urgency is performed for timely propagation of high priority messages to the destination region. In this paper, we incorporate the contention based MAC protocol 802.11e enhanced distributed channel access (EDCA) mechanism to implement a priority- based vehicle-to-vehicle (V2V) communication. Simulation results show that the proposed algorithm is successful in getting better throughput with lower average end-to-end delay than the algorithm with static/default parameters.