Vehicular ad hoc networks (VANETs) are gaining growing interest from both industry and academia. Driven by road safety requirements, the car manufacturers, transportation authorities and communications standards organizations are working together to make a quantum step in terms of vehicular information technology (IT) by equipping the vehicles with sensors, on-board processing and wireless communication modules. VANETs are composed of OBUs (On Board Units) and RSUs (Road Side Units). The communication standard used in VANETs is called DSRC (Dedicated Short Range Communication). With many essential vehicle components (radios, spectrum, standards, etc) coming into place, a lot of new applications are emerging beside road safety, which support not only safety related services, but also entertainment and mobile Internet access services. In this study, we propose a promising commercial application for file purchasing in VANETs, where a legitimate vehicle can purchase digital files/data through a roadside unit (RSU). Due to the high mobility of the vehicles, the contact period between an RSU and a vehicle could be insufficient to download the complete file. To purchase a digital file, a vehicle purchases a permission key from a fixed RSU and then begins to download the file from the RSU via vehicle-to-RSU communications (V2R) when it is in the transmission range of the RSU. Once the vehicle in the process of downloading a file leaves the transmission range of the RSU, its neighboring vehicles with a piece of the file cooperatively help to complete the file transfer via vehicle-to-vehicle (V2V) communications. Such a commercial file purchasing system can obviously initiate a new application scenario. However, it cannot be put into practice unless the security issues, such as the user privacy, incentives for inter-vehicle cooperation, and the copyright protection for the file content are well addressed. In order to deal with these security issues, we develop a secure business framework for the file purchasing system in this study. In this framework, we preserve the user privacy by using the pseudo identity for each vehicle. We stimulate the cooperation between vehicles through micro-payment incentive mechanism and guarantee the secure payment at the same time. To protect the digital file content from unauthorized distribution, we encrypt the file content before delivery to an end user and use digital fingerprint technology to generate a unique copy for each vehicle after delivery. In a word, we propose a file purchasing application in VANETs and also develop a secure framework for this application.

Vehicular ad hoc networks (VANETs) are gaining growing interest from both industry and academia. Driven by road safety requirements, the car manufacturers, transportation authorities and communications standards organizations are working together to make a quantum step in terms of vehicular information technology (IT) by equipping the vehicles with sensors, on-board processing and wireless communication modules. VANETs are composed of OBUs (On Board Units) and RSUs (Road Side Units). The communication standard used in VANETs is called DSRC (Dedicated Short Range Communication). With many essential vehicle components (radios, spectrum, standards, etc) coming into place, a lot of new applications are emerging beside road safety, which support not only safety related services, but also entertainment and mobile Internet access services. In this study, we propose a promising commercial application for file purchasing in VANETs, where a legitimate vehicle can purchase digital files/data through a roadside unit (RSU). Due to the high mobility of the vehicles, the contact period between an RSU and a vehicle could be insufficient to download the complete file. To purchase a digital file, a vehicle purchases a permission key from a fixed RSU and then begins to download the file from the RSU via vehicle-to-RSU communications (V2R) when it is in the transmission range of the RSU. Once the vehicle in the process of downloading a file leaves the transmission range of the RSU, its neighboring vehicles with a piece of the file cooperatively help to complete the file transfer via vehicle-to-vehicle (V2V) communications. Such a commercial file purchasing system can obviously initiate a new application scenario. However, it cannot be put into practice unless the security issues, such as the user privacy, incentives for inter-vehicle cooperation, and the copyright protection for the file content are well addressed. In order to deal with these security issues, we develop a secure business framework for the file purchasing system in this study. In this framework, we preserve the user privacy by using the pseudo identity for each vehicle. We stimulate the cooperation between vehicles through micro-payment incentive mechanism and guarantee the secure payment at the same time. To protect the digital file content from unauthorized distribution, we encrypt the file content before delivery to an end user and use digital fingerprint technology to generate a unique copy for each vehicle after delivery. In a word, we propose a file purchasing application in VANETs and also develop a secure framework for this application.

Vehicular ad hoc networks (VANET) is a class of ad hoc networks build to ensure the safety of traffic. This is important because accidents claim many lives. Trust and security remain a major concern in VANET since a simple mistake can have catastrophic consequence. A crucial point in VANET is how to trust the information transmitted when the neighboring vehicles are rapidly changing and moving in and out of range. Current reputation systems for VANET try to establish trust between entities, which might not be required for practical scenarios. Due to the ephemeral nature of VANET, reputation schemes for mobile ad hoc networks (MANETs) cannot be applied to VANET. In this thesis, we point out several limitations of reputation trust management schemes for VANET. In particular, we identify the problem of information cascading and oversampling, which commonly arise in social networks. Oversampling is a situation in which a node observing two or more nodes, takes into consideration both their opinions equally without knowing that they might have influenced each other in decision making. We show that simple voting for decision making, leads to oversampling. We propose a solution to overcome this problem in VANET. We also suggest new ways to merge reputation schemes with misbehavior detection schemes to establish a trustworthy VANET.

It is believed that the next few decades will witness the booming development of the Internet of Things (IoT). Vehicular network, as a significant component of IoT, has attracted lots of attention from both academia and industry in recent years. In the field of vehicular networks, Vehicular Ad hoc NETwork (VANET) is one of the hottest topics investigated. This dissertation focuses on VANET geocast, which is a special form of multicast in VANET. In geocast, messages are delivered to a group of destinations in the network identified by their geographic locations. Geocast has many promising applications, i.e., geographic messaging, geographic advertising and other location-based services. Two phases are usually considered in the geocast process: phase one, message delivery from the message source to the destination area by geographic routing; phase two, message broadcast within the destination area. This dissertation covers topics in the two phases of geocast in urban VANETs, where for phase one, a data-driven geographic routing scheme and a security and privacy preserving framework are presented; and for phase two, the networking connectivity is analyzed and studied. The contributions of this dissertation are three-fold. First, from a real-world data trace study, this dissertation studies the city taxi- cab mobility. It proposes a mobility-contact-aware geocast scheme (GeoMobCon)for metropolitan-scale urban VANETs. The proposed scheme employs the node mobility (two levels, i.e., macroscopic and microscopic mobilities) and contact history information. A buffer management scheme is also introduced to further improve the performance. Second, this dissertation investigates the connectivity of the message broadcast in urban scenarios. It models the message broadcast in urban VANETs as the directed connectivity problem on 2D square lattices and proposes an algorithm to derive the exact analytical solution. The approach is also applied to urban VANET scenarios, where both homogeneous and heterogeneous vehicle density cases are considered. Third, this work focuses on the security and privacy perspectives of the opportunistic routing, which is the main technique utilized by the proposed geographic routing scheme. It proposes a secure and privacy preserving framework for the general opportunistic-based routing. A comprehensive evaluation of the framework is also provided. In summary, this dissertation focuses on a few important aspects of the two phases of VANET geocast in urban scenarios. It shows that the vehicle mobility and contact information can be utilized to improve the geographic routing performance for large- scale VANET systems. Targeting at the opportunistic routing, a security and privacy preserving framework is proposed to preserve the confidentiality of the routing metric information for the privacy purpose, and it also helps to achieve the anonymous authentication and efficient key agreement for security purposes. On the other hand, the network connectivity for the message broadcast in urban scenarios is studied quantitatively with the proposed solution, which enables us to have a better understanding of the connectivity itself and its impact factors (e.g., bond probability and network scale). / Graduate

München, Techn. Univ., Diss., 2010.

Vehicular ad hoc networks (VANET) is a class of ad hoc networks build to ensure the safety of traffic. This is important because accidents claim many lives. Trust and security remain a major concern in VANET since a simple mistake can have catastrophic consequence. A crucial point in VANET is how to trust the information transmitted when the neighboring vehicles are rapidly changing and moving in and out of range. Current reputation systems for VANET try to establish trust between entities, which might not be required for practical scenarios. Due to the ephemeral nature of VANET, reputation schemes for mobile ad hoc networks (MANETs) cannot be applied to VANET. In this thesis, we point out several limitations of reputation trust management schemes for VANET. In particular, we identify the problem of information cascading and oversampling, which commonly arise in social networks. Oversampling is a situation in which a node observing two or more nodes, takes into consideration both their opinions equally without knowing that they might have influenced each other in decision making. We show that simple voting for decision making, leads to oversampling. We propose a solution to overcome this problem in VANET. We also suggest new ways to merge reputation schemes with misbehavior detection schemes to establish a trustworthy VANET.

Since supplying passenger safety is the fundamental purpose of establishing vehicular ad hoc networks, researchers are mainly concerned with giving a strategy to ensure meeting this demand. Rescue services vehicles are one of the primary components of VANET, and the messages they broadcast play a vital part in delivering safety. As a result, offering a routing protocol algorithm that prioritizes their messages and guarantees QoS is one approach to meet the core purpose of VANET, or in other words, safety. Grouping the vehicle nodes, also known as clustering, is one of the appropriate solutions for improving the performance of the routing protocol. Most traditional cluster-based topologies in VANET solely consider the mobility to pick the cluster head. While cluster head speed fluctuations can affect the number of cluster head choices and improve the VANET QoS. Furthermore, the fast movement of vehicles exposes clustering links to vulnerability and directly impacts reliability. In this research, we proposed a new efficient multi-hop cluster-based routing protocol that prioritizes emergency vehicles' messages and provides stable and reliable communications to ensure emergency messages are delivered effectively. The number of neighbors, the distance between the vehicle and BS, and the S/N power received by the base station (BS) are the criteria for selecting a cluster head (CH) in our proposed model. Each CH is in charge of transmitting data from other cluster members to the infrastructure directly or indirectly through the qualified adjacent cluster heads. The epigenomic workflow approach is employed in our design to establish efficient resource management in RSU computing nodes and decrease transmission latency. The transmitted messages from vehicles are divided into two separate queues (q1 and q2), while the priority message queue uses the TDMA protocol to disseminate. In this thesis, experiments and simulations were carried out utilizing the NS-2 tool with VanetMobisim integration to assess the efficacy of the suggested approach. Achieved results indicate that the proposed technique increases communication reliability and stability while improving QoS for messages provided by rescue services.

Vehicular Ad-hoc Network (VANET) is a special application of the Mobile Ad-hoc Network (MANET) for managing road traffic and substantially contributes to the development of Intelligent Transportation Systems (ITS). VANET was introduced as a standard for data communication between moving vehicles with and without fixed infrastructure. It aims to support drivers by improving safety and driving comfort as a step towards constructing a safer, cleaner and a more intelligent environment. Nowadays, vehicles are manufactured equipped with a number of sensors and devices called On Board Units (OBU) assisting the vehicle to sense the surrounding environment and then process the context information to effectively manage communication with the surrounding vehicles and the associated infrastructure. A number of challenges have emerged in VANET that have encouraged researchers to investigate this concept further. Many of the recent studies have applied different technologies for intelligent parking management. However, despite all the technological advances, researchers are no closer to developing a system that enables drivers to easily locate and reserve a parking space. Limited resources such as energy, storage space, availability and reliability are factors which could have contributed to the lack success and progress in this area. The task then is to close these gaps and present a novel solution for parking. This research intends to address this need by developing a novel architecture for locating and reserving a parking space that best matches the driver's preferences and vehicle profile without distracting the driver. The simple and easy-to-use mechanism focuses on the domain of an intelligent parking system that exploits the concept of InfoStation (IS) and context-aware system creating a single framework to locate and reserve a parking space. A three tier network topology comprising of vehicles, IS and the InfoStation Centre (ISC) has been proposed as the foundation of the on-street parking system architecture. The thesis attempts to develop the architecture of a parking management solution as a comfort-enhancing application that offers to reduce congestion related stress and improve the driver experience by reducing the time it takes to identify and utilise a parking space that is available.

Vehicular ad hoc networks (VANETs) have emerged as an area of interest for both industry and research scholars because they have become an essential part of intelligent transportation systems (ITSs). Many applications in VANET require sending a message to certain or all vehicles within a region, called geocast. Sometimes geocast requires that the message be kept alive within the region for a period of time. This time-stable geocast has a vital role in some ITS applications, particularly commercial applications. This study presents a novel time-stable geocast protocol that works well even in too sparse networks. Moreover, since commercial applications sometimes make it necessary to change the duration of the stable message within the region, the dynamic nature of a geocast protocol should allow this time to be extended, reduced, or canceled without any additional cost. Therefore, we call it a dynamic time-stable geocast, DTSG, protocol. It works in two phases (the pre-stable period and the stable period), and the simulation results show that it works well in its performance metrics (delivery ratio and network cost). In addition, these results validate the protocol prediction of its performance metrics. Moreover, with the informed time of zero, all the intended vehicles will be informed as soon as they enter the region. The fact that the protocol is independent of the networks’ density, the vehicles’ speed, and the vehicles’ broadcasting range, makes it more robust than others that fail in sparse networks or in high-speed nodes.

Vehicular ad hoc networks (VANETs) have emerged as an area of interest for both industry and research scholars because they have become an essential part of intelligent transportation systems (ITSs). Many applications in VANET require sending a message to certain or all vehicles within a region, called geocast. Sometimes geocast requires that the message be kept alive within the region for a period of time. This time-stable geocast has a vital role in some ITS applications, particularly commercial applications. This study presents a novel time-stable geocast protocol that works well even in too sparse networks. Moreover, since commercial applications sometimes make it necessary to change the duration of the stable message within the region, the dynamic nature of a geocast protocol should allow this time to be extended, reduced, or canceled without any additional cost. Therefore, we call it a dynamic time-stable geocast, DTSG, protocol. It works in two phases (the pre-stable period and the stable period), and the simulation results show that it works well in its performance metrics (delivery ratio and network cost). In addition, these results validate the protocol prediction of its performance metrics. Moreover, with the informed time of zero, all the intended vehicles will be informed as soon as they enter the region. The fact that the protocol is independent of the networks’ density, the vehicles’ speed, and the vehicles’ broadcasting range, makes it more robust than others that fail in sparse networks or in high-speed nodes.