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Vehicular ad-hoc networks (VANETs) are envisioned to provide many road and safety applications that will improve drivers' awareness and enhance the driving experience. Many of proposed applications are location-based that depend on sharing the location information of vehicles and events among neighboring nodes. The location-based applications should provide vehicle operators with knowledge of the current surrounding conditions to help them make appropriate traveling decisions, such as avoiding traffic congestion. Drivers expect to receive accurate and reliable information from other vehicles. Therefore, securing localization service integrity is important to support a VANET's overall system reliability. In this thesis, we study the exchanged location information in VANETs and designed a framework to prevent potential security threats that will violate users' privacy and overcome limitations that can impact the exchanged data integrity and reliability. The solution developed a secure neighborhood awareness service and shared localization information management protocol in a VANET. The proposed framework is constructed through several components: (i) a location verification protocol that will secure location information by providing a non-line-of-sight (NLOS) verification protocol to overcome moving obstacle effects; (ii) privacy-preserving location information management to detect data inconsistency and provide a recovery process while preventing attackers from tracking individual vehicles; (iii) a trust model evaluation mechanism based on neighborhood awareness; (iv) an adaptive beacon protocol that will reduce the number of messages and provide quality of service(QoS) control for network managers and authorities. We also propose a security evaluation model that quantifies the security attributes for the localization service in a VANET. The model will help evaluate an integrated security measures that are provided by different components of the network services.

This thesis presents a protocol for intervehicle communication for use in Vehicular Ad Hoc Networks (VANET). VANET is a natural extension of mobile ad hoc networks (MANET) in which the restrictions related to power and mobility are relaxed. The routing protocols used for MANETs are generally dependent on the state of the network. With changes in the network topology, routing messages are generated so that the states of the routers in the network are updated. In the case of VANETs, in which the level of node mobility is high, message-routing overhead has serious implications for the scalability and throughput of the routing protocol. This thesis introduces criteria that are recommended for use when protocols are designed for VANET applications and presents the Selected Node Geographic Forwarding (SNGF) protocol. The SNGF protocol implements controlled flooding in an efficient manner in order to reduce unnecessary communication overhead. The protocol has a destination discovery mechanism that allows it to initiate correspondence between nodes without reliance on static location services. The protocol avoids formation of clusters by using the concept of selective forwarding, thus providing the advantages of cluster based approaches without actually forming one itself. It effectively deals with blind flooding by introducing a comprehensive retransmission time delay in the nodes. This retransmission delay favors the nodes in the direction of the destination and prevents other nodes from retransmitting the same message. The SNGF protocol does not use routing tables, which require frequent updates in mobile networks, instead it relies on directing the messages to geographic locations which are forwarded by any available intermediary nodes. The protocol also provides techniques for handling network fragmentation which can be a frequent problem in vehicular networks. It is capable of delayed message transmission and multiple route discovery in the case of the non-availability of the shortest path to the destination. To evaluate the performance of the SNGF protocol, an extensive study of mobile networks was conducted using the NS2 simulator. The simulation results demonstrate the reachability of the protocol, its scalability advantages and its total independence from location services. The SNGF protocol allows each participating node to operate independently of other nodes in the network. Nodes in the network are able to communicate with other nodes without ever becoming dependent on intermediary nodes. This feature opens new possibility for individual node based application development in ad hoc networks. The traffic profiling is described as it would be observed by an independent node participating in VANET using the SNGF protocol. The node communicates with other nodes and collects relevant data through the discourse capability of SNGF. The data collected by the node is viewed as a snapshot in time of the traffic conditions down the road based upon which future traffic condition is predicted. Traffic profiling is investigated for different levels of VANET deployment. The simulation results show that the proposed method of traffic profiling in a VANET environment using the SNGF protocol is viable for even lower levels of deployment.

Improving road safety and traffic efficiency has been a long-term endeavor for the government, automobile industry and academia. Recently, the U.S. Federal Communication Commission (FCC) has allocated a 75 MHz spectrum at 5.9 GHz for vehicular communications, opening a new door to combat the road fatalities by letting vehicles communicate to each other on the roads. Those communicating vehicles form a huge Ad Hoc Network, namely Vehicular Ad Hoc Network (VANET). In VANETs, a variety of applications ranging from the safety related (e.g. emergence report, collision warning) to the non-safety related (e.g., delay tolerant network, infortainment sharing) are enabled by vehicle-to-vehicle (V-2-V) and vehicle-to-roadside (V-2-I) communications. However, the flourish of VANETs still hinges on fully understanding and managing the challenging issues over which the public show concern, particularly, security and privacy preservation issues. If the traffic related messages are not authenticated and integrity-protected in VANETs, a single bogus and/or malicious message can potentially incur a terrible traffic accident. In addition, considering VANET is usually implemented in civilian scenarios where locations of vehicles are closely related to drivers, VANET cannot be widely accepted by the public if VANET discloses the privacy information of the drivers, i.e., identity privacy and location privacy. Therefore, security and privacy preservation must be well addressed prior to its wide acceptance. Over the past years, much research has been done on considering VANET's unique characteristics and addressed some security and privacy issues in VANETs; however, little of it has taken the social characteristics of VANET into consideration. In VANETs, vehicles are usually driven in a city environment, and thus we can envision that the mobility of vehicles directly reflects drivers' social preferences and daily tasks, for example, the places where they usually go for shopping or work. Due to these human factors in VANETs, not only the safety related applications but also the non-safety related applications will have some social characteristics. In this thesis, we emphasize VANET's social characteristics and introduce the concept of vehicular social network (VSN), where both the safety and non-safety related applications in VANETs are influenced by human factors including human mobility, human self-interest status, and human preferences. In particular, we carry on research on vehicular delay tolerant networks and infotainment sharing --- two important non-safety related applications of VSN, and address the challenging security and privacy issues related to them. The main contributions are, i) taking the human mobility into consideration, we first propose a novel social based privacy-preserving packet forwarding protocol, called SPRING, for vehicular delay tolerant network, which is characterized by deploying roadside units (RSUs) at high social intersections to assist in packet forwarding. With the help of high-social RSUs, the probability of packet drop is dramatically reduced and as a result high reliability of packet forwarding in vehicular delay tolerant network can be achieved. In addition, the SPRING protocol also achieves conditional privacy preservation and resist most attacks facing vehicular delay tolerant network, such as packet analysis attack, packet tracing attack, and black (grey) hole attacks. Furthermore, based on the ``Sacrificing the Plum Tree for the Peach Tree" --- one of the Thirty-Six Strategies of Ancient China, we also propose a socialspot-based packet forwarding (SPF) protocol for protecting receiver-location privacy, and present an effective pseudonyms changing at social spots strategy, called PCS, to facilitate vehicles to achieve high-level location privacy in vehicular social network; ii) to protect the human factor --- interest preference privacy in vehicular social networks, we propose an efficient privacy-preserving protocol, called FLIP, for vehicles to find like-mined ones on the road, which allows two vehicles sharing the common interest to identify each other and establish a shared session key, and at the same time, protects their interest privacy (IP) from other vehicles who do not share the same interest on the road. To generalize the FLIP protocol, we also propose a lightweight privacy-preserving scalar product computation (PPSPC) protocol, which, compared with the previously reported PPSPC protocols, is more efficient in terms of computation and communication overheads; and iii) to deal with the human factor -- self-interest issue in vehicular delay tolerant network, we propose a practical incentive protocol, called Pi, to stimulate self-interest vehicles to cooperate in forwarding bundle packets. Through the adoption of the proper incentive policies, the proposed Pi protocol can not only improve the whole vehicle delay tolerant network's performance in terms of high delivery ratio and low average delay, but also achieve the fairness among vehicles. The research results of the thesis should be useful to the implementation of secure and privacy-preserving vehicular social networks.

Submitted by Luciana Sebin (lusebin@ufscar.br) on 2016-10-11T12:21:35Z No. of bitstreams: 1 DissASA.pdf: 1261155 bytes, checksum: c70182e69e5460100b08d408d4eeb58c (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-10-20T13:40:04Z (GMT) No. of bitstreams: 1 DissASA.pdf: 1261155 bytes, checksum: c70182e69e5460100b08d408d4eeb58c (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-10-20T13:40:12Z (GMT) No. of bitstreams: 1 DissASA.pdf: 1261155 bytes, checksum: c70182e69e5460100b08d408d4eeb58c (MD5) / Made available in DSpace on 2016-10-20T13:40:18Z (GMT). No. of bitstreams: 1 DissASA.pdf: 1261155 bytes, checksum: c70182e69e5460100b08d408d4eeb58c (MD5) Previous issue date: 2016-01-29 / Não recebi financiamento / The perspective of an accelerated growth of the Internet of Things, has been increasing the concern on how to make the infrastructure of networks more robust and energetically efficient. In this sense, opportunistic and dynamic networks, such as delay and disruption tolerant networks (DTN) and vehicular ad-hoc networks (VANET), need to be compatible with extremely efficient message routing algorithms. Examples of routing algorithms for opportunistic networks include the Epidemic and the Spray-and-Wait, which have high message transmission cost. With the objective of obtaining a more efficient communication, this work presents a new message routing approach based on dynamic graphs, known as Time-Varying Graphs (TVG). In the literature, there are algorithms which calculate optimal paths within a TVG, for example, the path which allows the minimum travel time for a message. This work proposes a distributed routing algorithm, named Time-Varying Shortest Path (TVFP), which calculates the optimal path in a TVG that allows message delivery within the shortest possible time. The algorithm was implemented in the ONE simulator and experiments were conducted in order to comparatively evaluate its performance against other DTN algorithms. The results show that TVFP has better performance than the other algorithms, delivering messages in shorter times and causing a smaller overhead due to generation of redundant and intermediate messages. / A perspectiva de um crescimento acelerado da Internet das Coisas tem aumentado a preocupação em tornar as redes sem infraestrutura mais robustas e eficientes energeticamente. Nesse sentido, redes oportunistas e dinâmicas, tais como as redes tolerantes a atrasos e desconexões (DTN) e as redes veiculares ad-hoc (VANET), precisam ser compatíveis com algoritmos de roteamento de mensagens mais eficientes. Exemplos de algoritmos de roteamento em redes DTN incluem o Epidemic e o Spray-and-Wait, que possuem alto custo de transmissão de mensagens. Com o objetivo de se obter uma comunicação mais eficiente, este trabalho apresenta uma nova abordagem de roteamento de mensagens baseada no uso de grafos dinâmicos, conhecidos no inglês como Time-Varying Graphs (TVG). Na literatura, existem algoritmos que calculam caminhos ótimos em TVGs, como por exemplo, busca do caminho que permite o menor tempo de viagem. Este trabalho propõe a criação de um algoritmo distribuído de roteamento e encaminhamento de mensagens em redes DTN, denominado Time-Varying Fastest Path (TVFP), que calcula o caminho a partir do TVG para se entregar a mensagem ao destino no menor tempo possível, utilizando uma única instância da mensagem. O algoritmo foi implementado no simulador ONE e experimentos foram conduzidos para avaliar seu desempenho comparativamente com outros algorimos para DTNs. Os resultados mostram que o TVFP obtem melhor desempenho que os demais algoritmos, fazendo com que a mensagem chegue mais cedo ao destino, e causando uma menor sobrecarga de geração de mensagens redundantes e intermediárias.

Vehicular Ad Hoc Network (VANET) is a sub class of mobile ad hoc networks. VANET provides wireless communication among vehicles and vehicle to road side equipments. The communication between vehicles is used for safety, comfort and for entertainment as well. The performance of communication depends on how better the routing takes place in the network. Routing of data depends on the routing protocols being used in network. In this study we investigated about different ad hoc routing protocols for VANET. The main aim of our study was to identify which ad hoc routing method has better performance in highly mobile environment of VANET. To measure the performance of routing protocols in VANET, we considered two different scenarios i.e. city and highway. Routing protocols were selected carefully after carrying out literature review. The selected protocols were then evaluated through simulation in terms of performance metrics i.e. throughput and packet drop. After simulation results, we used MATLAB to plot the graph to compare the results of selected routing protocols with each other. Moreover, we computed the sum of output from each scenario to clearly present the difference in results. From results, we observe that A-STAR shows better performance in form of high throughput and low packet drop as compare to AODV and GPSR in city environment, while GPSR shows better performance as compare to AODV in both highway and city environment of VANET. Based on the results of performance metrics in different environments of VANET, we realized that position based routing method of VANET outperformed the traditional ad hoc topology based routing. However, it is hard to provide any universal routing protocol that can deal with all the various environments of VANET. The selection of a single routing protocol is hard in VANET because the protocol performance depends on vehicle speed, driving environment etc. That may vary from one environment of network to another.

In this work, we provide a qualitative comparison between existing geocast protocols and then we present an efficient geocast routing protocol for VANET. This protocol is a semantic and self-decision geocast routing protocol for disseminating safety and non-safety information over VANET (SAS-GP). SAS-PG initially executes an algorithm to locally determine the semantic geocast area. Then, the protocol disseminates the information in three phases: Spread, Preserve, and Assurance, which utilize the traffic information system and the digital map. SAS-GP principally employs timer-based techniques in order to avoid overhead and broadcast storm problems; nonetheless, novel factors are enhanced to calculate the timer’s values in each phase. Simulation results demonstrate effective and reliable dissemination in terms of delivery ratio and number of false warnings compared to existing protocols when evaluated in high scale and realistic scenarios. Also, SAS-GP performs faster in notifying vehicles resulting in a higher geocast distance before approaching the location of the event.

As important components of intelligent transportation system, lane detection and tracking (LDT) and lane departure warning (LDW) systems have attracted great interest from the computer vision community over the past few years. Conversely, lane markings recognition (LMR) systems received surprisingly little attention. This thesis proposed a real-time lane assisting framework for intelligent vehicles, which consists of a comprehensive module and simplified module. To the best of our knowledge, this is the first parallel architecture that considers not only lane detection and tracking, but also lane marking recognition and departure warning. A lightweight version of the Hough transform, PPHT is used for both modules to detect lines. After detection stage, for the comprehensive module, a novel refinement scheme consisting of angle threshold and segment linking (ATSL) and trapezoidal refinement method (TRM) takes shape and texture information into account, which significantly improves the LDT performance. Also based on TRM, colour and edge informations are used to recognize lane marking colors (white and yellow) and shapes (solid and dashed). In the simplified module, refined MSER blobs dramatically simplifies the preprocessing and refinement stage, and enables the simplified module performs well on lane detection and tracking. Several experiments are conducted in highway and urban roads in Ottawa. The detection rate of the LDT system in comprehensive module average 95.9% and exceed 89.3% in poor conditions, while the recognition rate depends on the quality of lane paint and achieves an average accuracy of 93.1%. The simplified module has an average detection rate of 92.7% and exceeds 84.9% in poor conditions. Except the conventional experimental methods, a novel point cluster evaluation and pdf analysis method have been proposed to evaluate the performance of LDT systems, in terms of the stability, accuracy and similarity to Gaussian distribution.

Vehicular ad-hoc networks (VANETs) are envisioned to provide many road and safety applications that will improve drivers' awareness and enhance the driving experience. Many of proposed applications are location-based that depend on sharing the location information of vehicles and events among neighboring nodes. The location-based applications should provide vehicle operators with knowledge of the current surrounding conditions to help them make appropriate traveling decisions, such as avoiding traffic congestion. Drivers expect to receive accurate and reliable information from other vehicles. Therefore, securing localization service integrity is important to support a VANET's overall system reliability. In this thesis, we study the exchanged location information in VANETs and designed a framework to prevent potential security threats that will violate users' privacy and overcome limitations that can impact the exchanged data integrity and reliability. The solution developed a secure neighborhood awareness service and shared localization information management protocol in a VANET. The proposed framework is constructed through several components: (i) a location verification protocol that will secure location information by providing a non-line-of-sight (NLOS) verification protocol to overcome moving obstacle effects; (ii) privacy-preserving location information management to detect data inconsistency and provide a recovery process while preventing attackers from tracking individual vehicles; (iii) a trust model evaluation mechanism based on neighborhood awareness; (iv) an adaptive beacon protocol that will reduce the number of messages and provide quality of service(QoS) control for network managers and authorities. We also propose a security evaluation model that quantifies the security attributes for the localization service in a VANET. The model will help evaluate an integrated security measures that are provided by different components of the network services.

This diploma thesis aims to study VANET (vehicular ad hoc network), to describe the theory of this networks and describe attributes of these networks and to set the starting point for practical part. Thesis includes VANETs possibilities, its signal transportation and description of routing protocols. Another goal was to familiarize program NS-3 and set up simulation models in its interface. The main output of the practical part is program which simulates vehicle movement in Brno city and set the communication module which is adapted to fulfill the most realistic transmission capabilities. Practical part is divided to two parts. The goal of the first one was to simulate basic communication in theorized unrealistic scenario and the second part was the more realistic scenario. Overall, throughout the practical part was tested a variety of attributes, such as mobility models, standards, routing protocols and other parameters that provided diversity in final results. All the results, which consisted of summary of basic transmission capabilities and reclassification of the applicability of those technologies in real world, are discussed in the summary of the simulations output.