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Recently a number of communications schemes have been proposed for Vehicular Ad hoc Networks (VANETs). One of these, the Universal Geocast Scheme (UGS) proposed by Hossein Pishro-Nik and Mohammad Nekoui, provides for a diverse variety of VANET-specific characteristics such as time-varying topology, protocol variation based on road congestion, and support for non line-of-sight communication. In this research, the UGS protocol is extended to consider inter-vehicle multi-hop connections in intersections with surrounding obstructions along with single-hop communications in an open road scenario. Since UGS is a probabilistic, repetition-based scheme, it supports the capacity-delay tradeoffs crucial for periodic safety message exchange. The approach is shown to support both vehicle-to-vehicle and vehicle-to-infrastructure communication. This research accurately evaluates this scheme using network (NS-2) and mobility (SUMO) simulators, verifying two crucial elements of successful VANETs, received packet ratio and message delay. A contemporary wireless radio propagation model is used to augment accuracy. Results show a 6% improvement in received packet ratio in intersection simulations combined with a decrease in average packet delay versus a previous, well-known inter-vehicle communication protocol.

Vehicular Ad-hoc Networks (VANETs) provide networks for smart vehicles and will enable future systems to provide services that enhance the overall transportation experience. However, these applications require consideration to possible damage to both property and human life. Communication between vehicles requires data immutability and user privacies to provide safe operation of the system. Blockchains can provide these properties and more to create a more secure and decentralized system. However, a chain’s security comes from the chain length. VANETs’ ephemeral connections provide harm limits how much data can be exchanged during vehicle rendezvous. This thesis investigates lightweight blockchains that operate with lower overheads. A survey of current techniques to accomplish this are discussed in Chapter 1. Two techniques are demonstrated within two separate environments to demonstrate the network overhead reductions when using a lightweight blockchain with respect to network and storage loads within these VANET environments.

Vehicles are more frequently being built with hardware that supports wireless communica- tion capabilities. Dedicated short-range communications (DSRC) is a standard that enables the hardware on vehicles to communicate with one another directly rather than through external infrastructure such as a cellular tower. With DSRC supporting small-range communications, multi-hop routing is utilized when a packet needs to reach a long-range destination. A vehicular ad-hoc network (VANET) broadcast protocol (VBP) was developed. This thesis introduces VBP, an open-source framework for simulating multi-hop routing on mobile and wireless vehicular networks. VBP is built for the routing layer of the network simulation tool called network simulator 3 (ns-3) and contains a custom protocol that adapts to various traffic conditions on a roadway. To test VBP we ran six simulations across three traffic levels. Results confirm that VBP successfully routes packets or queues packets when a first or next hop is not available. The development process of VBP is documented to help researchers who are trying to create a custom routing protocol for ns-3.

This work first implements a prototype of the proof-of-location scheme Vouch in order for an evaluation to be conducted in a real-world environment. With simulations of the scheme showing promising results, the next step would be an evaluation of the schemes performance in the real-world. This report introduces the scheme and similar works in relation to implementation and evaluation. Method of implementation is presented followed by an evaluation. The evaluation focuses on detection accuracy of the scheme by investigating impacts of the inevitably arising staleness. Contributors of staleness are identified and their impacts on overall detection accuracy of Vouch are measured. With the prototype successfully implemented, measurements showed a trend in improving detection accuracy with higher proof update frequencies, reaching as high as 9̃5% in a high velocity environment. The results shows that the Vouch scheme not only gives promising results in simulation, but also in the real-world.

<p>Smart scheduling can be used to reduce infrastructure-to-vehicle</p> <p>energy costs in delay tolerant vehicular</p> <p>networks (Hammad et al., 2010).. In this thesis we show that by combining</p> <p>this with vehicle-to-vehicle (V2V) forwarding, energy efficiency can</p> <p>be increased beyond that possible in the single hop case. This is</p> <p>accomplished by having the roadside infrastructure forward packets</p> <p>through vehicles which are in energy favourable locations. We first</p> <p>derive offline bounds on the downlink energy usage for a given input</p> <p>sample function when V2V forwarding is used. Separate bounds are given</p> <p>for the off-channel and in-channel forwarding cases. These bounds are</p> <p>used for comparisons with a variety of proposed online scheduling</p> <p>algorithms. The paper then introduces online algorithms for both</p> <p>fixed bit rate and variable bit rate air interface options. The first</p> <p>algorithm is based on a greedy local optimization (GLOA). A version of</p> <p>this algorithm which uses a minimum cost flow graph scheduler is also</p> <p>introduced. A more sophisticated algorithm is then proposed which is</p> <p>based on a finite window group optimization (FWGO). Versions of these</p> <p>algorithms are also proposed which use in-channel vehicle-to-vehicle</p> <p>scheduling. The proposed algorithms are also adapted to the variable</p> <p>bit rate air interface case. Results from a variety of experiments</p> <p>show that the proposed scheduling algorithms can significantly improve</p> <p>the downlink energy requirements of the roadside unit compared to the</p> <p>case where vehicle-to-vehicle packet forwarding is not used. The</p> <p>performance improvements are especially strong under heavy loading</p> <p>conditions and when the variation in vehicle communication</p> <p>requirements or vehicle speed is high.</p> / Master of Applied Science (MASc)

<p>This thesis proposes different scheduling algorithm to be implemented on the Roadside Units in ITS environment. Both variable and constant bit rate cases are considered.</p> / <p>Vehicular Ad-hoc Networks (VANETs) will be an integral part of future Intelligent Trans- portation Systems (ITS). In highway settings where electrical power connections may not be available, road-side infrastructure will often be powered by renewable energy sources, such as solar power. For this reason, energy efficient designs are desirable.</p> <p>This thesis considers the problem of energy efficient downlink scheduling for road- side infrastructure. In the first part of the thesis, the constant bit rate (CBR) air interface case is investigated. Packet-based and timeslot-based scheduling models for the theoretical minimum energy bound are considered. Timeslot-based scheduling is then formulated as a Mixed Integer Linear Program (MILP). Following this, three energy efficient online scheduling algorithms with varying complexity are introduced. Results from a variety of experiments show that the proposed scheduling algorithms perform well when compared to the energy lower bounds.</p> <p>In the second part of the thesis, the variable bit rate (VBR) air interface option is considered. Offline scheduling formulations are derived that provide lower bounds on the energy required to fufill vehicle requests. An integer linear program (ILP) is introduced which can be solved to find optimal offline VBR schedules. Two flow graph based models are then introduced. The first uses Generalized Flow (GF) graphs and the second uses time expanded graphs (TEGs) to model the scheduling problem. Four online scheduling algorithms with varying energy efficiency, fairness and computational complexities are developed. The proposed algorithms’ performance is examined under different traffic scenarios and they are found to perform well compared to the lower bound.</p> / Doctor of Philosophy (PhD)

Tesis por compendio / [EN] Vehicular Ad-hoc Networks (VANET) are a special type of networks where the nodes involved in the communication are vehicles. VANETs are created when several vehicles connect among themselves without the use of any infrastructure. In certain situations the absence of infrastructure is an advantage, but it also creates several challenges that should be overcome. One of the main problems related with the absence of infrastructure is the lack of a coordinator that can ensure a certain level of quality in order to enable the correct transmission of video and audio. Video transmission can be extremely useful in this type of networks as it can be used for videoconferencing of by traffic authorities to monitor the scene of an accident. In this thesis we focused on real time video transmission, providing solutions for both unicast and multicast environments. Specifically, we built a real-world testbed scenario and made a comparison with simulation results to validate the behavior of the simulation models. Using that testbed we implemented and improved DACME, an admission control module able to provide Quality of Service (QoS) to unicast video transmissions. DACME proved to be a valid solution to obtain a certain level of QoS in multi-hop environments. Concerning multicast video transmission, we developed and simulated several flooding schemes, focusing specifically on VANET environments. In this scope, the main contribution of this thesis is the Automatic Copies Distance Based (ACDB) flooding scheme. Thanks to the use of the perceived vehicular density, ACDB is a zeroconf scheme able to achieve good video quality in both urban and highway environments, being specially effective in highway environments. / [ES] Las redes vehiculares ad-hoc (VANET) son un tipo especial de redes en las que los nodos que participan de la comunicación son vehículos. Las VANETs se crean cuando diversos vehículos se conectan entre ellos sin el uso de ninguna infraestructura. En determinadas situaciones, la ausencia de infraestructura es una ventaja, pero también crea una gran cantidad de desafíos que se deben superar. Uno de los principales problemas relacionados con la ausencia de infraestructura, es la ausencia de un coordinador que pueda asegurar un determinado nivel de calidad, para poder asegurar la correcta transmisión de audio y vídeo. La transmisión de vídeo puede ser de extrema utilidad en este tipo de redes ya que puede ser empleada para videoconferencias o por las autoridades de tráfico para monitorizar el estado de un accidente. En esta tesis nos centramos en la transmisión de vídeo en tiempo real, proveyendo soluciones tanto para entornos unicast como multicast. En particular construimos un banco de pruebas real y comparamos los resultados obtenidos con resultados obtenidos en un entorno simulado para comprobar la fiabilidad de estos modelos. Usando el mismo banco de pruebas, implementamos y mejoramos DACME, un módulo de control de admisión capaz de proveer de calidad de servicio a transmisiones de vídeo unicast. DACME probó ser una solución válida para obtener ciertos niveles de calidad de servicio en entornos multisalto. En lo referente a la transmisión de vídeo multicast, desarrollamos y simulamos diversos esquemas de difusión diseñados específicamente para entornos VANET. En este campo, la principal contribución de esta tesis es el esquema de difusión "Automatic Copies Distance Based" (ACDB). Gracias al uso de la densidad vehicular percibida, ACDB es un esquema, que sin necesidad de configuración, permite alcanzar una buena calidad de vídeo tanto en entornos urbanos como en autopistas, siendo especialmente efectivo en este último entorno. / [CA] Les xarxes vehiculars ad-hoc (VANET) son un tipus de xarxes especials a les que els diferents nodes que formen part d'una comunicació son vehicles. Les VANETs es formen quan diversos vehicles es connecten sense fer ús de cap infraestructura. A certes situacions l'absència d'una infraestructura suposa un avantatge, encara que també genera una gran quantitat de desafiaments que s'han de superar. U dels principals problemes relacionats amb l'absència d'infraestructura, és la manca d'un coordinador que puga garantir una correcta transmissió tant de video com d'àudio. La transmissió de video pot ser d'extrema utilitat a aquest tipus de xarxes, ja que es por emprar tant per a videoconferències com per part de les autoritats de trànsit per monitoritzar l'estat d'un accident. A aquesta tesi ens centrem en transmissió de video en temps real, proporcionant solucions tant a entorns unicast como a entorns multicast. Particularment, vam construir un banc de proves i obtinguérem resultats que comparàrem amb resultats obtinguts mitjançant simulació. D'aquesta manera validarem la fiabilitat dels resultats simulats. Fent ús del mateix banc de proves, vàrem implementar i millorar DACME, un mòdul de control d'admissió, capaç de proveir de qualitat de servici a transmissions de video unicast. DACME va provar ser una bona solució per obtindré un bon nivell de qualitat de servici en entorns de xarxes ad-hoc amb diversos salts. Si ens centrem a la transmissió de video multicast, vàrem implementar i simular diferents esquemes de difusió, específicament dissenyats per al seu ús a entorns VANET. La principal contribució d'aquesta tesi es l'esquema de difusió ACDB (Automatic Copies Distance Based). Fent ús de la densitat vehicular, ACDB es capaç d'obtindre una bona qualitat de video tant a ciutats com a vies interurbanes, sent a especialment efectiu a aquestes últimes. A més a més no es necessària cap configuració per part de l'usuari. / Torres Cortés, Á. (2016). Efficient real-time video delivery in vehicular networks [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/62685 / Compendio

Vehicular communication systems are integral for efficient highway operational management and for mitigating severe traffic congestion. While vehicular ad hoc networks (VANET) are reliable and provide avenues to minimal reliance on existing infrastructure, they can experience high communication overhead and network disruptions. Vehicular micro clouds (VMCs) provide a promising solution to overcome the challenges of VANET by reducing communication latency through cooperative and collaborative resource allocation and data offloading. This thesis offers a comparative performance analysis of freeway incident management and vehicle platooning, comparing VANET communications versus stationary and platoon-based dynamic VMCs. Specifically, it studies speed and lane-changing advisories in addition to freeway platooning. To further enhance the analysis, the performance of both communication architectures is evaluated using communication protocols of DSRC versus cellular technologies of C-V2X, 4G LTE, and 5G NR for latency, bandwidth, range, and deployment considerations. The system-level features, such as driving safety and vehicular mobility are measured to evaluate the efficacy of the communication systems under incident-induced traffic conditions. The study uses the AIMSUN microscopic traffic simulator to model and analyze the performance of the proposed systems. Key performance indicators include communication latency and packet loss ratio. In addition, the stationary and dynamic cloud systems show advantages in reducing travel time delay, even at high penetration rates of the connected vehicles, whilst reducing collision risks. On average, we observe improvements in travel time by 10% by implementing vehicular clouds over traditional ad-hoc networks. From a communications standpoint, the overall latency delay and packet loss are reduced by 7% and 11%, respectively, with the implementation of cloud models. The findings also delineate the benefits of dynamic cloud models, given their improved manoeuvrability, can maximize the computational capabilities of CVs, even at high market penetrations in large-scale freeway demands. The results suggest a shift towards more reliance on connected vehicular clouds to minimize the risks associated with message interference and system overload, whilst fostering advancements in intelligent freeway traffic management systems. / Thesis / Master of Applied Science (MASc)

Rede Ad hoc Veicular (VANET) é um subconjunto singular das redes ad hoc móveis (MANET), com o diferencial de que os nós são veículos providos de tecnologia própria de comunicação e que interagem para formar redes espontâneas, valendo-se de pouca ou nenhuma infraestrutura estabelecida previamente. VANETs admitem a integração de diferentes tecnologias sem fio na pretensão de mitigar adversidades, agregar segurança e eficiência ao tráfego. Na disseminação de dados, um salto único é suficiente para orientar os elementos ao alcance do sinal de rádio, e nós intermediários sustentam a comunicação aos demais, em encaminhamento multihop. Amparados em dispositivos embarcados, os veículos produzem registros, detectam sinais, trocam advertências e métricas. Avaliações dessas informações permitem ao condutor decisões ou reações antecipadas em situações adversas, a exemplo dos acidentes ou congestionamentos. Nesse contexto, a execução deste trabalho trata questões para elaborar estratégias adaptativas inteligentes de disseminação de dados, uma vez que as mesmas se consolidam como lastros da comunicação em VANET com condições adversas de operação. A abordagem proposta se utiliza de sistemas fuzzy para a detecção de congestionamento, com o propósito de agregar autonomia e adaptar a estratégia de disseminação às condições de tráfego identificadas. A convergência nos desenvolvimentos realizados se reflete na estratégia eFIRST, uma solução robusta para a detecção autônoma da condição atual de congestionamento que resguarda a disseminação adaptativa de alertas e abranda o problema da interrupção no tráfego. A abordagem se sustenta apenas na comunicação entre veículos e nos registros de identificação da vizinhança local, agregados em uma estratégia fuzzy e no ajuste adaptativo da potência do sinal de transmissão. Em conformidade com as tendências de condução e com os sistemas inteligentes, este desenvolvimento contribui com subsídios para ratificar a aproximação fuzzy como estratégia adaptativa às flutuações na densidade veicular, em diferentes cenários e regimes de tráfego. As avaliações comparativas do eFIRST respaldam concluir que a estratégia oportuniza o equilíbrio otimizado das perdas, colisões e cobertura, com superior alcance de propagação e redução dos congestionamentos. / Vehicular Ad hoc Network (VANET) is a unique subset of mobile ad hoc networks (MANET), with the difference that nodes are vehicles provided with their own communication technology and interact to form spontaneous networks, with little or no infrastructure previously established. VANETs support the integration of different wireless technologies in order to mitigate adversities, add security and efficiency to traffic. In the data dissemination, a single hop is sufficient to guide the elements within reach of the radio signal, and intermediary nodes support the communication with the others in multihop routing. Supported by embedded devices, vehicles produce records, detect signals, exchange warnings and metrics. Assessments of this information allow the driver to make decisions or react beforehand in adverse situations, such as accidents or traffic congestions. From the observations in this context, this work deals with questions to elaborate intelligent adaptive strategies in data dissemination, since they consolidate themselves as ballast communication in VANET with adverse operating conditions. The proposed approach uses fuzzy systems to detect traffic congestion, with the purpose of aggregating autonomy and adapting the dissemination strategy to the identified traffic conditions. The convergence in the developments performed is reflected in the eFIRST strategy, a robust solution for the autonomous detection of the current traffic congestion condition that protects the adaptive dissemination of alerts and reduces the problem of the interruption in the traffic. The approach is supported only by communication between vehicles and in local neighborhood identification records, aggregated in a fuzzy strategy and in the adaptive adjustment of transmission signal power. In accordance with the driving trends and with the intelligent systems, this development contributes with assistance for ratify the fuzzy approach as an adaptive strategy to fluctuations in vehicular density in different scenarios and traffic regimes. Comparative evaluations of eFIRST support the conclusion that the strategy favors the optimal balance of losses, collisions and coverage, with a greater range of propagation and reduction of congestion.