The United States has been going through a road accident crisis for many years. The National Safety Council estimates 40,000 people were killed and 4.57 million injured on U.S. roads in 2017. Direct and indirect loss from tra c congestion only is more than $140 billion every year. Vehicular Ad-hoc Networks (VANETs) are envisioned as the future of Intelligent Transportation Systems (ITSs). They have a great potential to enable all kinds of applications that will enhance road safety and transportation efficiency. In this dissertation, we have aggregated seven years of real-life tra c and incidents data, obtained from the Florida Department of Transportation District 4. We have studied and investigated the causes of road incidents by applying machine learning approaches to this aggregated big dataset. A scalable, reliable, and automatic system for predicting road incidents is an integral part of any e ective ITS. For this purpose, we propose a cloud-based system for VANET that aims at preventing or at least decreasing tra c congestions as well as crashes in real-time. We have created, tested, and validated a VANET traffic dataset by applying the connected vehicle behavioral changes to our aggregated dataset. To achieve the scalability, speed, and fault-tolerance in our developed system, we built our system in a lambda architecture fashion using Apache Spark and Spark Streaming with Kafka. We used our system in creating optimal and safe trajectories for autonomous vehicles based on the user preferences. We extended the use of our developed system in predicting the clearance time on the highway in real-time, as an important component of the traffic incident management system. We implemented the time series analysis and forecasting in our real-time system as a component for predicting traffic flow. Our system can be applied to use dedicated short communication (DSRC), cellular, or hybrid communication schema to receive streaming data and send back the safety messages. The performance of the proposed system has been extensively tested on the FAUs High Performance Computing Cluster (HPCC), as well as on a single node virtual machine. Results and findings confirm the applicability of the proposed system in predicting traffic incidents with low processing latency. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2018. / FAU Electronic Theses and Dissertations Collection

Vehicular Ad hoc Networks (VANETs) have the potential to enable various kinds of applications aiming at improving road safety and transportation efficiency. These applications require uni-cast routing, which remains a significant challenge due to VANETs characteristics. Given VANET dynamic topology, geographic routing protocols are considered the most suitable for such network due to their scalability and low overhead. However, the optimal selection of next-hop nodes in geographic routing is a challenging problem where the routing performance is highly affected by the variable link quality and bandwidth availability. In this dissertation, a number of enhancements to improve geographic routing reliability in VANETs are proposed. To minimize packet losses, the direction and link quality of next-hop nodes using the Expected Transmission Count (ETX) are considered to select links with low loss ratios. To consider the available bandwidth, a cross-layer enchantment of geographic routing, which can select more reliable links and quickly react to varying nodes load and channel conditions, is proposed. We present a novel model of the dynamic behavior of a wireless link. It considers the loss ratio on a link, in addition to transmission and queuing delays, and it takes into account the physical interference e ect on the link. Then, a novel geographic routing protocol based on fuzzy logic systems, which help in coordinating di erent contradicting metrics, is proposed. Multiple metrics related to vehicles' position, direction, link quality and achievable throughput are combined using fuzzy rules in order to select the more reliable next-hop nodes for packet forwarding. Finally, we propose a novel link utility aware geographic routing protocol, which extends the local view of the network topology using two-hop neighbor information. We present our model of link utility, which measures the usefulness of a two-hop neighbor link by considering its minimum residual bandwidth and packet loss rate. The proposed protocol can react appropriately to increased network tra c and to frequent topology dis-connectivity in VANETs. To evaluate the performance of the proposed protocols, extensive simulation experiments are performed using network and urban mobility simulation tools. Results confirm the advantages of the proposed schemes in increased traffic loads and network density. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2018. / FAU Electronic Theses and Dissertations Collection

Wireless ad-hoc networks are based on a cooperative communication model, where all nodes not only generate traffic but also help to route traffic from other nodes to its final destination. In such an environment where there is no infrastructure support the lifetime of the network is tightly coupled with the lifetime of individual nodes. Most of the devices that form such networks are battery-operated, and thus it becomes important to conserve energy so as to maximize the lifetime of a node. In this thesis, we present JTP, a new energy-aware transport protocol, whose goal is to reduce power consumption without compromising delivery requirements of applications. JTP has been implemented within the JAVeLEN system. JAVeLEN~\cite{javelen08redi}, is a new system architecture for ad hoc networks that has been developed to elevate energy efficiency as a first-class optimization metric at all protocol layers, from physical to transport. Thus, energy gains obtained in one layer would not be offset by incompatibilities and/or inefficiencies in other layers. To meet its goal of energy efficiency, JTP (1) contains mechanisms to balance end-to-end vs. local retransmissions; (2) minimizes acknowledgment traffic using receiver regulated rate-based flow control combined with selected acknowledgments and in-network caching of packets; and (3) aggressively seeks to avoid any congestion-based packet loss. Within this ultra low-power multi-hop wireless network system, simulations and experimental results demonstrate that our transport protocol meets its goal of preserving the energy efficiency of the underlying network. JTP has been implemented on the actual JAVeLEN nodes and its benefits have been demoed on a real system.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / Atualmente, a tecnologia celular està presente em todos os aspectos da vida cotidiana: lares, escritÃrios, indÃstrias, etc. Tal tecnologia teve um rÃpido crescimento durante as duas Ãltimas dÃcadas tentando acompanhar o aumento do volume de trÃfego nas redes de comunicaÃÃo sem-fio. Naturalmente, ao propor modelos mais realistas possÃveis, com o propÃsito de caracterizar fenÃmenos que afetam a qualidade do sinal ou o desempenho do sistema, novas ideias, concepÃÃes e outras ferramentas surgem para descrever tais situaÃÃes. Este à o caso da Geometria EstocÃstica ou, particularmente, o processo pontual de Poisson, o qual vem sendo frequentemente utilizado como um modelo de rede celular, a partir da localizaÃÃo aleatÃria dos nÃs na rede. Diante desta ferramenta matemÃtica, à possÃvel implantar estaÃÃes rÃdio base na rede externa celular, bem como pontos de acesso baseados em picocÃlulas, femtocÃlulas, etc. AlÃm disso, permite-se quantificar a interferÃncia, Ãrea de cobertura, probabilidade de outage, dentre outros. Estes resultados tambÃm levam em consideraÃÃo o impacto de mobilidade no desempenho de tais redes. Nesse contexto, este trabalho analisarà redes ad-hoc sem-fio propondo expressÃes analÃticas para as seguintes mÃtricas de caracterizaÃÃo de desempenho: interferÃncia e conectividade de transmissÃo. Essas mÃtricas levam em consideraÃÃo tanto a razÃo sinal-ruÃdo mais interferÃncia (signal-to-interference-plus-noise ratio (SINR)) como a razÃo sinal-interferÃnca (signal-to-interference ratio (SIR)), em que neste caso, a potÃncia de ruÃdo à considerada nula. Especificamente, o fenÃmeno interferÃncia serà caracterizado via modelo shot-noise segundo um processo pontual chamado de processo pontual marcado (marked point process (MPP)), sendo este mais realista do que o tradicional modelo de Poisson. AlÃm disso, este tipo de modelo incorpora os efeitos de propagaÃÃo de rÃdio de pequena e larga escala e sobretudo as diferentes tecnologias de detecÃÃo e tratamento de sinal. Paralelamente, adotaremos um canal de rÃdio com desvanecimento Nakagami-m. Por fim, o tratamento matemÃtico para o modelo proposto torna-se um fator desafiador deste trabalho, visto que, tais resultados generalizam alguns jà publicados na literatura, os quais adotam alguns parÃmetros menos realistas. / Currently, cellular technology is present in all aspects of everyday life: homes, offices, industries, etc. Such technology had grown rapidly over the last two decades trying to follow up with the increased traffic volume on the networks of wireless communication. Naturally, to propose possible more realistic models, with the purpose of characterizing phenomena that affect the signal quality or performance system, new ideas, concepts and other tools to describe such situations arise. This is the case of Stochastic Geometry or, particularly, the point process Poisson, which has been often used as a model for cellular network from the random node locations in the network. Faced with this mathematical tool, it is possible deploy base stations in cellular external network and access points based picocells, femtocells, etc. Moreover, it allows to quantify the interference, coverage area, outage probability, among others. These results also consider the impact of mobility on the performance of such networks. In this context, this thesis will analyze ad-hoc wireless networks offering analytical expressions for the following metrics of performance characterization: interference and transmission connections. These metrics take into account both signal-to-interference-plus-noise ratio (SINR) and signal-to-interference ratio (SIR), in which case, the noise power is considered null. Specifically, the interference phenomena will be characterized via shot-noise model according to a point process called marked point process (MPP), this being more realistic than the traditional Poisson model. Furthermore, this type of model incorporates effects of radio propagation small and large scale, mainly the different technologies for the detection and signal processing. In parallel, we will adopt a radio channel with Nakagami-m fading. Finally, the mathematical treatment for the proposed model becomes a challenging factor in this work, since such results generalize some already published in the literature, which adopt some less realistic parameters.

Mi, Wengang. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 80-85). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgement --- p.iii / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Path loss and fading channel --- p.2 / Chapter 1.2 --- Relay Channel --- p.4 / Chapter 1.3 --- Power allocation --- p.6 / Chapter 1.4 --- Network coding --- p.8 / Chapter 1.5 --- Outline of the thesis --- p.8 / Chapter 2 --- Background Study --- p.10 / Chapter 2.1 --- Cooperative communication --- p.10 / Chapter 2.1.1 --- User cooperation diversity --- p.11 / Chapter 2.1.2 --- Cooperative diversity --- p.14 / Chapter 2.1.3 --- Coded cooperation --- p.18 / Chapter 2.2 --- Power control and resource allocation in cooperative communication --- p.19 / Chapter 2.3 --- Network coding --- p.21 / Chapter 3 --- Power allocation in DF system --- p.24 / Chapter 3.1 --- Introduction --- p.24 / Chapter 3.2 --- System Model --- p.25 / Chapter 3.3 --- BER analysis with power allocation --- p.27 / Chapter 3.3.1 --- BER analysis of single relay system --- p.27 / Chapter 3.3.2 --- Generalization for N-relay cooperation system --- p.30 / Chapter 3.4 --- Approximation --- p.31 / Chapter 3.5 --- Conclusion --- p.37 / Chapter 4 --- Network coding cooperation --- p.38 / Chapter 4.1 --- Introduction --- p.38 / Chapter 4.2 --- System model --- p.39 / Chapter 4.3 --- Performance analysis --- p.44 / Chapter 4.3.1 --- Network coding cooperation --- p.47 / Chapter 4.3.2 --- Conventional repetition cooperation --- p.48 / Chapter 4.3.3 --- Simulation result --- p.49 / Chapter 4.4 --- More nodes with network coding --- p.52 / Chapter 4.4.1 --- System model: to be selfish or not --- p.53 / Chapter 4.4.2 --- Performance analysis --- p.56 / Chapter 4.4.3 --- Simulation result --- p.62 / Chapter 4.5 --- Further discussion --- p.63 / Chapter 5 --- Conclusion --- p.64 / Chapter A --- Equation Derivation --- p.66 / Chapter A.l --- Proof of proposition 1 --- p.66 / Chapter A.2 --- Generalized solution --- p.68 / Chapter A.3 --- System outage probability of generous scheme --- p.69 / Chapter A.4 --- System outage probability of selfish scheme --- p.74 / Bibliography --- p.79

A wireless Ad-hoc network is a group of wireless devices that communicate with each other without utilising any central management infrastructure. The operation of Ad-hoc networks depends on the cooperation among nodes to provide connectivity and communication routes. However, such an ideal situation may not always be achievable in practice. Some nodes may behave maliciously, resulting in degradation of the performance of the network or even disruption of its operation altogether. The ease of establishment, along with the mobility capabilities that these networks offer, provides many advantages. On the other hand, these very characteristics, as well as the lack of any centralised administration, are the root of several nontrivial challenges in securing such networks. One of the key objectives of this thesis is to achieve improvements in the performance of Ad-hoc networks in the presence of malicious nodes. In general, malicious nodes are considered as nodes that subvert the capability of the network to perform its expected functions. Current Ad-hoc routing protocols, such as the Ad-hoc On demand Distance Vector (AODV), have been developed without taking the effects of misbehaving nodes into consideration. In this thesis, to mitigate the effects of such nodes and to attain high levels of security and reliability, an approach that is based on the utilisation of the behaviour history of all member nodes is proposed. The aim of the proposed approach is to identify routes between the source and the destination, which enclose no, or if that is not possible, a minimal number, of malicious nodes. This is in contrast to traditional approaches that predominantly tend to use other criteria such as shortest path alone. Simulation and experimental results collected after applying the proposed approach, show significant improvements in the performance of Ad-hoc networks even in the presence of malicious nodes. However, to achieve further enhancements, this approach is expanded to incorporate trust levels between the nodes comprising the Ad-hoc network. Trust is an important concept in any relation among entities that comprise a group or network. Yet it is hard to quantify trust or define it precisely. Due to the dynamic nature of Ad-hoc networks, quantifying trust levels is an even more challenging task. This may be attributed to the fact that different numbers of factors can affect trust levels between the nodes of Ad-hoc networks. It is well established that fuzzy logic and soft computing offer excellent solutions for handling imprecision and uncertainties. This thesis expands on relevant fuzzy logic concepts to propose an approach to establish quantifiable trust levels between the nodes of Ad-hoc networks. To achieve quantification of the trust levels for nodes, information about the behaviour history of the nodes is collected. This information is then processed to assess and assign fuzzy trust levels to the nodes that make up the Ad-hoc network. These trust levels are then used in the routing decision making process. The performance of an Ad-hoc network that implements the behaviour history based approach using OPtimised NETwork (OPNET) simulator is evaluated for various topologies. The overall collected results show that the throughput, the packet loss rate, and the round trip delay are significantly improved when the behaviour history based approach is applied. Results also show further enhancements in the performance of the Ad-hoc network when the proposed fuzzy trust evaluation approach is incorporated with a slight increase in the routing traffic overhead. Given the improvements achieved when the fuzzy trust approach is utilised, for further enhancements of security and reliability of Ad-hoc networks, future work to combine this approach with other artificial intelligent approaches may prove fruitful. The learning capability of Artificial Neural Networks makes them a prime target for combination with fuzzy based systems in order to improve the proposed trust level evaluation approach. / Doctor of Philosophy (PhD)

<p>The increasing usage of information technology in military affairs raises the need for robust high capacity radio networks. The network will be used to provide several different types of services, for example group calls and situation awareness services. All services have specific demands on packet delays and packet losses in order to be fully functional, and therefore there is a need for a Quality of Service (QoS) mechanism in the network. </p><p>In this master thesis we examine the possibility to provide a QoS mechanism in Ad Hoc networks by using priority queues. The study includes two different queuing schemes, namely fixed priority queuing and weighted fair queuing. The performance of the two queuing schemes are evaluated and compared with respect to the ability to provide differentiation in network delay, i.e., provide high priority traffic with lower delays than low priority traffic. The study is mainly done by simulations, but for fixed priority queuing we also derive a analytical approximation of the network delay. </p><p>Our simulations show that fixed priority queuing provides a sharp delay differentiation between service classes, while weighted fair queuing gives the ability to control the delay differentiation. One of those queuing schemes alone might not be the best solution for providing QoS, instead we suggest that a combination of them is used.</p>

<p>This thesis involved a research of mechanisms of MAC layer in the ad-hoc networks environment, the ad-hoc networks in the terminology of the standard are called IBSS Independent Basic Service, these type of networks are very useful in real situation where there are not the possibility of display a infrastructure, when there isn’t a network previous planning. </p><p>The connection to a new network is one of the different with the most common type of Wireless Local Area Networks (WLAN) that are the ones with infrastructure. The connection is established without the presence of a central station, instead the stations discover the others with broadcast messages in the coverage area of each station. In the context of standard 802.11 networks the communication between the stations is peer to peer, only with one hop. To continue with initiation process is necessary the synchronization between the different stations of his timers.</p><p>The other capital mechanism that is treated is the medium access mechanism, to hold a shared and unreliable medium, all the heavy of this issue goes to the distributed coordination function DCF.</p><p>In this moment there is an emergent technology, WIMAX or standard IEEE 802.16, like the standard 802.11 is a wireless communication protocol. Some comparison between the MAC layer mechanisms would be realized between these two standards</p>

Recently, researchers have introduced the notion of super-peers to improve signaling efficiency as well as lookup performance of peer-to-peer (P2P) systems. In a separate development, recent works on applications of mobile ad hoc networks (MANET) have seen several proposals on utilizing mobile fleets such as city buses to deploy a mobile backbone infrastructure for communication and Internet access in a metropolitan environment. This paper further explores the possibility of deploying P2P applications such as content sharing and distributed computing, over this mobile backbone infrastructure. Specifically, we study how city buses may be deployed as a mobile system of super-peers. We discuss the main motivations behind our proposal, and outline in detail the design of a super-peer based structured P2P system using a fleet of city buses. / Singapore-MIT Alliance (SMA)

Thesis (M.S.E.C.E)--University of Delaware, 2006. / Principal faculty advisor: Leonard J. Cimini, Jr., Electrical and Computer Engineering. Includes bibliographical references.