Thesis (Ph.D.)--University of Western Sydney, 2007. / A thesis submitted to the University of Western Sydney, College of Health and Science, School of Computing and Mathematics, in fulfilment of the requirements for the degree of Doctor of Philosophy. Includes bibliography.

Thesis--Auburn University, 2008. / Abstract. Vita. Includes bibliographical references (p. 45-48).

Road traffic safety has been a subject of worldwide concern. Dedicated short range communications (DSRC) is widely regarded as a promising enabling technology for collaborative safety applications (CSA), which can provide robust communication and affordable performance to build large scale CSA system. The main focus of this thesis is to develop solutions for DSRC QoS control in order to provide robust QoS support for CSA. The first design objective is to ensure robust and reliable message delivery services for safety applications from the DSRC networks. As the spectrum resources allocated to DSRC network are expected to be shared by both safety and non-safety applications, the second design objective is to make QoS control schemes bandwidth-efficient in order to leave as much as possible bandwidth for non-safety applications. The first part of the thesis investigates QoS control in infrastructure based DSRC networks, where roadside access points (AP) are available to control QoS control at road intersections. After analyse DSRC network capabilities on QoS provisioning without congestion control, we propose a two-phases adaptive QoS control method for DSRC vehicle networks. In the first phase an offline simulation based approach is used to and out the best possible system configurations (e.g. message rate and transmit power) with given numbers of vehicles and QoS requirements. It is noted that with different utility functions the values of optimal parameters proposed by the two phases centralized QoS control scheme will be different. The conclusions obtained with the proposed scheme are dependent on the chosen utility functions. But the proposed two phases centralized QoS control scheme is general and is applicable to different utility functions. In the second phase, these configurations are used online by roadside AP adaptively according to dynamic traffic loads. The second part of the thesis is focused on distributed QoS control for DSRC networks. A framework of collaborative QoS control is proposed, following which we utilize the local channel busy time as the indicator of network congestion and adaptively adjust safety message rate by a modified additive increase and multiplicative decrease (AIMD) method in a distributed way. Numerical results demonstrate the effectiveness of the proposed QoS control schemes.

Ad-Hoc mesh networks offer great promise. Low-cost ad-hoc mesh networks can be built using popular IEEE 802.11 equipment, but such networks are unable to guarantee each node a fair share of bandwidth. Furthermore, hidden node problems cause collisions which can cripple the throughput of a network. This research proposes a novel mechanism which is able to overcome hidden node problems and provide fair bandwidth sharing among nodes on ad-hoc 802.11 networks, and can be implemented on existing network devices. The scheme uses TDM (time division multiplexing) with slot reservation. A distributed beacon packet latency measurement mechanism is used to achieve node synchronisation. The distributed nature of the mechanism makes it applicable to ad-hoc 802.11 networks, which can either grow or fragment dynamically.

Thesis (PhD)-- Stellenbosch University, 2013. / ENGLISH ABSTRACT: The hidden terminal problem, coupled with high node mobility apparent in vehicular networks, present challenges to e cient communication between vehicles at the Medium Access Control (MAC) layer. Both of these challenges are fundamentally problems of lack of awareness, and manifest most prominently in the broadcasting of safety messages in infrastructure-free vehicle-to-vehicle communications. The design of existing contention-free and contention-based MAC approaches generally assumes that nodes that are in range of one another can take steps to coordinate communications at the MAC layer to overcome the hidden terminal problem and node mobility. Unicasting with the existing MAC standard, IEEE 802.11p, implicitly assumes an awareness range of twice the transmission range (a 1-hop awareness range) at most, since handshaking is used. For broadcasting, the assumption implies an awareness range that is at most equal to the transmission range, since only carrier sensing is used. Existing alternative contention-free approaches make the same assumption, with some protocols explicitly using a 1-hop awareness range to avoid packet collisions. This dissertation challenges the convention of assuming that a 1-hop awareness range is su cient for networks with high mobility, such as VANETs. In this dissertation, the impact of awareness range and management of the awareness information on MAC performance is researched. The impact of the number of slots that is required to support the awareness range is also evaluated. Three contention-free MAC protocols are introduced to support the research. The rst is an improved version of an existing MAC method, which is used to demonstrate the e ects on performance of changes to awareness management. The second MAC uses three competing processes to manage awareness information. The second MAC is designed for a con gurable awareness range and con gurable number of slots, and is used to evaluate the e ects of awareness range and number of slots on MAC performance. The third MAC is random access based and is used to evaluate the impact on performance of removing awareness completely. An analytical model is developed to support the simulated results. The simulation results demonstrate that awareness range, awareness information management, and number of slots used are key design parameters that signi cantly impact on MAC performance. The results further show that optimal awareness-related design parameters exist for given scenarios. Finally, the proposed contention-free and random access MAC methods are simulated and performance compared with IEEE 802.11p. All three outperform the contentionbased standard IEEE 802.11p. / AFRIKAANSE OPSOMMING: Die versteekte-nodus-probleem, gekoppel met die hoë vlakke van nodusbeweging teenwoordig in voertuignetwerke, bied uitdagings vir doeltre ende kommunikasie tussen voertuie in die medium-toegangbeheer- (MAC) vlak. Beide van hierdie probleme spruit uit beperkte bewustheid, en manifesteer veral in die uitsaai van veiligheidsboodskappe in infrastruktuurvrye voertuig-na-voertuig-kommunikasie. Die ontwerp van bestaande wedywerende en nie-wedywerende MAC benaderings neem aan dat nodusse wat binne bereik van mekaar is, stappe kan neem om kommunikasie op die MAC-vlak te koördineer, ten einde probleme met versteekte nodusse en mobiliteit te oorkom. Vir punt-tot-puntkommunikasie met IEEE 802.11p, impliseer dié aanname 'n bewustheidstrekking van hoogstens twee keer die radiobereik (1-hop bewustheidstrekking), aangesien bladskud gebruik word. In die geval van uitsaai, impliseer die aanname 'n bewustheidstrekking hoogstens gelyk is aan die radiobereik, aangesien slegs draeropsporing gebruik word. Nie-wedywerende metodes maak dieselfde aanname, met sommiges wat eksplisiet 1-hop-bewustheidstrekking gebruik om pakkieverliese te voorkom. Hierdie verhandeling wys dat hierdie aanname nie geld vir netwerke met hoë mobiliteit nie, soos wat die geval is vir VANET. In hierdie verhandeling word die impak van bewustheidstrekking en bestuur van die bewustheidsinligting in die MAC-vlak ondersoek. Die impak van die aantal tydgleuwe wat nodig is om die bewustheidstrekking te ondersteun word ook ondersoek. Drie nie-wedywerende metodes word bekendgestel om die navorsing te ondersteun. Die eerste is 'n verbeterde weergawe van 'n bestaande MAC, wat gebruik word om die e ekte van bewustheidsbestuur op MAC-werkverrigting te beoordeel. Die tweede MAC is ontwerp om veranderbare bewustheidstrekking en hoeveelheid tydgleuwe te ondersteun, en word gebruik om die e ekte van bewustheidstrekking en hoeveelheid tydgleuwe op MAC werkverrigting aan te beoordeel. Die derde MAC is ewetoeganklik (onbewus van omliggende nodusse) en word gebruik om die impak van die verwydering van bewustheid op werkverrigting te ondersoek. 'n Analitiese model is ontwikkel om die simulasieresultate te ondersteun. Die simulasieresultate dui aan dat bewustheidstrekking, bestuur van bewustheidsinligting, en hoeveelheid tydsgleuwe sleutel-ontwerpsveranderlikes is wat 'n beduidende impak het op MAC werkverrigting. Die resultate wys verder dat optimale ontwerpsveranderlikes, in terme van bewustheid, bestaan vir gegewe scenario's. Laastens, word die nie-wedywerende en ewetoeganklike MAC-metodes wat gesimuleer word se werkverrigting vergelyk met IEEE 802.11p. Al drie MAC metodes vaar beter as die wedywerende standaard, IEEE 802.11p.

Cette thèse porte sur l'étude des techniques de fusion de données réparties et incertaines au sein d’un réseau de véhicules pour gérer la confiance dans les autres véhicules ou dans les données reçues. L'algorithme de fusion distribuée proposé est basé sur les fonctions de croyance et est appliqué par chaque nœud à la réception des messages. In se base sur la gestion d'une connaissance directe, locale à chaque nœud et d'une connaissance distribuée diffusée dans le réseau. Cette dernière résulte de la fusion des messages par un opérateur adapté prenant en compte les cycles éventuels et limitant l'effet de "data incest". Chaque nœud peut être autonome pour estimer la confiance mais la coopération entre les véhicules permet d'améliorer et de rendre plus robuste cette estimation. L'algorithme peut être adapté au cas d'étude en considérant un ou plusieurs éléments d'observation et en prenant en compte l'obsolescence des données. Lorsqu'il y a plusieurs éléments d'observation, se pose le problème de l'association de données nécessaire avant l'étape de combinaison. Un nouvel algorithme d'association a été formalisé dans le cadre des fonctions de croyance. Il a été démontré que ce problème est équivalent à un problème d'affectation linéaire, qui peut être résolu en temps polynomial. Cette solution est à la fois optimale et beaucoup plus efficace que d'autres approches développées dans ce formalisme. La gestion de la confiance dans les nœuds et dans les données échangées ont été illustrées par la mise en œuvre de deux applications : la détection de faux nœuds dans une attaque Sybil et la gestion de la confiance dans les cartes dynamiques pour la perception augmentée. / This thesis focuses on the study of fusion techniques for distributed and uncertain data in a vehicle network in order to manage the confidence in other vehicles or in received data. The proposed distributed fusion algorithm is based on belief functions and is applied by each node when it receives messages. It is based on the management of direct knowledge, local for each node, and the management of a distributed knowledge broadcasted over the network. The distributed knowledge is the result of the fusion of messages by a suitable operator taking into account the possible cycles and limiting the effect of "data incest". Each node can be autonomous to estimate confidence but cooperation between vehicles can improve and make more robust this estimation. The algorithm can be adapted to the case of study by considering one or more elements of observation and taking into account the data obsolescence. When there are multiple elements of observation, the data association is necessary before the combination step. A new association algorithm was formalized in the framework of belief functions.It has been shown that this problem is equivalent to a linear assignment problem which can be solved in polynomial time. This solution is both optimal and more effective than other approaches developed in this formalism. The confidence management in the nodes and in the received data were illustrated by the implementation of two applications : the detection of false nodes in a Sybil attack and the distributed dynamic maps for enhanced perception

Multi-hop broadcast is one of the main approaches to disseminate data in VANET. Therefore, it is important to design a reliable multi-hop broadcast protocol, which satis es both reachability and bandwidth consumption requirements. In a dense network, where vehicles are very close to each other, the number of vehicles needed to rebroadcast the message should be small enough to avoid a broad- cast storm, but large enough to meet the reachability requirement. If the network is sparse, a higher number of vehicles is needed to retransmit to provide a higher reachability level. So, it is obvious that there is a tradeo between reachability and bandwidth consumption. In this work, considering the above mentioned challenges, we design a number of smart broadcast protocols and evaluate their performance in various network den- sity scenarios. We use fuzzy logic technique to determine the quali cation of vehicles to be forwarders, resulting in reachability enhancement. Then we design a band- width e cient fuzzy logic-assisted broadcast protocol which aggressively suppresses the number of retransmissions. We also propose an intelligent hybrid protocol adapts to local network density. In order to avoid packet collisions and enhance reachability, we design a cross layer statistical broadcast protocol, in which the contention window size is adjusted based on the local density information. We look into the multi-hop broadcast problem with an environment based on game theory. In this scenario, vehicles are players and their strategy is either to volunteer and rebroadcast the received message or defect and wait for others to rebroadcast. We introduce a volunteer dilemma game inspired broadcast scheme to estimate the probability of forwarding for the set of potential forwarding vehicles. In this scheme we also introduce a fuzzy logic-based contention window size adjustment system. Finally, based on the estimated spatial distribution of vehicles, we design a transmission range adaptive scheme with a fuzzy logic-assisted contention window size system, in which a bloom lter method is used to mitigate overhead. Extensive experimental work is obtained using simulation tools to evaluate the performance of the proposed schemes. The results con rm the relative advantages of the proposed protocols for di erent density scenarios. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection

This dissertation presents the results of research that led to the development of a novel reputation and trust-based monitoring paradigm for secure and reliable computing in Wireless Sensor Networks (WSNs). WSNs have undergone tremendous technological advances over the last few years. They have caused a giant leap toward "proactive computing," a paradigm where computers anticipate human needs and, when necessary, act on their behalf. Therefore, we cannot deploy such a critical technology without first addressing the security and privacy challenges to ensure that it does not turn against those whom it is meant to benefit. The core application of WSNs is to detect and report events, be it military or civilian applications. The building blocks of a WSN are small, battery-powered, lowcost, self-contained devices called "sensors" that measure factors like light, temperature, pressure, vibration, motion, etc. A WSN usually consists of hundreds of thousands of sensors that operate in unattended, hostile territories to monitor a given geographical area. Once deployed, the wireless sensors self-organize into ad-hoc wireless networks in order to cope with the dynamics of the surveillance field. During the post deployment phase, the wireless sensors aggregate data, then process and generate a report, which is subsequently relayed from one sensor to the next using secure multi-hop routing until the data reaches its desired destination, which is usually the sink. Since sensors operate in unattended and hostile territories, the adversary can capture a sensor node physically and extract all the information stored onboard, including cryptographic keying material. With this unique situation, WSNs are subject to a unique attack referred to as an "Insider Attack," in which the adversary becomes a legitimate member of the network being represented by the captured node. / To overcome this unique situation, a distributed Reputation and Trust-based Monitoring System (RTMS) is required. The most critical contribution of this dissertation work has been the proposal and design of a novel, clique-based, distributed group-key establishment protocol with specific application to RTMSs. We have also proposed and evaluated the application of RTMS models for securing beacon-based localization in WSNs addressing information asymmetry attacks, and proposed a novel k-parent tree model for securing broadcast communication in WSNs with an underlying RTMS model. Other issues addressed in this dissertation work include the proposal of a Connected Dominating Set (CDS) based reputation dissemination and bootstrapping model. This model also enables secure, certificateless node mobility and enables the model to be robust to ID Spoofing and node replication attacks. / by Avinash Srinivasan. / Thesis (Ph.D.)--Florida Atlantic University, 2008. / Includes bibliography. / Electronic reproduction. Boca Raton, FL : 2008 Mode of access: World Wide Web.

Many emerging mobile networks aim to provide wireless network services without relying on any infrastructure. The main challenge in these networks comes from their self-organized and distributed nature. There is an inherent reliance on collaboration among the participants in order to achieve the aimed functionalities. Therefore, establishing and quantifying trust, which is the driving force for collaboration, is important for applications in mobile networks. This dissertation focuses on evaluating and quantifying trust to stimulate collaboration in mobile networks, introducing uncertainty concepts and metrics, as well as providing the various analysis and applications of uncertainty-aware reputation systems. Many existing reputation systems sharply divide the trust value into right or wrong, thus ignoring another core dimension of trust: uncertainty. As uncertainty deeply impacts a node's anticipation of others' behavior and decisions during interaction, we include it in the reputation system. Specifically, we use an uncertainty metric to directly reflect a node's confidence in the sufficiency of its past experience, and study how the collection of trust information may affect uncertainty in nodes' opinions. Higher uncertainty leads to higher transaction cost and reduced acceptance of communication. We exploit mobility to efficiently reduce uncertainty and to speed up trust convergence. We also apply the new reputation system to enhance the analysis of the interactions among mobile nodes, and present three sample uncertainty-aware applications. We integrate the uncertainty-aware reputation model with game theory tools, and enhance the analysis on interactions among mobile nodes. / Instead of reactively protecting the mobile networks from existing attacks as in the traditional security paradigms, the analysis in this dissertation gives more insights on nodes' rationality in the interaction, which will enable the mechanism design in mobile networks to be security and incentive compatible. Moreover, we present three sample applications, in which we clearly identify the challenges, specifically formalize the problems, and cleverly employ the uncertainty mitigation schemes. These applications show that the uncertainty definition and mitigation schemes can benefit a broad range of applications, including fields such as security, network services, and routing. / by Feng Li. / Vita. / Thesis (Ph.D.)--Florida Atlantic University, 2009. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2009. Mode of access: World Wide Web.

This thesis consists of the development of a web based wireless sensor network (WSN) monitoring system using smartphones. Typical WSNs consist of networks of wireless sensor nodes dispersed over predetermined areas to acquire, process, and transmit data from these locations. Often it is the case that the WSNs are located in areas too hazardous or inaccessible to humans. We focused on the need for access to this sensed data remotely and present our reference architecture to solve this problem. We developed this architecture for web-based wireless sensor network monitoring and have implemented a prototype that uses Crossbow Mica sensors and Android smartphones for bridging the wireless sensor network with the web services for data storage and retrieval. Our application has the ability to retrieve sensed data directly from a wireless senor network composed of Mica sensors and from a smartphones onboard sensors. The data is displayed on the phone's screen, and then, via Internet connection, they are forwarded to a remote database for manipulation and storage. The attributes sensed and stored by our application are temperature, light, acceleration, GPS position, and geographical direction. Authorized personnel are able to retrieve and observe this data both textually and graphically from any browser with Internet connectivity or through a native Android application. Web-based wireless sensor network architectures using smartphones provides a scalable and expandable solution with applicability in many areas, such as healthcare, environmental monitoring, infrastructure health monitoring, border security, and others. / by Anthony M. Marcus. / Thesis (M.S.C.S.)--Florida Atlantic University, 2011. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2011. Mode of access: World Wide Web.