10 research outputs found

    OPTIMISING APPLICATION PERFORMANCE WITH QOS SUPPORT IN AD HOC NETWORKS

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    The popularity of wireless communication has increased substantially over the last decade, due to mobility support, flexibility and ease of deployment. Among next generation of mobile communication technologies, Ad Hoc networking plays an important role, since it can stand alone as private network, become a part of public network, either for general use or as part of disaster management scenarios. The performance of multihop Ad Hoc networks is heavily affected by interference, mobility, limited shared bandwidth, battery life, error rate of wireless media, and the presence of hidden and exposed terminals. The scheduler and the Medium Access Control (MAC) play a vital role in providing Quality of Service (QoS) and policing delay, end-to-end throughput, jitter, and fairness for user application services. This project aims to optimise the usage of the available limited resources in terms of battery life and bandwidth, in order to reduce packet delivery time and interference, enhance fairness, as well as increase the end-to-end throughput, and increase the overall network performance. The end-to-end throughput of an Ad Hoc network decays rapidly as the hop count between the source and destination pair increases and additional flows injected along the path of an existing flow affects the flows arriving from further away; in order to address this problem, the thesis proposes a Hop Based Dynamic Fair Scheduler that prioritises flows subject to the hop count of frames, leading to a 10% increase in fairness when compared to a IEEE 802.11b with single queue. Another mechanism to improve network performance in high congestion scenarios is network-aware queuing that reduces loss and improve the end-to-end throughput of the communicating nodes, using a medium access control method, named Dynamic Queue Utilisation Based Medium Access Control (DQUB-MAC). This MAC provides higher access probability to the nodes with congested queue, so that data generated at a high rate can be forwarded more effectively. Finally, the DQUB-MAC is modified to take account of hop count and a new MAC called Queue Utilisation with Hop Based Enhanced Arbitrary Inter Frame Spacing (QU-EAIFS) is also designed in this thesis. Validation tests in a long chain topology demonstrate that DQUB-MAC and QU-EAIFS increase the performance of the network during saturation by 35% and 40% respectively compared to IEEE 802.11b. High transmission power leads to greater interference and represents a significant challenge for Ad Hoc networks, particularly in the context of shared bandwidth and limited battery life. The thesis proposes two power control mechanisms that also employ a random backoff value directly proportional to the number of the active contending neighbours. The first mechanism, named Location Based Transmission using a Neighbour Aware with Optimised EIFS for Ad Hoc Networks (LBT-NA with Optimised EIFS MAC), controls the transmission power by exchanging location information between the communicating nodes in order to provide better fairness through a dynamic EIFS based on the overheard packet length. In a random topology, with randomly placed source and destination nodes, the performance gain of the proposed MAC over IEEE 802.11b ranges from approximately 3% to above 90% and the fairness index improved significantly. Further, the transmission power is directly proportional to the distance of communication. So, the performance is high and the durability of the nodes increases compared to a fixed transmission power MAC such as IEEE 802.11b when communicating distance is shorter. However, the mechanism requires positional information, therefore, given that location is typically unavailable, a more feasible power control cross layered system called Dynamic Neighbour Aware – Power controlled MAC (Dynamic NA -PMAC)is designed to adjust the transmission power by estimating the communicating distance based on the estimated overheard signal strength. In summary, the thesis proposes a number of mechanisms that improve the fairness amongst the competing flows, increase the end-to-end throughput, decrease the delay, reduce the transmission power in Ad Hoc environments and substantially increase the overall performance of the network

    Game-Theoretic Frameworks and Strategies for Defense Against Network Jamming and Collocation Attacks

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    Modern networks are becoming increasingly more complex, heterogeneous, and densely connected. While more diverse services are enabled to an ever-increasing number of users through ubiquitous networking and pervasive computing, several important challenges have emerged. For example, densely connected networks are prone to higher levels of interference, which makes them more vulnerable to jamming attacks. Also, the utilization of software-based protocols to perform routing, load balancing and power management functions in Software-Defined Networks gives rise to more vulnerabilities that could be exploited by malicious users and adversaries. Moreover, the increased reliance on cloud computing services due to a growing demand for communication and computation resources poses formidable security challenges due to the shared nature and virtualization of cloud computing. In this thesis, we study two types of attacks: jamming attacks on wireless networks and side-channel attacks on cloud computing servers. The former attacks disrupt the natural network operation by exploiting the static topology and dynamic channel assignment in wireless networks, while the latter attacks seek to gain access to unauthorized data by co-residing with target virtual machines (VMs) on the same physical node in a cloud server. In both attacks, the adversary faces a static attack surface and achieves her illegitimate goal by exploiting a stationary aspect of the network functionality. Hence, this dissertation proposes and develops counter approaches to both attacks using moving target defense strategies. We study the strategic interactions between the adversary and the network administrator within a game-theoretic framework. First, in the context of jamming attacks, we present and analyze a game-theoretic formulation between the adversary and the network defender. In this problem, the attack surface is the network connectivity (the static topology) as the adversary jams a subset of nodes to increase the level of interference in the network. On the other side, the defender makes judicious adjustments of the transmission footprint of the various nodes, thereby continuously adapting the underlying network topology to reduce the impact of the attack. The defender\u27s strategy is based on playing Nash equilibrium strategies securing a worst-case network utility. Moreover, scalable decomposition-based approaches are developed yielding a scalable defense strategy whose performance closely approaches that of the non-decomposed game for large-scale and dense networks. We study a class of games considering discrete as well as continuous power levels. In the second problem, we consider multi-tenant clouds, where a number of VMs are typically collocated on the same physical machine to optimize performance and power consumption and maximize profit. This increases the risk of a malicious virtual machine performing side-channel attacks and leaking sensitive information from neighboring VMs. The attack surface, in this case, is the static residency of VMs on a set of physical nodes, hence we develop a timed migration defense approach. Specifically, we analyze a timing game in which the cloud provider decides when to migrate a VM to a different physical machine to mitigate the risk of being compromised by a collocated malicious VM. The adversary decides the rate at which she launches new VMs to collocate with the victim VMs. Our formulation captures a data leakage model in which the cost incurred by the cloud provider depends on the duration of collocation with malicious VMs. It also captures costs incurred by the adversary in launching new VMs and by the defender in migrating VMs. We establish sufficient conditions for the existence of Nash equilibria for general cost functions, as well as for specific instantiations, and characterize the best response for both players. Furthermore, we extend our model to characterize its impact on the attacker\u27s payoff when the cloud utilizes intrusion detection systems that detect side-channel attacks. Our theoretical findings are corroborated with extensive numerical results in various settings as well as a proof-of-concept implementation in a realistic cloud setting

    Bio-signal data gathering, management and analysis within a patient-centred health care context

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    The healthcare service is under pressure to do more with less, and changing the way the service is modelled could be the key to saving resources and increasing efficacy. This change could be possible using patient-centric care models. This model would include straightforward and easy-to-use telemonitoring devices and a flexible data management structure. The structure would maintain its state by ingesting many sources of data, then tracking this data through cleaning and processing into models and estimates to obtaining values from data which could be used by the patient. The system can become less disease-focused and more health-focused by being preventative in nature and allowing patients to be more proactive and involved in their care by automating the data management. This work presents the development of a new device and a data management and analysis system to utilise the data from this device and support data processing along with two examples of its use. These are signal quality and blood pressure estimation. This system could aid in the creation of patient-centric telecare systems

    Indoor Positioning and Navigation

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    In recent years, rapid development in robotics, mobile, and communication technologies has encouraged many studies in the field of localization and navigation in indoor environments. An accurate localization system that can operate in an indoor environment has considerable practical value, because it can be built into autonomous mobile systems or a personal navigation system on a smartphone for guiding people through airports, shopping malls, museums and other public institutions, etc. Such a system would be particularly useful for blind people. Modern smartphones are equipped with numerous sensors (such as inertial sensors, cameras, and barometers) and communication modules (such as WiFi, Bluetooth, NFC, LTE/5G, and UWB capabilities), which enable the implementation of various localization algorithms, namely, visual localization, inertial navigation system, and radio localization. For the mapping of indoor environments and localization of autonomous mobile sysems, LIDAR sensors are also frequently used in addition to smartphone sensors. Visual localization and inertial navigation systems are sensitive to external disturbances; therefore, sensor fusion approaches can be used for the implementation of robust localization algorithms. These have to be optimized in order to be computationally efficient, which is essential for real-time processing and low energy consumption on a smartphone or robot

    Engineering and built environment project conference 2014: book of abstracts - Toowoomba, Australia, 22-26 September 2014

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    Book of Abstracts of the USQ Engineering and Built Environment Conference 2014, held Toowoomba, Australia, 22-26 September 2014. These proceedings include extended abstracts of the verbal presentations that are delivered at the project conference. The work reported at the conference is the research undertaken by students in meeting the requirements of courses ENG4111/ENG4112 Research Project for undergraduate or ENG8411/ENG8412 Research Project and Dissertation for postgraduate students

    Tematski zbornik radova međunarodnog značaja. Tom 3 / Međunarodni naučni skup “Dani Arčibalda Rajsa”, Beograd, 10-11. mart 2016.

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    In front of you is the Thematic Collection of Papers presented at the International Scientific Conference “Archibald Reiss Days”, which was organized by the Academy of Criminalistic and Police Studies in Belgrade, in co-operation with the Ministry of Interior and the Ministry of Education, Science and Technological Development of the Republic of Serbia, National Police University of China, Lviv State University of Internal Affairs, Volgograd Academy of the Russian Internal Affairs Ministry, Faculty of Security in Skopje, Faculty of Criminal Justice and Security in Ljubljana, Police Academy “Alexandru Ioan Cuza“ in Bucharest, Academy of Police Force in Bratislava and Police College in Banjaluka, and held at the Academy of Criminalistic and Police Studies, on 10 and 11 March 2016. The International Scientific Conference “Archibald Reiss Days” is organized for the sixth time in a row, in memory of the founder and director of the first modern higher police school in Serbia, Rodolphe Archibald Reiss, PhD, after whom the Conference was named. The Thematic Collection of Papers contains 165 papers written by eminent scholars in the field of law, security, criminalistics, police studies, forensics, informatics, as well as by members of national security system participating in education of the police, army and other security services from Belarus, Bosnia and Herzegovina, Bulgaria, China, Croatia, Greece, Hungary, Macedonia, Montenegro, Romania, Russian Federation, Serbia, Slovakia, Slovenia, Spain, Switzerland, Turkey, Ukraine and United Kingdom. Each paper has been double-blind peer reviewed by two reviewers, international experts competent for the field to which the paper is related, and the Thematic Conference Proceedings in whole has been reviewed by five competent international reviewers. The papers published in the Thematic Collection of Papers contain the overview of contemporary trends in the development of police education system, development of the police and contemporary security, criminalistic and forensic concepts. Furthermore, they provide us with the analysis of the rule of law activities in crime suppression, situation and trends in the above-mentioned fields, as well as suggestions on how to systematically deal with these issues. The Collection of Papers represents a significant contribution to the existing fund of scientific and expert knowledge in the field of criminalistic, security, penal and legal theory and practice. Publication of this Collection contributes to improving of mutual cooperation betw

    Queensland University of Technology: Handbook 1999

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    The Queensland University of Technology handbook gives an outline of the faculties and subject offerings available that were offered by QUT

    Queensland University of Technology: Handbook 2008

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    The Queensland University of Technology handbook gives an outline of the faculties and subject offerings available that were offered by QUT
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