Saudi Cultural Missions Theses & Dissertations
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Item Restricted Software and Hardware Redundancy Approaches to Improve Performance and Service Availability in Fog Computing(Saudi Digital Library, 2023-12-28) Alraddady, Sara; Soh, BoonFog computing is a new distributed computing paradigm. It was introduced to address the massive increase in the number of connected devices since cloud computing faces difficulties handling all requests placed simultaneously. This new paradigm , which is an extension of cloud computing, can increase the efficiency of services provided in many sectors including health care, industry, agriculture, environmental hazard management, smart cities, and autonomous transportation. Some sectors, such as health care and autonomous driving, are highly non-tolerant of delays. In such sectors, high response time and poorly available services can lead to fatal results endangering the lives of many. On the contrary, other sectors such as e-commerce and telecommunication companies can tolerate delays to a certain extent, yet there is always a cost. Delays in such systems do not result in fatalities, as can happen in non-delay tolerant sectors, although delays can cause degraded quality of service and financial loss. Hence, regardless of the level of delay tolerance, delays are not desired. Given the distributed and diverse nature of fog computing, there are some challenges such as device heterogeneity that need be addressed to prepare fog computing for commercial use. Because any device can be a fog node, energy constraints must be considered to maximise device utilisation while still delivering the required quality of service. Also, different devices have various connecting methods which increase complex network connectivity for fog computing. It is also important to consider preventing fog node from exploitation and ensuring that requests are not randomly processed by different fog nodes. This thesis incorporates a management layer in fog computing to address the identified challenges. The proposed model was evaluated using simulations in iFogSim. The results show improved performance in important metrics such as execution time and bandwidth consumption compared to several fog architectures. For higher availability, a duplex management system is proposed and designed using Petri nets. A Markov chain is used to calculate failure probabilities for each node in the management layer, and availability analysis is presented.7 0Item Restricted Towards Reliable Logging in the Internet of Things Networks(2022) Alhajaili, Sara; Jhumka, ArshadThe Internet of things is one of the most rapidly developing technologies, and its low cost and usability make it applicable to various critical disciplines. Being a component of such critical infrastructure needs, these networks have to be dependable and offer the best outcome. Keeping track of network events is one method for enhancing network reliability, as network event logging supports essential processes, such as debugging, checkpointing, auditing, root-cause analysis, and forensics. However, logging in the IoT networks is not a simple task. IoT devices are positioned in remote places with unstable connectivity and inadequate security protocols, making them vulnerable to environmental flaws and security breaches. This thesis investigates the problem of reliable logging in IoT networks. We concentrate on the problem in the presence of Byzantine behaviour and the integration of logging middleware into the network stack. To overcome these concerns, we propose a technique for distributed logging by distributing loggers around the network. We define the logger selection problem and the collection problem, and show that only the probabilistic weak variant can solve the problem. We examine the performance of the Collector algorithm in several MAC setups. We then explore the auditability notion in IoT; we show how safety specification can be enforced through the analogies of fair exchange. Next, we review our findings and their place in the existing body of knowledge. We also explore the limits we faced when investigating this problem, and we finish this thesis by providing opportunities for future work.9 0