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design of reliable decentralized computer systems
Title
The design of reliable decentralized computer systems.
Creator
Wu, Jie., Florida Atlantic University, Fernandez, Eduardo B., College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description
With the increase in the applications of computer technology, there are more and more demands for the use of computer systems in the area of real-time applications and critical systems. Reliability and performance are fundamental design requirements for these applications. In this dissertation, we develop some specific aspects of a fault-tolerant decentralized system architecture. This system can execute concurrent processes and it is composed of processing elements that have only local...
Show moreWith the increase in the applications of computer technology, there are more and more demands for the use of computer systems in the area of real-time applications and critical systems. Reliability and performance are fundamental design requirements for these applications. In this dissertation, we develop some specific aspects of a fault-tolerant decentralized system architecture. This system can execute concurrent processes and it is composed of processing elements that have only local memories with point-to-point communication. A model using hierarchical layers describes this system. Fault tolerance techniques are discussed for the applications, software, operating system, and hardware layers of the model. Scheduling of communicating tasks to increase performance is also addressed. Some special problems such as the Byzantine Generals problem are considered. We have shown that, by combining reliable techniques on different layers and with consideration of system performance, one can provide a system with a very high level reliability as well as performance.
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Date Issued
1989
PURL
http://purl.flvc.org/fcla/dt/12237
Subject Headings
Electronic digital computers--Reliability, Fault-tolerant computing, System design, Computer software--Reliability
Format
Document (PDF)
selectively redundant file system
Title
A selectively redundant file system.
Creator
Veradt, Joy L., Florida Atlantic University, Fernandez, Eduardo B., College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description
Disk arrays have been proposed as a means of achieving high performance, reliability and availability in computer systems. This study looks at the RAID (Redundant Array of Inexpensive Disks) disk array architecture and its advantages and disadvantages for use in personal computer environments, specifically in terms of how data is protected (redundant information) and the tradeoff required to achieve that protection (sacrifice of disk capacity). It then proposes an alternative to achieving a...
Show moreDisk arrays have been proposed as a means of achieving high performance, reliability and availability in computer systems. This study looks at the RAID (Redundant Array of Inexpensive Disks) disk array architecture and its advantages and disadvantages for use in personal computer environments, specifically in terms of how data is protected (redundant information) and the tradeoff required to achieve that protection (sacrifice of disk capacity). It then proposes an alternative to achieving a real-time method of protecting a user's data, which involves the modification of an operating system's file system to implement selective redundancy at the file level. This approach, based on modified RAIDs, is shown to be considerably more efficient in using the capacity of the available disks. It also provides flexibility in allowing users to tradeoff space for reliability.
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Date Issued
1992
PURL
http://purl.flvc.org/fcla/dt/14844
Subject Headings
Computer files--Reliability, Systems software--Reliability, Databases--Reliability
Format
Document (PDF)
Scheduling for composite event detection in wireless sensor networks
Title
Scheduling for composite event detection in wireless sensor networks.
Creator
Ambrose, Arny Isonja, Florida Atlantic University, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description
Wireless sensor networks are used in areas that are inaccessible, inhospitable or for continuous monitoring. The main use of such networks is for event detection. Event detection is used to monitor a particular environment for an event such as fire or flooding. Composite event detection is used to break down the detection of the event into the specific conditions that need to be present for the event to occur. Using this method, each sensor node does not need to carry every sensing component...
Show moreWireless sensor networks are used in areas that are inaccessible, inhospitable or for continuous monitoring. The main use of such networks is for event detection. Event detection is used to monitor a particular environment for an event such as fire or flooding. Composite event detection is used to break down the detection of the event into the specific conditions that need to be present for the event to occur. Using this method, each sensor node does not need to carry every sensing component necessary to detect the event. Since energy efficiency is important the sensor nodes need to be scheduled so that they consume [sic] consume as little energy as possible to extend the network lifetime. In this thesis, a solution to the sensor Scheduling for Composite Event Detection (SCED) problem will be presented as a way to improve the network lifetime when using composite event detection.
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Date Issued
2008
PURL
http://purl.flvc.org/fcla/dt/186333
Subject Headings
Sensor networks, Wireless communication systems, Embedded computer systems, Computer systems, Reliability
Format
Document (PDF)
Probabilistic predictor-based routing in disruption-tolerant networks
Title
Probabilistic predictor-based routing in disruption-tolerant networks.
Creator
Yuan, Quan., College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description
Disruption-Tolerant Networks (DTNs) are the networks comprised of a set of wireless nodes, and they experience unstable connectivity and frequent connection disruption because of the limitations of radio range, power, network density, device failure, and noise. DTNs are characterized by their lack of infrastructure, device limitation, and intermittent connectivity. Such characteristics make conventional wireless network routing protocols fail, as they are designed with the assumption the...
Show moreDisruption-Tolerant Networks (DTNs) are the networks comprised of a set of wireless nodes, and they experience unstable connectivity and frequent connection disruption because of the limitations of radio range, power, network density, device failure, and noise. DTNs are characterized by their lack of infrastructure, device limitation, and intermittent connectivity. Such characteristics make conventional wireless network routing protocols fail, as they are designed with the assumption the network stays connected. Thus, routing in DTNs becomes a challenging problem, due to the temporal scheduling element in a dynamic topology. One of the solutions is prediction-based, where nodes mobility is estimated with a history of observations. Then, the decision of forwarding messages during data delivery can be made with that predicted information. Current prediction-based routing protocols can be divided into two sub-categories in terms of that whether they are probability related: probabilistic and non-probabilistic. This dissertation focuses on the probabilistic prediction-based (PPB) routing schemes in DTNs. We find that most of these protocols are designed for a specified topology or scenario. So almost every protocol has some drawbacks when applied to a different scenario. Because every scenario has its own particular features, there could hardly exist a universal protocol which can suit all of the DTN scenarios. Based on the above motivation, we investigate and divide the current DTNs scenarios into three categories: Voronoi-based, landmark-based, and random moving DTNs. For each category, we design and implement a corresponding PPB routing protocol for either basic routing or a specified application with considering its unique features., Specifically, we introduce a Predict and Relay routing protocol for Voronoi-based DTNs, present a single-copy and a multi-copy PPB routing protocol for landmark-based DTNs, and propose DRIP, a dynamic Voronoi region-based publish/subscribe protocol, to adapt publish/subscribe systems to random moving DTNs. New concepts, approaches, and algorithms are introduced during our work.
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Date Issued
2009
PURL
http://purl.flvc.org/FAU/359928
Subject Headings
Routers (Computer networks), Computer network protocols, Computer networks, Reliability, Computer algorithms, Wireless communication systems, Technological innovations
Format
Document (PDF)
Design and implementation of efficient routing protocols in delay tolerant networks
Title
Design and implementation of efficient routing protocols in delay tolerant networks.
Creator
Liu, Cong., College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description
Delay tolerant networks (DTNs) are occasionally-connected networks that may suffer from frequent partitions. DTNs provide service despite long end to end delays or infrequent connectivity. One fundamental problem in DTNs is routing messages from their source to their destination. DTNs differ from the Internet in that disconnections are the norm instead of the exception. Representative DTNs include sensor-based networks using scheduled intermittent connectivity, terrestrial wireless networks...
Show moreDelay tolerant networks (DTNs) are occasionally-connected networks that may suffer from frequent partitions. DTNs provide service despite long end to end delays or infrequent connectivity. One fundamental problem in DTNs is routing messages from their source to their destination. DTNs differ from the Internet in that disconnections are the norm instead of the exception. Representative DTNs include sensor-based networks using scheduled intermittent connectivity, terrestrial wireless networks that cannot ordinarily maintain end-to-end connectivity, satellite networks with moderate delays and periodic connectivity, underwater acoustic networks with moderate delays and frequent interruptions due to environmental factors, and vehicular networks with cyclic but nondeterministic connectivity. The focus of this dissertation is on routing protocols that send messages in DTNs. When no connected path exists between the source and the destination of the message, other nodes may relay the message to the destination. This dissertation covers routing protocols in DTNs with both deterministic and non-deterministic mobility respectively. In DTNs with deterministic and cyclic mobility, we proposed the first routing protocol that is both scalable and delivery guaranteed. In DTNs with non-deterministic mobility, numerous heuristic protocols are proposed to improve the routing performance. However, none of those can provide a theoretical optimization on a particular performance measurement. In this dissertation, two routing protocols for non-deterministic DTNs are proposed, which minimizes delay and maximizes delivery rate on different scenarios respectively. First, in DTNs with non-deterministic and cyclic mobility, an optimal single-copy forwarding protocol which minimizes delay is proposed., In DTNs with non-deterministic mobility, an optimal multi-copy forwarding protocol is proposed. which maximizes delivery rate under the constraint that the number of copies per message is fixed . Simulation evaluations using both real and synthetic trace are conducted to compare the proposed protocols with the existing ones.
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Date Issued
2009
PURL
http://purl.flvc.org/FAU/210522
Subject Headings
Computer network protocols, Computer networks, Reliability, Computer algorithms, Wireless communication systems, Technological innovations
Format
Document (PDF)
Physical Layer Security of Wireless Transmissions Over Fading Channels
Title
Physical Layer Security of Wireless Transmissions Over Fading Channels.
Creator
Blanc, Sadrac, Aalo, Valentine A., Florida Atlantic University, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description
The open nature of the wireless medium makes the wireless communication susceptible to eavesdropping attacks. In addition, fading and shadowing significantly degrade the performance of the communication system in the wireless networks. A versatile approach to circumvent the issues of eavesdropping attacks while exploiting the physical properties of the wireless channel is the so-called physical layer-security. In this work, we consider a model in which two legitimate users communicate in the...
Show moreThe open nature of the wireless medium makes the wireless communication susceptible to eavesdropping attacks. In addition, fading and shadowing significantly degrade the performance of the communication system in the wireless networks. A versatile approach to circumvent the issues of eavesdropping attacks while exploiting the physical properties of the wireless channel is the so-called physical layer-security. In this work, we consider a model in which two legitimate users communicate in the presence of an eavesdropper. We investigate the performance of the wireless network at the physical layer that is subject to a variety of fading environments that may be modeled by the Rayleigh, Nakagami-m, and Generalized-K distributions, to mention a few. We use the secrecy outage probability (SOP) as the standard performance metrics to study the performance of the wireless networks. We propose two different approaches to compute the secrecy outage probability, and derive explicit expressions for the secrecy outage probability that allow us to characterize the performance of the wireless networks. Specifically, we use a direct integration approach as well as a Taylor series base approach to evaluate the secrecy outage probability. Finally, we use computer simulations, based on MATLAB, to confirm the analytical results.
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Date Issued
2016
PURL
http://purl.flvc.org/fau/fd/FA00004729, http://purl.flvc.org/fau/fd/FA00004729
Subject Headings
Data encryption (Computer science), Digital communications -- Reliability -- Mathematics, Internetworking (Telecommunication), Radio wave propagation, Wireless communication systems -- Security measures
Format
Document (PDF)