Typescript (photocopy). / Digitized by Kansas Correctional Industries / Department: Computer Science.

Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1978. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Vita. / Bibliography: leaf 58. / B.S.

Thesis. 1976. M.S.--Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science. / Microfiche copy available in Archives and Engineering. / Bibliography: leaves 119-121. / M.S.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Vita. / Bibliography: leaves 83-86. / by Moses Hsingwen Ma. / M.S.

Thesis. 1977. M.S.--Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography : leaves 131-139. / M.S.

Motivated by the fact that the contention graph associated with ICN is a Markov random field (MRF) with respect to the probability distribution of its system states, and that the belief propagation algorithm (BP) is an efficient way to solve "inference" problems in graphical models such as MRF, we study how to apply BP algorithms to the analysis and control of CSMA wireless networks. We investigate three applications: (1) computation of link throughputs given link access intensities; (2) computation of link access intensities required to meet target link throughputs; and (3) optimization of network utility via the control of link access intensities. We show that BP solves the three problems with exact results in tree networks and has manageable computation errors in a network with loopy contention graph. In particular, we show how a generalized version of BP, GBP, can be designed to solve the three problems above with higher accuracy. Importantly, we show how the BP and GBP algorithms can be implemented in a distributed manner, making them useful in practical CSMA network operation. / The above studies focus on computation and control of "equilibrium" link throughputs. Besides throughputs, an important performance measure in CSMA networks is the propensity for starvation. In this thesis, we show that links in CSMA wireless networks are particularly susceptible to "temporal" starvation. Specifically, certain links may have good equilibrium throughputs, yet they can still receive no throughput for extended periods from time to time. We develop a "trap theory" to analyze temporal throughput fluctuations. The trap theory serves two functions. First, it allows us to derive new mathematical results that shed light on the transient behavior of CSMA networks. Second, we can develop automated analytical tools for computing the "degrees of starvation" for CSMA networks to aid network design. We believe that the ability to identify and characterize temporal starvation as established in this thesis will serve as an important first step toward the design of effective remedies for it. / This thesis investigates the performance and control of CSMA wireless networks. To this end, an analytical model of CSMA wireless networks that captures the essence of their operation is important. We propose an Ideal CSMA Network (ICN) model to characterize the dynamic of the interactions and dependency of links in CSMA wireless networks. This model allows us to address various issues related to performance and control of CSMA networks. / We show that the throughput distributions of links in ICN can be computed from a continuous-time Markov chain and are insensitive to the distributions of the transmission time (packet duration) and the backoff countdown time in the CSMA MAC protocol given the ratio of their means rho, referred to as the access intensity. An outcome of the ICN model is a Back-of-the-Envelope (BoE) approximate computation method that allows us to bypass complicated stochastic analysis to compute link throughputs in many network configurations quickly. The BoE computation method emerges from ICN in the limit rho → infinity. Our results indicate that BoE is a good approximation technique for modest-size networks such as those typically seen in 802.11 deployments. Beyond serving as the foundation for BoE, the theoretical framework of ICN is also a foundation for understanding and optimization of large CSMA networks. / Kai, Caihong. / Adviser: Soung Chang Liew. / Source: Dissertation Abstracts International, Volume: 73-03, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 180-183). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

The Advanced Encryption Standard (AES) is the new standard for cryptography and has gained wide support as a means to secure digital data. Hence, it is beneficial to develop an implementation of AES that has a high throughput. SIMD technology is very effective in increasing the performance of some cryptographic applications. This thesis describes an optimized implementation of the AES in software based on Intel's SIMD architecture. Our results show that our technique yields a significant increase in the performance and thereby the throughput of AES. They also demonstrate that AES is a good candidate for optimization using our approach. / Graduation date: 2004

This dissertation proposes a model supporting the creation of trustable privacies in public online spaces, with the model demonstrating the potential for supporting trustable data handling in the qualitative domain. Privacy and trust, from the pivotal perspective of the individual were identified as crucial intangibles in the qualitative research and personal trust domains. That both privacy and trust depend heavily upon credible mechanisms for privacy became clear during the literature review and interview processes. Privacy, in its many forms, is a concept requiring greatly varying degrees of anonymity, confidentiality and control (Rotenberg, 2001; Lessig, 1998) and this was position was validated by literature and by qualitative comments by academic interviewees. Facilitation of secondary users including academics, public and private organisations, communities, casual information browsers is a goal of this research. This goal of facilitation is supported by the model proposed, and is discussed in Chapter 6, where future work is discussed. The core requirement to address confidentiality, ethics, privacy, ownership and control of data (Corti, 2000) is satisfied by the model as proposed and discussed. Expected outcomes of this research project are summarised as: • Proposed model for the creation of trustable privacies in public spaces. [Primary outcome] • Promotion of collaboration amongst domains and disciplines through improved universal access to archived data [Secondary outcome] • Identification of application domains outside of the initially identified domain set [Secondary outcome]. Self-Contained ReposItory ProcesSIng Template (SCRIPSIT) describes a model supporting a decentralised, trustable set of structures and mechanisms. SCRIPSIT has its eponymous origin in the Latin word scripsit, meaning "he or she wrote". / Thesis (M.A.)-University of KwaZulu-Natal, Durban, 2004.

Wireless networks afford many benefits compared to wired networks in terms of their usability in dynamic situations, mobility of networked devices, and accessibility of hazardous environments. The devices used in these networks are generally assumed to be limited in resources such as energy, memory, communications range, and computational ability. Operating in remote or hostile environments, this places them in danger of being compromised by some malicious entity. This work addresses these issues to increase the security of these networks while still maintaining acceptable levels of networking performance and resource usage. We investigate new methods for data encryption on personal wireless hand-held devices. An important consideration for resource-constrained devices is the processing required to encrypt data for transmission or for secure storage. Significant latency from data encryption diminishes the viability of these security services for hand-held devices. Also, increased processing demands require additional energy for each device, where both energy and processing capability are limited. Therefore, one area of interest for hand-held wireless devices is being able to provide data encryption while minimizing the processing and energy overhead as a cost to provide such a security service. We study the security of a wavelet-based cryptosystem and consider its viability for use in hand-held devices. This thesis also considers the performance of wireless sensor networks in the presence of an adversary. The sensor nodes used in these networks are limited in available energy, processing capability and transmission range. Despite these resource constraints and expected malicious attacks on the network, these networks require widespread, highly-reliable communications. Maintaining satisfactory levels of network performance and security between entities is an important goal toward ensuring the successful and accurate completion of desired sensing tasks. However, the resource-constrained nature of the sensor nodes used in these applications provides challenges in meeting these networking and security requirements. We consider link-compromise attacks and node-spoofing attacks on wireless sensor networks, and we consider the performance of various key predistribution schemes applied to these networks. New key predistribution techniques to improve the security of wireless sensor networks are proposed.

Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Fekri, Faramarz; Committee Member: James McClellan; Committee Member: John Copeland; Committee Member: Steven McLaughlin; Committee Member: Yajun Mei. Part of the SMARTech Electronic Thesis and Dissertation Collection.