ASU Electronic Theses and Dissertations
This collection includes most of the ASU Theses and Dissertations from 2011 to present. ASU Theses and Dissertations are available in downloadable PDF format; however, a small percentage of items are under embargo. Information about the dissertations/theses includes degree information, committee members, an abstract, supporting data or media.
In addition to the electronic theses found in the ASU Digital Repository, ASU Theses and Dissertations can be found in the ASU Library Catalog.
Dissertations and Theses granted by Arizona State University are archived and made available through a joint effort of the ASU Graduate College and the ASU Libraries. For more information or questions about this collection contact or visit the Digital Repository ETD Library Guide or contact the ASU Graduate College at gradformat@asu.edu.
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- Creators: Zhang, Yanchao
transmitted according to multi-channel slotted Aloha principles. The
random access is controlled through a limit W on the number of
transmission attempts and a timeout period for uniform backoff after a
collision. We model the LTE-Advanced random access system by formulating
the equilibrium condition for the ratio of the number of requests
successful within the permitted number of transmission attempts to those
successful in one attempt. We prove that for W≤8 there is only one
equilibrium operating point and for W≥9 there are three operating
points if the request load ρ is between load boundaries ρ1
and ρ2. We analytically identify these load boundaries as well as
the corresponding system operating points. We analyze the throughput and
delay of successful requests at the operating points and validate the
analytical results through simulations. Further, we generalize the
results using a steady-state equilibrium based approach and develop
models for single-channel and multi-channel systems, incorporating the
barring probability PB. Ultimately, we identify the de-correlating
effect of parameters O, PB, and Tomax and introduce the
Poissonization effect due to the backlogged requests in a slot. We
investigate the impact of Poissonization on different traffic and
conclude this thesis.
The first part consists of three chapters, with a focus on secondary-user authentication. Chapter One gives an overview of the challenges and existing solutions in spectrum-misuse detection. Chapter Two presents SpecGuard, the first crowdsourced spectrum-misuse detection framework for DSA systems. In SpecGuard, three novel schemes are proposed for embedding and detecting a spectrum permit at the physical layer. Chapter Three proposes SafeDSA, a novel PHY-based scheme utilizing temporal features for authenticating secondary users. In SafeDSA, the secondary user embeds his spectrum authorization into the cyclic prefix of each physical-layer symbol, which can be detected and authenticated by a verifier.
The second part also consists of three chapters, with a focus on crowdsourced spectrum sensing (CSS) with privacy consideration. CSS allows a spectrum sensing provider (SSP) to outsource the spectrum sensing to distributed mobile users. Without strong incentives and location-privacy protection in place, however, mobile users are reluctant to act as crowdsourcing workers for spectrum-sensing tasks. Chapter Four gives an overview of the challenges and existing solutions. Chapter Five presents PriCSS, where the SSP selects participants based on the exponential mechanism such that the participants' sensing cost, associated with their locations, are privacy-preserved. Chapter Six further proposes DPSense, a framework that allows the honest-but-curious SSP to select mobile users for executing spatiotemporal spectrum-sensing tasks without violating the location privacy of mobile users. By collecting perturbed location traces with differential privacy guarantee from participants, the SSP assigns spectrum-sensing tasks to participants with the consideration of both spatial and temporal factors.
Through theoretical analysis and simulations, the efficacy and effectiveness of the proposed schemes are validated.
the core network thus forming the most important segment for connectivity. Access
Networks have multiple physical layer medium ranging from fiber cables, to DSL links
and Wireless nodes, creating practically-used hybrid access networks. We explore the
hybrid access network at the Medium ACcess (MAC) Layer which receives packets
segregated as data and control packets, thus providing the needed decoupling of data
and control plane. We utilize the Software Defined Networking (SDN) principle of
centralized processing with segregated data and control plane to further extend the
usability of our algorithms. This dissertation introduces novel techniques in Dynamic
Bandwidth allocation, control message scheduling policy, flow control techniques and
Grouping techniques to provide improved performance in Hybrid Passive Optical Networks (PON) such as PON-xDSL, FiWi etc. Finally, we study the different types of
software defined algorithms in access networks and describe the various open challenges and research directions.