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Pages
- Title
- Secure and efficient spectrum sharing and QoS analysis in OFDM-based heterogeneous wireless networks
- Creator
- Alahmadi, Ahmed S.
- Date
- 2016
- Collection
- Electronic Theses & Dissertations
- Description
-
"The Internet of Things (IoT), which networks versatile devices for information exchange, remote sensing, monitoring and control, is finding promising applications in nearly every field. However, due to its high density and enormous spectrum requirement, the practical development of IoT technology seems to be not available until the release of the large millimeter wave (mmWave) band (30GHz-300GHz). Compared to existing lower band systems (such as 3G, 4G), mmWave band signals generally require...
Show more"The Internet of Things (IoT), which networks versatile devices for information exchange, remote sensing, monitoring and control, is finding promising applications in nearly every field. However, due to its high density and enormous spectrum requirement, the practical development of IoT technology seems to be not available until the release of the large millimeter wave (mmWave) band (30GHz-300GHz). Compared to existing lower band systems (such as 3G, 4G), mmWave band signals generally require line of sight (LOS) path and suffer from severe fading effects, leading to much smaller coverage area. For network design and management, this implies that: (i) MmWave band alone could not support the IoT networks, but has to be integrated with the existing lower band systems through secure and effective spectrum sharing, especially in the lower frequency bands; and (ii) The IoT networks will have very high density node distribution, which is a significant challenge in network design, especially with the scarce energy budget of IoT applications. Motivated by these observations, in this dissertation, we consider three problems: (1) How to achieve secure and effective spectrum sharing? (2) How to accommodate the energy limited IoT devices? (3) How to evaluate the Quality of Service (QoS) in the high density IoT networks? We aim to develop innovative techniques for the design, evaluation and management of future IoT networks under both benign and hostile environments. The main contributions of this dissertation are outlined as follows. First, we develop a secure and efficient spectrum sharing scheme in single-carrier wireless networks. Cognitive radio (CR) is a key enabling technology for spectrum sharing, where the unoccupied spectrum is identified for secondary users (SUs), without interfering with the primary user (PU). A serious security threat to the CR networks is referred to as primary user emulation attack (PUEA), in which a malicious user (MU) emulates the signal characteristics of the PU, thereby causing the SUs to erroneously identify the attacker as the PU. Here, we consider full-band PUEA detection and propose a reliable AES-assisted DTV scheme, where an AES-encrypted reference signal is generated at the DTV transmitter and used as the sync bits of the DTV data frames. For PU detection, we investigate the cross-correlation between the received sequence and reference sequence. The MU detection can be performed by investigating the auto-correlation of the received sequence. We further develop a secure and efficient spectrum sharing scheme in multi-carrier wireless networks. We consider sub-band malicious user detection and propose a secure AES-based DTV scheme, where the existing reference sequence used to generate the pilot symbols in the DVB-T2 frames is encrypted using the AES algorithm. The resulted sequence is exploited for accurate detection of the authorized PU and the MU. Second, we develop an energy efficient transmission scheme in CR networks using energy harvesting. We propose a transmitting scheme for the SUs such that each SU can perform information reception and energy harvesting simultaneously. We perform sum-rate optimization for the SUs under PUEA. It is observed that the sum-rate of the SU network can be improved significantly with the energy harvesting technique. Potentially, the proposed scheme can be applied directly to the energy-constrained IoT networks. Finally, we investigate QoS performance analysis methodologies, which can provide insightful feedbacks to IoT network design and planning. Taking the spatial randomness of the IoT network into consideration, we investigate coverage probability (CP) and blocking probability (BP) in relay-assisted OFDMA networks using stochastic geometry. More specifically, we model the inter-cell interference from the neighboring cells at each typical node, and derive the CP in the downlink transmissions. Based on their data rate requirements, we classify the incoming users into different classes, and calculate the BP using the multi-dimensional loss model."--Pages ii-iii.
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- Title
- Mobility and communication in wireless robot and sensor networks
- Creator
- Pei, Yuanteng
- Date
- 2011
- Collection
- Electronic Theses & Dissertations
- Description
-
Mobility is a primary goal of many wireless communication systems. In recent years, mobile multi-hop wireless networks, such as mobile wireless sensor networks and wireless robot networks, have attracted increased attention and have been extensively studied. However, most current research does not consider the interdependence of communication and mobility and much assume an obstacle-free environment in their problem modeling and solving process.In this dissertation, we discuss several...
Show moreMobility is a primary goal of many wireless communication systems. In recent years, mobile multi-hop wireless networks, such as mobile wireless sensor networks and wireless robot networks, have attracted increased attention and have been extensively studied. However, most current research does not consider the interdependence of communication and mobility and much assume an obstacle-free environment in their problem modeling and solving process.In this dissertation, we discuss several research topics relevant to the above two issues of communication and mobility in wireless robot and sensor networks. First, we present multi-robot real-time exploration, which calls for the joint consideration of mobility and communication: it requires video and audio streams of a newly explored area be transmitted to the base station in a timely fashion as robots explore the area. Simulations show that our mobility model has achieved both improved communication quality and enhanced exploration efficiency.Second, we further investigate the above problem with two critical and real-world network conditions: (1) heterogeneous transmission ranges and link capacities, and (2) the impact of interference. The conditions increase the model complexity but significantly influence the actual available bandwidth and the required node size in placement. We jointly consider the relay placement and routing with these two critical conditions.Third, we introduce an online relay deployment paradigm to support remote sensing and control when mobile nodes migrate farther from the base station in a cost-effective system of mobile robots, static sensors and relays. A novel multi-robot real-time search method called STAtic Relay aided Search (STARS) is presented to allow robots to search in a known environment. Its solution is based on our near-optimal solution to a new variation of the multi-traveling salesman problem: precedence constrained two traveling salesman (PC2TSP).Fourth, we propose a heterogenous multi-robot exploration strategy with online relay deployment for an unknown environment called Bandwidth aware Exploration with a Steiner Traveler (BEST). In BEST, a relay-deployment node (RDN) tracks the FNs movement and places relays when necessary to support the video/audio streams aggregation to the base station. This problem inherits characteristics of both the Steiner minimum tree and traveling salesman problems. Extensive simulations show that BEST further enhances the exploration efficiency.While the first four topics deal with communication and mobility issues in powerful but expensive robotic systems, the fifth topic focuses on a special type of low cost, limited capability mobile sensors called hopping sensors, whose unique method of movement makes them suitable for rugged terrains. We present (1) a distributed message forwarding model called Binary Splitting Message Forwarding (BSMF) and (2) a grid based movement model unique to these hopping sensors. Simulation shows that our scheme significantly reduces the communication overhead and achieves relatively constant total energy consumption with varying amount of obstructions.Finally, we discuss the future work directions of this research work. We believe that a heterogeneous mobile platform to support real-time stream transmission by mobile robots, static sensor and communication devices, have great potential in various civilian and military applications, where the communication quality of service is critically important, as well as the mobility efficiency.
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- Title
- Impacts of communication delays on wireless-based automated vehicle control systems
- Creator
- Liu, Yu
- Date
- 2007
- Collection
- Electronic Theses & Dissertations
- Title
- Mechanisms for combining infrared and ultrasound signals for indoor wireless localization
- Creator
- Rurangirwa, David
- Date
- 2007
- Collection
- Electronic Theses & Dissertations
- Title
- Noise tolerant compression protocols for wireless environments
- Creator
- Perkins, Stephen James, 1967-
- Date
- 1997
- Collection
- Electronic Theses & Dissertations
- Title
- Telecom infrastructure modernization and universal service in developing countries : the role of cellular/wireless technologies
- Creator
- Baltais, Arno
- Date
- 1995
- Collection
- Electronic Theses & Dissertations
- Title
- Advanced receivers for WCDMA downlink
- Creator
- Desai, Keyur
- Date
- 2004
- Collection
- Electronic Theses & Dissertations
- Title
- A cooperative ad hoc network to support efficient access to Internet data
- Creator
- Kang, Seung-Seok
- Date
- 2004
- Collection
- Electronic Theses & Dissertations
- Title
- Transparent shaping of existing software to support pervasive and autonomic computing
- Creator
- Sadjadi, S. Masoud
- Date
- 2004
- Collection
- Electronic Theses & Dissertations
- Title
- Network planning and dimensioning process in WCDMA
- Creator
- Abusaid, Osama Mustafa
- Date
- 2010
- Collection
- Electronic Theses & Dissertations
- Title
- Large-signal RF simulation and characterization of electronic devices using Fermi kinetics transport
- Creator
- Miller, Nicholas Charles
- Date
- 2017
- Collection
- Electronic Theses & Dissertations
- Description
-
Design of radio frequency (RF) power amplifiers (PAs) for wireless communications requires small- and large-signal data collected from the underlying transistors, including scattering parameters (S-Parameters) and load-pull (LP), to determine optimal impedance targets. High speed devices operating with fundamental frequencies above 35 GHz present extreme challenges for measuring the harmonic signals resulting from nonlinear effects. Predictive physics based simulations in conjunction with...
Show moreDesign of radio frequency (RF) power amplifiers (PAs) for wireless communications requires small- and large-signal data collected from the underlying transistors, including scattering parameters (S-Parameters) and load-pull (LP), to determine optimal impedance targets. High speed devices operating with fundamental frequencies above 35 GHz present extreme challenges for measuring the harmonic signals resulting from nonlinear effects. Predictive physics based simulations in conjunction with compact modeling capabilities are promising alternatives to expensive and time-consuming measurements. To date, tools either exist in the electron transport domain or in the behavioral modeling domain and a key goal is to treat these problems simultaneously because they are strongly coupled at millimeter wave frequencies. Accurate physics based simulations of high speed and high power transistors require proper treatment of hot-electron, self-heating, and full-wave effects. The Boltzmann solver called Fermi kinetics transport (FKT) has been shown to capture all of these important physical effects. FKT can approach the accuracy of Monte Carlo methods while maintaining the computational efficiency of deterministic solvers. The latter trait allows simulation of large electronic devices such as the output stages of PAs. Previous work on FKT provided proof of concept results which demonstrated its versatility and accuracy as an electronic device simulation framework.The purpose and contribution of this thesis is the use of FKT as a predictive TCAD tool to generate RF data required for PA design. This work begins with a thorough investigation of the underlying physical equations and their numerical solution for electronic device simulations. Included in this investigation is an analysis of the full-wave discretization technique called Delaunay-Voronoi surface integration (DVSI), a derivation of the FKT device equations and their discretization in energy- and real-space, and a detailed account on the numerical solution of the fully coupled nonlinear system of equations. The detail provided in this work is meant to provide future device engineers and researchers a thorough understanding of the numerical framework for their application and simulation needs. The FKT device simulator is then applied to real device geometries to generate useful data for RF circuit designers. Extensions of the FKT method required for large-signal LP simulations are presented with representative applications. Additionally, compact behavioral models are extracted directly from FKT device simulations, enabling a computationally efficient means for simulated LP data generation. The resulting TCAD tool is a promising simulation capability for high power RF transistor design and characterization. It is anticipated that PA design for 5G applications will be using techniques like these in the near future.
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- Title
- Building a location-based prioritized overlay multicast in ad-hoc environments
- Creator
- Liu, Yunhao
- Date
- 2003
- Collection
- Electronic Theses & Dissertations
- Title
- On SNR aware analysis and modeling of 802.11b link-level residual errors
- Creator
- Prabhu Parrikar, Utpal M.
- Date
- 2006
- Collection
- Electronic Theses & Dissertations
- Title
- Improving data transmission reliability and throughput in wireless sensor networks
- Creator
- Lee, Ee Foong
- Date
- 2008
- Collection
- Electronic Theses & Dissertations
- Title
- A framework for handling user mobility in wireless ATM networks
- Creator
- Lin, Hui-Tang
- Date
- 1998
- Collection
- Electronic Theses & Dissertations
- Title
- Welfare impacts of spectrum governance regimes : an economic-engineering study
- Creator
- Ting, Yi-Feng Carol
- Date
- 2005
- Collection
- Electronic Theses & Dissertations
- Title
- Coding over resource-constrained wireless networks
- Creator
- Halloush, Rami D.
- Date
- 2012
- Collection
- Electronic Theses & Dissertations
- Description
-
In practice, wireless networks operate under multiple, mostly severe, constraints (bandwidth, energy resources, etc). Consequently, efficient techniques have to be employed in communicating data with sufficiently high data rates (depending on the application) while complying with the imposed constraints. Distributed Video Coding (DVC) and Network Coding (NC) are amongst the most dominant techniques employed in constrained data networks. In this dissertation, we address these two techniques...
Show moreIn practice, wireless networks operate under multiple, mostly severe, constraints (bandwidth, energy resources, etc). Consequently, efficient techniques have to be employed in communicating data with sufficiently high data rates (depending on the application) while complying with the imposed constraints. Distributed Video Coding (DVC) and Network Coding (NC) are amongst the most dominant techniques employed in constrained data networks. In this dissertation, we address these two techniques with the objective of realizing practical and efficient data networking solutions that fit in resource constrained wireless networks. In one part of the dissertation we address DVC over Visual Sensor Networks (VSNs) from a practical point of view, i.e., unlike a large body of research work related to this topic where the focus is on theoretical analysis and simulation, we study the practical aspects that arise when deploying DVC over real visual sensors. To that end, we develop a Resource-constrained DVC (RDVC) codec, deploy it over some of the widely used visual sensors, and conduct precise energy measurements that are used throughout our study.One RDVC-related challenge that we address in this dissertation is source rate estimation, i.e., trying to efficiently identify the source rate to be used in encoding a frame. This question is crucial since sending more bits than necessary will lead to inefficiency in compression while sending fewer bits will lead to failure in decoding. We propose a practical solution that completely eliminates the need for the costly feedback messages.Another challenge we address is the global choice between a DVC encoding option that involves intensive computations and leads to less transmission versus another choice with minimal computations that implies higher transmission-energy overhead. We carry out an operational energy-distortion analysis for a variety of options available to RDVC on visual sensors.Polar codes are the first codes proven to achieve capacity while having low encoding and decoding complexity. This motivates us to employ polar codes in our DVC platform. We compare the performance of polar codes with the more established and more investigated Low Density Parity Check Accumulate (LDPCA) codes in the context of DVC. Our results show that polar codes offer a clear advantage when coding smaller size image blocks. Consequently, polar codes could represent a viable solution for distributed sensor networks that capture low-resolution video signals. In the final part of the dissertation, we survey state-of-the-art NC solutions designed to achieve high throughput transmission in multicasting over wireless mesh networks while maintaining 100% packet delivery ratio. We propose HopCaster; a scheme that employs the cache-and-forward transport strategy. We show that HopCaster achieves significant performance gains compared to schemes that employ the end-to-end transport strategy.
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- Title
- The uses of cellular telephony in Taiwan
- Creator
- Hsu, Hsiu-Yueh
- Date
- 1992
- Collection
- Electronic Theses & Dissertations
- Title
- Tackling the challenges of wireless interference and coexistence
- Creator
- Huang, Jun
- Date
- 2012
- Collection
- Electronic Theses & Dissertations
- Description
-
Recent years have witnessed the phenomenal penetration rate of wireless networks in our daily lives, ranging from 802.11-based wireless LANs that provide ubiquitous Internet access, to 802.15.4-based wireless sensor networks that carry out various mission-critical tasks such as security surveillance and patient monitoring. However, despite the advances in the field of wireless networking, how to design high-performance wireless networks remains an open problem because of the fundamental...
Show moreRecent years have witnessed the phenomenal penetration rate of wireless networks in our daily lives, ranging from 802.11-based wireless LANs that provide ubiquitous Internet access, to 802.15.4-based wireless sensor networks that carry out various mission-critical tasks such as security surveillance and patient monitoring. However, despite the advances in the field of wireless networking, how to design high-performance wireless networks remains an open problem because of the fundamental challenges of wireless interference and coexistence.Interference is the fundamental factor that limits the link concurrency of wireless networks. Due to the broadcast nature of wireless channel, concurrent transmissions on the same frequency interfere with each other over the air, resulting in lower throughput and higher delivery delay. Handling interference in wireless networks is difficult because of the hidden terminal problem and the exposed terminal problem. Although the former is well studied in existing literature, the later is not, especially in networks where multiple bit rates are available.Another challenge is that interference significantly hinders the coexistence of different wireless technologies. In particular, recent studies show that wireless coexistence is becoming a growing issue due to the unprecedented proliferation of wireless devices in the unlicensed 2.4GHz band. When devices of heterogeneous physical layer operating on the same frequency, interference is more difficult to resolve as devices cannot decode the signals of each other. Moreover, co-existing devices commonly transmit at different powers, which leads to unfair channel usage. The issue is particularly critical to lower power wireless devices. This thesis tackles the fundamental challenges of wireless interference and coexistence to the link layer design of wireless networks. In particular, we identify two problems in the design of existing link layer protocols, and advance the state-of-the-art by offering practical solutions: (1) the rate-adaptive exposed terminal problem where link concurrency cannot be fully exploited by conventional link layers because of they are oblivious to the bit rate diversity; and (2) the blind terminal problem where existing link layer protocols fail to work in co-existing environments due to the heterogeneous physical layer and power asymmetry of co-existing devices. We motivate this research by showing that existing link layer protocols are surprisingly ineffective in handling these problems. Our experiments pinpoint the fundamental reasons of such ineffectiveness and reveal their implications on the design of link layer protocols. We then develop practical solutions to tackle the identified problems. Extensive testbed-based experiments validate the design of proposed solutions, and demonstrate their significant performance gains over existing link layer protocols.
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- Title
- Autoconfiguration and security for wireless networks
- Creator
- Zhou, Hongbo
- Date
- 2005
- Collection
- Electronic Theses & Dissertations