Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 39 for “"ALOHA"”.
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Analyzing performance of SIC with multiple power multichannel Aloha
… when used with multiple power, multichannel Aloha. We use the fluid model to analyze the performance of the system under various circumstances. We also simulate the performance of a SIC system over a single channel. SIC increases the throughput of a multiple power system up to around 100%. …
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Performance analysis of ALOHA networks utilizing multiple signal power levels
… transfer delay of both slotted and unslotted ALOHA networks utilizing multiple received power levels to create beneficial power capture effects in environments where near perfect capture does not occur. The throughput achievable can be greatly increased when two received power levels are …
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Searching for Pōhakuloa: A Citizen Scientist’s Journey in Aloha ‘Āina
<p>This dissertation tells a story about the United States (US) military’s land occupation of two Indigenous Hawaiian <em>wahi pana </em>(sacred places), on O’ahu and Hawai’i Island, which have produced widespread health concerns regarding exposure to military toxins. I conducted six months of …
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Distributed Multiple Access for OFDMA Femtocells
… un-optimized random access protocol such as Aloha would perform much better than an optimized power controlled network in most of the unsaturated traffic scenarios. This result serves as a strong motivation for the design of OFDMA-aware random access protocols that utilize the inherent …
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Satellite multiple access protocols for land mobile terminals. A study of the multiple access environment for land mobile satellite terminals, including the design analysis and simulation of a suitable protocol and the evaluation of its performance in a U.K. system.
… is suggested for a large system. Reservation ALOHA schemes are appraised in a TDMA environment and an adaptive reservation multiple access protocol is proposed and analysed for a wide range of mobile communication traffic profiles. The system can cope with short and long data messages as well …
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Simulation of an Anti-Collision Algorithm for RFID Systems using a Code Division Multiple Access with Adaptive Interference Cancellation (CDMA/AIC) Approach with Dynamic Processing Gain (Gp)
… Access (TDMA) approach with anti-collision ALOHA-type algorithms. The time slots and frames of the tags are manipulated to deal with the collision problem. They work with different ALOHA protocol variants that are always trying to reduce the number of collisions compared to the previous …
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Dimensions of microbial biodiversity in the North Pacific subtropical Gyre
… and their metabolic potential at Station ALOHA, a long-term study site representative of the North Pacific Subtropical Gyre (NPSG). We observed changes in diversity and community composition at Station ALOHA across time, ocean depth and on plastic debris, a new anthropogenically derived …
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Packet data communications over coded CDMA with hybrid type-II ARQ
… analytical model, customarily employed for ALOHA system with pure or hybrid type-I ARQ, cannot be applied for this case, an expanded analytical model is introduced. It can be regarded as a network of queues and Jackson and Burke's theorems can be applied to simplify the analysis. The second …
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In-Flight Fatigue Crack Monitoring of an Aircraft Engine Cowling
… for ripping the top of a fuselage off an Aloha Airlines Boeing 737-200 as it carried passengers over the Pacific Ocean, killing some aboard. This tragedy is perhaps a precursor of problems to come, as our nation’s aircraft age. These planes experience fatigue as they perform their daily …
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Force Feedback and Tactile Sensing for Robotic Teleoperation of Contact Rich Manipulation Tasks
… robots new skills. We propose augmenting the ALOHA bimanual teleoperation system with haptic feedback to obtain higher quality expert demonstrations. We add two types of haptic feedback: force feedback and cutaneous feedback in both a real and simulation teleoperation system. Additionally, we …
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Performance analysis of star architecture packet-switched VSAT networks using random code division multiple access
… Third, we presented a delay analysis of the ALOHA DS-CDMA/TDM channel to determine the total service time of a packet originating from either the VSAT or the hub station. In addition to its multiple access capability, this thesis is concerned with the use of direct-sequence spread-spectrum …
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Multiple access protocols for multichannel communication systems
… Time Division Multiple Access (TDMA) and Slotted ALOHA (S-ALOHA) alongside a channelized architecture, which is based on the idea of multiplexing by dividing total transmission capacity into a fixed number of frequency channels. We develop mathematical models that describe the overall delay for …
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Metagenomic approaches for examining the diversity of large DNA viruses in the biosphere
… giant viruses previously surveyed from Station ALOHA in the Pacific Ocean. St. ALOHA is located near Hawaii and represents oligotrophic gyres which the majority of the ocean is made of them. I focused on 11 MAGs of giant viruses to get insight into their phylogenetic characteristics, genomic …
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A Reconfigurable Random Access MAC Implementation for Software Defined Radio Platforms
… our two random access MAC implementations: Aloha with Explicit ACK and Aloha with Implicit ACK. A point-to-point link was tested with our protocol and then this link was extended to a 3-hop (4 nodes) network. To improve our protocols' efficiency, we implemented carrier sensing on the FPGA of …
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A dynamic and robust random multiple-access scheme for communication over satellite channels with interference
… proposes a combined system using the slotted ALOHA protocol as its random multiple access scheme along with direct sequence spread spectrum coding to provide channel robustness and low probability of detection. We estimate the transmission power achievable by a transportable interferer using …
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Fundamentals of the Simplex Communication Channel With Retransmissions
… or medium. Such random access techniques as ALOHA and slotted ALOHA have been successfully implemented in a number of wireless applications. One of the major drawbacks of these algorithms is the necessity of a return path from the central station to each system user, which makes their use …
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Advanced random access techniques for satellite communications
… this work, starting from the latest findings on Aloha-based Random Access schemes, the optimization of such techniques and their use in closed-loop scenarios is investigated with particular regard to the Return Channel over Satellite of Digital Video Broadcasting. The thesis starts with a summary …
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DMACS: a media access protocol for single-hop wavelength division multiplexed lightwave networks
… is based on the Dynamic Interleaved Slotted Aloha (DISA) protocol. It improves on DISA by adding a common control channel that provides reservations for constant bit-rate traffic, acknowledgments, and global flow control. DMACS supports connection setup and tear down, different traffic …
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Energy harvesting-aware design of wireless networks
… as time division multiple access (TDMA), framed-ALOHA (FA) and dynamic-FA (DFA) are investigated in the presence of EH-capable devices. A new ALOHA-based MAC protocol tailored to EH-networks, referred to as energy group-DFA (EG-DFA), is then proposed. In EG-DFA nodes with similar energy …
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Construction and phenotypic screening of mid-size insert marine microbial environmental genomic libraries
… collected at Hawaii Ocean Time-series station ALOHA in plasmid cloning vector pMCL200 under the inducible control of the PLAC promoter. To begin to evaluate the utility of such libraries for gene expression-based screens, this library was screened phenotypically for clones expressing genes that …
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