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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Design of a Microprocessor Controlled Telecommunication System

Maroutsos, George J. 01 January 1976 (has links)
Recent advancements in Large Scale Integration Technology have made available devices, such as microprocessors, analog gates and “three state” logic, that provide the designer with a wide range of possibilities in the design of telecommunication systems. A microprocessor and analog gates are utilized in this design to demonstrate the feasibility of implementing a flexible Telecommunication System. The microprocessor is programmed to control, through software, the system functions. The feasibility of systems highly adaptable to the needs of individual subscribers is thus demonstrated.
22

INFRASTRUCTURE-FREE SECURE PAIRING OF MOBILE DEVICES

Liu, Chunqiu 07 November 2016 (has links)
Mobile devices have advanced tremendously during the last ten years and have changed our daily life in various ways. Secure pairing of mobile devices has become a significant issue considering the huge quantity of active mobile device connections and mobile traffic. However, current commonly used file sharing mobile applications rely on servers completely that are always targeted by attackers. In this thesis work, an innovative mechanism is proposed to generate symmetric keys on both mobile devices independently from a shared movement in arbitrary pattern, which means no server needs to be involved and no data exchange needed. A secret wireless-communication channel can then be established with a particular network strategy.
23

Stack Protection Mechanisms In Packet Processing Systems

Wu, Peng 01 January 2013 (has links) (PDF)
As the functionality that current computer network can provide is becoming complicated, a traditional router with application-specific integrated circuit (ASIC) implementation can't satisfy the flexibility requirements. Instead, a programmable packet forward system based on a general-purpose processor could provide the flexibility. While this system provides flexibility, a new potential security issue arises. Usually, software is involved as the packet forward system is programmable. The software's potential vulnerability, especially as to the remote exploits, becomes an issue of network security. In this thesis work, we proposed a software stack overflow vulnerability on click modular router and show how a disastrous denial-of-service attack on click modular router could be triggered by a single packet. In our research work, click modular router runs on Linux operating system based on general-purpose hardware. We actually showed that even a software router run within a modern operating system's protection is vulnerable by elaborate attack. And we checked the possible stack protection mechanisms on modern OS based on general-purpose hardware and proposed a possible stack protection mechanism for embedded OS.
24

Hardware Implementation of Queue Length Based Pacing on NetFPGA

Dwaraki, Abhishek 01 January 2011 (has links) (PDF)
Optical packet switching networks are the foundation for next generation high speed Internet and are fast becoming the norm rather than an option. When such high speed optical networks are taken into account, one of the key considerations is packet buffering. The importance of packet buffering plays an even bigger role in optical networks because of the physical and technological constraints on the buffer sizes that can be implemented. Existing protocols, in many real world scenarios do not perform well in such networks. To eliminate such scenarios where there is a high possibility of packet loss, we use packet pacing. The proposed pacing scheme aims to reduce or eliminate packet losses arising from packet bursts in small-buffer networks. This thesis deals with a proposed hardware design and implementation of the packet pacing system on a NetFPGA. Our results show that the packet pacer can be implemented with a low overhead on hardware resources.
25

A Multi-Carrier Collaborative Solution to Minimize Connectivity-Loss

Wong, Michael 01 June 2016 (has links) (PDF)
Nearly two-thirds of Americans own a smart phone, and 19% of Americans rely on their smartphone for either accessing valuable information or staying connected with their friends and family across the globe [15]. Staying always-on and always-connected to the Internet is one of the most important and useful features of a smartphone. This connection is used by almost every single application on the device including web browsers, email clients, messaging applications, etc. Unfortunately, the cellular networks on our smartphones are not perfect and do not always have cellular signal. Our devices often lose Internet connection when users are on the go and traveling. This thesis presents a novel in-depth implementation and evaluation of what we can achieve when a user loses network connectivity. BleHttp, a library for Android, was developed that uses Bluetooth Low Energy to connect to other devices using a different carrier within close proximity of each other and make HTTP requests. In our results, we saw 100% success rates on HTTP requests with connected devices on a good connection. Average round trip times were tested to be as low as 1.5 seconds.
26

Examining Ambiguities in the Automatic Packet Reporting System

Finnegan, Kenneth W 01 December 2014 (has links) (PDF)
The Automatic Packet Reporting System (APRS) is an amateur radio packet network that has evolved over the last several decades in tandem with, and then arguably beyond, the lifetime of other VHF/UHF amateur packet networks, to the point where it is one of very few packet networks left on the amateur VHF/UHF bands. This is proving to be problematic due to the loss of institutional knowledge as older amateur radio operators who designed and built APRS and other AX.25-based packet networks abandon the hobby or pass away. The purpose of this document is to collect and curate a sufficient body of knowledge to ensure the continued usefulness of the APRS network, and re-examining the engineering decisions made during the network’s evolution to look for possible improvements and identify deficiencies in documentation of the existing network.
27

Wi-Fi Sensing: Device-Free In-Zone Object Movement Detection

Schnorr, Nicholas P 01 December 2021 (has links) (PDF)
Wi-Fi Sensing is becoming a prominent field with a wide range of potential applications. Using existing hardware on a wireless network such as access points, cell phones, and smart home devices, important information can be inferred about the current physical environment. Through the analysis of Channel State Information collected in the Neighborhood Discovery Protocol process, the wireless network can detect disturbances in Wi-Fi signals when the physical environment changes. This results in a system that can sense motion within the Wi-Fi network, allowing for movement detection without any wearable devices. The goal of this thesis is to answer whether Wi-Fi Sensing can enable useful applications at the enterprise level. The main applications we will focus on are presence detection and in-zone movement detection. Our contributions include: 1. A scalable, statistical analysis system that generates a heatmap and detects movement in a 12 x 9 meter zone with 98 percent accuracy, as well as a 6 x 9 meter zone with 88 percent accuracy. 2. A broad dataset collected for evaluation in an enterprise setting. 3. An end-to-end CSI data visualization and analysis application.
28

The Micro Check-In Framework for the Next Generation of Location-Based Applications

Kacha, Shraddha 01 June 2012 (has links) (PDF)
Today's mobile computing platforms provide new, convenient possibilities for location-based commercial activity. In particular, the global positioning system (GPS) provides location data for local advertising and retail activity. In this thesis, we take the next step and introduce the concept of micro check-in. Micro check-in is a simple framework that allows users to match their current location to specific objects or places at a resolution much finer than that allowed by GPS based check-in. We show that micro check-in enables customers to reveal their location at a fine level of granularity. By describing the concepts of points of service, service providers, users, and the enabling technology, we present a generalized, abstract, framework for designing, developing, and analyzing micro check-in based systems. We discuss several new applications that open up as a result of the combination of real-life and digital communication channel as a result of the micro check-in process. For example, micro check-in could prove quite useful to customers at a restaurant table, a gym equipment station, an exhibit at a museum and many more. This thesis studies micro check-in applied to the process of ordering food from a table at a restaurant and present the beneficial tradeoffs enabled by micro check-in. We find that the micro check-in framework has promising applications in several areas, but specifically utilize the restaurant application, OnTable, to prove the potential use of the micro check-in framework.
29

Traffic Privacy Study on Internet of Things – Smart Home Applications

Patel, Ayan 01 August 2020 (has links) (PDF)
Internet of Things (IoT) devices have been widely adopted in many different applications in recent years, such as smart home applications. An adversary can capture the network traffic of IoT devices and analyze it to reveal user activities even if the traffic is encrypted. Therefore, traffic privacy is a major concern, especially in smart home applications. Traffic shaping can be used to obfuscate the traffic so that no meaningful predictions can be drawn through traffic analysis. Current traffic shaping methods have many tunable variables that are difficult to optimize to balance bandwidth overheads and latencies. In this thesis, we study current traffic shaping algorithms in terms of computational requirements, bandwidth overhead, latency, and privacy protection based on captured traffic data from a mimic smart home network. A new traffic shaping method - Dynamic Traffic Padding is proposed to balance bandwidth overheads and delays according to the type of devices and desired privacy. We use previous device traffic to adjust the padding rate to reduce the bandwidth overhead. Based on the mimic smart home application data, we verify our proposed method can preserve privacy while minimizing bandwidth overheads and latencies.
30

Store and Forward Routing for Sparse Pico-Satellite Sensor Networks with Data-Mules

Koritza, Trevor Joseph 01 June 2009 (has links) (PDF)
Satellites are playing an increasingly important role in collecting scientific information, providing communication services, and revolutionizing navigation. Until recently satellites were large and very expensive, creating a high barrier to entry that only large corporations and government agencies could overcome. In the past few years the CubeSat project at California Polytechnic University in San Luis Obispo (Cal Poly) has worked to refine the design and launching of small, lightweight, and less expensive satellites called pico-satellites, opening space up to a wider audience. Now that Cal Poly has the launch logistics and hardware under control, a new problem has arisen. These pico-satellites are within communication range of a ground station only 40 minutes a day. This, combined with their 1200 bps communication speed, limits the usefulness of the satellite missions to those only transmitting small amounts of data back to Earth. This thesis proposes a novel protocol that allows a sparse network of pico-satellites to communicate among one another and to larger satellites called data mules, which relay the information back to the ground station at much higher speeds. The data mules are able to provide higher speeds because they are larger satellites with less power constraints. This protocol makes it possible for a pico-satellite to send more data over a given amount of time with less end-to-end delay. When every satellite has large amounts of data almost three times as much aggregate data can be sent through the network, and almost five times more data can be sent if only a single satellite has large amounts of data to send. The end-to-end delay is cut almost in half when sending 1 MB of data per day per satellite and is decreased by a factor of at least three when sending large amounts of data from only one satellite.

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