Electrical and Computer Engineering

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This is the collection for the University of Waterloo's Department of Electrical and Computer Engineering.

Research outputs are organized by type (eg. Master Thesis, Article, Conference Paper).

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Browsing Electrical and Computer Engineering by Author "Agnew, Gordon"

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    Computation Reduction for Angle of Arrival Estimation Based on Interferometer Principle
    (University of Waterloo, 2017-09-28) Chandail, Mukul; Agnew, Gordon; Golab, Wojciech
    Advancement in wireless technology and the oncoming of the Internet of Things (IoT) marked an incredible growth in the wireless connectivity, ultimately concluding to a major expansion in the mobile electronics industry. Today, around 3.1 billion users are reported being connected to the internet, along with 16.3 billion mobile electronic devices. The increasing connectivity has lead to an increase in demand for mobile services, consequently, increasing demand for location services and mobility analytics. The most common location tracking or direction finding devices are found in the form of Global Positioning System (GPS) which provides location data for a client device using satellites-based lateration techniques. However, the use of the GPS is fairly limited to large distances and often tend to fail when smaller distances are concerned. This thesis aims to dive into the study of different direction finding algorithms based on angle of arrival estimation specifically pertaining to the indoor location tracking and navigation, also known as hyperlocation. The thesis will go over the main elements used in direction finding systems while looking at some of the present research done in this respective field of interest. Afterwards, the thesis will focus on a specific angle of arrival estimation algorithm which is widely being used for hyerplocation solutions and propose an alteration in the algorithm in order to achieve a faster runtime performance on weaker processors. A comparison between the accuracies will be made between the original algorithm and the suggested solution, followed by a runtime comparison on different processing units.
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    A Detailed Characterization of 60 GHz Wi-Fi (IEEE 802.11ad)
    (University of Waterloo, 2017-02-22) Holmes-Mitra, Daniel; Agnew, Gordon; Gebotys, Catherine
    The emergence of wireless local area network (WLAN) standards and the global system of mobile communication (GSM) in the early 1990s incited tremendous growth in the demand for wireless connectivity. Iterative technological enhancements to cellular and WLAN improved wireless capacity and created a breadth of new mobile applications. The continued increase in display resolutions and image quality combined with streaming displacing satellite/cable has created unprecedented demands on wireless infrastructure. Data-caps on cellular networks deter over consumption and increasingly shift the growing burden to Wi-Fi networks. The traditional 2.4/5 GHz Wi-Fi bands have become overloaded and the increasing number of wireless devices in the home, public, and workplace create difficult challenges to deliver quality service to large numbers of client stations. In dense urban areas, the wireless medium is subjected to increased interference due to overlapping networks and other devices communicating in the same frequency bands. Improvements to conventional Wi-Fi are approaching their theoretical limits and higher order enhancements require idealized conditions which are seldom attainable in practice. In an effort to supplant to scaling capacity requirements a very high frequency WLAN amendment has been proposed (IEEE 802.11ad). IEEE 802.11ad, also referred to as Wireless Gigabit (WiGig), operates in the globally unlicensed 60 GHz band and offers channel bandwidths nearly 100x as wide as 802.11n. The higher bandwidth facilitates multi-Gbps throughput even with the use of lower complexity modulation coding schemes (MCS). IEEE 802.11ad relies heavily on rate adaptation and high beamforming gain to mitigate interference and fading as signals in the 60 GHz band suffer from higher atmospheric ab- sorption and free space path loss (FSPL). Due to the unique nature of 60 GHz wireless there have been numerous research efforts. Many studies have been directed at simulation and modeling of the 60 GHz channel. However modeling the channel is difficult as real- world environments are highly dynamic with varying link quality and conditions which cannot be accurately predicted by conventional techniques. Some research is focused on medium access control (MAC) enhancements to improve overall capacity by coordinating concurrent links or reducing communication overhead for example. Lastly, there has been a limited amount of real world testing of 802.11ad due to lack of availability of commercial platforms and measurement instrumentation. Some researchers tested early generation devices in certain use cases such as in vehicles for media streaming, in data centers to augment the wired network, or in basic indoor and outdoor environments. This research contains two main components. In the first study, analytical models are applied to estimate line of sight (LOS) 802.11ad performance for realistic antenna param- eters. The second part contains a comprehensive evaluation of performance and reliability of early generation 802.11ad hardware. This characterization emphasizes environmen- tal performance (e.g. conference room, cubical farm, open office), multiple-client testing (multiclient), multiple network interference (spatial re-use), and stability in the presence of station mobility, physical obstructions, and antenna misalignment. In order to evaluate 802.11ad, early generation platforms from technology vendors were used in extensive test suites. The hardware tested included docks for wireless personal area networking (WPAN) applications, client laptop stations, and reference design access points (APs). Finally, a customized proof-of-concept (PoC) platform was engineered which allowed finer control over front end antenna configuration parameters such as: topology, placement and orienta- tion. The PoC also served as a suitable means to identify practical limitations and system design engineering challenges associated with supporting directional multi-Gbps (DMG) communication in the 60 GHz band.
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    Using Shamir's Secret Sharing Scheme and Symmetric Key Encryption to Achieve Data Privacy in Databases
    (University of Waterloo, 2016-09-01) Tawakol, Abdel Maguid; Agnew, Gordon
    The Internet has become an essential tool for communication and information access, and with growing demand, new challenges and usage continue to surface. A complimentary tool that came to exist in recent years is Cloud Computing - an economical solution that serves as an alternative to owning and running computing facilities. While cloud computing has many advantages, there are a number of issues that hamper the adoption of cloud computing. Some of the major concerns, can be classified into one of the following groups: traditional security, availability, and third-party data control. The first set of concerns, revolve around security threats that can expose clients private data. The second set of concerns, revolve around the compromise of the operation of the applications in the cloud. Finally, the last set of concerns involve the legal implications of data and applications being held by a third party. Different solutions exist to deal with traditional security, availability, and third-party data control, separately, but one way to handle traditional security, and third-party data control, is through data encryption. The client has to take responsibility for ensuring that the data is setup in such a way, that even if the cloud service provider is compromised, or has a malicious intent, it is not able to get anything from the customers data. Of course, encrypting the data introduces limitations, with varying tradeoffs for different systems. In this work, we use Shamirs Secret Sharing Scheme and a symmetric key cryptographic system (AES) to encrypt data at a field level, such that it can be stored in the cloud without compromising data privacy. Using Shamirs Secret Sharing Scheme to encrypt numeric field values, gives us the ability to perform efficient addition, subtraction, and multiplication on the encrypted numeric field values. We explore two different ways of using Shamir Secret Sharing Scheme and AES, and discuss the advantages and disadvantages of each. We then propose, and complete, a software implementation for the proposed system. The implementation is used in order to compare execution time, memory usage, and bandwidth usage, to the plaintext and MySQL encrypted versions of the database. Analyzing the benchmarks, we can see how the performance varies for different query types when run on tables with different number of records and field types giving the reader an idea about the cost and tradeoffs of the system.