Bradley Department of Electrical and Computer Engineering

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https://hdl.handle.net/10919/18738
From pervasive computing, to smart power systems, Virginia Tech ECE faculty and students delve into all major areas of electrical and computer engineering. The main campus is in Blacksburg, and the department has additional research and teaching facilities in Arlington, Falls Church, and Hampton, Virginia.

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Browsing Bradley Department of Electrical and Computer Engineering by Author "Abdel-Rahman, Mohammad J."

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    Aperture synthesis of time-limited X waves and analysis of their propagation characteristics
    Chatzipetros, Argyrios A.; Shaarawi, Amr M.; Besieris, Ioannis M.; Abdel-Rahman, Mohammad J. (Acoustical Society of America, 1998-05-01)
    The feasibility of exciting a localized X-wave pulse from a finite aperture is addressed. Also, the possibility of using a finite-time excitation of a dynamic aperture to generate a finite-energy approximation to an X-wave pulse is explored. The analysis is carried out by using a Gaussian time window to time limit the infinite X-wave initial excitation. Huygens' construction is used to calculate the amplitude of the radiated wave field away from the finite-time source. The decay rate of the peak of the X wave is compared to that of a quasi-monochromatic signal. It is shown that the finite-time X-wave propagates to much farther distances without significant decay. Furthermore, the decay pattern of the radiated X-wave pulse is derived for a source consisting of an array of concentric annular sections. The decay behavior of the radiated pulse is similar to that of an X-wave launched from a finite-time aperture. This confirms the fact that time windowing the infinite energy X-wave excitation is a viable scheme for constructing finite apertures. A discussion of the diffraction limit of the X-wave pulse is also provided.
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    Indoor Millimeter-Wave Systems: Design and Performance Evaluation
    Kibilda, Jacek; MacKenzie, Allen B.; Abdel-Rahman, Mohammad J.; Yoo, Seong Ki; Giordano, Lorenzo Galati; Cotton, Simon L.; Marchetti, Nicola; Saad, Walid; Scanlon, William G.; Garcia-Rodriguez, Adrian; Lopez-Perez, David; Claussen, Holger; DaSilva, Luiz A. (IEEE, 2020-06-01)
    Indoor areas, such as offices and shopping malls, are a natural environment for initial millimeter-wave (mmWave) deployments. Although we already have the technology that enables us to realize indoor mmWave deployments, there are many remaining challenges associated with system-level design and planning for such. The objective of this article is to bring together multiple strands of research to provide a comprehensive and integrated framework for the design and performance evaluation of indoor mmWave systems. This article introduces the framework with a status update on mmWave technology, including ongoing fifth generation (5G) wireless standardization efforts and then moves on to experimentally validated channel models that inform performance evaluation and deployment planning. Together these yield insights on indoor mmWave deployment strategies and system configurations, from feasible deployment densities to beam management strategies and necessary capacity extensions.
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    Market-Driven Stochastic Resource Allocation Framework for Wireless Network Virtualization
    Gomez, Marcela M.; Chatterjee, Shubhajeet; Abdel-Rahman, Mohammad J.; MacKenzie, Allen B.; Weiss, Martin B. H.; DaSilva, Luiz A. (IEEE, 2020-03-01)
    Wireless network virtualization is emerging as a potential game-changer for fifth-generation wireless networks. Virtualization of network resources (e.g., infrastructure and spectrum) brings several advantages. One key advantage is that various network operators can robustly share their virtualized network resources to extend coverage, increase capacity, and reduce costs. However, inherent features of wireless communications, e.g., the uncertainty in user equipment locations and channel conditions, impose significant challenges on virtualization and sharing of the network resources. In this context, we propose a novel three-layered virtualization framework, based on a matching game model and stochastic resource allocation. Our proposed architecture aims at guaranteeing user satisfaction and maximizing the revenue for operators, with reasonable computational complexity, and affordable network overhead.