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2022 Seminars


Cognitive Radar: Foundations and Frontiers

Charles Thornton - 12/02/2022

Abstract: Since 2006, over a dozen conceptual papers on "cognitive radar" have appeared in leading academic journals and magazines. Various biological mechanisms have been promoted as potential sources of inspiration for intelligent sensing, and several analytical frameworks have been proposed. In this talk, we will begin with an examination of some key technical ideas underpinning this field of research. We will then take a decision-theoretic perspective, and highlight how cognitive radar problems serve as a natural meeting point of communication and control theories. Finally, we will motivate some open problems in intelligent sensing from both theoretical and operational standpoints.

Bio: harles Thornton is a Ph.D. candidate with Wireless @ Virginia Tech. He received the BS degree from Johns Hopkins University in 2018 and the MS degree from Virginia Tech in 2020, both in electrical engineering. His research interests include cognitive radar, reinforcement learning, and online learning. In particular, he is interested in sample complexity and generalization issues in online learning, connections between machine learning and source coding, and practical issues in learning-based cognitive radar.

On the Role of THz Bands in 6G Wireless Networks: A Fellowship of Communication and Sensing

Christina Chaccour - 11/11/2022

Abstract: Wireless communication at the terahertz (THz) frequency bands (0.1 - 10 THz) is viewed as one of the cornerstones of tomorrow’s 6G wireless systems. Owing to the large amount of available bandwidth, if properly deployed, THz frequencies can potentially provide significant wireless capacity performance gains and enable high-resolution environment sensing. However, operating a wireless system at high-frequency bands such as THz is limited by a highly uncertain and dynamic channel. Effectively, these channel limitations lead to unreliable, intermittent links as a result of an inherently short communication range and a high susceptibility to blockage and molecular absorption. Consequently, such impediments could disrupt the THz band’s promise of high-rate communications and high-resolution sensing capabilities. In this context, this talk panoramically examines the steps needed to efficiently and reliably deploy and operate next-generation THz wireless systems that will synergistically support a fellowship of communication and sensing services. For this purpose, we first set the stage by describing the fundamentals of the THz frequency band. Based on these fundamentals, we characterize and comprehensively investigate seven unique defining features of THz wireless systems: 1) Quasi-opticality of the band, 2) THz tailored wireless architectures, 3) Synergy with lower frequency bands, 4) Joint sensing and communication systems, 5) PHY layer procedures, 6) Spectrum access techniques, and 7) Real-time network optimization. These seven defining features allow us to shed light on how to re-engineer wireless systems as we know them today so as to make them ready to support THz bands and their unique environments. On the one hand, THz systems benefit from their quasi-opticality and can turn every communication challenge into a sensing opportunity, thus contributing to a new generation of versatile wireless systems that can perform multiple functions beyond basic communications. On the other hand, THz systems can capitalize on the role of intelligent surfaces, lower frequency bands, and machine learning (ML) tools to guarantee robust system performance. We conclude our exposition by presenting the key THz 6G use cases along with their associated major challenges and open problems. Ultimately, the goal of this talk is to chart a forward-looking roadmap that exposes the necessary solutions and milestones for enabling THz frequencies to realize their potential as a game changer for next-generation wireless systems.

Bio: Christina Chaccour (S’17) received the B.E. degree (Summa Cum Laude) in Electrical Engineering from Notre Dame University-Louaize, Lebanon, in 2018 and the M.S. degree in Electrical Engineering from Virginia Tech, Blacksburg, VA, USA, in 2020. She is currently pursuing the Ph.D. degree with the Bradley Department of Electrical and Computer Engineering, Virginia Tech, where her research interests include wireless communications, 5G and 6G networks, extended reality, terahertz frequency bands, machine learning, and semantic communications. She has derived some of the first performance analysis results on the potential of networking at THz frequencies. Christina is the co-founder of the startup Internet of Trees (IOTree); IOTree has won many local and international awards. She has held summer internship positions at Ericsson Inc., Plano, TX, USA, and Cadence Design Systems, Munich GmBh. She was the recipient of the best paper award for her peer-reviewed conference paper at the 10th IFIP Conference on New Technologies, Mobility, and Security (NTMS), Canary Islands, in 2019. Additionally, Christina was the recipient of the exemplary reviewer (fewer than 2) award from IEEE Transactions on Communications in 2021. She has also served as a reviewer and a technical program committee member for various IEEE transactions and flagship conferences.

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For information on the Wireless @ Virginia Tech Seminar Series, please contact Dr. Harpreet Dhillon.