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Tutorial: Cognitive Radio Technology for Dynamic Spectrum Access:
Spectrum Sensing, Waveform Design and Implementation
Presented by:
Dr. Vasu Chakravarthy, AFRL/Sensors Directorate, USA
Dr. Zhiqiang Wu, Wright State University, USA
Course Description:
Spectrum Congestion is a concern to both military and commercial applications. Recent studies have suggested that spectrum congestion is mainly due to the inefficient use of spectrum rather than its unavailability. Dynamic Spectrum Access (DSA) and Cognitive Radio (CR) are two terminologies which are used in the context of improved spectrum efficiency and usage. The advent of CR has created a paradigm shift in wireless communications and instigated a change in FCC policy towards spectrum regulations. Cognitive Radio is a cross-cutting multi disciplinary technology requiring concepts such as: Signal processing, Wireless Communications, Antenna theory, Network protocols, Pattern recognition and Machine learning, to name a few. Even though CR technology’s main objective is to identify unused spectrum and improve spectrum efficiency, it indirectly translates to unrealized monetary gain resulting from new applications and users. This has resulted in interest from not only technologists (engineers) but also from policy makers (attorneys) and corporate business.
This tutorial’s main emphasis will be on the physical layer design and implementation of cognitive radio and to also provide the audience with an in-depth understanding of cognitive radio and its enabling technologies. Different DSA models will be discussed. Next, major components of CR and DSA will be identified. An overview of the candidate Multi-Carrier (MC) waveforms such as Orthogonal Frequency Division Multiplexing (OFDM), MC-Code Division Multiple Access (MC-CDMA), Carrier Interferometry (CI)-MC-CDMA, Transform Domain Communication System (TDCS) and their non-contiguous versions will be presented. A general Spectrally Modulated, Spectrally Encoded (SMSE) expression encompassing all the above MC waveforms will be presented. This will be followed by a novel Soft Decision (SD) SMSE framework in the design of two CR enabling waveforms namely, CR-Overlay and CR-Underlay waveforms. Different application of these two CR waveforms will also be examined. Furthermore, hardware implementation of cognitive radio nodes using USRP (Universal Software Radio Peripheral) boards and GNU radio software will be discussed. We will provide hands-on laboratory of a USRP based cognitive radio video transmission in the tutorial as well.
Dr. Vasu D. Chakravarthy, Senior Electronics Engineer, Air Force Research Laboratories, Sensors Directorate, USA
Education: Dr. Vasu Chakravarthy received his B.S in Electrical Engineering from University of Illinois at Chicago in 1988, M.S and Ph.D. in Electrical Engineering from Wright State University in 1998 and 2008 respectively.
Accomplishments/Research Interests: Vasu Chakravarthy has been with AFRL since 1996 with an experience background in RF data links, Digital Receivers, Software GPS receivers and Communication Countermeasures. Prior to his tenure at AFRL, Vasu Chakravarthy has several years of experience in developing Test Program Sets (TPS) for Minuteman II/III and Advanced Cruise Missiles guidance systems at Newark Air Force Base, Aerospace Guidance and Metrology Center, Newark, OH. His recent focus has been in addressing problems related to Improvised Explosive Devices (IED) and developing Cognitive Jammer concepts. Research interest includes physical layer waveforms and signal processing algorithms related to Digital and Wireless Communications, issues related to Dynamic Spectrum Access and Cognitive Radio technologies. He has been associated with Cognitive Radio related research since 2000 and his Ph.D. dissertation entitled “Evaluation of Overlay/Underlay Waveform via SD-SMSE Framework for Enhancing Spectrum Efficiency” focused on designing a novel cognitive radio waveform. He has co-authored more than 20 refereed journal and conference record papers in the areas of his research interests. He holds 2 U.S. patents.
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Dr. Zhiqiang Wu, Assistant Professor, Electrical Engineering Department, Wright State University, USA
Education: Dr. Zhiqiang Wu received his BS from Beijing University of Posts and Telecommunications in 1993, his MS from Peking University in 1996, and his PhD from Colorado State University in 2002, all in electrical engineering.
Accomplishments/Research Interests: Zhiqiang Wu worked for Motorola and the Chinese Academy for Telecommunication Technologies as a research engineer for three years. He taught at West Virginia University Institute of Technology from 2003 to 2005. Currently he is an assistant professor at Electrical Engineering department of Wright State University. Dr. Wu has over 10 years experience with wireless communication and signal processing. He is the major author of the national CDMA network management standard of China. He also co-authored the book Multi-carrier Transmission Technologies for Wireless Communications published by Kluwer Academic Publisher. |
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