Qing Zhao, University of California, Davis, USA and Ananthram Swami, Army Research Lab, USA
Dynamic spectrum access (DSA) has emerged as a new area of research to deal with the paradox that spectrum is scarce but underutilized. DSA is also a vital component to facilitate emerging peer-to-peer applications. To realize the potentials of the envisioned DSA strategies, advances in the technical areas of signal processing, communications, and networking are crucial. DSA also relies on a context-aware and autonomously reconfigurable radio, referred to as cognitive radio, which forms the physical platform.
This tutorial will elucidate key issues and challenges, and the state-of-the-art theories and techniques for cognitive radio networks. This tutorial will also cover a number of newly obtained results on the design of opportunistic spectrum access networks within a decision theoretic framework as noted below. This tutorial will provide attendees with a critical understanding of the current research and provide linkages between signal processing and networking aspects of DSA. We aim to cover cognitive radio for DSA with both breadth and depth.
BREADTH: We will first provide a detailed taxonomy of DSA, in which various approaches are categorized under three models: dynamic exclusive use, open sharing, and hierarchical access models. This taxonomy will help unify the terminology of this emerging field, in which many confusing terms have been coined by now. Potentials, challenges, and recent advances in each approach will be examined under this taxonomy. We will also cover applications of and regulatory issues related to DSA.
DEPTH: We will then give an in-depth treatment of the spectrum overlay approach under the hierarchical access model. Compared to other approaches to DSA, spectrum overlay (we will use the synonym “Opportunistic Spectrum Access (OSA)”) is perhaps the most compatible with the current spectrum management policies and legacy wireless systems, and has received the most attention.
We focus on the technical aspects of OSA. We will present a decision-theoretic framework based on the theory of Partially Observable Markov Decision Process (POMDP). This framework offers a unifying approach to address fundamental design issues and tradeoffs under practical constraints in OSA. We tackle the design of the physical, MAC, and network layers of OSA systems, providing a relatively complete design within one coherent framework. Such a coherent approach based on a rigorous mathematical theory allows us to systematically examine fundamental issues and inter-layer interactions in OSA networks, to characterize the optimal performance achieved by a joint design of various system parameters at different layers.
Qing Zhao received the Ph.D. degree in Electrical Engineering in 2001 from Cornell University, Ithaca, NY. From 2001 to 2003, she was a communication system engineer with Aware, Inc., Bedford, MA. She returned to academe in 2003 as a postdoctoral research associate with the School of Electrical and Computer Engineering at Cornell University. In August 2004, she joined the Department of Electrical and Computer Engineering at UC Davis where she is currently an assistant professor. Her research interests are in the general area of signal processing, communications, and wireless networking.
Qing Zhao is an Associate editor of IEEE Transactions on Signal Processing; an elected member of IEEE Signal Processing Society Signal Processing for Communications (SP-COM) Technical Committee; Guest editor of IEEE Signal Processing Magazine Special Issue on Resource-Constrained Signal Processing, Communications, and Networking; Guest editor of IEEE Journal of Selected Topics in Signal Processing Special Issue on Signal Processing and Networking for Dynamic Spectrum Access; Technical program co-chair of The First International Workshop on Cognitive Wireless Networks, 2007; Co-organizer of Special Session on Signal Processing and Networking for Dynamic Spectrum Access at ICASSP 2007; Co-organizer of Special Session on Fundamental Theory for Dynamic Spectrum Access at CrownCom 2007; co-organizer of the special session on Energy Constrained Signal Processing, Communications, and Networking at MILCOM 2005, and on Signal Processing for Sensor Networks at MILCOM 2004. She served as Publications Chair for IEEE SPAWC 2005; and on the TPC for Globecom 2007, VTC 2007, SSP 2007, SPAWC 2007, ICC 2006, ICDT 2006, Radio and Wireless Symposium, 2006 and 2007.
She received the 2000 IEEE Signal Processing Society Young Author Best Paper Award. She presented a tutorial on Cross- Layer Design for Application-Specific Large-Scale Sensor Networks at IEEE MILCOM 2005, and on Signal Processing for Random Access in Wireless Networks: A Cross Layer Approach, at IEEE WCNC 2004. She is the PI of several NSF and DoD projects on cognitive radio and sensor networks.
Ananthram Swami received the B.Tech. degree from IIT, Bombay; the M.S. degree from Rice University, Houston; and the Ph.D. degree from the University of Southern California (USC), all in Electrical Engineering. He has held positions with Unocal Corporation, USC, CS-3 and Malgudi Systems. He was a Statistical Consultant to the California Lottery, developed a Matlab-based toolbox for non-Gaussian signal processing, and has held visiting faculty positions at INP, Toulouse. He is currently with the US Army Research Laboratory (ARL) where his work is in the broad area of signal processing, wireless communications and networking, including both sensor networks and MANETs. Swami is an ARL Fellow.
He is an associate editor of the IEEE Transactions on Wireless Communications. He has served as an AE for IEEE Transactions on Signal Processing, IEEE Signal Processing Letters, IEEE Transactions on Circuits & Systems-II, and IEEE Signal Processing Magazine. He was chair of the IEEE Signal Processing Society's TC on Signal Processing for Communications; co-organizer and co-chair of the 1993 IEEE-SPS HOS Workshop, the 1996 IEEE-SPS SSAP Workshop, and the 1999 ASA-IMA Workshop on Heavy-Tailed Phenomena. He was co-guest editor of a 2004 special issue (SI) of the IEEE Signal Processing Magazine (SPM) on `Signal Processing for Networking', a 2006 SPM SI on `Distributed signal processing in sensor networks', a 2006 EURASIP JASP SI on Reliable Communications over Rapidly Time-Varying Channels', and a 2006 EURASIP JWCN SI on `Wireless mobile ad hoc networks', and lead Guest editor of IEEE Journal of Selected Topics in Signal Processing Special Issue on Signal Processing and Networking for Dynamic Spectrum Access. He was a co-organizer of a Special Session on Signal Processing and Networking for Dynamic Spectrum Access at ICASSP 2007; and a Co-organizer of a Special Session on Fundamental Theory for Dynamic Spectrum Access at CrownCom 2007.