Seminar: ECE Faculty Candidate
Monday February 26 11:00 - 11:50am Kelley 1007 Osvaldo Simeone Adjunct Professor/ Post-Doc New Jersey Institute of Technology Beyond centralized licensed wireless networks: distributed synchronization and cognitive radio In recent years, the interest of both academia and industry in the field of wireless communications has shifted from the conventional paradigm of centralized (cellular) licensed networks to decentralized wireless structures, such as ad hoc and sensor networks, and to unlicensed spectrum access, usually referred to as cognitive radio. In this talk, two key issues in these emerging areas are addressed: distributed synchronization (self-organization) of decentralized wireless networks and quality-of-service (stability) guarantee in cognitive radio. In the first part of the talk, the problem of distributed time synchronization in decentralized networks is tackled. A large number of applications in such networks is enabled by, or benefit from, the availability of a common time-scale among the participating nodes, e.g., tracking of moving objects via sensor networks and coordinated medium access control. Achieving and maintaining synchronization in decentralized scenarios poses new challenges in terms of scalability and energy efficiency, and offers new opportunities through the interplay with specific distributed estimation/ detection applications. In this context, an interesting solution is investigated that is based on the exchange of local time information among neighboring nodes at the physical layer (i.e., via transmission of a train of common waveforms that follows the local clock). Available analytical results are reported, along with numerical examples that corroborate the main conclusions and lend evidence to some interesting phenomena, such as "small-world" effects of shadowing on distributed synchronization. In the second part of the talk, unlicensed spectrum access (cognitive radio) is studied by focusing on a simple model with two single-user links, one licensed to use the spectral resource (primary) and one unlicensed (secondary or cognitive). According to the cognitive radio principle, the activity of the secondary link is required not to interfere with the performance of the primary within the limits imposed by a given quality-of-service guarantee. The presented analysis aims at studying the impact on the system performance of: i) traffic dynamics; ii) sensing errors due to fading at the secondary link; iii) power allocation at the secondary transmitter based on long-term measurements; iv) cooperation (relaying) between secondary and primary transmitters. Throughout the talk, open problems are emphasized along with opportunities for research. Biography: Osvaldo Simeone is currently an adjunct professor and Post-Doc researcher at the New Jersey Institute of Technology (NJIT), Newark, NJ. He received the M.Sc. degree (with honours) and the Ph.D. degree in Information Engineering from Politecnico di Milano, Milan, Italy in 2001 and 2005 respectively. His current research interests lie in the field of information theory and signal processing aspects of wireless systems with emphasis on cooperative communications, ad hoc wireless networks, MIMO systems, cognitive radio and distributed synchronization.
_______________________________________________ Colloquium mailing list [email protected] https://secure.engr.oregonstate.edu/mailman/listinfo/colloquium
