Events Calendar

Integrated Systems Seminar Series

Speaker: Prof. Danijela Cabric, UCLA

Talk Title: Energy-Efficient Wideband Spectrum Sensing and Modulation Classification

Abstract: Motivated by the spectrum scarcity problem, Cognitive Radios (CRs) have been proposed as a way to opportunistically allocate unused spectrum licensed to Primary Users (PUs). In this context, Secondary Users (SUs) sense the spectrum to detect the presence or absence of PUs, and use the unoccupied bands while maintaining a predefined probability of misdetection. Further, modulation classification, the process of identifying the modulation class employed by the transmitter, helps identify who is occupying a given frequency band and distinguish PUs from other users and interference. Sensing wideband channels increases the chance of finding unoccupied spectrum, and therefore increases the throughput of the CR network. The narrow-band approach for wideband spectrum sensing involves sensing multiple narrow-band channels either simultaneously, or in parallel. Both solutions either require additional receiver chains, or incur additional delays in the sensing results. Therefore, sensing wideband channels in an energy-efficient manner is highly desirable. However, wideband spectrum sensing unfolds many challenges that have not been considered in the past. In this work, we aim at answering the following fundamental question: What are the limitations of wideband spectrum sensing and modulation classification, and what are the methods to overcome them? We propose low-complexity algorithms for both cyclostationary spectrum sensing and modulation classification. Further, as a result of wideband sampling, high-rate and high-resolution ADCs become hard to design and are power hungry. As a solution to that, we propose a method to perform cyclostationary spectrum sensing using compressive sensing measurements. Moreover, given that the sampling rate of the sensing radio cannot be adapted to all signals being sensed, we study the impact of sampling clock offsets and imperfect estimates of transmit parameters on cyclostationary features. This comprehensive system level study is vital to the robust and energy-efficient design of wideband spectrum sensing and modulation classification engines for CRs.

Biography: Dr. Danijela Cabric received the Dipl. Ing. degree from the University of Belgrade, Serbia, in 1998, and the M.Sc. degree in electrical engineering from the University of California, Los Angeles, in 2001. She received her Ph.D. degree in electrical engineering from the University of California, Berkeley, in 2007, where she was a member of the Berkeley Wireless Research Center. In 2008, she joined the faculty of the Electrical Engineering Department at the University of California, Los Angeles as an Assistant Professor. Dr. Cabric received the Samueli Fellowship in 2008, the Okawa Foundation Research Grant in 2009, Hellman Fellowship in 2012 and the National Science Foundation Faculty Early Career Development (CAREER) Award in 2012. She serves as an Associate Editor in IEEE Journal on Selected Areas in Communications (Cognitive Radio series) and IEEE Communications Letters, and TPC Co-Chair of 8th International Conference on Cognitive Radio Oriented Wireless Networks (CROWNCOM) 2013. Her research interests include novel radio architecture, signal processing, and networking techniques to implement spectrum sensing functionality in cognitive radios.

Host: Prof. Hossein Hashemi and Prof. Mike Chen

Location: Hughes Aircraft Electrical Engineering Center (EEB) - 248

Audiences: Everyone Is Invited

Contact: Hossein Hashemi