Spectrum Sensing for Cognitive Radios

Zhi Quan
Advisor: Ali H. Sayed

Monday, May 18, 2009 at 9:00am-11:00am
Engr IV Room 67-124

Abstract:
Traditional spectrum allocation policies are facing scarce radio frequency (RF) resources due to the proliferation of wireless services. To improve spectral utilization, the FCC has recently allowed unlicensed wireless devices to opportunistically use vacant frequency bands, especially vacant TV broadcast bands, provided that they do not cause harmful interference. To this end, cognitive radio has emerged as an intelligent wireless communication technology to revolutionize spectral utilization. As a fundamental problem arising in the cognitive ratio technology, spectrum sensing needs to reliably detect weak primary signals over a targeted wide frequency band to identify spectral holes for opportunistic communications. However, it is generally difficult for cognitive radios to reliably detect weak primary signals due to the absence of cooperation between the primary and secondary users. This talk addresses three important design challenges for spectrum sensing in cognitive radio networks: spectrum sensing at very low SNR, cooperative spectrum sensing, and wideband spectrum sensing. We propose and develop advanced signal processing algorithms to optimize spectrum sensing performance for cognitive radio systems.

Biography:
Zhi Quan is currently a Ph.D. candidate in Electrical Engineering at University of California, Los Angeles (UCLA). He received his B.E. degree in Telecommunications Engineering from Beijing University of Posts and Telecommunications, China, and M.S. degree in Electrical Engineering from Oklahoma State University (OSU), Stillwater, OK. He was a visiting scholar with the Department of Electrical Engineering at Princeton University (Princeton, NJ) in 2007. He worked with the Qualcomm Research Center at Qualcomm Inc (San Diego, CA) in 2008, where he is now a Sr. Systems Engineer. He has published over 30 journal and conference papers in the areas of statistical signal processing, wireless communications and networking, cognitive radios, and multimedia. His recognitions include Chancellor's Dissertation Year Fellowship (UCLA, 2008-2009) and Research Excellence Award (OSU, 2004), and his work was included into the IEEE Top 100 Articles.