Feedback-driven Opportunistic Access Strategies in Cognitive

Friday, April 30, 2010 - 11:11am


Tuesday, May 4, 2010
1:00 – 2:00 PM
Computer Science Conference Room, Harold Frank Hall Rm. 1132

HOST: Heather Zheng

Computer Science, UC Davis

Title: Feedback-driven Opportunistic Access Strategies in Cognitive
Radio Networks

Abstract: Cognitive radio is a promising technology to mitigate spectrum
shortage in wireless communications. It enables secondary users (SUs)
to opportunistically access low-occupancy primary spectral bands as
long as the primary user (PU) access is protected. We venture beyond
the “listen-before-tal” strategy that is common in many traditional
cognitive radio access schemes by exploiting the bi-directional nature
of most primary communication systems. By intelligently choosing their
transmission parameters based on the observation of primary user (PU)
communications, we show that secondary users (SUs) in a cognitive
network can achieve higher spectrum usage while protecting the PU in a
distributed fashion with neither a central controller nor message

If time permits, I will discuss our recent project on
user-profile-driven dynamic power management on cellular platforms. In
this project, our goal is to develop an energy management framework for
smart phones to maximize user experience, through both
user-profile-driven power management and collaborative execution. There
are two unique aspects of the proposed approach: 1) The explicit usage
of user profile, i.e., resource management should not be
one-size-fit-all; and 2) The dynamic nature of power management, i.e.,
power management should depend on the context such as time of the day,
remaining battery lever, and network condition.


Xin Liu is an associate professor in the Computer Science Department at
the University of California, Davis. Before joining UC Davis, she was a
postdoctoral research associate in the Coordinated Science Laboratory at
UIUC. She received her Ph.D. degree in electrical
engineering from Purdue University in 2002. Her research is on wireless
communication networks, with a focus on resource allocation and
cognitive radio networks. She received the Best Paper of Year Award of
the Computer Networks Journal in 2003 for her work on
opportunistic scheduling. She received NSF CAREER award in 2005 for her
research on cognitive radio networks. She received the Outstanding
Engineering Junior Faculty Award from the College of Engineering,
University of California, Davis, in 2005.