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Summary: Opportunity Detection for OFDMA Systems with
Timing Misalignment
Mustafa E. S¸ahin, Ismail Guvenc , Moo-Ryong Jeong , and H¨useyin Arslan
Dept. of Electrical Engineering, University of South Florida, Tampa, FL, 33620
DOCOMO Communications Laboratories USA, Inc., 3240 Hillview Avenue, Palo Alto, CA, 94304
Email: msahin@mail.usf.edu, {iguvenc,jeong}@docomolabs-usa.com, arslan@eng.usf.edu
Abstract-- Accurate detection of spectrum opportunities within
the frequency band of an orthogonal frequency division multiple
access (OFDMA) system is a critical requirement for the real-
ization of a coexisting cognitive radio. In this paper, we analyze
the opportunity detection performances of energy detection and
ESPRIT algorithms in the presence of timing misalignments in
uplink (UL) OFDMA. For the energy detector, the statistics
of subcarrier power are derived, and the accuracy of these
derivations is verified through simulations. The feasibility of
opportunity detection in an asynchronous UL-OFDMA system is
proven. Also, it is shown that energy detection has a considerably
better performance than the ESPRIT algorithm especially when
the subcarrier assignments change frequently.
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