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Summary: IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS, VOL. , NO. , 2009 1
Opportunity Detection for OFDMA-Based
Cognitive Radio Systems with Timing Misalignment
Mustafa E. S¸ahin, Ismail Guvenc, Member, IEEE,
and H¨useyin Arslan, Senior Member, IEEE
Abstract-- Accurate detection of spectrum opportunities within
the frequency band of an orthogonal frequency division multiple
access (OFDMA) system carries critical importance for OFDMA-
based cognitive radios. In this paper, we analyze the opportunity
detection performances of energy detection and ESPRIT (esti-
mation of signal parameters by rotational invariance techniques)
algorithms in the presence of timing misalignments in uplink
(UL) OFDMA. For the energy detector, the statistics of subcarrier
power are derived considering timing misalignments, and they
are verified through computer simulations. Using these statistics,
which take inter-carrier-interference (ICI) effects into account,
receiver operating characteristics (ROCs) of the energy detector
receiver are obtained. It is shown that energy detection has a
considerably better performance than ESPRIT, especially when
the subcarrier assignment changes frequently. Moreover, a closed
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