  This work presents an analytical framework for characterizing the performance
of cooperative and noncooperative spectrum sensing schemes by figuring out the
tradeoff between the achieved diversity and coding gains in each scheme. Based
on this analysis, we try to answer the fundamental question: can we dispense
with SUs cooperation and still achieve an arbitrary diversity gain? It is shown
that this is indeed possible via a novel technique that can offer diversity
gain for a single SU using a single antenna. The technique is based on the
usage of a reconfigurable antenna that changes its propagation characteristics
over time, thus creating an artificial temporal diversity. It is shown that the
usage of reconfigurable antennas outperforms cooperative as well as
non-cooperative schemes at low and high Signal-to-Noise Ratios (SNRs).
Moreover, if the channel state information is available at the SU, an
additional SNR gain can also be achieved.
