  Cognitive radio and dynamic spectrum access represent a new paradigm shift in
more effective use of limited radio spectrum. One core component behind dynamic
spectrum access is the sensing of primary user activity in the shared spectrum.
Conventional distributed sensing and centralized decision framework involving
multiple sensor nodes is proposed to enhance the sensing performance. However,
it is difficult to apply the conventional schemes in reality since the overhead
in sensing measurement and sensing reporting as well as in sensing report
combining limit the number of sensor nodes that can participate in distributive
sensing. In this paper, we shall propose a novel, low overhead and low
complexity energy detection based cooperative sensing framework for the
cognitive radio systems which addresses the above two issues. The energy
detection based cooperative sensing scheme greatly reduces the quiet period
overhead (for sensing measurement) as well as sensing reporting overhead of the
secondary systems and the power scheduling algorithm dynamically allocate the
transmission power of the cooperative sensor nodes based on the channel
statistics of the links to the BS as well as the quality of the sensing
measurement. In order to obtain design insights, we also derive the asymptotic
sensing performance of the proposed cooperative sensing framework based on the
mobility model. We show that the false alarm and mis-detection performance of
the proposed cooperative sensing framework improve as we increase the number of
cooperative sensor nodes.
