Abstract:
Cognitive Radio (CR) is an adaptive radio system developed to overcome the issue of
ine cient utilization of licensed radio spectrum . CR technology enables both licensed
and unlicensed users to communicate on same channel depending on the requirements
provided that no interference is caused at PU due to unlicensed transmission. Spectrum
is allocated dynamically depending on the usage and requirements of users in cognitive
radio networks. The unlicensed secondary users can use vacant frequency bands already
assigned to licensed users or transmit simultaneously along with the primary user on a
same band with reduced power level. It detect the signal from the primary user to nd
the spectrum holes and choose the best channel for the unlicensed users to maintain a
given quality of service. The SU vacate the band whenever the primary users reappears.
In this report, we try to study a fast and e cient sensing technique that can be used
to maintain a desired quality of service along with providing less sensing time and more
time for transmission for the cognitive network. We have also tried exploiting detection
of the primary user signal in both fading as well as non fading channels to cope up
with practical usage scenarios. Finally, we derive the optimal voting rule and minimum
number of collaborating CRs required for any detector to work e ciently in cooperative
spectrum sensing
