The evolution of future wireless communication systems imposes a strong
requirement on the efficiency of spectrum usage, which is expected to be
leveraged by interacting and cooperating cognitive radios forming wider cognitive
radio systems. Dynamic Spectrum Access (DSA) is a potential means to improve
spectrum usage. A key step in realizing DSA is to obtain spectral occupancy
information provided by spectrum sensors. Subsequently, nodes in a CRS
analyze spectrum usage to find unused spectrum (often referred to as white
spaces). Then the system makes a decision on the best opportunities considering
regulatory policy, transceiver capacity, and so on. In such an operation, sensing
information exchange plays a fundamental and key role in enabling efficient
DSA. Cognitive Radio having the great key mechanism of enabling spectrum
awareness in the Spectrum sensing. This project deals with spectrum sensing of
different bands. Spectrum sensing uses dynamic spectrum model without
troubling the primary users. This may improves the radio frequency usage of
spectrum and it is done when both unlicensed and licensed reducing
interference and also by usage of licensed users for identifying the white spaces.
The concept spectrum sensing is important to secondary users in cognitive radio
to operate without interfering the primary users. Spectrum sensing is done in
different bands of wireless communication like Wi-Fi, Bluetooth, GSM, CDMA
etc.