International Journal of Scientific Research Engineering &Technology (IJSRET)
There is a growing demand for spectrum to accommodate future wireless services and applications. The present fixed allocation schemes have indicated a low utilization of the spectrum over both space and time. Hence, to satisfy the demands of applications it can be inferred that dynamic spectrum usage is a required necessity. According to the IEEE 802.22 standard the unlicensed secondary devices can operate in the licensed TV band, because this is the high underutilized licensed band, so long they do not interfere the licensed primary users.