The radio frequency is a limited natural resource and getting enabled day by day due to growing demand of the wireless communication applications. To operate on a specific frequency band, license are needed. The use of radio spectrum in each country is governed by the corresponding government agencies. In conventional technique each user is assigned a license to operate in a certain frequency band. Most of the time spectrum remains unused. The allocated spectrum is not utilized properly; it varies with time, frequency and geographical locations. Thus to overcome the spectrum scarcity and...