Description

Cognitive Radio network has the ability to increase the spectrum utilization Cognitive Radio network has the ability to increase the spectrum. In order to use the licensed spectrum, cognitive radio networks should detect the under-utilized licensed frequency bands (overlay). At the same time the unused spectrum also need efficient resource allocation (underlay). The proposed method will describe about joint Joint Overlay and Underlay Spectrum Access Mechanism Nowadays the power and subcarrier allocation has play a vital role in CR network using OFDM. In generally the resource allocation will only power or subcarrier allocation separately in CR network The proposed method will be described Joint overlay and underlay Spectrum Access Mechanism. For given interference constraints, a significant improvement in the transmission rate is achieved by allocating and loading power with the JOU SAM. The proposed optimal scheme can lead to an unfairness among CR users in sharing the total transmission rate; therefore, we also propose a suboptimal subcarrier-allocation scheme that can guarantee a certain level of fairness among CR users.