Cognitive radio based on Cooperative spectrum sharing with imperfect CSI

Cognitive radio is an emerging technology that aims for efficient spectrum usage. Cognitive radios have been proposed as a solution to the spectrum underutilization problem and have been proven to increase spectrum efficiency . However, in this we are analyzing the performance of the cognitive radio based on cooperative spectrum sharing. Here we propose a twophase spectrum sharing protocol which supports relaying functionality, it take the advantage of situation when primary system is fails to achieve its target rate due to weak channel situations the secondary system allocates some of its transmitters for helping the primary system to achieve its target rate by acting as decode –and-forward relay .As a reward the secondary system gains spectrum access by using remaining transmitters to transmit its own signal. Analytic and simulation results confirm the efficiency of the proposed spectrum sharing protocol. We show that the both primary and secondary are able to achieve better outage performance with increasing the secondary transmitters. And also it is shown that primary user’s interference probability is always equal to 0.75 when CSI of interference links is imperfect. Keywords— Cooperative spectrum sharing, selection of relay, imperfect CSI, outage probability.