Cognitive partners in wireless networks

Cognitive radio has been proposed as the means for secondary users to promote the efficient utilization of the spectrum by exploiting the existence of spectrum holes. Meanwhile, cooperative diversity techniques can improve the transmission rate and reliability of wireless networks. In this paper, both the case of relay participating in the cognitive networks and the case of relay selection are considered. Further an optimal cognitive relay partner selection project is tabled to improve the transmission performance. Finally, the simulation results demonstrate the relationship between average SNR and ergodic capacity in cognitive relay networks. Also, it is observed that more spared relay nodes supply better throughput performance.