SNR Maximization through CSI based Relay-Subset Selection in Amplify-and- Forward Cognitive Radio Networks

This paper addresses the issues in Underlay Cognitive Radio Networks employing amplify-and-forward relaying. The secondary users operating in an underlay mode in the frequency band of primary users must satisfy interference constraints to keep primary communication undisturbed. We propose a solution to this problem using cognitive relays and perform channel state information (CSI) based relay selection to choose an optimal subset of relays from the whole relay set, which maximizes secondary system performance while satisfying interference threshold of the primary network. We aim to give priority to those relays which exhibit better channel conditions towards destination as compared to the primary user. Simulation results prove the effectiveness of the proposed scheme. Keywords-component; Amplify-and-Forward, Channel State Information, Cognitive Radio Networks