Filter-and-forward relay beamforming for OFDM-based cognitive networks

In this paper, filter-and-forward (FF) relay beamforming for orthogonal frequency-division multiplexing (OFDM)-based cognitive two-way relay networks is proposed. In this scheme, two secondary transceivers communicate with each other through multiple relays simultaneously under the primary network transmission over the same spectrum. Our goal is to enhance the quality of service of the secondary network through the maximization of the worst subcarrier signal to interference and noise ratio subject to transmit power constraints. Simulation results show that the proposed FF relay beamforming improves system performance in comparison to the traditional amplify-and-forward relaying scheme in OFDM-based cognitive environments.