Cooperative AF Relaying With Beamforming and Limited Feedback in Cognitive Radio Networks

This letter studies cooperative beamforming for dual-hop amplify and forward cognitive relay networks comprising a pair of secondary source-destination and multiple antenna relay in the presence of a pair of primary transmitter-receiver. The aim of this work is to improve the secondary system performance with limited feedback from the primary receiver while using a mean value-based power allocation strategy. We derive closed-form expressions for the outage probability and average error probability over Rayleigh fading channels. Numerical and simulation results demonstrate the impact of the limited feedback on the secondary system performance and show that an acceptable performance is achieved when compared with the case of perfect channel state information.