A review on beamforming techniques for cognitive multi-antenna relay network

Cognitive radio is widely expected to be the next Big Bang in wireless communications. Spectrum is a scarce resource and it used efficiently by incorporating beamforming in the multi-antenna relay for cognitive networks. In this paper, both the adaptive beamforming for the relay networks and the performance estimation at the secondary user receiver in cognitive networks were discussed. Special attention is given to the system capacity of the cognitive networks at the secondary user receiver.