Joint beamforming and power allocation in cognitive radio via feedback

In this paper, joint beamforming and power allocation via cooperation feedback and local feedback is considered in cognitive radio (CR) downlink where primary user (PU) coexists with multiple secondary users (SUs). The objective is to maximize the sum-rate of SUs while satisfying interference power constraint to PU and the total transmission power constraint of SUs. To effectively mitigate the interference to the PU, the zero-forcing (ZF) beamforming is designed at secondary transmitter (ST) based on quantized feedback channel state information (CSI). For power allocation, we introduce a game approach based on statistical analysis of the quantization error and propose an iterative distributed algorithm. Moreover, the existence of Nash equilibrium (NE) is analyzed. Simulation results demonstrate the effectiveness of the proposed scheme.