Single-antenna selection for MISO cognitive cadio

Cognitive radio with multiple antennas has promised significant improvements in spectrum efficiency. However the cost of radio frequency (RE) chains limits the application of multiple antennas. In this paper, we consider a scenario where the primary system can afford some interference and only one antenna is selected among N antennas in the secondary system. We first analyse the performance of the minimum interference selection, the maximum data power, and the maximum sum capacity strategies. Then we propose a maximum signal power to leak interference power ratio (SLIR) strategy, which considers both the leaked interference to the primary system and the data power simultaneously. The simulation results show that our proposed method achieves a better trade-off between two coexisting systems and can obtain good overall capacity performance.