Interference mitigation in MIMO-OFDM cognitive radio systems using phase rotation

In this paper, we propose a new technique to reduce the interference caused by high OFDM sidelobes to the primary users in MIMO-OFDM cognitive systems. The proposed technique does not affect the rate of the system and has very low complexity. We also analyze the performance of the technique for a class of flat fading channels and show that the analytical results agree with simulations. Furthermore, for frequency selective fading channels, numerical results show that the performance is almost the same as that obtained analytically for flat fading channels.