A Novel Semi-Blind Polarization Adaption Technique for Cognitive Users

In this work, a Semi-Blind Polarization Adaption (SBPA) technique that utilizes the sampled primary signals and channel reciprocity is proposed for cognitive users. The proposed technique can adjust transmit polarization without any prior information, while the channel state information is only necessary for deriving the receive polarization. This is a significant difference between the proposed technique and the conventional polarization adaption techniques for cognitive users. The noise in the sampled primary signals is suppressed to reduce its adverse effect, and the performance of the proposed SBPA technique relies on the number of primary signal samples. Simulation results shows that the proposed technique outperforms the traditional polarization adaption techniques in circumstances with channel estimation errors. The proposed SBPA technique can be used to extend the application of cognitive radio, especially when the channel information between secondary users and primary users is difficult to derive.