Research On The Secure Communication Technology In Physical Layer For Multiple Antennas

The technology of wireless communication is now widely used in satellite communication,microwave communication and mobile communication, etc. Since the openness of wireless link, it’seasier to monitor and insert into transmission process. So it is important to ensure the securecommunication. Existing domestic and international researches are mainly in upper layer technologyof secure communication, while relatively less research has been carried out in physical layer.According to the transmission characteristic of physical layer, this paper puts forward secure methodsof physical layer transmission. The main contributions of the paper are:1. Based on the beamforming methods in receiver and sender, a joint artificial noisebeamforming method is proposed to ensure secure communication. To obtain the optimal value ofantenna weight coefficients and parameters for artificial noise, the SNR bound of desired receiver andinterception receiver is limited in the optimization criterion. The simulation results show that thistechnique obtains a feasible radiation pattern and performs well in communication withanti-interception ability.2. Based on the research of directional modulation, the in-phase and out-phase dual-beammodulation techniques used in secure communication are given out. This technique can differentiatesignals received from different directions, so that the signal constellation received by interceptionreceiver is scrambled and demodulated. The simulation results show that the BER performance ofinterception receiver is deteriorated.3. A security method based on antenna virtual motion of circular array is proposed to guaranteethe information un-eavesdropped during wireless communication. This technique uses harmoniccomponents generated by the switching function of antenna. And the switching mode is controlled bya spread-spectrum sequence. In this way, a spread-spectrum modulation signal is modulated by spreadspectrum sequence and spatial information. Distinguished from those restricted to azimuth plane thismethod can realize secure communication in azimuth plane and elevation plane. Simulation resultsshow that the proposed method offers a good performance in secure communication of azimuth planeand elevation plane.