| Summary: | 碩士 === 國立清華大學 === 通訊工程研究所 === 100 === Because the signal transmission in wireless communication is essentially broadcasting, the transmitted information is easily wire-tapped by malicious eavesdroppers. As a result, physical layer security of wireless communication has gained more and more attention in recent years. Methods such as artificial noise have been proposed to guarantee physical layer security, where part of the transmit power is sacrificed to generate artificial noise for interfering eavesdroppers. In this work, we consider a MISOSE OFDM system and propose a new approach to improve physical layer security. The idea of the proposed method is to exploit the property that cyclic delays change the effective channels of the intended receiver and eavesdroppers. By properly designing a compensation factor and multiply it to the transmitted data symbol, we can recover the channel of the intended receiver while keeping the distortion on the channel of eavesdroppers. Simulation results show that the proposed method can distort the channel at eavesdroppers and degrade their BPSK and 16-QAM BER more than the method of using artificial noise. Moreover, simulation results on the channel capacity of eavesdropper also match with the BER results.
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