Secure Transmission Algorithm Based on Subcarrier Sorting and XOR Operation in OFDM Systems

摘要

Considering an OFDM modulation based system including one pair of legitimate transceivers and one eavesdropping node, we design a physical layer security transmission algorithm, which first sorts the subcarriers in terms of the legitimate channel's quality and then sends one half of original information bits over the first half better subcarriers while the XOR results of two halves of information bits over the rest subcarriers with poorer channel quality. This algorithm can achieve perfect security without reducing the spectrum utilization of the system. Further, in order to improve bit-error-rate (BER) performance of the legitimate receiver, the subcarrier power is optimally allocated to minimize the BER of the legitimate receiver. The simulation results show that the proposed scheme could obtain better performance at the legitimate receiver under the condition of perfect security when the ideal channel reciprocity at both ends of the legitimate transmission is assumed. The designed power distribution scheme can further reduce the legitimate receiver's BER effectively.