Physical layer security enhancement for SISO-OFDMA systems via time-reversal filtering and resource allocation
摘要
This paper investigates the design and optimization of the physical layer security scheme for downlink orthogonal frequency division multiple access (OFDMA) systems with a single transmit antenna. Time reversal (TR) filtering is employed to increase the subchannel quality discrepancy between the legitimate channel and the eavesdropping channel, which plays a similar role to that of pre-coding in multi-antenna systems. The null space artificial noise (AN) is generated by exploiting the degree of freedom provided by the cyclic prefix and is superimposed on the signals to jam the eavesdropper. In order to minimize the transmit power consumption and promote energy efficiency, the subcarrier assignment for each user, signal power allocation for each subchannel, and AN power are jointly optimized under the constraint of the minimum secrecy rate for each user. The effectiveness of the proposed scheme is verified by simulation.