Secure performance of time reversal precoding technique in miso OFDM systems

Time reversal (TR) has been identified as a promising precoding technique to ensure physical layer security in wireless communications. This paper compares the secure performance of TR and maximum ratio transmission (MRT) precoding techniques in terms of achievable secrecy rate in MISO OFDM systems. Simulation results show that secrecy capacities of both precoding techniques increase with the transmit signal-to-noise ratio (SNR) and the achievable secrecy rate comparisons between them depend on the number of transmit antennas and transmit SNR. When the number of transmit antennas is small, the achievable secrecy rate of MISO TR OFDM is always better than its counterpart in MISO MRT OFDM, but the difference of the two decreases to zero as the transmit SNR increases; whereas the number of transmit antennas is large, achievable secrecy rates of the two precoding techniques become equivalent.