Tomlinson-Harashima precoding for physical layer security in MIMO-OFDM systems

This paper proposes a physical layer security technique using Tomlinson-Harashima precoding (THP) for multiple-input multiple-output (MIMO) systems under the presence of a passive eavesdropper. In the proposed scheme, a transmitter performs THP considering both the channel for the legitimate receiver and the randomly generated channel for an imaginary receiver which does not exist actually. Since the imaginary receiver's channel is arbitrarily generated at the transmitter, the eavesdropper cannot estimate it. Therefore, the proposed scheme can provide secure communications. Moreover, in THP, the transmitter performs the precoding so that the diversity can be obtained at the receiver. Therefore, the proposed scheme can achieve a higher mutual information. From simulation results, we show that the proposed scheme achieves a better mutual information compared to the existing artificial fast fading schemes.