Secrecy-enhancing scheme for spatial modulation

In this letter, we propose a new secrecy enhancement scheme for spatial modulation systems by exploiting the knowledge of the legitimate channel state information to rotate the indices of the transmit antennas and the constellation symbols, which are mapped into spatial and constellation bits. A secrecy rate analysis shows that the eavesdropper cannot recover any information carried by spatial and constellation bits. The numerical results on the secrecy rate and the bit error rate verify the effectiveness and robustness of the proposed scheme.