Secure Multiuser MIMO Downlink Transmission Via Precoding-Aided Spatial Modulation

This letter generalizes the precoding-aided spatial modulation (PSM) to a multiuser (MU) downlink scenario. With precoding vectors elaborately designed, a proposed MU-PSM scheme has the capability to resist a multiple antenna eavesdropper. Specifically, signal precoding matrices (SPMs) are designed to cancel the MU interference and modulate partial information bits on the indices of receive antennas. To improve physical layer security, scrambling on SPMs is conceived to construct a fast-varying precoding matrix, which contributes to the degradation at Eve's blind estimation and detection. Moreover, issues of detection algorithms and a lower bound of secrecy rate are addressed to verify security enhancement in the proposed scheme.