Unique Decomposition Constellation Group Based Secure Multipath MISO Communications

In this paper, a novel secure wireless communication scheme based on the unique decomposition constellation group (UDCG) is proposed for multipath multi-input single-output (MISO) systems, where dynamic metasurface antennas (DMA) are deployed at the base station. In the proposed communication scheme, multipath channel state information (CSI) is firstly estimated with the aid of DMA's high spatial resolution. Then, a group of distinct sub-constellations, which constitutes a UDCG, is employed to assign different symbols to the multipath components. Meanwhile, orthogonal precoding based on the multipath CSI is implemented to eliminate the interference among different multipath components. As a result, the superposed signals at the legitimate receiver rather than the illegitimate receiver can be uniquely determined. Finally, a precoding optimization problem is investigated to improve the secrecy capacity of the proposed scheme. Computer simulation results demonstrate that the proposed scheme effectively mitigates the eavesdropping risk from illegitimate receivers and achieves a better secrecy capacity.