Secure Index Modulation for RIS-Aided Vehicle Road Cooperation Networks

The reconfigurable intelligent surface (RIS)-aided vehicle road cooperation (VRC) scheme is a promising technique. However, the security issue of the RIS-VRC systems is still a crucial problem due to the high connectivity of multiple vehicles under the broadcasting environment. Within this study, based on the potential of the RIS-VRC system, a novel low-complexity consecutive artificial noise (CAN) with legal channel state information (CSI) and a low-cost and spectral-efficient secure index modulation (IM) design physical-layer security (PLS) scheme is detailed. Specifically, an information symbol consisting of a modulation symbol and artificial noise (AN) devised based on the CSI of the legitimate link across two consecutive time intervals is transmitted. At the receiver, the decoding scheme relies on two consecutive time intervals which can enable the ideal elimination of AN solely at the authorized vehicle is proposed. Nevertheless, given the independence of the CSI for the legitimate links and the illegitimate links, the unauthorized vehicle remains vulnerable to AN interference. Moreover, the antenna selection method based on minimum Euclidean distance (MED-TAS) is proposed to guarantee the requisite number of transmitting antennas for IM. Finally, the expressions of the secrecy rate are deduced by considering the disparity in the attainable mutual information between the authorized vehicle and the eavesdropping vehicle. Compared with traditional PLS schemes, the numerical outcomes affirm the capability of the proposed scheme to attain enhanced security performance with much lower complexity.