Mapping-Varied Spatial Modulation for Physical Layer Security: Transmission Strategy and Secrecy Rate

In this paper, a novel transmission strategy, referred to as mapping-varied spatial modulation, is proposed for physical layer security, where the transmitter varies mapping patterns for the radiated information and the antenna information of spatial modulation, based on the instantaneous pattern of legitimate channel quality information that is unknown to eavesdroppers. Therefore, eavesdroppers cannot successfully decode the confidential information and the transmission over the legitimate link is secured from the wire-tap of eavesdroppers, without relying on higher-layer encryption. An important virtue of the proposed transmission strategy is that the transmitter does not need to know eavesdroppers' channels states at all. To further demonstrate the advantage of this scheme, its secrecy rate was formulated for the purpose of facilitating the performance evaluation. Moreover, illustrative numerical results pertaining to the metrics of ergodic secrecy rate and secrecy outage probability not only substantiate the validity of the proposed transmission strategy, but also provide useful references for the system design with the mapping-varied spatial modulation, from the view of physical layer security.