under imperfect channel state information (CSI) is proposed. In this scheme, the legitimate
receiver is always accompanied by an eavesdropper, and the secrecy enhancing of the SSK
system is realized by adding the designed artificial noise (AN). Since the AN is designed by
the CSI of the legitimate channel, it can be canceled at the legitimate receiver and remained
at the eavesdropper. In addition, the impacts of the CSI estimation error on the secrecy rate …