Date Added: Dec 2012
Secure communication in the Multi-User and Multi-Eavesdropper (MUME) scenario is considered in this paper. It has been shown that secrecy can be improved when the transmitter simultaneously transmits information-bearing signal to the intended receivers and artificial noise to confuse the eavesdroppers. Several processing schemes have been proposed to limit the Co-Channel Interference (CCI). In this paper, the authors propose the Increasing Security Degree of Freedom (ISDF) method, which takes idea from the Dirty-Paper Coding (DPC) and ZF beam-forming. By means of known interference pre-cancelation at the transmitter, they design each pre-coder according to the previously designed pre-coding matrices, rather than other users' channels, which in return provides extra freedom for the design of pre-coders.