On the Secure Degrees of Freedom in the K-User Gaussian Interference   Channel
  This paper studies the K-user Gaussian interference channel with secrecy constraints. Two distinct network models, namely the interference channel with confidential messages and the one with an external eavesdropper, are analyzed. Using interference alignment along with secrecy pre-coding at each transmitter, it is shown that each user in the network can achieve non-zero secure Degrees of Freedoms (DoFs) in both scenarios. In particular, the proposed coding scheme achieves (K-2)/(2K-2) secure DoFs for each user in the interference channel with confidential messages model, and (K-2)/2K secure DoFs in the case of an external eavesdropper. The fundamental difference between the two scenarios stems from the lack of channel state information (CSI) about the external eavesdropper. Remarkably, the results establish the positive impact of interference on the secrecy capacity of wireless networks. 
Onur Ozan Koyluoglu, Hesham El Gamal, Lifeng Lai, H. Vincent Poor