Using Simple Relays to Improve Physical-Layer Security
This paper studies different uses of two cooperating relays to improve the secrecy rate of a wiretap channel. These two relays are assumed to perform only simple functions: either Amplify-and-Forward (AF) or jamming. Complex functions such as Decode-and-Forward (DF) are not considered. The authors study three modes of cooperation: Cooperative Jamming (CJ), AF-aided beamforming and mixed AF-aided beamforming and CJ, all with individual relay power constraints. While CJ is known in the literature, their efforts are spent on AF-aided beamforming and mixed AF-aided beamforming and CJ.