Physical Layer Security Studies In Multi-user Communications

Physical layer security is dedicated to the secure transmission of information flows at the physical layer of the wireless networks.With rapid deployment of wireless communication nodes and explosive prosperity of corresponding technology,researches on physical layer security has also drawn significant attention.One of the core problems in physical layer security is to optimize a variety of communication systems for the purpose of enhancing the security against eavesdropping.The diversity of the wireless networks may be attributed to the attributed to the complexity of its developing history.Due to the variety of scenarios and characteristics of the wireless networks,it is of significant importance to integrate the physical layer security technology into the specific wireless communication network.This article mainly focuses on multi-user code division multiple access(CDMA)and multiple antenna(MIMO)wireless communication networks,and proposes a physical layer security scheme which utilizes the multi-user interference to mitigate the eavesdropping and thus enhance the security.Specifically,the main works and contributions of this article are listed as follows:(1)Particularly,we propose to weaken the eavesdropping and reduce the possibility of retrieving the confidential information by utilizing the multi-user interference of the multi-user communication system.As for the legitimate users,it is necessary to reduce the interference and ensure communication between the transmitter and the legitimate user.For the eavesdropper,we need to enhance the multi-user interference,which demand the unification of interference utilization and interference avoidance.(2)For multi-user code division multiple access communication system,under the assumption of known eavesdropper channel state information,we propose to design the spread code to enhance system security.(3)For the multi-user multi-antenna communication system,under the assumption of known the eavesdropper channel information and unknown eavesdropper channel information,we propose to design the beamformers and the transmitting power at the transmitter and the receiver to weaken the eavesdropper eavesdropping.