Physical Layer Security Performance Of Cooperative Wireless Communication System

Nowadays,the physical layer security of the amplify-and-forward(AF)and decode-and-forward(DF)cooperative wireless communication systems is a research hotspot of wireless communication.In order to further improve the performance of the physical layer security,multiple input and multiple output(MIMO)technologies,multi-relay selection techniques,multi-user diversity techniques and combinations of the above techniques can be adopted.The common relay system architecture include three-node single relay systems,multi-branch multi-relay systems,multi-hop systems,multi-relay and multi-user systems,etc.The physical layer security of multi-hop adaptive DF relay systems,multi-relay and multi-user selection adaptive DF systems with transmit antenna selection(TAS)/receive maximal ratio combining(MRC),AF systems with relay selection and channel prediction,and multi-relay and multi-user selection AF systems with TAS/MRC were investigated in this thesis,respectively.A brief review of physical layer security of DF relay systems and AF relay systems were presented in chapter 1,respectively.The physical layer security performance of multi-hop adaptive DF relay systems was investigated in chapter 2,the expressions for non-zero secrecy capacity probability,secrecy outage probability and asymptotic secrecy outage probability under high signal-to-noise ratio were derived,the research results show that the secrecy diversity gain of the multi-hop adaptive DF relay systems is the number of receive antennas of the destination node.In order to improve the physical layer security performance of multi-relay and multi-user adaptive DF systems,a physical layer security enhancement scheme for multi-relay and multi-user adaptive DF systems with TAS/MRC was proposed,the expressions for non-zero secrecy capacity probability,secrecy outage probability and asymptotic secrecy outage probability of the above DF systems were derived,the research results show that the secrecy diversity gain of the adaptive DF systems with multi-relay and multi-user selection is the product of the number of transmit antennas at the optimal relay node,the number of receive antennas at the optimal destination node,and the number of destination nodes.An implementation scheme using channel prediction to enhance the physical layer security of the AF systems with relay selection was proposed in chapter 3,the physical layer security performance of the above AF systems in multi-eavesdropper scenario was investigated,numerical and simulation results show that using channel prediction can reduce the impact of feedback delay on the physical layer security performance of the AF systems with relay selection.A physical layer security enhancement scheme for multi-relay and multi-user AF systems with TAS/MRC was proposed,the physical layer security performance of the above AF systems in single eavesdropper scenario was investigated,the research results show that the secrecy diversity gain of multi-relay and multi-user AF systems with TAS/MRC is the minimum value between the product of the number of transmit antennas at source,the number of receive antennas at the optimal relay node,and the number of relay nodes,and the product of the number of transmit antennas at the optimal relay node,the number of receive antennas at the optimal destination node,and the number of destination nodes.Chapter 4 is the conclusion of this thesis.