Security Performance Analysis And Optimization Of Cooperative Communication System In Eavesdropping Environment

In wireless communication,the traditional encryption technology encrypts signal through secret key in high-rise with encryption algorithm.However,the encryption algorithm used is usually very complex.The physical layer security creatively uses the physical characteristics of the wireless channel to ensure the secure transmission of signals and greatly improves the security of wireless communication.Cooperative communication obtains the corresponding spatial diversity by sharing the antennas between neighboring users in multi-user communication environment,and it can improve the capacity of system effectively.In actual wireless communication,cooperative communication combined with physical layer security can ensure the reliability,effectiveness,and security of communication process.This paper aims to reduce the secrecy outage probability,analyzes and studies the relay selection and power allocation in cooperative communication under eavesdropping environment.The research contents are as follows:In terms of relay selection under decode-and-forward protocol,considering the channel model that both source and relay nodes can be eavesdropped,and the closed-form expressions of system's secrecy outage probability in both eavesdropping scenarios of passive eavesdropping and active eavesdropping are analyzed and given.Finally,simulation results validate the correctness of the expressions.In terms of power allocation under amplify-and-forward protocol,a power allocation factor is derived based on the instantaneous channel state information of the legitimate channels,then the limited total transmit power is allocated to the source node and the relay node through the allocation factor.Simulation results validate that secrecy performance of system can be improved effectively through power allocation.