Research On Relay Selection Of Cooperative Communication System In Eavesdropping Environment

While wireless communication is rapidly developing and widely used,the security problems exposed by itself are becoming more and more serious.As a medium for information transmission,the wireless channel has an open transmission environment,which makes it inevitable that the information will be eavesdropped by potential illegal users during the transmission process.In the past,the encryption mechanism to guarantee the information security would face the threat of cracking with the change of available computing resources.However,physical layer security is different from the encryption mechanism that relies on computational heaping.Instead,it innovatively utilizes the inherent characteristics of wireless channels to complete data encryption in combination with transmission signal at the physical layer to ensure information security,and has become the main research direction in the field of wireless communication information security.In view of this,this paper aims to improve the information security of wireless communication system,and conducts research on information security based on the perspective of relay selection.The main research work is as follows:(1)For a cooperative communication scenario where feedback delay exists,the channel state information at the time of relay selection may be outdated with respect to the data transmission time,and the selection of relay node using outdated channel state information will inevitably affect the reliability of relay selection.Considering the existence of feedback delay,the third chapter of the paper takes the security outage probability of communication system as the entry point,gives the relay selection strategy based on the minimum security outage probability under the scenario of outdated channel state information,and makes simulation analysis.(2)Cooperative jamming is introduced into the cooperative communication system under the eavesdropping environment,and the relay selection strategy of optimal relay node and jammer node is adopted,that is,two different relay nodes are selected as the forwarding node and jammer node respectively to jointly ensure the information security.On this basis,the fourth chapter of the paper takes the maximum security capacity of the communication system as the entry point to derive the power allocation factor,and gives a low complexity power allocation scheme for the optimization of relay selection.