The Research On Physical Layer Security Of Cooperative Communication Network

In cooperative communication, the users share their antennas and forward eachother’s data, so system forms the spatially distributed gain. And the same time, thedevelopment of cooperative communication provides a new direction for the physicallayer security. Based on the wiretap channel model which proposed by Wyner, we caninvestigate the physical layer security from two aspects: cooperative communicationcan enhance the main channel conditions and the friendly jamming can reduce thewiretap channel conditions, both of them can improve the safety performance.The untrusted model is usual in the actual cooperation strategy where the role ofthe relay is not only a cooperating partner but also a potential eavesdropper. In thispaper, we investigate performance of cooperative diversity in the presence of selfishrelay which doesn’t conform to the rule of cooperation at all time. Through theaveraged BER and secrecy capacity, we find the misbehavior of relay can degrade thesystem performance. And a selfish behavior detection technique is necessary tomaintain stable cooperation and assist secure cooperative transmission at the physicallayer.The detection technique in this paper calculates the correlation ratio betweensignals received from the diversity branches to determine the relay’s behavior inamplify and forward cooperation strategy. The relay is captured by an adversary andaims to help the eavesdropper which called malicious jammer relay also isinvestigated in this paper. By theoretical analysis and simulation for the outageprobability and some others parameters in the presence of malicious jammer relay. Itfinds that the performance of system depends on the position of relay. So it can befriendly jamming by changing the position of relay.In the end of this paper, features of security in practical are studied and theimpacts of node’s location on the system’s security are investigated based on thesoftware defined radio test bed.