Research On The Technologies Of Physical Layer Security In Wireless Relay System

Along with the improvement of people's material living standards,high-quality communication has become a necessity in people's daily life.A quick,stable and secure wireless communication demand is imminent,which is a grave challenge and rare development opportunity for current wireless communication technology.Traditional wired communication security technology using encryption focuses on the problem of secure transmission at the network layer and above.However,higher complexity is required to improve the corresponding security level as the computational capability becomes increasingly powerful.Due to its open transmission characteristics,wireless communication is confronted with more serious security challenges,and thereby,physical layer security transmission technology,which is independent of the computational complexity,has become a hot issue in the wireless communication field.In this paper,we focus on physical layer security in wireless relay system.Firstly,we study the design of the physical layer security transmission scheme with joint cooperative relaying and jamming,and then analyze the transmission scenario with untrusted relay.Finally,a relay transmission scheme based on antenna array redundancy is proposed.The main contributions of this paper are summarized as follows:1)For the physical layer security transmission system based on joint cooperative relaying and jamming,a relay grouping scheme and a power allocation scheme which do not depend on the eavesdropping channel information are proposed.Firstly,the relay nodes are divided into the cooperative relaying group(CRG)and the cooperative jamming group(CJG)according to the channel state information between the source node and the relay nodes.And then the power allocation is optimized under the constraint of the system transmission power and the number of relay nodes,which effectively improves the system capacity and protects the security of confidential information transmission.Finally,the effectiveness of the transmission scheme is validated by simulations.2)For the wireless cooperative relay system in the presence of untrusted relay,a physical layer security transmission scheme based on antenna array redundancy is proposed.By selecting the transmit antenna randomly at the source node and transmitting confidential information with the designed beamforming vector,the channel state at the untrusted relay and the eavesdropper is randomized while the legitimate destination node can receive the confidential information normally.The simulation results show that the proposed transmission scheme can produce high bit error rate at the untrusted relay and the eavesdropper,and thus the problem of untrusted relay's existence in wireless relay system is solved.