Research On Cooperative Spectrum Sharing Based On Physical Layer Security

With the rapid growth of wireless communication technology,the demand for the quality of wireless communication is getting higher.As the wireless communication brings convenience to people,the problems of their own are becoming more obvious.On the one hand,the traditional static and fixed spectrum allocation strategy leads to poor spectrum utilization.The way by combining the advantages of cognitive radio and cooperative communication to improve spectrum utilization has received significant attention at home and abroad.In the existing spectrum sharing access,secondary user transmits PT's secrecy information and own information in the same spectrum,which will lead to mutual interference between them.Under the background of cognitive radio,this thesis studies the dynamic spectrum access to resist interference and improve the resources utilization at the same time based on DF cooperation.On the other hand,communication security is becoming a critical issue due to the broadcast and openness nature of wireless transmission.Physical layer security(PHY)has received significant attention due to its potential to improve the security of information transmission in wireless communication.This thesis studies the dynamic spectrum access to prevent eavesdropping based on physical layer security.Generally,this thesis investigates the joint resources allocation to maximize the secondary system transmission rate while satisfying the secrecy transmission rate requirements of primary system.The main work and achievements are as follows:1.While the eavesdropper only wiretaps in the first phase,an anti-jamming spectrum access strategy based on joint optimization of power and bandwidth is proposed.In this situation,to avoid mutual interference and improve the system's security,combined with the channel characteristics,this thesis introduces artificial noise in the authorization system.In the first phase,PT divides power into two different parts for transmitting secrecy information and own artificial noise,PR transmits artificial noise simultaneously.In the second phase,ST divides spectrum into two different parts for transmitting secrecy information and own information to resist manual interference.We study the joint optimization of the bandwidth and power allocation to maximize ST's transmission rate while satisfying PT's secrecy transmission rate requirements.In order to further improve resources utilization,we propose an anti-jamming spectrum access strategy based on joint optimization of time,power and bandwidth on the basis of former method.Simulation results demonstrate a significant enhancement with above proposed methods.While the eavesdropper only wiretaps in the two phases,an anti-jamming spectrum access strategy based on joint optimization of power and bandwidth is proposed.If eavesdropper is intelligent and knows that ST forwards secrecy information in the second phase,it also keeps wiretapping in this phase.In the second phase,ST allocates part power and bandwidth to forward secrecy information while ST transmits secrecy information in the same spectrum simultaneously.To keep transmission safe,the secrecy information is designed to be canceled at eavesdropper combined with channel characteristics.Similarity,ST divides spectrum into two different parts for transmitting secrecy information and own information to resist manual interference.We study the joint optimization of the bandwidth and power allocation to maximize ST's transmission rate while satisfying PT's secrecy transmission rate requirements.Simulation results demonstrate a significant enhancement with above proposed methods.