| With the rapid development of information and communication technology,more complicated network architectures,network topologies,access technologies,service requirements,and more and more mobile devices impose critical challenges on the secure wireless transmission techniques.When the eavesdropper becomes a smart attacker,how to design a reasonable strategy to make the game between the legitimate user and the smart attacker incline to the legitimate user will become an interesting problem,especially when we want to improve the physical layer security.Besides,how to improve the physical layer security of different wireless communication systems in the presence of eavesdroppers has become an important problem in wireless communication.In addition,buffer-aided wireless communication has received attention due to its ability to significantly improve the transmission performance of system and reduce power consumption.In this thesis,we focus on the physical layer security of wireless communication system.Firstly,the game theory is used to analyze the equilibrium conditions of smart attacker and legitimate user,and reinforcement learning is used to find the optimal transmission strategy.Secondly,the eavesdropper model with buffer aided mechanism and the buffer aided multiple-access transmission system were studied to design an effective buffer-aided transmission strategy to improve the security performance.In this paper,from the perspectives of system model,transmission scheme and performance analysis,the MIMO communication system in the presence of smart attacker,the buffer-aided eavesdrop model and the buffer-aided multiple-Access transmission system in the presence of eavesdropper will be investigated in depth.Firstly,the MIMO transmission against a smart attacker has recently been formulated as a non-collaborative game,in which both the MIMO transmitter and the malicious attacker try to maximize their predefined utilities.By carefully analyzing the Nash Equilibrium(NE),we focus on the conditions,in which the gaming results incline to the malicious attacker instead of the MIMO transmitter.In this adverse case,it is highly desirable to develop an effective mechanism to suppress the attack intention by the attacker for better secure communication.Motivated by this,an adaptive secure MIMO transmission scheme was proposed to make the MIMO transmitter better resist malicious attackers in adverse channel conditions.,e analysis results confirm us that the proposed adaptive transmission scheme provides us a choice to enhance the secure MIMO transmission performance in adverse conditions.Secondly,buffer-aided secure transmission design over wiretap channel is investigated,in which a source node provisioned with data buffer is supposed to deliver its confidential message to the sink node in the presence of an eavesdropper.Firstly,in the presence of eavesdroppers,the traditional long-term power transmission strategy is designed to maximize the security performance.Secondly,thesis proposed optimal buffer assisted adaptive secure transmission scheme.Bye using the Lagrange dual decomposition method,the optimal flow control mechanism and power allocation are given.Then,using Lyapunov optimization theory,an adaptive scheduling scheme based on delay security is designed.At last,the inherent trade-off among power consumption,transmission delay and implemented security rate is revealed.Finally,buffer-aided adaptive multiple-access transmission system is studied.Firstly,the traditional two user transmission scheme is designed,including OMA transmission and multiple-access transmission.Secondly,the traditional buffer-aided two user transmission scheme is designed.Then,we study the adaptive buffer-aided multiple-access transmission system,and fully consider the impact of data storage and long-term resource allocation on the average achievable rate region of the system.Theoretical and numerical results show that the proposed scheme can effectively improve the security performance of the multiple-access transmission system.Finally,a tradeoff among average power,average queue delay and security throughput is found.In a word,thesis investigated buffer-aided wireless communication system in eavesdropping environment,explores the game between smart attacker and legitimate transmitter,and the impact of data buffer on the transmission performance and power allocation of legitimate transmitter,and unveiled the trade-off and among the transmission rate,energy consumption and transmission delay. |
