Wireless Secure Transmission Based On User Selection And Codec Optimization

Physical layer security,which is an anti-eavesdropping technology assisting in upper encryption,can disturb eavesdropping with the help of transmission characteristics of wireless channels.Interference is usually regarded as a detrimental factor that degrades the wireless network performance.However,it can be utilized to guarantee the secure transmission in a multi-user multiple-input multiple-output interference network with eavesdroppers,without introducing other resources.A joint user selection and codec optimization scheme is proposed to enhance the security of transmission.Meanwhile,the fairness of user selection is studied to solve the unequal resource distribution problem due to the fixed network topology.It maintains the stability of long-term network transmission.The main work includes:(1)Fading occurrence during transmission results in great reduction of the signal energy.Thus,path loss can be a standard for user selection.In the multi-user interference network,a suboptimal user selection scheme is performed that only relies on the distance information between nodes.Based on user selection,the codec matrixes are joint optimized to maximize the secrecy rate with the rate threshold of other users guaranteed.(2)The optimization problem is mixed non-convex,which is difficult to solve.An alternating iterative optimization algorithm is proposed to obtain the optimal solution by transforming the problem into a convex second-order cone programming.The essence of transceivers optimization is to weaken the eavesdropping performance by means of internetwork interference and to improve the transmission quality of the private user by proper power distribution.Thus,the security of system can be enhanced.(3)When the network topology is fixed,user selection result is also constant.In order to guarantee each user to enjoy the secure transmission,fairness is explored.The user in the current time slot transmission is determined by the sum of throughputs of the first few time slots.The smaller the throughput of the first few time slots,the greater the probability that can be selected as the secure user.The revised solution allows all users to have opportunities of transmitting privately,which contributes to the stable development of the network.