Research On Secure Communication Transmission Method Based On Selection Diversity

With the development of mobile communications,increasingly complex network structure makes information security transmission more vulnerable to threat.Although high-level security protocols and encryption algorithms based on the key system can improve the information security to a certain extent,it can not overcome the adverse impact on the information security caused by the broadcast characteristics of wireless channels and the rapidly increasing computing power.The physical layer security technology ensures the security of information transmission directly from the physical layer by making full use of the complicated spatial and time-varying characteristics of the wireless channel.Currently,a new emerging method for prolonging the lifetime of energy-constrained relay nodes in a wireless communication network is to utilize the ambient radio-frequency signal and to simultaneously perform energy harvesting and information processing.This paper has carried on the research of secure communication method in view of the time switching-based relaying protocol(TSR),the study of relay secure transmission scheme combined with cooperative jamming and the full-duplex multiuser diversity relay secure transmission scheme are studied.In the above two researches,the multiuser diversity technique is combined with the TSR and cooperative jamming techniques,and the relay selectes the desired user through opportunistic user selection scheme.Then,we derive the exact expressions of the ergodic achievable secrecy rate(EASR)and the exact secrecy throughput.To obtain the optimal parameter,we propose a low complexity linear search algorithm,named bisection method.The third researche is to apply the multiuser diversity technique,full-duplex technique and cooperative jamming to ensure the security of information transmission.Moreover,two user selection schemes are proposed according to the multiuser communication scenario,and we derive the exact expression of EASR for the user selection scheme I and the exact instantaneous security capacity for the user selection scheme II.The results of the analysis are verified by Monte Carlo simulations on MATLAB platform.The researche results reveal that,the security performance of multiuser diversity relay networks with cooperative jamming technology is better than the security relay network without introducing this technology,and the proposed bisection method is convenient and efficient.We can find through the comparison of two user selection schemes that,the security performance of the user selection scheme II is better than the user selection scheme I with the increase of the total transmission power per time slot.The optimal user selection scheme can guide the design of the realistic secure communication in the multiuser relay network.