Cooperative Jamming Based Wireless Physical Layer Security Transmission Strategy

With the rapid development of wireless network and ever-increasing demand of secure transmission, physical layer security can provide a new way for wireless communication security. The basic idea is utilizing the inherent characteristics of wireless channel to improve security performance. Cooperative communication is capable of offering more opportunities for physical layer security implementation since it exploits multi-dimensional degree of freedom from frequency domain, and time-space domain. Therefore, from the perspective of physical layer security, we focus on the transmission strategy which is based on cooperative jamming. Besides, power allocation is studied to maximize the available secrecy rate under certain power constraints. Our research achievements are as follows.Firstly, we investigate an AF-based one-way relay network with an eavesdropper and propose a security transmission strategy which takes advantage of cooperative jamming and cooperative diversity. The one-way relay wiretap channel model is constructed, then the expression of the available secrecy rate is derived. Furthermore, the optimization problem aiming at maximizing the available secrecy rate via power allocation is analyzed, and the optimal solution is determined by SQP interative algorithm. The results show that the proposed approach can increase the secrecy level, and that a positive secrecy rate can be achieved even when the eavesdropper may be near the source.Secondly, we popularize the rearch on physical layer security to an AF-based two-way relay network with an eavesdropper. An interactive security transmission strategy based on cooperative jamming is proposed, and then a two-way relay wiretap channel model is established. After that, the overall secrecy rate is formulated. Moreover, the secrecy rate optimization problem is analyzed and the optimal power allocation solution is solved by SQP algorithm. Simulation results vertify the efficiency of the proposed strategy via reasonable power allocation.