Secure Performance Analysis And Optimal Resources Allocation For Cognitive Radio Two-way Relay Networks

With popularity of smart mobile phones, there appears an increasing demand for wireless data rate service, which brings about the problem of scarcity of spectrum resources. The measurements shows that licensed users (primary users) of spectrum are idle in most of the time. While the primary users are idle, the unlicensed users (secondary users) are unable to access into the spectrum. The precious spectrum resource is considerably wasted. Cognitive radio technology has been recognized as a key technology to solve this dilemma, which allow secondary users to access into the spectrum when the primary users are idle and improve the efficiency of spectrum utilization. On the other hand, by resorting to the technique of network coding in physical layer, two-way relay technique can break the limitation of half-duplex data transmission, improve the spectrum efficiency while enhancing the system reliability, is also an effective technique that can do help to increase spectrum utilization, has become the hot topic of the research in wireless communications.Combination of the two technologies will result in cognitive radio two-way relay network, which is the focus of this work. In this thesis, we firstly investigate the system performance of two-way relay channel against an eavesdropper and derive the intercept probability. Secondly, an optimization problem is formulated, which aims to maximize the average data rate. It should be noticed that the formulated optimization problem is nonconvex and thus achieving the global optimal solution is a tough challenge. Subsequently, we utilize an algorithm to solve the formulated problem by combing bilevel optimization and monotonic programming. Finally, numerical results are provided to show the how the intercept probability varies with respect to transmission power and rate, and demonstrate the effectiveness of our proposed optimization algorithm. Our work can provide guidance for theoretical research and practical applications of cognitive radio relay communication systems.