In order to solve the problem of intercellular eavesdropping in Device to Device (D2D) communication, an anti-eavesdropping secure transmission scheme based on artificial noise assisted Time-Reversal (TR) was proposed. Firstly, the interference between cells was eliminated under the cross-cell channel model. Secondly, the ability of eavesdropping users to steal information was deteriorated by sending artificial noise to the base station to assist TR technology. Finally, in order to meet the needs of cellular users for service quality and maximize the system traversal secrecy rate, the power control allocation scheme with convex optimization was adopted to maximize the transmitted power of D2D users. Through simulation experiment analysis, compared with the artificial noise scheme, this scheme improves the achievable secrecy rate of 0.8 b·s^-1·Hz^-1 under the same Signal-to-Noise Ratio (SNR). In addition, with the increase of the number of neighboring cells, this scheme has improvement on the reachable secrecy rate more and more obvious.

Aiming at the cross-layer interference between the macrocell user layer and the femtocell user layer and the same layer interference between femtocells in the macrocell-femtocell dual-layer network model, a resource allocation algorithm based on femtocell base stations was proposed. The algorithm consists of two parts:the one is that, the Macrocell base station firstly used the improved difference method, set the virtual Macro User Equipment (MUE), and turned it into a balanced assignment problem and allocated the channel to the macrocell user, and then used water-filling algorithm for power allocation to ensure the transmission of macrocell users. The other part is that, on the basis of guaranteeing the service quality of the macrocell users, an Enhanced Ant Colony Optimization (EACO) algorithm was adopted to group the femtocells after setting the pheromone concentration range, which avoided the possibility that the original ant colony algorithm may fall into a local optimum. Then, a heuristic algorithm and a distributed power allocation algorithm were used to allocate the channel and power to the Femto User Equipment (FUE) respectively. The spectral efficiency was maximized under the data rate requirement of the femtocell users. The simulation results show that EACO effectively suppresses cross-layer interference and same-level interference, which can guarantee the data rate requirement of users and improve the efficiency of network spectrum effectively.

Since the evaluation of Distributed Denial of Service (DDoS) is inaccurate and network security situational evaluation is not comprehensive, a new network security situational awareness model based on information fusion was proposed. Firstly, to improve the accuracy of evaluation, a situation assessment method of DDoS attack based on the information of data packet was proposed; Secondly, the original Common Vulnerability Scoring System (CVSS) was improved and the leak vulnerability was evaluated to make the assessment more comprehensive; Then, according to the combination of objective weight and subjective weight, the method of calculating the combined weights and optimizing the results by Sequence Quadratic Program (SQP) algorithm was raised to reduce the uncertainty of fusion; Finally, the network security situation was got by fusing three aspects evaluation. To verify the original evaluation of DDoS was inaccurate, a testing platform was built and the alarm of the same DDoS differed by 3 orders of magnitude. Compared to the original method based on alarm, the steady and accurate result of evaluation was obtained based on data packet. The experimental results show that the proposed method can improve the accuracy of evaluation results.