不同于传统无线通信网络，认知无线网络由于认知和重构功能的引入而存在着认知信息泄漏、“频谱陷阱”、模仿主用户窃听等安全隐患。本项目以物理层安全机理研究及其在认知网络中的实际应用为目标，旨在从物理层解决认知无线网络的安全可靠传输问题，推动认知无线电通信走向实用化。首先，基于认知网络的实际安全需求，构建认知无线网络的窃听信道模型；然后，以该模型为基础，分析机会频谱接入机制下认知无线网络的安全传输性能。通过研究频谱感知、动态频谱接入和安全性能之间的关系来进一步揭示物理层安全在认知无线网络中应用的规律；最后，依据不同准则和信道信息条件，联合优化设计波束成形、人工噪声、协作干扰、功率分配等物理层安全传输算法，并搭建数值仿真平台，验证模型和算法的有效性。

Different from general wireless communication networks, cognitive wireless network has its own characteristics and security requirements, such as cognitive data losing, spectrum trap, primary user emulation eavesdropping, and so on, because of the introductions of cognitive and reconfiguration functions. In this project, our aim is the foundational research of physical layer security and its application in cognitive wireless networks, which is expected to address the secure and reliable transmission problem and force the practical application of cognitive radio communications. Firstly, based on the practical security requirements of cognitive networks, we will construct the wiretap channel models. Secondly, based on these models, we will analyze the secrecy performance of cognitive wireless network based on opportunistic spectrum access and study the relations between spectrum sensing, dynamics spectrum access and the achievable secrecy performance to explore the regularity of physical layer security in cognitive wireless networks. Finally, based on different rules and channel state information conditions, we will investigate the security mechanism and transmission polices by jointly designing different strategies, such as beamforming, artificial noise, cooperative jamming, power allocation, and so on. Moreover, we construct a numerical simulation platform to verify the validity of the proposed models and algorithms.