Study On Physical Layer Security Of Cognitive Radio Network Based On Convex Optimization

Network security is one of the main research question of wireless networks,but also successful promotion and application of the basic conditions for a wireless network. Moreover, the number of users of wireless networks is increasing and the continued deterioration of the wireless network environment, security problem of the wireless network is facing more and more severe challenges.The encryption key is traditional network security technology.Using all kinds of algorithms in the network protocol stack layer encrypt messages, to guarantee the security of information.However, when presented with a new encryption algorithm, decipher algorithm often will follow.The key encryption technology can effectively ensure the safety communication in wireless networks, but the price to pay is very high computational complexity. Secret key encryption technology from the point of view of the network protocol layer and physical layer security is different,it is to the wireless network communication security problem to consider using a completely different angle. Because of the physical channel of a wireless network is open, the transmission with multipath and fading characteristics, these characteristics make the communication security problem of wireless networks face more severe than wired network.Wireless physical layer security issues in this paper, several different were studied, according to the problems put forward to improve the security of the algorithm. In this process, the main findings obtained following:1) The MISO cognitive radio network physical layer security problems with artificial noise is studied, design noise convariance and beamforming vector of transmitter. By using semi-definite relaxing technique, the optimization problem is not convex, convert it into a semi-definite programming, then it is easily solved. Using worst-case optimization approach to design robust transmitter when the CSI is not certain.2) Cooperative jamming based MISO cognitive radio network physical layer security problems is studied. We transmit artificial noise through a cooperative node to interfere the eavesdropper.We present two kinds of algorithms : partial orthogonal projection(POP) and complete orthogonal projection(COP). We resolve the complex problem into two sub-problems. Simulation results show that COP and POP can raise the secrecy rate.3) The MISO cognitive radio network physical layer security problems with energy harvesting function is studied. In cognitive radio networks, the secondary receiver to and idle secondaryreceivers can harvest energy from the received signal. By guaranteeing the quality of service of secondary users and interference of primary user less than a a predetermined value premise, the optimal resource allocation scheme is designed.