Studies Of Physical Layer Security Transmission Strategy In Wireless Network

Physical layer security as a reliable security technology for next generation mobile communication network has drown great attention. Different from traditional key encryption approach, physical layer security encrypts data by exploiting reciprocity and uniqueness of physical channels, and makes the amount of useful information obtained by eavesdropper tending to zero. It is identified as a promising strategy to access strong security. In this dissertation, we study the physical layer security transmission strategy based on the development trend of the next generation mobile communication network, and aim to provide theoretical basis and practical reference for construction of mobile network.Considering the security in a single cell multi-antennas scenario with multi terminals, we propose a transmission strategy with matched-filter pre-coding and artificial noise generated at the base station for secure downlink scenario. With this transmission strategy, we derive the closed form expression of the ergodic secrecy capacity, and optimize the power allocation between the secrecy signal and artificial noise by using genetic algorithm to obtain the maximum ergodic secrecy capacity. The simulation results reveal that the strategy can obtain a better secrecy capacity in the optimal power allocation scheme ignoring the impact of different path loss, when the number of base station antennas is larger than the number of terminals.In the second part of this dissertation, downlink of a multi-cell massive MIMO system is considered. We propose a multi-cell BS-selection-based artificial noise transmission strategy, which allows the local cell to select the most appropriate base station among all cells to generate artificial noise. We discuss two scenarios of different base station selection results, and derive the tight lower bound of the ergodic secrecy rate of these two scenarios respectively. Genetic algorithm is utilized in this strategy to optimize the power allocation by maximizing the lower bound of the ergodic secrecy rate. The simulation results reveal that the BS-selection-based artificial noise strategy is effective to ensure the communication security in multi-cell system.