Transmission Security Analysis For Link With Multi-antenna

In recent years, the popularity of personal smart mobile communication terminals indicates that the wireless communication technology has been integrated into all as-pects of people’s life. The information carried on the wireless link becomes more and more important and more and more sensitive, but the feature of transmission in the open air makes information much more easier to be wiretapped, so guaranteeing the security of user information becomes so important. To achieve this goal, symmetric-key cryp-tography and public-key cryptography which are widely used in wired networks are applied to nowaday wireless communication. However, it has been proven that the se-cret key distribution process of those cryptographies is vulnerable to be attacked and consumes too much resources when applied in wireless networks. Due to the size and cost constraints, the energy and computing power of mobile terminals are limited, it is hard to support encryption algorithms with high complexity. Fortunately, physical layer security offers us a different choice, which exploits the multipath and fading char-acteristics of the wireless channel to provide information security protection. In our work, we study the typical cellular scenario in which the transmitter has multi-antenna while both the receiver and the eavesdropper have only one antenna. Beamforming and noise injection are utilized to enhance the security of wireless channel. We anal-ysed the effect of transmit antennas’ number and artificial noise’s power on channel security, by giving the probability distribution functions of SNRs of signals received by receiver and eavesdropper in the condition that only beamforming is used and the condition that both beamforming and noise injection are utilized, and then deriving the closed-form expressions for the probability of non-zero secrecy capacity, the secrecy outage probability and the average secrecy capacity. We also applied secret key agree-ment to generate keys and analysed the influence of beamforming and noise injection on key rate.