Research On Security Performance Of MISOME System With Security Outage Probability Constraints

The broadcast nature of the wireless channel makes it vulnerable to potential eavesdropping.Physical layer security exploits the characteristic of wireless channel to guarantee secure transmission between legitimate parties.With fast development of 5G and MIMO system,physical layer security based on MIMO has become hot topics.In this thesis we use techniques such as artificial noise,transmit antenna selection and transmit beam forming to construct a MISOME system making up to legitimate channel' CSI disadvantage in MISOME system compared with eavesdropping channel.1)Artificial noise and Transmit beam forming were adopted to construct AN adaptive system.In MISOME system,the traditional performance metric EST does not have any constraint regarding SOP,which means the amount of information leaked to Eve when system is operating at the optimal might be beyond a maximum tolerable threshold.So in this thesis we added secrecy outage constraints to work with EST in calculating secrecy capacity.Moreover we analyzed how the constraint,the number of transmit antennas,the number of eavesdropper antennas,SNR of main channel and SNR of eavesdropping channel impact the security performance of MISOME system.As numerical results indicated a).After adding secrecy outage constraints,although system might not be able to achieve the best EST,it prevents system from operating on low secure transmission probability;b).System achieves higher EST as number of transmit antennas grows or quality of main channel improves,however when number of transmit antennas becomes large enough,EST tends not to increase anymore;c).System achieves lower EST as number of eavesdropper antennas grows or quality of eavesdropping channel improves,however when number of transmit antennas becomes large enough,EST tends not to decrease anymore.2)A transmission scheme adopting Transmit antenna selection(TAS),and Transmit beam forming(TBF)was proposed as TAS adaptive(OSAS)to reduce hardware cost and improve antenna efficiency at transmitter.The TAS adaptive(OSAS)scheme was compared with AN adaptive scheme adopting artificial noise technique in terms of security performance.As numerical results indicated a).As the maximum allowed SOP decreases,TAS adaptive(OSAS)scheme shows a lower resilience than AN adaptive scheme while OSAS requires less feedback overhead and fewer transmit circuits;b).Security performance of AN adaptive scheme shows a strong sensitivity to number of transmit antennas while TAS adaptive(OSAS)scheme presents a profound sensitivity over number of antennas at eavesdropper and the average SNR of eavesdropper channel.3)Considering selecting the best antenna in TAS bringing limitation to secrecy capacity of TAS adaptive system,we proposed to select multiple good antennas to construct TAS adaptive(OMAS)scheme.As numerical results indicated: a).TAS provides better security performance when using more than just one transmit antenna,and EST of TAS adaptive(OMAS)system first increases then deceases as number of selected antennas increases;b).With number of equipped transmit antennas increasing,the optimal selected antennas number to achieve the highest EST grows;c).TAS adaptive(OMAS)system shows better security performance than AN adaptive system with even less transmit circuit cost.