A Study On Physical Layer Secure Communications Based On Circular 4d Antenna Arrays

As the modern wireless communication system rapidly evolves, the security issues in wireless communication are drawing more and more attentions. In order to perform a more strict prevention from wiretaps, it is necessary to perform further on their security feature of the whole communication system, both on software and hardware level. A new type of antenna arrays is appearing in physical layer security communications, namely, the 4-D antenna arrays. As a mutation of traditional phased array,the 4-D antenna brings the fourth dimensional variable- “time”- into the traditional 3-D spatial antenna arrays. It is one of the cutting edge antenna technologies nowadays which has the following characteristics: being able to realize the direction diagram of low sidelobe or ultra-low-sidelobe, high performance with low cost, formation of multiple beam, high design freedom, etc. More notably, it is possible to apply the 4-D antenna arrays to security communications at the desired transmission directions, using the unique sideband modulation effect of the 4-D antenna arrays.By combining the 4-D antenna arrays and circular antenna arrays, this thesis proposed a novel approach for possible security communication within 2-D space. A relatively thorough theoretical and experimental study is then carried out. The main contents of the thesis includes:1. Based on the fundamental theory of 4D antenna arrays, conduct numerical analysis on the security communication feature of circular 4D antenna arrays is conducted, in both fixed and random timing sequence, and conduct an analysis of wrong bit ratio for the BPSK signal sent by circular 4-D antenna arrays. The simulation result shows that circular antenna arrays can realize secure communication of analog and digital signals in 2-D space, which is different from previous researches that are limited to azimuth plane private communication.2. Use simulation tool to design a broadband printed circular-dipole-antenna arrays. The arrays can send non-modulated signals in required direction while send modulated signals in other directions with the cooperation of CPLD controlled circuit along with well-designed frequency, signal bandwidth and switch timing sequence.3. Synthesis the circular 4-D antenna arrays based on Differential Evolution Algorithm, and simulate the model in HFSS. Using the commercial software HFSS electromagnetic simulate the model of circular array and using Differential Evolution Algorithm calling HFSS dates, randomly optimize it range and phase.This paper does systematical and intensive researches on the design of circular 4-D antenna array and its security feature, and validates the possibility of its implementation of private communication system on physical level. The research work of this paper indicates that the circular 4-D antenna arrays have extremely good advantage and potential in physical secure communication area.