基于相位调制表面的方向调制物理层安全通信系统研究

发布时间：2019-06-10 22:57

【摘要】：无线通信物理层安全是利用无线信号传输过程中无线通信系统物理层的自身特性,通过设计无线通信系统物理层的编码、调制和传输方式保障无线通信信息在物理层的安全传输。作为上层网络加密协议的补充,物理层安全的研究有助于应对传统信息加密方式所面临的挑战。为了进一步提升无线通信信号在物理层传输过程中的安全性,本文利用电磁散射特性可调的相位调制表面,基于方向调制技术提出了一种新型的方向数据加密通信系统。首先研究了相位调制表面的电磁特性,利用差分进化算法优化了其结构中有源频率选择表面的电控方案,提升了相位调制表面的吸波性能。继而将相位调制表面作为反射面天线的可控特性反射面,以高于激励信号信息速率的电控频率将相位调制表面中的有源层在强弱反射状态间高速切换,对馈源发射的激励信号进行空间采样后发射至自由空间。以该方式发射的无线通信信号在空间不同方向具有不同的接收信号星座图,只在特定方向上可以还原通信信息,在其余方向由于接收信号星座图的畸变无法解调出通信信息。同时该发射信号相比激励信号带宽大大扩展致使信号频谱隐藏于背景噪声,使得敌对方难以探知并干扰期望接收机的正常通信。仿真结果表明,本文研究的通信系统中所传输的方向数据加密信号具备低截获概率、低检测概率特性,并且具备一定的抗干扰、抗多径信道衰落的能力,提高了无线通信信号在物理层传输过程中的安全性。
[Abstract]:The security of wireless communication physical layer is to make use of the characteristics of the physical layer of wireless communication system in the process of wireless signal transmission, and to design the coding of the physical layer of wireless communication system. The modulation and transmission mode ensures the secure transmission of wireless communication information in the physical layer. As a supplement to the upper network encryption protocol, the research of physical layer security is helpful to meet the challenges faced by the traditional information encryption methods. In order to further improve the security of wireless communication signal in the process of physical layer transmission, a new directional data encryption communication system based on directional modulation technology is proposed by using the phase modulation surface with adjustable electromagnetic scattering characteristics. Firstly, the electromagnetic characteristics of the phase modulation surface are studied, and the electronic control scheme of the active frequency selective surface in the structure is optimized by using the differential evolution algorithm, which improves the absorbing performance of the phase modulation surface. Then the phase modulation surface is used as the controllable characteristic reflector of the reflector antenna, and the active layer in the phase modulation surface is switched at a high speed between the strong and weak reflection states at an electronic control frequency higher than the excitation signal information rate. The excitation signal transmitted by the feed is sampled in space and transmitted to free space. The wireless communication signals transmitted in this way have different received signal constellations in different directions in space, and the communication information can only be restored in a specific direction. In the other directions, the communication information can not be solved because of the distortion of the received signal constellation. At the same time, compared with the excitation signal, the bandwidth of the transmitted signal is greatly expanded, which makes the signal spectrum hidden in the background noise, which makes it difficult for the enemy to detect and interfere with the normal communication of the desired receiver. The simulation results show that the direction data encrypted signal transmitted in the communication system studied in this paper has the characteristics of low probability of interception, low detection probability, anti-interference and anti-fading ability of multi-path channel. The security of wireless communication signal in the process of physical layer transmission is improved.
【学位授予单位】：南京邮电大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN918

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