【作者】 刘峰；

【导师】 王伶；

【作者基本信息】 西北工业大学 ， 信息与通信工程， 2019， 博士

【摘要】 随着无线通信技术的飞速发展,军事通信和金融服务等关键领域的信息安全愈发得到重视。传统无线安全传输方法大多是基于密钥的加密技术,其安全性依赖于密钥复杂度。然而,随着移动互联网和超级计算机的发展,安全漏洞不断显现。物理层安全最核心的优点是无密钥性,仅利用无线信道的随机性来保证信息传输的安全。方向调制作为一种新兴的多天线物理层安全技术受到研究者的密切关注,其利用合法信道和窃听信道之间的差异,将有用信息发送到期望方向上,同时在非期望方向上将有用信息扰乱,进而实现更加安全可靠的无线信息传输。本文针对物理层信息安全问题,研究了基于方向调制的物理层安全通信技术,论文主要研究工作与创新性贡献包括以下五个部分:(1)针对传统单目标优化方向调制信号信息波束较宽导致安全性低的问题,研究了基于混合优化算法的多目标方向调制信号综合方法。利用阵列天线的射频端优化法实现方向调制,结合混合粒子群优化-遗传算法进行多目标优化,保证了方向调制信号的信息波束宽度窄特性。仿真证实了所提方向调制信号的误码率方向图存在较小旁瓣,进一步提高了信息无线传输的物理层安全性能。(2)针对传统天线子集调制信号信息波束外安全性低的问题,提出了基于线性稀疏阵列的方向调制技术。利用线性阵列稀疏率随机选择和阵列型式随机选择来综合方向调制信号,使得在非期望方向上星座图严重混叠。仿真实验证实,基于线性稀疏阵的方向调制技术可以增加非期望方向的误码率,明显增强信息传输安全性,同时线性稀疏阵的使用进一步降低了系统成本。(3)针对传统方向调制技术存在安全性不足和频谱效率低的问题,分别从采样角度和信号处理角度提出了基于极化敏感阵列的多波束方向调制技术。根据误码率指标,在窃听用户已知发端极化信息和窃听用户未知发端极化信息两种场景下,分析了极化敏感阵列多波束方向调制技术的安全性能。仿真结果表明,基于极化敏感阵列的多波束方向调制技术在提高频谱效率的同时,有效增强方向调制系统物理层安全。(4)针对标量单阵列方向调制技术实现角度依赖安全传输的局限性,分别提出了基于单载波多阵列模型和多载波多阵列模型的两种方向调制技术。结合多阵列模型,分别对基站和合法用户接收机的结构进行了详细设计,分别从误符号率、安全速率和鲁棒性分析了所设计的方向调制方案的安全性能。仿真结果表明,基于多阵列的方向调制技术能实现角度-距离依赖的安全精准无线传输。(5)针对窃听用户位于期望方向或毗邻期望用户时传统方向调制系统安全性无法保证的问题,分别设计了基于MP-WFRFT和常规混沌加扰的方向调制方案与基于无特征混沌加扰和人工噪声的方向调制方案。通过结合MP-WFRFT技术和混沌加扰技术来提高传统方向调制系统的物理层安全性能。分别从误符号率、安全速率、鲁棒性和抗截获性能指标分析了所提方案的性能。仿真实验证实,结合MP-WFRFT和混沌加扰的方向调制技术能有效解决传统方向调制技术存在的邻域安全问题。更多还原

【Abstract】 Nowadays,information security has become the core and key of wireless communication,especially when wireless communication technology is applied to financial services and military communication.A traditional way to solve security problems in wireless transmissions is based on key-based encryption,whose security depends heavily on key complexity.With the development of mobile Internet and supercomputers,the security risks are gradually exposed.The most significant advantage of physical layer security(PLS)is that it does not require complex digital keys to encrypt useful information.From the perspective of information theory,the security of information transmission has been studied,and secure transmission can be guaranteed only by using the physical characteristics of the wireless channel.Directional modulation(DM),as an emerging and promising physical layer security technology in wireless transmission,has received extensive attention from academia and industry.DM utilizes the difference between the main channel and the eavesdropping channel to send useful information to desired direction(s)while disrupting useful information in undesired directions,thereby enabling more secure information transmission.In view of the physical layer information security issue,PLS communication techniques based on DM have been deeply studied in this dissertation.The main work and innovative contributions of the dissertation include the following five parts:(1)Based on the basic principle of directional modulation based on the RF(Radio Frequency)frontend optimization method of array antennas,a synthesis technique of directional modulation signal based on hybrid Particle Swarm Optimization(PSO)and Genetic Algorithm(GA)is proposed.Compared with the traditional directional modulation signal,the directional modulation signal transmitted by the proposed method has a narrower information beamwidth,and the bit error rate(BER)pattern has fewer significant side lobes,which can further improve the security performance of wireless transmission.(2)A DM technique based on linear sparse array(LSA)is proposed,which uses random selection of sparse rate and array pattern to synthesize the DM signals.The simulation results show that the sparse array optimization DM technique can significantly increase the bit error rate in the undesired direction,which can significantly enhance the information transmission security,and the use of linear sparse array further reduces the system cost.(3)Two DM techniques based on single-carrier and multi-carrier multiple antenna arrays models are proposed,and it is composed of the structure of base station and legitimate users,which is designed in detail,and the performance analysis of the proposed DM schemes from three metrics: symbol error rate(SER),secrecy rate and robustness respectively.The simulation results show that the DM technology based on multiple antenna arrays can realize secure and accurate transmission of confidential information and partially solve the neighbourhood security problem of traditional DM schemes.(4)A DM technique based on multi-parameter weighted-type fractional Fourier transform(MP-WFRFT)and chaotic scrambling is proposed.Specifically,the basic principle and implementation method of MP-WFRFT technology and chaotic scrambling technology are introduced,and the performance of the proposed DM scheme is analyzed from four metrics:SER,secrecy rate,robustness and anti-interception performance.The simulation results show that the DM technology based on MP-WFRFT and chaotic scrambling can solve the neighbourhood security problem of traditional DM schemes.(5)A multi-beam DM technique based on polarization sensitive array is proposed from the perspective of sampling and signal processing,where the security performance of the polarization sensitive array based DM technique is analyzed according to the SER index under the two scenarios of eavesdropper knowing the origin polarization states and eavesdropper unknowing origin polarization states.The simulation results show that the DM technique based on a polarization sensitive array can enhance the security of traditional DM schemes.更多还原