物理层安全无线通信中的方向调制技术研究

【作者】 朱伟；

【导师】 陆锦辉； 束锋；

【作者基本信息】 南京理工大学 ， 电子与通信工程（专业学位）， 2018， 硕士

【摘要】 传统的无线通信系统基于密钥加密,其安全性严重依赖于密钥的复杂度,已逐渐暴露出其安全隐患。更为基础的物理层安全无需复杂的密钥,而是从信息论的角度探究无线传输的理论安全性。方向调制作为一种新兴的物理层安全无线传输技术,近年来获得了学术界与工业界的广泛关注,其基本思想是将隐私信息发送到期望方向上,同时利用人工噪声干扰窃听方向。本文重点研究了方向调制技术中隐私信息与人工噪声的波束成形算法设计,主要内容包括:(一)为了提高方向调制多用户MIMO系统安全和速率,提出了基于泄漏的隐私信息和人工噪声波束成形向量设计方法,基本思路如下:最大化期望方向隐私信息功率,同时最大化窃听方向人为噪声功率。仿真结果表明:所提多用户方向调制合成方法的安全和速率性能优于传统正交法,且随信噪比增加,性能优势更加明显。例如,在信噪比为15dB时,所提方法的安全和速率性能比传统正交法相提高近40%。(二)为了解决传统的稳健方向调制需要获得角度测量误差统计特性的问题,提出无需误差统计特性的盲稳健方向调制合成方法,通过主瓣积分将隐私信号的功率集中到期望方向的主瓣区间内,同时将人工噪声的功率集中到所有窃听方向角区间内。仿真结果表明:存在方向角测量误差时,所提盲稳健方向调制在误比特率和安全和速率性能上均优于现有的正交法和泄漏法,当已知非完美窃听方向信息时,所提方法的期望方向误比特率性能提升近一个数量级。(三)针对传统方向调制中的安全隐患问题:当窃听者移动到期望方向主瓣内时可以窃听到隐私信息,提出基于多中继协作的安全精准无线传输新方案。在该方案中,多台中继站利用方向调制技术将隐私信息的波束成形主瓣对准期望位置,形成隐私信息能量主峰。仿真结果表明:当窃听者位于期望方向主瓣内时,所提安全精准无线传输新方案仅在期望位置处获得高的接收信干噪比,非期望位置由于随机相位导致能量相互抵消,人为噪声恶化接收信噪比,最终使非期望区域无法正确恢复隐私信息。更多还原

【Abstract】 The security of the traditional key-based secure wireless communication system relies heavily on the computation complexity of the key and has gradually exposed its potential security risks.However,more fundamental physical layer security(PLS)without complex keys explores the information-theoretical security of wireless transmission.Directional modulation(DM),as an emerging PLS wireless transmission technique,has gained widespread attention in academia and industry in recent years.Its basic idea is to send confidential information to the desired direction while utilizing artificial noise(AN)to interfere the eavesdropping direction.This paper focuses on the design of beamforming algorithms for confidential messages and AN in DM techniques,and the main contents are as follows:1)In order to improve the secrecy sum rate(SSR)of the multiuser MIMO DM system,the leakage-based beamformer is proposed and its basic idea is as follows:confidential information and AN beamforming vectors are designed by maximizing the signal-to-leakage-and-noise ratio(SLNR)criterion,i.e.,maximizing the power of the confidential information in the desired direction and the AN power in eavesdropping region,respectively.The simulation results show that the SSR performance of the proposed method for multiuser DM is superior to the traditional orthogonal method.And with the increase of signal-to-noise ratio(SNR),the SSR performance advantage of the proposed method will be more significant.For example,when the SNR is 15dB,the SSR performance of the proposed method is improved by nearly 40%compared with the traditional orthogonal method.2)To solve the problem that the traditional robust DM needs to obtain the statistical characteristics of angle measurement error,a blind robust DM synthesis without knowing statistical characteristic of error is proposed.The concept of main-lobe-integration(MLI)is introduced to arrange the power of confidential signals to the main lobes of the desired directions,while forcing the power of AN to the main lobes of eavesdropping directions.The simulation results show that the proposed blind robust DM performs better than the existing orthogonal method and leakage-based method in terms of both BER and SSR performance when the angle estimation error exists.With the knowledge of imperfect eavesdropping direction information,the proposed method show about an order-of-magnitude BER improvement over that of the existing methods.3)Aiming at the security risk problem in the traditional DM that the eavesdropper can intercept the confidential information when it moves into the main lobe of the desired direction,a novel scheme of secure precise wireless transmission based on multi-relay cooperation is proposed.In this scheme,multiple relays use the DM technique to make the beamforming main lobes of the confidential information point to the desired location,where the main energy peak of confidential information is formed.The simulation results show that when the eavesdropper is located in the main lobe of the desired direction,the proposed novel scheme of secure precise wireless transmission only achieves the peak received signal-to-interference-plus-noise ratio(SINR)value at the desired position.Due to the random phase,the power in the undesired region is offset each other,and the received SINR is weakened by AN.Finally,the confidential information cannot be recovered in the undesired region.更多还原