基于反馈控制的分布式安全波束成型算法研究

【作者】 徐凯；

【导师】 谢宁； 李健乾；

【作者基本信息】 深圳大学 ， 电子与通信工程（专业学位）， 2017， 硕士

【摘要】 近些年来,物理层安全技术受到广泛关注与研究,是未来通信系统中的关键技术之一。其基本思想是利用合法接收端较窃听端有更好的信号接收质量(如:信噪比),来实现安全通信。另外,传统的分布式波束成型技术经过多年的发展,已日趋成熟,但是针对安全通信的分布式波束成型技术仍是一个挑战。本学位论文主要研究基于物理层安全技术的分布式波束成型问题。在物理层安全技术研究的最新进展中,基于衰落窃听信道的研究成为热点。在这些研究中,绝大部分需要利用合法接收端将信道信息反馈给发射端。在实际应用中,发射端要获得准确的实时信道信息往往是十分困难的,这使得现有的物理层安全技术在实际应用中受到了很大限制。而引入误差的原因主要分为三大类:第一类、估计误差;第二类、延时;第三类、反馈链路容量受限。本学位论文提出了基于单比特反馈信息的分布式安全波束成型系统。在新系统中,合法接收端除了反馈单比特控制信息外,不需要反馈其它任何形式的信道信息,只需要较少的网络资源就能使得系统的安全容量得到提升。基于新系统,本学位论文设计出一个与之对应的分布式安全波束成型算法,称为分布式相位失配安全波束成型算法。新算法的优势如下:第一、利用合法接收端反馈的单比特信息来控制每个分布式发射节点发射人造噪声的相位,并通过连续负反馈与累加正反馈机制来提升算法的收敛速度,具有很高的实际应用价值;第二、新算法在分布式发射节点与合法收发端都引入了人造噪声,即使在窃听端装备多天线时,新算法仍可以干扰窃听端对信道方向信息的估计准确度,使得系统的安全容量得到进一步提升;第三、当通信环境存在信道漂移时,由于累加正反馈机制的作用,新算法可以追踪信道漂移,使得新算法在复杂通信环境中仍能实现分布式安全通信。最后,新算法在其参数选取上具有较好的鲁棒性。通过大量的仿真实验,本学位论文通过仿真实验对新算法进行了深入研究,证明了其有效性与优越性。更多还原

【Abstract】 Recent years,research work on the technology of physical layer security(PLS)has attracted much attention,which is one of key technologies in the future communication system.The basic idea of PLS is to achieve secure communication by making some performance metric(e.g.,signal to noise ratio(SNR))of the legitimate receiver better by compared with the eavesdropper.Moreover,the traditional technology of distributed transmitting beamforming(DTB)became popular with many years of development,but there are some challenges for the PLS in DTB.The motivation of this thesis is to make a research on the PLS in DTB.The recent progress of PLS focuses on the fading wiretap channel,and most of them require the legitimate receiver to feedback the channel state information(CSI)to the transmitter.However,to acquire the precise CSI is not feasible under some situations,which limits the application of some exiting approaches of PLS in practice.There are three sources to cause the uncertainty of CSI,which are estimation errors,delay and the capacity limitation of feedback link.This thesis proposes a new system of secure DTB based on one-bit feedback information.Note that the proposed system requires only one-bit feedback information transmitted from the legitimate receiver instead of any CSI,which takes little network resources to improve the secrecy capacity.Based on the proposed system,this thesis further design an implementation algorithm,referred to as secure distributed transmitting beamforming with phase mismatch(SDTB-PM).The superiority of SDTB-PM includes: firstly,only one-bit feedback information from the legitimate receiver is required to control the phase offset of an artificial noise(AN)in each distributed transmitter.Furthermore,SDTB-PM utilizes the cumulative positive feedback information and the successive negative feedback information to improve the convergence speed;Secondly,the legitimate transmitters and receiver of SDTB-PM introduce AN to lower the estimation precise of the channel direction information(CDI)obtained by the eavesdropper,even it utilizes the technique of multiple antennas;Thirdly,due to the mechanism of the cumulative positive feedback information,SDTB-PM can track the phase drift and then work well in a complex communication environment.At last,SDTB-PM has a good robustness on parameters selection.Through simulation results,the proposed SDTB-PM has been analyzed carefully to validate its superiority.更多还原