基于人工噪声辅助的物理层安全通信系统峰均比研究

发布时间：2018-06-28 10:45

本文选题：无线通信 + 物理层安全　；参考：《南京邮电大学》2017年硕士论文

【摘要】：随着计算机技术的快速发展,以密码学为基础的上层加密技术面临严峻的挑战。为了确保无线通信系统中传输信息的安全性能,物理层安全成为信息安全领域一个新的研究热点。人工噪声辅助的物理层安全通信技术是利用多天线收发增加无线通信信息传输过程中的安全性能的经典方法,该技术通过在期望信道的零空间发射人工噪声来降低窃听信道的信道容量,从而提高系统的安全信道容量来确保无线通信信息在物理层中的安全性能。现有的研究文献从不同的方面详细论述了人工噪声辅助物理层安全通信系统这一技术的性能,如通信信号与人工噪声信号的功率分配问题、收发天线数目问题以及协作方式的人工噪声辅助方式等。但现有的研究忽略了人工噪声辅助的物理层安全通信系统中发射信号高峰均比的特性,本文针对这个问题展开做出了如下三个方面的研究:(1)现有的人工噪声辅助的物理层安全通信系统的研究都是在发射系统放大器门限无穷大的理想情况下研究系统的安全信道容量,本文从实际系统放大器存在门限的角度分析了人工噪声辅助物理层安全通信信号峰均比的互补累积分布以及放大器门限对于系统安全信道容量的影响,从而说明系统降低发射信号峰均比特性的必要性。(2)本文提出了一种基于噪声子空间旋转不变性的发射信号峰均比降低算法,利用发射机产生的噪声子空间旋转不影响噪声子空间与期望信道零空间的正交性和对窃听接收机干扰性能这一特性来降低发射信号的峰均比,并且基于差分遗传算法求解出不同噪声子空间对应的旋转角度的最优解。但算法搜索的维度随着发射天线数的增加而增加,发射机计算负担急剧增加。为了降低算法的复杂度方便系统的工程实现,本文同时给出了一种基于部分旋转角度的次优算法,利用有限的角度集合减低发射信号的峰均比特性。(3)现有的方向调制信号噪声子空间功率分配都是等功率分配的,改变不同噪声子空间的功率分配有利于降低发射信号的峰均比特性。本文提出了一种基于凸优化算法的噪声子空间功率分配发射信号峰均比降低算法。首先建立以最小化峰均比为目标函数噪声子空间功率分配系数为可行域的非凸优化问题;针对该凸优化问题,我们通过分式规划,DC规划等数学方法将其转化为求解一系列的凸的子问题,从而逼近原非凸问题的解;针对约束条件是非凸的,我们通过线性约束逼近该非凸约束,从而通过非凸问题的三重优化算法分配噪声子空间的功率,达到优化发射信号的峰均比特性的目的。
[Abstract]:With the rapid development of computer technology, the upper layer encryption technology based on cryptography is facing a severe challenge. In order to ensure the security performance of information transmission in wireless communication systems, physical layer security has become a new research hotspot in the field of information security. The physical layer security communication technology assisted by artificial noise is a classical method to increase the security performance in the process of wireless communication information transmission by using multi-antenna transceiver. This technique can reduce the channel capacity of eavesdropping channel by transmitting artificial noise in the zero space of desired channel, thus improving the security channel capacity of the system to ensure the security performance of wireless communication information in the physical layer. The performance of the artificial noise aided physical layer secure communication system, such as the power allocation between the communication signal and the artificial noise signal, is discussed in detail in the existing research literature. The number of transceiver antennas and the artificial noise auxiliary mode of cooperative mode are also discussed. However, the existing research neglects the peak-to-average ratio of transmitted signals in the physical layer secure communication system assisted by artificial noise. In this paper, the following three aspects have been studied: (1) the research of the existing physical layer security communication system aided by artificial noise is studied under the ideal condition of the infinite threshold of the amplifier of the transmitting system. Security channel capacity, In this paper, the complementary cumulative distribution of PAPR and the influence of amplifier threshold on the capacity of the system security channel are analyzed from the point of view of the existence threshold of the actual system amplifier. Therefore, it is necessary to reduce the peak-to-average ratio (PAPR) characteristics of the system. (2) in this paper, a PAPR reduction algorithm based on the rotation invariance of noise subspace is proposed. The noise subspace rotation produced by the transmitter does not affect the orthogonality between the noise subspace and the zero space of the desired channel and the interference performance to the eavesdropping receiver to reduce the peak-to-average ratio of the transmitted signal. And the optimal solution of rotation angle corresponding to different noise subspace is obtained based on differential genetic algorithm (DGA). However, the dimension of algorithm search increases with the increase of the number of transmit antennas, and the computational burden of transmitter increases sharply. In order to reduce the complexity of the algorithm to facilitate the engineering implementation of the system, this paper also gives a sub-optimal algorithm based on partial rotation angle. Using a finite set of angles to reduce the peak-to-average ratio (PAPR) characteristics of the transmitted signal. (3) the existing direction-modulated signal noise subspace power allocation is equal power distribution. Changing the power allocation of different noise subspaces can reduce the peak-to-average ratio (PAPR) characteristics of the transmitted signals. In this paper, a new algorithm based on convex optimization is proposed to reduce the peak-to-average ratio (PAPR) of transmit signals with noise subspace power allocation. Firstly, a non-convex optimization problem in which the noise subspace power allocation coefficient is a feasible region with the objective function of minimizing the peak-to-average ratio (PAPR) is established. We transform it into a series of convex subproblems by means of fractional programming and other mathematical methods, so as to approach the solution of the original non-convex problem, for the constraint condition is non-convex, we approach the non-convex constraint by linear constraint. In order to optimize the peak-to-average ratio (PAPR) characteristics of transmitted signals, the power of noise subspace is allocated by a triple optimization algorithm for non-convex problems.
【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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