基于无线信道特征的物理层安全编码技术研究

发布时间：2018-02-24 08:02

本文关键词： 物理层安全安全编码无线信道特征等效信道模型人工噪声　出处：《解放军信息工程大学》2014年硕士论文　论文类型：学位论文

【摘要】：物理层安全利用无线信道多样性以及通信双方信道特征的唯一性、互易性防止信息在通信链路底层泄露,是一种针对无线通信特点设计的信息安全保障方法。安全编码作为物理层安全的关键技术之一,将编码的纠错特性与无线信道特征有机结合,差异化合法接收者与第三方窃听者的接收性能,实现合法通信双方信息的安全可靠传输。但是,目前的安全编码研究还存在以下问题:1)对信道特征的差异性利用不充分,导致安全编码获得的安全增益受限;2)缺乏安全编码与传输技术的联合设计,导致安全编码效率及系统功率利用率降低。本文依托国家自然科学基金项目,对物理层安全编码技术展开专门研究。针对上述问题,论文首先提出了两种与合法信道时域特征强耦合的安全编码方法:基于信道衰落幅度差异的物理层安全编码方法和基于信道特征扰动相位的物理层安全编码方法。然后研究了安全编码与人工噪声方法的联合设计,以提高安全编码的效率及系统功率利用率。主要研究内容包括:1、提出了基于信道衰落幅度差异的物理层安全编码方法。首先,证明了信道能量相同条件下,低密度校验码中私密信息节点传输时所对应的信道衰落幅度越小,越有利于该处的信息正确恢复;然后选取合法信道衰落幅度最小的位置作为私密信息位,并将私密信息隐藏在随机序列中,形成有利于合法接收者译码的条件;再结合私密信息置乱,将窃听者的译码残余比特错误扩散到整个码字中。仿真结果表明,该方法提高了窃听者的误比特率,相比于仅信息置乱的方法,安全间隙缩小了5dB。2、提出了基于信道特征扰动相位的物理层安全编码方法。首先,通过合法信道衰落幅度与相位扰动权值幅度信息的乘积,确定对发射符号进行相位随机扰动的边界范围;然后,以发射端在平均功率约束下随机产生的幅度信息,连同在相位扰动边界范围内随机选取的相位信息,共同构成相位扰动权值;最后,以所得的相位扰动权值对每个待发射符号进行预编码,使得合法接收者在相位扰动下仍具有稳定的抗噪声性能,而窃听者接收符号的相位信息模糊无法正确译码。仿真结果表明,在相同发射功率和信道噪声的情况下,窃听者的误比特率接近0.5。3、提出了基于等效信道模型的安全编码与传输联合设计方法。首先建立了无线物理层等效信道模型,分析了影响安全编码与人工噪声传输方法性能的关键参数;然后定量描述了人工噪声方法在不同误比特率门限下加权矢量和噪声矢量对等效信道特征的影响,以及不同等效信道特征对安全编码误比特率门限的影响,建立起安全编码与人工噪声之间的紧密联系;最后,以最大化私密信息码率为目标设计出两者的联合优化算法。仿真结果表明,该方法能使私密信息码率达到0.43,提高了安全编码效率;安全性余量相比0.35sR?时简单级联的方法缩小约3dB,提高了系统的功率利用率。
[Abstract]:The only physical layer security using wireless channel diversity and communication channel characteristics, the reciprocity in the bottom to prevent information communication link leak, is a kind of information security method of wireless communication. The design characteristics of security encoding as one of the key technologies of physical layer security, combining the characteristics of the error correction encoding and wireless channel characteristics the receiving performance difference of legitimate receiver and third party eavesdropper, to achieve safe and reliable transmission of information between two legal parties. However, there are the following problems of current safety encoding: 1) differences in utilization of channel characteristics is not sufficient, resulting in security gain restricted security encoding obtained; 2) combined with the lack of safety design encoding with the transmission technology, which leads to the decrease of power efficiency and safety rate of encoding system used. Based on the National Natural Science Fund project, the safety of the physical layer encoding The research on the technology. Aiming at the above problems, this paper put forward two kinds of security encoding method and legitimate channel characteristics in time domain coupling: physical layer based on the channel fading amplitude differences in the safety encoding method and based on the physical layer channel characteristics of phase perturbation method. Combined with the design of security encoding and security of encoding and artificial noise method in order to improve the efficiency, power system security and encoding efficiency. The main research contents include: 1, the physical layer channel fading amplitude difference encoding method based on security. First of all, proved that the channel can amount under the same conditions, the channel of low density parity check codes in the transmission of private information node corresponding to the fading amplitude is small the more conducive to the correct recovery; and then select the legitimate channel fading amplitude minimum position as private information, and private information hidden in random order In the column, conducive to the formation of the legitimate receiver decoding conditions; combined with private information scrambling, the residual bit error diffusion decoding eavesdropper to the entire codeword. The simulation results show that this method improves the eavesdropper bit error rate, compared to the only information scrambling method, safety clearance reduced by 5dB.2, put forward the physical layer channel disturbance phase encoding method based on security. First, the product through legal channel fading amplitude and phase perturbation amplitude weight information, determine the phase boundary of random disturbance transmitted symbols; then, the amplitude information at the transmitter at random from the average power constraints, together with the phase perturbation phase boundary information in the range of randomly selected, together constitute the phase perturbation weights; finally, the phase perturbation weights to each transmitted symbol to be pre encoding, the legitimate receiver in phase Who still has the anti noise performance and stable perturbations, the eavesdropper receives a symbol phase information fuzzy cannot correct decoding. The simulation results show that under the same transmit power and channel noise, the bit error rate of the eavesdropper is close to 0.5.3, puts forward the safety encoding and joint design method of equivalent transmission channel model based on first. Wireless physical layer equivalent channel model is established, and analyzed the key parameters affecting the performance of security encoding and artificial noise transmission method; and then describe the artificial noise method in different bit error rate threshold weighted vector and the noise vector of the equivalent channel characteristics, and different characteristics to affect the safety of the equivalent channel encoding bit error rate threshold and establish close relationship between safety and artificial noise encoding; finally, to maximize the private information rate is designed for joint optimization of the two The simulation results show that the private information rate is 0.43 and the security coding efficiency is increased by this method. The security margin is reduced by about 3dB compared to the 0.35sR concatenation method, and the power utilization ratio of the system is improved.

【学位授予单位】：解放军信息工程大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN92

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