基于图案隐藏的物理层安全跳空通信技术研究

发布时间：2018-07-06 20:00

本文选题：物理层安全 + 随机加扰　；参考：《解放军信息工程大学》2014年硕士论文

【摘要】：跳空通信是一种通过快速随机切换空域收发信道,增加窃听者获取信息难度的物理层安全技术。目前,跳空通信技术主要存在以下两个问题:1)现有跳空通信均依靠预先协商的跳空图案切换空域收发信道,跳空图案存在泄露风险,给系统带来安全隐患;2)跳空通信由于在良莠不齐的等效空域信道之间快速切换,信息传输速率较低。针对上述问题,本文依托国家自然科学基金项目,对基于图案隐藏的物理层安全跳空通信技术展开研究。本文首先建立基于图案隐藏的跳空通信模型。在该模型指导下,针对MIMO系统提出了基于时域差分跳空的物理层安全机制,并给出了其在MIMO单用户和多用户场景下的实现方法;针对SIMO-OFDM系统,从频域角度出发,提出了基于频域参考跳空的物理层安全方法;在图案隐藏的基础上,针对MIMO跳空系统信息传输速率较低的问题,提出了基于信息导向跳空的物理层安全方法。具体的研究内容包括:1、基于时域差分跳空的MIMO系统物理层安全机制。通过在发送信号中添加人工干扰,使合法用户接收到的空域信号随机快变;使用合法用户上一时刻接收的空域信号,作为当前时刻合法用户的接收权向量,与主信道组合得到等效收发信道,由此实现随机跳空。由于主信道与窃听信道的差异性及等效信道分布的随机性,窃听者无法跟踪跳空过程,从而无法通过干扰抑制方法实现窃听。对MIMO单用户和多用户场景,分别通过在等效信道的零空间发送人工噪声和多用户干扰得到随机快变的空域接收信号,实现时域差分跳空。2、基于频域参考跳空的SIMO-OFDM系统物理层安全方法。每个符号周期,发送端随机选择合法用户天线,使用多个参考子载波带来的冗余向选中天线传递随机参考变量,同时对非选中天线形成零陷,所选天线与参考变量共同组成跳空图案。然后,各数据子载波根据跳空图案对调制符号进行随机加权,合法用户从参考子载波获取跳空图案并正确解调,从而实现跳空传输。窃听者无法获取跳空图案,从而无法跟踪建立稳定信道用于窃听。理论分析和仿真结果表明:窃听者无法通过差分译码及盲解调方法实现窃听,BPSK调制的情况下,其误码率接近0.5。3、基于信息导向跳空的MIMO系统物理层安全方法。保密信息分为信号调制符号(RMS)和信道调制符号(CMS)两部分,使用跳空集合中各等效空域信道的差异性调制CMS,根据CMS选择等效空域信道发送RMS。CMS将信息保密性与跳空图案保密性相结合,起到同时传输保密信息和生成跳空图案的作用。理论分析和仿真结果表明,窃听者无法跟踪跳空过程,从而无法实现窃听;而由于跳空过程承载了一部分保密信息,主信道传输速率得到提高,信噪比为10dB的情况下,传输速率提高了0.5bit/s/Hz。
[Abstract]:Air-hop communication is a kind of physical layer security technology which increases the difficulty for eavesdroppers to obtain information by switching spatial transceiver channels at random. At present, there are two main problems in the air-hopping communication technology: 1) the existing air-hopping communication all rely on the pre-negotiated air-hopping pattern to switch the space-domain transceiver channel, and the air-hopping pattern has the risk of leakage. Due to the fast switching between the good and bad equivalent airspace channels, the information transmission rate is low. In order to solve the above problems, this paper, relying on the project of National Natural Science Foundation, studies the secure air-hopping communication technology in the physical layer based on pattern hiding. In this paper, we first establish a pattern-hiding-based hopping communication model. Under the guidance of the model, a physical layer security mechanism based on time-domain difference hopping is proposed for MIMO systems, and its implementation method in MIMO single-user and multi-user scenarios is given. A physical layer security method based on frequency domain reference hopping is proposed, and a physical layer security method based on information guidance is proposed to solve the problem of low transmission rate of MIMO air-hopping system based on pattern hiding. The specific research content includes: 1, MIMO system physical layer security mechanism based on time domain difference space hopping. By adding artificial interference to the transmitted signal, the spatial domain signal received by the legitimate user is changed at random, and the airspace signal received by the legitimate user at the last moment is used as the receiving weight vector of the legitimate user at the current time. The equivalent transceiver channel is obtained by combining with the main channel, and the random hopping is realized. Because of the difference between primary channel and eavesdropping channel and the randomness of equivalent channel distribution, eavesdroppers can not track the hopping process, so they can not achieve eavesdropping by interference suppression method. For MIMO single-user and multi-user scenarios, random and fast spatial received signals are obtained by transmitting artificial noise and multi-user interference in the null space of the equivalent channel, respectively. The physical layer security method of SIMO-OFDM system based on frequency-domain reference hopping is implemented. For each symbol period, the sender randomly selects the legitimate user antenna, transmits random reference variables to the selected antenna using redundancy brought by multiple reference subcarriers, and forms a null trap on the unselected antenna. The selected antenna and the reference variables together form an empty pattern. Then, each data subcarrier carries on the random weight to the modulation symbol according to the hopping pattern, the legitimate user acquires the hopping pattern from the reference subcarrier and demodulates correctly, thus realizes the hopping transmission. Eavesdroppers can't get hopping patterns, so they can't track and establish stable channels for eavesdropping. Theoretical analysis and simulation results show that eavesdroppers can not achieve BPSK modulation by differential decoding and blind demodulation, and the BER is close to 0.5.3. The physical layer security method of MIMO system based on information oriented hopping is proposed. The secret information is divided into two parts: signal modulation symbol (RMS) and channel modulation symbol (CMS). The CMSs are modulated by the difference of each equivalent spatial channel in the empting-hopping set, and the RMS.CMS is sent according to the CSS-selected equivalent airspace channel, which combines the information secrecy with the air-hopping pattern secrecy, which plays the role of transmitting the secret information and generating the empty hopping pattern simultaneously. Theoretical analysis and simulation results show that the eavesdropper can not track the hopping process, so that the eavesdropping can not be realized. However, the transmission rate of the main channel is improved and the signal-to-noise ratio (SNR) is 10dB because the hopping process carries part of the secret information. The transmission rate increased by 0.5 bits / s / Hz.
【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】：TN918

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