MIMO系统灵巧式干扰技术研究

发布时间：2018-11-25 17:49

【摘要】：近年来,随着军事思想和通信体制的不断发展与变革,通信干扰的作用显得越来越重要。多输入多输出(MIMO)系统由于具有高频谱利用率、大容量等特点,已被广泛地应用于军事和民用领域。针对MIMO系统的干扰,传统干扰手段大多是基于在目标信号所在的载频范围内添加噪声等方式,虽仍然有效,但其固有的干扰功率大、不利于隐蔽、无法持续干扰等缺点限制了其应用场景和范围。而且,随着近年来抗干扰技术的不断发展,也给干扰带来了极大的挑战。灵巧式干扰是通过采用较低的干扰功率在隐蔽自身的前提下,针对某一通信系统的特点设法扰乱其数字信号传输的某一关键环节。因此,针对MIMO系统的灵巧式干扰就具有巨大的应用前景。本文主要围绕MIMO系统灵巧式干扰开展了一系列探索性研究。首先,对MIMO系统的特点进行了分析,并介绍了常用的同步以及信道估计算法,为后续分析灵巧式干扰对同步以及信道估计的影响奠定了基础。然后,分析了基于导频置零的信道估计干扰策略以及训练序列置零的同步干扰策略。为了进一步减少上述干扰策略对于信道等先验信息的要求,提出一种性能折中的改进型信道估计干扰策略。该策略首先需要侦听机识别出目标信号的导频,通过对导频重构并发送以达到导频污染的目的,进而导致合作接收机的信道估计出现错误。仿真结果表明,该策略在低干信比条件下具有良好的干扰效果。为了克服干扰信号与目标信号之间相对时延差对干扰效果的影响,提出一种同步欺骗式干扰策略。该策略通过在合作接收端的同步过程中构造虚假相关峰值,从而达到欺骗同步的目的。仿真结果表明,该策略能利用相对时延差这一不利因素,在干信比为0dB以上时具有较好的干扰效果。最后,为了给干扰机在天线数目的选择上提供参考,提出了一种基于改进型盖尔圆的天线数目盲估计算法,保证了在低信噪比条件下良好的估计性能。出于降低在干扰信号构造过程中对帧参等先验信息要求的目的,探讨了一种基于二阶统计量的干扰信号构造策略。该策略首先构造干扰信号的二阶统计量,进而根据二阶统计量进行干扰信号的构造。从而可以实现以较低的干扰功率实施有效的干扰。仿真结果表明,该策略可以在进一步降低干扰信号对帧参等先验信息要求的基础上获得较好的干扰效果。
[Abstract]:In recent years, with the development and reform of military thought and communication system, communication interference is becoming more and more important. Multi-input multiple-output (MIMO) systems have been widely used in military and civilian fields due to their high spectral efficiency and large capacity. For the interference of MIMO system, most of the traditional jamming methods are based on adding noise in the carrier frequency range of the target signal. Although it is still effective, its inherent interference power is large, which is not conducive to concealment. Its application scenarios and scope are limited by its disadvantages such as unsustainable interference and so on. Moreover, with the continuous development of anti-jamming technology in recent years, it also brings great challenges to interference. Dexterous interference is a key part of digital signal transmission which is disturbed by using low interference power and hiding itself according to the characteristics of a communication system. Therefore, the dexterous interference for MIMO system has a great application prospect. In this paper, a series of exploratory researches are carried out around the dexterous interference of MIMO system. Firstly, the characteristics of MIMO system are analyzed, and the commonly used synchronization and channel estimation algorithms are introduced, which lays a foundation for the subsequent analysis of the influence of dexterous interference on synchronization and channel estimation. Then, the channel estimation interference strategy based on pilot zero and the synchronization jamming strategy of training sequence zeroing are analyzed. In order to further reduce the need for prior information such as channel, a performance compromise improved channel estimation interference strategy is proposed. The strategy first requires the listener to identify the pilot of the target signal. By reconstructing the pilot frequency and transmitting it to achieve the purpose of pilot pollution, the channel estimation error of the cooperative receiver will occur. The simulation results show that the strategy has good interference effect under the condition of low signal-to-interference ratio. In order to overcome the influence of the relative delay difference between the jamming signal and the target signal on the jamming effect, a synchronous deception jamming strategy is proposed. The strategy constructs false correlation peaks in the synchronization process of the cooperative receiver, so as to achieve the purpose of spoofing synchronization. The simulation results show that the strategy can take advantage of the unfavorable factor of relative delay difference and has a better jamming effect when the ratio of signal to interference is above 0dB. Finally, in order to provide a reference for the selection of the number of antennas of the jammer, an improved algorithm for blind estimation of antenna numbers based on the improved Gaelic circle is proposed, which ensures a good estimation performance under the condition of low signal-to-noise ratio (SNR). In order to reduce the requirement of a priori information such as frame parameters in the construction of interference signals, a strategy of constructing interference signals based on second-order statistics is discussed. Firstly, the second order statistics of the interference signal are constructed, and then the second order statistics are used to construct the interference signal. Thus, the effective interference can be implemented with lower interference power. Simulation results show that the proposed strategy can achieve better interference effect on the basis of further reducing the requirement of prior information such as frame parameters.
【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN919.3

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