高速多量子阱激光器混沌保密通信系统研究

研究了外部光注入高速多量子阱激光器激光混沌全光保密通信系统,导出系统同步方程,理论证明并数值实现了系统的同步,分析了增加反馈系数以缩短同步时间且增强系统同步稳定性的方法。研究分析了多量子阱激光器混沌隐藏和混沌键控保密通信全光调制解调系统模型,数值模拟了具有正弦调制信号的调制频率0．2GHz混沌模拟保密通信和数字信号调制速率20Gb／s的混沌数字保密通信以及调制速率0．05Gb／s混沌键控保密通信的应用,系统确实具有较高的保密性能和反破译能力;分析了混沌数字信号保密通信调制带宽20Gb／s调制解调时的同步误差以及混沌键控调制速率,系统都具有非常好的调制解调特性,且在高速混沌通信中,系统解调具有相对较小的同步误差,而1Gb／s是混沌键控通信的速率上限。     

A novel algorithm to analyze the dynamics of digital chaotic maps in finite-precision domain

Chaotic maps are widely used to design pseudo-random sequence generators, chaotic ciphers, and secure communication systems. Nevertheless, the dynamic characteristics of digital chaos in finite-precision domain must be degraded in varying degrees due to the limited calculation accuracy of hardware equipment. To assess the dynamic properties of digital chaos, we design a periodic cycle location algorithm (PCLA) from a new perspective to analyze the dynamic degradation of digital chaos. The PCLA can divide the state-mapping graph of digital chaos into several connected subgraphs for the purpose of locating all fixed points and periodic limit cycles contained in a digital chaotic map. To test the versatility and availability of our proposed algorithm, the periodic distribution and security of 1-D logistic maps and 2-D Baker maps are analyzed in detail. Moreover, this algorithm is helpful to the design of anti-degradation algorithms for digital chaotic dynamics. These related studies can promote the application of chaos in engineering practice.     

一种基于强跟踪滤波的混沌保密通信方法

提出了一种基于强跟踪滤波器的混沌保密通信方法. 在发送端, 混沌映射和信息符号被建模成非线性状态空间模型, 信息符号被加性混沌掩盖或乘性混沌掩盖调制, 然后通过信道输出. 在接收端, 驱动信号被接收, 使用带有贝叶斯分类器(信息符号估计)的强跟踪滤波器算法动态地恢复信息符号. Logistic混沌映射的仿真表明, 当信息符号为二进制编码时, 不管是加性混沌掩盖调制还是乘性混沌掩盖调制, 强跟踪滤波器均能较好地从混沌信号中恢复信息符号. 与扩展卡尔曼滤波器相比, 由于卡尔曼滤波器对于离散的信息符号跟踪能力差, 混沌映射中信息符号难以恢复, 比特误码率高. 因此, 这种基于强跟踪滤波器的混沌保密通信方法是有效的.     

自调频混沌系统及其调频码耦合同步

提出了一个闭环自调频混沌系统, 对压控振荡器输出进行采样, 采样值经非线性变换后产生控制压控振荡器下一时刻频率的调频码. 利用一维分岔图、二维分岔图和Lyapunov指数等研究了该系统的动力学行为; 并利用峰值均值功率比、频谱以及输出信号的相关函数等分析了该系统的应用特性. 研究表明, 该系统有复杂的动力行为, 展现分岔、多稳态和混沌等现象, 产生的信号具有低峰值均值功率比和宽频带的特性. 同时还讨论了利用调频码实现系统同步的可能性, 证实了简单的控制器可以实现自调频系统的同步. 在电路实验中, 压控振荡器用数字频率合成技术实现, 实验结果与理论分析一致. 关键词： 混沌 多稳态 峰值均值功率比 同步     

Chaos communication based on synchronization of discrete-time chaotic systems

A novel chaos communication method is proposed based on synchronization of discrete-time chaotic systems. This method uses a full-order state observer to achieve synchronization and secure communication between the transmitter and the receiver. Further, we present a multiple-access chaotic digital communication method by combining the observer with the on-line least square method. Simulation results are also given for illustration.     

Efficient Quantum Private Communication Based on Dynamic Control Code Sequence

Based on chaos and quantum properties, we propose a quantum private communication scheme with dynamic control code sequence. The initial sequence is obtained via chaotic systems, and the control code sequence is derived by grouping, XOR and extracting. A shift cycle algorithm is designed to enable the dynamic change of control code sequence. Analysis shows that transmission efficiency could reach 100 % with high dynamics and security.     

An Error Compensation Method for Improving the Properties of a Digital Henon Map Based on the Generalized Mean Value Theorem of Differentiation

Continuous chaos may collapse in the digital world. This study proposes a method of error compensation for a two-dimensional digital system based on the generalized mean value theorem of differentiation that can restore the fundamental performance of chaotic systems. Different from other methods, the compensation sequence of our method comes from the chaotic system itself and can be applied to higher-dimensional digital chaotic systems. The experimental results show that the improved system is highly consistent with the real chaotic system, and it has excellent chaotic characteristics such as high complexity, randomness, and ergodicity.     

基于现场可编程门阵列技术的混沌数字通信系统——设计与实现

提出了基于IEEE-754标准和现场可编程门阵列(FPGA)技术的混沌数字通信系统的通用设计与硬件实现的一种新方法,实现了混沌加密体制与传统密码体制的结合.根据Euler算法,对连续混沌系统作离散化处理,通过FPGA硬件设计混沌离散系统,使其产生作为密钥的混沌数字序列,其中加密算法采用置乱扩展技术,并对算法进行了分析.设计驱动响应式同步保密通信系统,构建包含信号在内的闭环,实现发送端与接收端离散混沌系统的同步.以网格蔡氏混沌系统为例,对该保密通信系统进行了FPGA硬件实验,给出了技术实现过程、算法流程、硬 关键词： 网格多涡卷蔡氏电路 置乱扩展矩阵 现场可编程门阵列技术 混沌数字通信系统     

Periodic locking of chaos in semiconductor lasers with optical feedback

We show how a chaotic system can be locked to emit a periodic waveform belonging to its chaotic attractor. We numerically demonstrate our idea in a system composed of a semiconductor laser driven to chaos by optical feedback from an external cavity. The clue is the injection of an appropriate periodic signal that modulates the phase and amplitude of the intra-cavity radiation, a chaotic analogy of conventional mode-locking. The result is a time process that manifests a chaotic signature embedded in a long-scale periodic train.     

一种基于混沌系统部分序列参数辨识的混沌保密通信方法

本文提出一种混沌保密通信方法,即混沌系统的部分序列用于混沌系统参数辨识其他序列用于通信保密.利用混沌蚁群优化算法对部分序列混沌系统进行参数辨识,以达到了解混沌系统全部信息的目的.在参数辨识过程中引入参数空间和蚁群空间,通过空间变换函数使参数空间与蚁群空间之间相互变换.文中使用Lorenz系统进行数值试验,其结果验证混沌系统部分序列参数辨识及混沌保密通信的可行性.     

Chaotic digital communication by encoding initial conditions

We investigate the possibility to improve the noise performance of a chaotic digital communication scheme by utilizing further dynamical information. We show that by encoding the initial information of the chaotic carrier according to the transmitting bits, extra redundance can be introduced into the segments of chaotic signals corresponding to the consecutive bits. Such redundant information can be exploited effectively at the receiver end to improve the noise performance of the system. Compared to other methods (e.g., differential chaos shift keying), straightforward application of the proposed modulation/demodulation scheme already provides significant performance gain in the low signal-to-noise ratio (SNR) region. Furthermore, maximum likelihood precleaning procedure based on the Viterbi algorithm can be applied before the demodulation step to overcome the performance degradation in the high SNR region. The study indicates that it is possible to improve the noise performance of the chaotic digital communication scheme if further dynamics information is added to the system.     

Digital transmission for improved synchronization of analog chaos generators in communications systems

We present a method for synchronization of chaos generators based on transmission of an analog chaotic waveform in a digital form. Experimental comparisons between digital and analog transmission of chaos from a delayed differential feedback system are performed. Synchronization is demonstrated to be between 18 and 39 dB (or equivalently 63 to 7943 times) better for digital transmission than analog. Coherent chaotic modulation and demodulation is demonstrated in a situation where there is no effective synchronization using analog transmission.     

光纤混沌相位编码保密通信系统理论研究

通过耦合激光混沌相位控制同步系统和光纤信道，提出外部光注入半导体激光器激光混沌相 位控制光纤同步以及混沌相位相移键控外调制光纤保密通信系统理论模型，数值实现了在相 位控制器控制下的远程光纤混沌同步.理论分析了光纤自相位调制对混沌信号以及对同步的 影响，导出了光纤混沌最大传输距离公式.通过连续键控调制相位控制器实现了光纤激光混 沌相位相移键控编码调制发射，设置接收系统相位控制器控制激光相位相移实现了光纤激光 混沌同步解调.数值模拟了具有比特率50Mbit/s远程光纤混沌数字编码通信系统的应用，详 细地进行了在远距离光纤传输中的系统参数失配以及系统抗噪声能力的数值分析. 关键词： 混沌 同步 光纤混沌通信 半导体激光器 相位     

利用时空混沌同步进行数字加密通信

提出一种利用时空混沌同步的计算机网络数字加密通信方案,并用软件实现了语音双工实时密码通信.在该方案中,收、发端两个单向耦合映射格点(OCOML)系统被同一混沌信号所驱动而达到同步,其时空混沌输出信号分别用作加密和解密的密钥序列,OCOML的耦合参数为系统的主密钥.系统的主要优点是传输效率高,便于用软件实现实时通信,且通信的安全性获得了改善. 关键词： 时空混沌同步 密码系统 传输效率     

面向全光物理随机数发生器的混沌实时光采样研究

基于混沌激光实现全光物理随机数发生器的物理基础是完成对混沌光信号的高速实时全光采样. 本文利用偏振无关的SOA构建出TOAD全光采样门, 以光反馈半导体激光器产生混沌激光, 对混沌激光的全光采样可行性进行了原理性实验论证, 实现了对光反馈半导体激光器产生的6.4 GHz带宽的混沌激光5 GSa/s的实时、高保真全光采样. 进一步研究显示, 光采样周期与外腔反馈时间成比例与否对混沌信号弱周期性的抑制水平影响显著. 当两者不成比例时, 可有效消除原始混沌信号的弱周期性, 有利于高质量物理随机数的产生.     

激光器自发辐射噪声对混沌光通信系统的影响

构建了基于外光反馈的混沌光通信系统模型, 通过引入Langevin噪声源, 建立了包含自发辐射噪声特性的主从式速率方程. 利用所得数学模型, 研究了系统中可能存在的两类同步:全混沌同步和普通注入锁模型混沌同步; 分析了两端激光器自发辐射噪声对此二类同步以及系统收发两端混沌信号的影响; 最后,以2.5Gb/s伪随机数字调制下的混沌掩蔽方式为例,介绍了系统的加/解密过程以及噪声对系统解码性能的影响. 关键词： 混沌光通信 外光反馈 光注入 混沌同步 自发辐射噪声     

基于FPGA技术的混沌加密系统研究

提出了一种基于混沌加密算法和传统加密算法的混沌加密系统, 并采用FPGA技术进行了硬件开发. 根据离散化和数字化技术, 将Henon映射和Logistic映射作离散化处理, 采用Verilog HDL语言和FPGA技术产生迭代序列, 结合传统加密算法, 基于Xilinx的FPGA开发平台进行了硬件实验研究, 并给出了该系统通过互联网上实现了文件加密和解密的通信实验, 结果显示具有网络通信的应用潜力.     

Chaos synchronization and communication of the polarization modes for two unidirectionally coupled vertical-cavity surface-emitting lasers

We theoretically investigate the synchronization performance of the polarization modes of two unidirectionally coupled vertical-cavity surface-emitting lasers (VCSELs), where the master VCSEL subjects to polarization-preserved optical feedback and the slave VCSEL subjects to polarization-preserved optical injection. We demonstrate that high synchronization can be achieved between corresponding polarization components of the master laser and the slave laser. We also analyze the influence of the internal mismatched parameters on the synchronization performance. Furthermore, this system is used to dual-channel communication and the different transmitted digital information is respectively recovered at each polarization branch of the slaver laser successfully with the encryption scheme of chaos masking (CM). The results open an opportunity for multichannel chaotic communication by utilizing different polarization components in single-mode or multi-transverse-mode VCSELs.     

Effect of transmission fiber and amplifier noise on optical chaos synchronization

Optical chaos propagation has few constraints peculiar to itself which do not become as significant in conventional nonchaotic optical communication. We have investigated the effects of transmission fiber nonlinearities, dispersion and noise of erbium doped fiber amplifier (EDFA) on chaotic signal synchronization in lumped and distributed configuration. It is found that the effects of fiber dispersion can be easily compensated; however, the effects of fiber nonlinearity on chaos cannot be overdone and must be avoided. Three distinct configurations with different combinations of standard telecommunication fiber, dispersion compensation fiber and lumped and distributed EDF for amplification are analysed. The results are compared in terms of sync diagrams and noise figure. The chaos after propagation through distributed amplification performs better as compared to lumped amplification. Also, a new quantitative measure for the calculation of deviation in sync diagram of chaos is introduced.     

基于半导体环形激光器的高速双向双信道混沌保密通信

提出了一种利用半导体环形激光器(SRLs)的新型高速双向、双信道混沌保密通信系统. 在该系统中, 首先利用交叉双光反馈对驱动激光器的顺时针模式和逆时针模式的混沌延时特征进行抑制. 然后将此混沌信号注入到一对响应激光器对应的顺时针模和逆时针模中, 以实现带宽的增强及混沌同步. 最后基于响应激光器之间的混沌同步, 实现高速率、双向、双信道的混沌保密通信. 通过对驱动激光器在交叉双光反馈作用下的混沌特性、以及响应激光器在不同条件下的同步特性进行了相关理论和仿真研究, 结果表明: 驱动激光器在合适的交叉双光反馈作用下可以产生延时特性被良好隐藏的顺时针模式和逆时针模式混沌信号; 在该混沌信号的注入下, 响应激光器输出的混沌信号带宽可以得到明显增强; 通过设置合适注入强度值和频率失谐值, 响应激光器之间可实现高质量的等时混沌同步. 最后, 对系统的双向、双信道混沌保密通信特性进行了讨论. 当10 Gbit/s信号传输距离为10 km时, 解调信息Q因子值仍可保持在6以上.