A new scheme of digital communication using chaotic signals in MIMO channels

This paper proposes a new digital communication scheme,which uses chaotic signals based on the adaptive synchronization and parameter identification technique of chaotic systems reported recently.Due to the multi signal character,this scheme combines the chaotic signal transmission with the MIMO channel technique in a wireless environment,which is different from the traditional chaotic communication frameworks.From a practical perspective,an outline of modulation,channel model,demodulation and non-coherent detection is investigated.Furthermore,system performance is evaluated by simulations,and improvements on this scheme are also discussed.     

Information theoretic conditions for tracking in leader-follower systems with communication constraints

In this paper, we introduce a general framework for tracking in leader-follower systems under communication constraints, in which the leader and follower systems as well as the corresponding controllers are spatially distributed and connected over communication links. We provide necessary conditions on the channel data rate of each communication link for tracking of the leader-follower systems. By considering the forward and feedback channels as one cascade channel, we also provide a lower bound for the data rate of the cascade channel for the system to track a reference signal such that the tracking error has finite second moment. Examples and simulations are provided to demonstrate some of the results.     

动态交通分配与信号控制的组合模型及算法研究

This paper presents a generalized bi-level programming model of combined dynamic traffic assignment and traffic signal control, and especially analyzes a procedure for determining the equilibrium queuing delays on saturated links for dynamic network signal control satisfying the FIFO (first-in-first-out) rule. The chaotic optimal algorithm proposed in this paper can not only present the optimal signal settings, but also calculate, at each interval, the link inflow rates and outflow rates for the dynamic user optimal problem, and provide real-time information for the travelers. Finally, a numerical example is given to illustrate the application of the proposed model and solution algorithm, and comparison shows that this model has better system performance.     

Research on Combined Dynamic Traffic Assignment and Signal Control

This paper presents a generalized bi-level programming model of combined dynamic traffic assignment and traffic signal control,and especially analyzes a procedure for determining the equilibrium queuing delays on saturated links for dynamic network signal control satisfying the FIFO (first-in-first-out)rule.The chaotic optimal algorithm proposed in this paper can not only present the optimal signal settings,but also calculate,at each interval,the link inflow rates and outflow rates for the dynamic user optimal problem,and provide real-time information for the travelers.Finally,a numerical example is given to illustrate the application of the proposed model and solution algorithm, and comparison shows that this model has better system performance.     

Encrypted Finite-Horizon Energy-to-Peak State Estimation for Time-Varying Systems Under Eavesdropping Attacks: Tackling Secrecy Capacity

This paper is concerned with the problem of finitehorizon energy-to-peak state estimation for a class of networked linear time-varying systems.Due to the inherent vulnerability of network-based communication,the measurement signals transmitted over a communication network might be intercepted by potential eavesdroppers.To avoid information leakage,by resorting to an artificial-noise-assisted method,we develop a novel encryption-decryption scheme to ensure that the transmitted signal is composed ...     

Space-time coding and signal processing for MIMO communications

Rapid growth in mobile computing and other wireless multimedia services is inspiring many research and development activities on high-speed wireless communication systems.Main challenges in this area include the development of efficient coding and modulation signal processing techniques for improving the quality and spectral efficiency of wireless systems.The recently emerged space-time coding and signal processing techniques for wireless communication systems employing multiple transmit and receive antennas offer a powerful paradigm for meeting these challenges.This paper provides an overview on the recent development in space-time coding and signal processing techniques for multiple-input multiple-output (MIMO) communication systems.We first review the information theoretic results on the capacities of wireless systems employing multiple transmit and receive antennas.We then describe two representative categoriesof space-time systems,namely,the BLAST system and the space-time block coding system,both of which have been proposed for next-generation high-speed wireless system.Signal processing techniques for channel estimation and decoding in space-time systems are also discussed. Finally,some other coding and signal processing techniques for wireless systems employing multiple transmit and receive antennas that are currently under intensive research are also briefly touched upon.     

Application research on the chaos synchro-nization self-maintenance characteristic to secret communication

Chua's circuit, which is improved to integrate conveniently, is presented. A drive-response chaotic synchronization system is constructed, which possesses a certain stability, resisting-disturbance, and so on. By means of research, it can be concluded that the chaotic synchronization system is provided with the character- istic of chaos synchronization self-maintenance. Utilizing the characteristic, the critical problem of how to simultaneously transmit the controlling signal of chaotic synchronization and the secret signal at a channel can be solved, and that a prac- tical experiment validates the method; as a result, the research in the paper pro- vides the foundation of putting chaos into practice application to secret commu- nication.     

Call for papers Special issue on Learning and control in cooperative multi-agent systems

Cooperative control of multi-agent systems linked by communication networks is a well-developed and still growing field. The interplay of the individual agent dynamics and the communication graph topology results in intriguing and often surprising behaviors that are not manifested in the study of control systems for single-agent dynamics. This field brings systems theory, feedback control, graph theory, communication systems, complex systems theory to provide rigorous analysis and design for multiple dynamical systems interconnected by a graph information flow structure. Applications have been made to vehicle formation control, coordinated multi-satellite control, electric power system control, robotics, autonomous airborne systems, manufacturing production lines, and the synchronization of dynamical processes in chemistry, physics, biology, and chaotic systems.     

Set-Membership Filtering Approach to Dynamic Event-Triggered Fault Estimation for a Class of Nonlinear Time-Varying Complex Networks

The present study addresses the problem of fault estimation for a specific class of nonlinear time-varying complex networks, utilizing an unknown-input-observer approach within the framework of dynamic event-triggered mechanism(DETM).In order to optimize communication resource utilization, the DETM is employed to determine whether the current measurement data should be transmitted to the estimator or not. To guarantee a satisfactory estimation performance for the fault signal,an unknown-input-ob...     

Unified Smith Predictor Based H∞ Wide-Area Damping Controller to Improve the Control Resiliency to Communication Failure

Inter-area low frequency oscillation in power system is one of the major problems for bulk power transmission through weak tie lines.Use of wide-area signal is more effective than the local area signal in damping out the inter-area oscillations.Wide area measurement system(WAMS)is convenient to transmit the wide area signal through the communication channel to the remote location.Communication failure is one of the disastrous phenomena in a communication channel.In this paper,a dual input single output(DISO)Hm controller is designed to build the control resiliency by employing two highest observability ranking wide area signals with respect to the critical damping inter-area mode.The proposed controller can provide sufficient damping to the system and also the system remains stabilized if one of the wide-area signals is lost.The time delay is an unwanted phenomenon that degrades the performance of the controllers.The unified Smith predictor approach is used to design a Hm controller to handle the time delay.Kundur's two-area and IEEE-39 bus test systems are considered to verify the effectiveness of the proposed controller.From the simulation results,it is verified that,the proposed controller provides excellent damping performance at normal communication and improves the controller resiliency to counteract the communication failure.     

Digital secure communication via chaotic systems

This paper presents a novel secure communication system for digital signal transmissions. It contains four important parts: modulation, chaotic transmitter, chaotic receiver, and demodulation. The modulation mechanism is to modulate each of delivered bit information to be a carrier signal in the continuous form. Then this carrier signal is taken as a parameter of the chaotic system, called the unified chaotic system. Such a system possesses three different types of chaos characterizations depending on its system's parameter, and this guarantees the communication security more. In the public channel, only three chaotic state variables are delivered and this means that the important carrier information is efficiently screened. According to chaotic states received in the receiver terminal, the continuous carrier signal is decrypted using certain adaptation mechanisms. Finally, the proposed demodulation method can successfully recover the original bit information which is embedded in the communication systems. Some simulation results are provided to verify the efficiency of the proposed secure communication system.     

用时域补偿实现混沌同步的方法

利用时间连续的混沌系统进行保密通信时,停产中传输的是宽带的混沌信号,由于实际的停产总是带限的,这就大在的限制了混沌在通信中的应用。一种改进的方法是在发射端用波波器滤去混沌信号的高频部分,只传输低频部分。而在接收产端用本地产生的混汪信号的高频部分来补偿接收到的信号作为接收端混沌系统的驱动信号。文中提出的方法是在发射端对要发射的混沌信号进行采样,只传输这些时间离散的采样值。在接收端则用本地产生的采样时     

基于系统重构的混沌保密通信系统的信息检取

在仅能得到混沌发送信号并能获得足够多未加通信信息的发送信号的情况下，分别对通信信息调制入和未调制入混沌发送系统的两类混沌保密通信系统进行研究。首先用发送信号进行系统重构，然后用重构系统以及未加通信信息的重构点为领域对加有通信信息的发送信号进行一下步预测。文中推导出发送信号、预测信号之差与通信信息之间的关系，并从发送信号中直接提取通信信号。以Ｌｏｒｅｎｚ系统为例说明本文结论。     

语音混沌掩盖保密通信系统研究与实现

本文在DSP平台上构建了实时语音混沌掩盖保密通信系统。首先通过分析混沌掩盖信号和语音信号的功率谱,研究了安全性,从而给出了低通滤波器和放大器相结合的方法,产生适用于混沌掩盖的信号。其次针对DSP系统发送端和接收端的同步误差积累导致失步问题,给出周期强制同步方法,使同步误差被控制在峰-峰值100mV～250mV的范围内。实现了基于Lorenz系统的语音混沌掩盖保密通信,通信的语音质量基本满足要求。     

基于DSP Builder的混沌保密通信的研究与实现

采用DSP Builder开发工具,利用混沌信号实现对通信数字信号的加密与解密.首先在Simulink中建立系统通信模型,采用FM对混沌信号进行差分键控形成FM-DCSK信号,然后用数字信号控制FM-DCSK信号,形成调制信号,并在接收端进行信号恢复,然后进行仿真,生成硬件描述语言下载到系统板,实现混沌保密通信.     

基于多涡卷混沌系统的数字保密通信方案

为增强传统的混沌保密通信系统抗干扰能力和提高其保密性,提出了一种基于多涡卷混沌系统同步的数字保密通信方案.在该加密方案中,利用多涡卷混沌系统的特点来构造流密码.数值模拟结果表明:该保密通信系统具有很高的抗差函数攻击能力,在同步信号被干扰时,保密通信系统具有一定的抗误码率.     

多层异构蜂窝网络混沌通信载波衰减仿真

为了最大程度的了解多层异构蜂窝网络混沌通信载波的特性和衰减规律,从而提升分析结果的准确性,提出多层异构蜂窝网络混沌通信载波衰减分析方法。分析获得多层异构蜂窝网络的拓扑结构与混沌通信的流程,融合KlausDostert与ManfredZimmermann理论,得到多径效应,并构建多径模型,运用该模型对混沌通信载波进行分析,得出不同的路径内信号衰减的规律性。在此基础上构建FIR滤波器,采用FIR滤波器将多径衰减和信号延时组合,进而得到映射信号幅值的特性。构建自回归滑动平均模型,通过该模型映射混沌通信载波的衰减特性。仿真结果证明,分析得到了通信载波的特性与衰减规律,拥有良好的信道时变性,能够更有效的对多层异构网络通信起到保密作用。     

基于改进混沌扩频序列的多用户混沌扩频通信系统的研究与仿真

提出一种改进混沌扩频序列,并将其应用在多用户混沌扩频通信系统中,给出了多用户混沌扩频通信系统的理论推导和SIMULINK仿真模型。对该系统进行了详细的性能分析,包括信噪比、用户数、改进混沌扩频序列的分形参数和初始值等各自对系统误码率的影响,并比较了改进混沌扩频序列与传统混沌扩频序列的系统误码率随信噪比和用户数的变化情况。结果表明改进混沌扩频序列要好于传统混沌扩频序列的系统误码率,具有较好的抗噪声和抗多址干扰的能力。     

基于混沌调制技术的卫星隐蔽通信性能分析

针对利用传统DS扩频技术实现的卫星隐蔽通信易被截获的情况,利用混沌信号的特性,提出了一种基于相干混沌移位键控信号的卫星隐蔽通信方案.采用离散基带模型阐述了系统原理并分析了其隐蔽性能、抗干扰性能,然后通过建立基于混沌调制技术的卫星隐蔽通信仿真模型进行性能仿真.仿真结果表明,使用相干混沌移位键控信号完成卫星隐蔽通信同样可以具有较好的隐蔽性和抗干扰性,方案的提出对基于混沌调制技术的卫星隐蔽通信提供了理论支持.