基于一种混沌同步方法的多进制数字信息通信方案

本文利用基于线性系统稳定性准则的SC混沌比例投影同步方法,提出一种全新的多进制数字信息混沌保密通信方案.将多进制数字信号调制到发送端系统的雅克比矩阵和比例因子中,然后在接收端构造的子系统中判断并解调出数字信号.以传输10进制数字信息为例,利用Lorenz混沌吸引子进行数值模拟仿真,详细分析了通信过程中数字信息的同步性、安全性以及解码精度.仿真结果和数值分析证明了该多进制数字信息混沌调制方案的正确性和有效性.     

基于MIMO技术的DCSK通信方案的性能分析

MIMO技术在不增加信号带宽和发射功率的情况下,通过在发送端和接收端分别使用多个发送天线和接收天线来抑制信道衰落和噪声。利用MIMO技术的优势,设计了一种基于差分混沌键控（DCSK）的MIMO-DCSK混沌通信方案。针对这一方案,通过进一步的数学推导,得到系统在高斯信道下的理论误码率公式,并在MATLAB环境中进行了仿真验证。理论分析和仿真结果表明：在相同的信噪比条件下,MIMO-DCSK混沌通信系统的误码率比传统DCSK通信系统要小得多。因此,MIMO-DCSK混沌通信方案能够有效改善混沌通信系统的误码性能。     

用户多中继两跳MIMO系统中的容量分析

针对多中继MIMO无线通信系统,分析了多中继纯两跳情况下的中继处理方法,并将单中继多用户系统中的中继处理技术推广到多中继情况,同时应用脏纸编码算法,分别得到了两种中继处理技术下的信道容量,最后对它们的性能进行了仿真和比较。     

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.     

A chaotic communication system of improved performance based on the Derivative-free nonlinear Kalman filter

The Derivative-free nonlinear Kalman Filter is used for developing a communication system that is based on a chaotic modulator such as the Duffing system. In the transmitter’s side, the source of information undergoes modulation (encryption) in which a chaotic signal generated by the Duffing system is the carrier. The modulated signal is transmitted through a communication channel and at the receiver’s side demodulation takes place, after exploiting the estimation provided about the state vector of the chaotic oscillator by the Derivative-free nonlinear Kalman Filter. Evaluation tests confirm that the proposed filtering method has improved performance over the Extended Kalman Filter and reduces significantly the rate of transmission errors. Moreover, it is shown that the proposed Derivative-free nonlinear Kalman Filter can work within a dual Kalman Filtering scheme, for performing simultaneously transmitter–receiver synchronisation and estimation of unknown coefficients of the communication channel.     

宽带MIMO信道下的并行干扰抵消接收机

基于数据块传输模型,将窄带MIMO并行干扰抵消接收机推广到宽带MIMO信道,在理想信道和信道估计下,通过仿真评估了所提出的宽带MIMO并行干扰抵消接收机的性能。仿真结果表明：所建议的方案在宽带MIMO信道下的性能好于窄带MIMO信道下的性能,在宽带MIMO信道下,接收机可获得比窄带下更大的分集增益。     

一个基于广义混沌同步系统的数字水印算法

混沌同步的发现为有关混沌的保密通讯研究提供了新的拓广空间。根据广义混沌同步的基本理论构建了一个新的广义混沌同步系统(GCS);利用GCS,提出了一个基于小波变换的鲁棒性数字水印算法。数值模拟实例对该文的理论结果进行了验证,理论分析及实验结果表明,给出的数字水印算法对常用的图像处理方法有较好的鲁棒性。     

无信号间干扰的相关延迟-差分混沌移位键控混沌通信方案

现有的差分混沌移位键控（DCSK）通信系统主要的缺陷是传输速率较低，为此提出了一种无信号间干扰的相关延迟-差分混沌移位键控（CD-DCSK）通信方案。在发送端，由正交信号发生器产生两路正交混沌信号，并经符号函数归一化以保持发送信号的能量恒定，然后，这两路混沌信号与其延迟不同时间间隔后的混沌信号分别调制1 bit数据信息形成一帧发送信号。在解调端，采用相关解调提取数据信息，通过检测相关器输出结果的符号恢复信息比特。利用高斯近似（GA）法分析了系统在加性高斯白噪声（AWGN）信道下的理论误码率（BER）性能，并与经典的混沌通信系统进行了比较。分析及实验结果表明：与DCSK系统相比，无信号间干扰的CD-DCSK系统的传输速率提升了50个百分点，且其误码性能优于相关延迟移位键控（CDSK）系统。     

异结构混沌系统同步及其在保密通信中的应用*

根据主动控制思想和Lyapunov稳定性定理,构造主动控制器使得两个异结构的混沌系统在短时间内实现同步,并证明了混沌同步的鲁棒稳定性;利用MATLAB的Simulink技术进行数字仿真,将同步的异结构混沌系统应用到混沌掩盖和混沌参数调制保密通信中。仿真结果表明,异结构混沌系统能够实现稳定的同步,且在混沌掩盖和混沌参数调制保密通信中,有用信号均能有效地在接收端恢复出来。     

Turbo equalization for block fading MIMO channels using random signal mapping

We present a novel turbo equalization scheme for block fading MIMO channels, where diversity is achieved using random signal mapping. We show that the computational complexity of the proposed scheme is not a function of the number of transmit antennas, and compares favorably to the complexity of similar systems based on space-time trellis codes and space-time block codes. Finally, we provide simulation results showing that the proposed scheme achieves full diversity, and investigate its performance in terms of the number of transmit antennas, ISI length and imperfect channel knowledge.     

MIMO信道中衰落信号的多谱勒功率谱

MIMO系统中的角度功率谱有多种分布形式,所以经典多普勒功率谱不再适用。针对常用的均匀分布、余弦分布、高斯分布和拉氏分布的入射波角度功率谱,分别推导了多谱勒功率谱解析式。通过仿真比较了不同角度功率谱下的多普勒功率谱,并分析各种参数对其的影响。这些工作对MIMO信道中频率扩散的刻画做了拓展。     

Control strategy with adaptive quantizer’s parameters under digital communication channels

A stabilizing controller designed without considering quantization may not be effectively implemented for the systems with quantized information due to quantization errors. Hence, an interesting issue is how to design the quantizer such that the desired system performance can be still attained by the above controller. In this work, a new control strategy with on-line updating the quantizer’s parameter is proposed. This scheme may ensure the controlled system to attain the same dynamic performance, _H∞$H_{\infty }$ disturbance attenuation level, as the one without signal quantization. A practical adjusting rule on quantizer’s parameter is proposed such that the state-dependent parameter is available on both sides of encoder/decoder. Finally, some numerical examples have been provided to illustrate the present control scheme.     

分数阶混沌系统同步及其保密通信

针对参数未知的分数阶Chen混沌系统,研究其同结构同步以及与分数阶Lü混沌系统的异结构同步问题。利用分数阶系统稳定性理论和拉普拉斯变换理论,设计并证明了系统的反馈控制器,给出了一种分数阶混沌保密通信系统。运用分数阶微积分的预估——校正算法进行数值仿真,验证了所提出方法的有效性。     

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。     

异结构混沌系统同步及其在保密通信中的应用

针对统一混沌系统和Qi混沌系统的模型,根据主动控制思想和Lyapunov稳定性定理,构造主动控制器使得这两个异结构的混沌系统实现同步,并且实现了驱动系统参数已知而响应系统参数未知的异结构混沌系统的白适应同步,并且能较怏的辨析出系统的未知参数．并利用MATLAB进行数字仿真,将同步的异结构混沌系统应用到混沌掩盖和混沌扩频保密通信中．仿真结果表明,异结构混沌系统能够实现稳定的同步,且在混沌掩盖和混沌扩频保密通信中,有用信号均能有效地在接收端恢复出来．     

Optimal tracking performance of MIMO control systems with communication constraints and a code scheme

This paper investigates the issue of the optimal tracking performance for multiple-input multiple-output linear time-invariant continuous-time systems with power constrained. An H₂ criterion of the error signal and the signal of the input channel are used as a measure for the tracking performance. A code scheme is introduced as a means of integrating controller and channel design to obtain the optimal tracking performance. It is shown that the optimal tracking performance index consists of two parts, one depends on the non-minimum phase zeros and zero direction of the given plant, as well as the reference input signal, while the other depends on the unstable poles and pole direction of the given plant, as well as on the bandwidth and additive white noise of a communication channel. It is also shown that when the communication does not exist, the optimal tracking performance reduces to the existing normal tracking performance of the control system. The results show how the optimal tracking performance is limited by the bandwidth and additive white noise of the communication channel. A typical example is given to illustrate the theoretical results.     

空域相关MIMO信道容量的研究

研究了在空域相关条件下MIMO通信系统的信道容量问题,利用Wishart矩阵的联合特征值概率密度函数显式给出了平坦性瑞利衰落信道的各态历经容量的可计算公式,利用Matlab所进行的数值计算表明：与已有的蒙特卡洛方法相比,公式提高了计算速度。数值计算结果还进一步表明了影响空间相关性的天线间距、来波角度和角度扩展这三个参数与信道容量之间的关系。     

统一混沌系统同步及其保密通信

研究了混沌系统的广义同步和基于状态观测器同步。利用这两种同步方法,研究了统一混沌系统的同步控制。研究发现：同步后的响应系统能保持混沌状态。在此基础上,提出了全双工保密混沌通信系统,理论分析和仿真实验表明了该通信方案的可行性和有效性。