Chaotic Transmitter Research Articles

Chaotic laser time series prediction based on an improved logistic mapping algorithm echo state network

Chaos synchronization plays vital functions in the fields of optical chaos secure communication. The synchronization performance can be significantly degraded by parameter mismatches between the chaotic transmitter and receiver. In this paper, the Deep-Logistical Mapping Echo State Network (D-LMESN) is proposed to enhance the performance of chaos synchronization. The network is upgraded by using an improved logical mapping algorithm and a deep reserve pool structure with phase space reconstruction. Results show that D-LMESN exhibits better performance in the prediction of chaotic time series, thanks to the adaptive parameter adjustment, which increases the ability to capture the dynamic characteristics of complex systems. Compared with ESN, the mean square error of this model is reduced by 55% and 72%, respectively, in chaotic laser simulation and actual data experiments. This provides a new possibility, to our knowledge, for the development of chaotic secure communication.

Prototyping the Symmetry-Based Chaotic Communication System Using Microcontroller Unit

Chaos-based communications are a promising application of chaos theory and nonlinear dynamics. Their key features include concealed transmission, high security, and native broadband signals. Many studies have recently been published devoted to this technology. However, the practical implementations of chaos-based communications are rare due to multiple shortcomings: high hardware requirements, complex signal processing algorithms, and a lack of efficient modulation techniques for chaotic signals. In this study, we consider a simple hardware prototype of a coherent chaos-based communication system based on a novel type of modulation: adaptive symmetry of the finite-difference scheme used in a chaos generator. We explicitly demonstrate the possibility of covertly transmitting data using a chaotic transmitter and receiver implemented in a general-purpose microcontroller unit. A comparison between traditional parameter and symmetry modulation is given through a return map analysis and bit error rate estimation. The communication secrecy is analyzed using quantified return map analysis. The obtained results confirm the possibility of creating chaos-based communication systems based on symmetry modulation.

Experimental validation of new non-coherent chaotic modulation via SDR implementation

In this article, a new non-coherent chaotic modulation based on the classical Frequency Modulation (FM) technique is proposed and experimentally validated under realistic wireless communication scenarios by using Software Defined Radio (SDR) technology. In the proposed modulation, named FM-Chip Averaging Chaotic On-Off Keying (FM-CACOOK), we simply combine the FM modulation with the recent proposed chaotic modulation technique CA-COOK. Firstly, we validate the proposed technique via several Matlab simulations scenarios in the context of wireless chaotic transmission through different IEEE 802.15.4a channel models. In this context, we choose the Office LOS (Line Of Sight) and NLOS (Non Line Of Sight), the industrial LOS, the Outdoor LOS and the Open Outdoor NLOS in order to make a mixture of indoor and outdoor environments for LOS and NLOS propagation. Secondly, we implement the proposed modulation by using GNU-Radio Companion (GRC) software. For this, several new GRC blocks have been added to perform and test the FM-CACOOK modulation in SDR platforms such as RTL-SDR dongle and HackRF. Finally, experimental tests have been performed to demonstrate the reliability and the strengths of the considered modulation. The obtained experimental results validate our solution by deriving the Bit Error Rate (BER) performances curve of FM-CACOOK compared to that of Differential Chaos-Shift Keying (DCSK), which is the reference chaotic modulation, and to that of the recent CA-COOK modulation.

A revisit to the past plague epidemic (India) versus the present COVID-19 pandemic: fractional-order chaotic models and fuzzy logic control.

India is one of the worst hit regions by the second wave of COVID-19 pandemic and ‘Black fungus’ epidemic. This paper revisits the Bombay Plague epidemic of India and presents six fractional-order models (FOMs) of the epidemic based on observational data. The models reveal chaotic dispersion and interactive coupling between multiple species of rodents. Suitable controllers based on fuzzy logic concept are designed to stabilise chaos to an infection-free equilibrium as well as to synchronise a chaotic trajectory with a regular non-chaotic one so that the unpredictability dies out. An FOM of COVID-19 is also proposed that displays chaotic propagation similar to the plague models. The index of memory and heredity that characterise FOMs are found to be crucial parameters in understanding the progression of the epidemics, capture the behaviour of transmission more accurately and reveal enriched complex dynamics of periodic to chaotic evolution, which otherwise remain unobserved in the integral models. The theoretical analyses successfully validated by numerical simulations signify that the results of the past Plague epidemic can be a pathway to identify infected regions with the closest scenarios for the present second wave of Covid-19, forecast the course of the outbreak, and adopt necessary control measures to eliminate chaotic transmission of the pandemic.

Controlling a chaotic anti-synchronized oscillator by a phase interplayed optical injected seed with an FBG sensor

In this simmulation study, a fiber Bragg grating (FBG) sensor is used to partially separat a signal emitted from a laser diode (LD1), which is originally modulated with a noise source. Separation done into two parts; reflected, in which a phase is interpayed (similarly to Michelson interferometry) in order to make it differ than that passed without reflection. The two separated signals, remixed agin with themselves and additionally add to a third signal came from second laser diode (LD2), which is also modulated with a noise source furthermore to a frequency message. Output signal resulted from this interferometry, originally based on two self electro optic effect devices (seed) undergoes external optical injection. Thus these two osillators followes anti-synchronization within their emission. Observation and analyses was based on detremination for their final output spectra from periodic to chaotic. FBG sensor used in this experiment is play a role of temperature (T) and/or Stress (S) controlling to the incident signal for LD1.Results shows that LD1 signal cannot modify output final signal, unless several parameters are carfuley tuned. These parameters are; LD1 seed, LD2 seed, LD1 phase (filtering with FBG). These results approves noval application for operating sensors in parallel to optical communications in order to satisfy the application of high level security with two antisynchronized lasers within one chaotic transmitter.

Investigation of Ber Performances in Chaotic-Secured Optical Fiber Communication Systems using the 4-PAM Modulation Scheme

This paper presents a numerical simulation investigation on the bit error rate in a chaotic-secured fiber channel and a conventional fiber channel when propagating independently. The investigated communication system uses the pulse-amplitude modulation scheme (4-PAM) at the bit rate of 10 Gbps, the fiber length of 100 km, and the operation wavelength of 1550 nm. Our simulation results demonstrate both chaotic and non-chaotic transmission channels can well operate with the bit rate up to 20 Gbps with the BER smaller than 10-5 if dispersion and fiber loss issues are appropriately compensated without needing forwarderror-correction, showing high potential in physically secured optical fiber communication systems.

Dynamical characteristics of the piezotronic ZnO nanowire device in ballistic transport and its MEMS/NEMS resonator hybrid

In this work, the dynamical analysis of carrier transportation in a typical piezoelectric device working in the ballistic regime is conducted. Based on the quantum scatting theory, the Poisson and Schrödinger equations are combined for calculating the dynamical transmission coefficient of the metal–piezoelectric ZnO–metal structure subject to sinusoidal and rectangular external stresses. The roles played by the spanning width of induced piezopotential and incident electron energy in affecting transmission probability are further discussed and clarified, respectively. The cutoff frequency of the piezoelectric device is also studied. Moreover, MEMS/NEMS hybrids specified by double/single-clamped ZnO quantum wire micro/nano-electromechanical resonator hybrids are proposed. Through a comprehensive numerical simulation, it is revealed that the rich nonlinear dynamics of the resonator can be subtly transferred to the piezoelectric device, and the chaotic transmission in the piezoelectric device can arise in two-dimensional parameter space with respect to time and incident electron energy. Therefore, the hybrids are endowed with the ability to detect amplitude changes by measuring ultra-sensitive quantum tunneling current. The study sheds light on developing quantum piezotronics and its related MEMS/NEMS integrations.

Encrypting A 7.88ghz Frequency Message Within A Chaotic Carrier by Optical Feedback

A new laser system is suggested and experimentally verified as a chaotic transmitter for a secure optical communication system. The laser source kind is a distributed feedback with a peak wavelength 1310nm and maximum power 5mW. A doubly external cavity with 85cm of length is constructed via air.Chaotic signal is achieved successfully after the laser reach of coherence collapse, with a very wide band spectrum (12GHz). This value is capable to increase subjecting to several parameters based on optical feedback (OFB) such as laser current operating level, beam focusing, polarization control, etc. In order to test a message hiding possibility, a frequency message is modulated directly into the laser, which is connected with the laser source using a bias tee. For the free running (solitary) semiconductor laser, the maximum available direct current modulation is: 3GHz/mA, while this value can be increased by this technique. This gives the possibility for very high modulation values and increasing data package volume that can send securely in the applications that requires immunity.

Effect of ADC parameters on neural network based chaotic optical communication

The performance of traditional chaotic optical communications depends on the matching parameters of the chaotic transmitter and receiver. The chaotic receiver based on the neural network (NN) can solve the dependence on matching parameters, but the analog-to-digital converter (ADC) has an effect on the decryption performance. In this paper, the effects of sampling rate and digitalizing bit for ADC on NN-based chaotic optical communication systems with different feedback strengths at different bit rates are numerically studied. The results show that the requirements for ADC will be higher if the feedback becomes stronger. In order to achieve higher speed chaotic optical communications, the ADC with higher performance is needed. These results can give guidance for the applications of NN-based high-speed chaotic optical communication systems.

32 Gb/s chaotic optical communications by deep-learning-based chaos synchronization.

Chaotic optical communications were originally proposed to provide high-level physical layer security for optical communications. Limited by the difficulty of chaos synchronization, there has been little experimental demonstration of high-speed chaotic optical communications, and point to multipoint chaotic optical networking is hard to implement. Here, we propose a method to overcome the current limitations. By using a deep-learning-based scheme to learn the complex nonlinear model of the chaotic transmitter, wideband chaos synchronization can be realized in the digital domain. Therefore, the chaotic receiver can be significantly simplified while still guaranteeing security. A successful transmission of 32 Gb/s messages hidden in a wideband chaotic optical carrier was experimentally demonstrated over a 20 km fiber link. We believe the proposed deep-learning-based chaos synchronization method will enable a new direction for further development of high-speed chaotic optical communication systems and networks.

Generalized analytical solutions for secure transmission of signals using a simple communication scheme with numerical and experimental confirmation

A novel explicit analytical solution is reported for the transmission and recovery of information signals using a simple communication scheme. Analytical solutions are obtained for the normalized state equations of coupled second-order chaotic transmitter and receiver systems embedding the information signal. The analytical solution of the difference system obtained from the state equations of the transmitter and receiver systems has been identified as a measure of the recovered information signal which is transmitted securely by chaotic masking. The analytical solutions are used to reveal the nature of synchronization and the enhancement of the amplitude of recovered information signal. The difference signal of the coupled state variables indicating the recovered information signal obtained through numerical simulations is presented to validate the analytical results. The electronic circuit experimental results are presented to confirm the analytical and numerical results of the communication scheme discussed.

Chaos Synchronization Error Compensation by Neural Network

Chaos synchronization is the foundation of chaotic optical communications. The parameter mismatch between chaotic transmitter and receiver will significantly degrade the synchronization performance. In this letter, neural network is proposed to improve the performance of chaos synchronization. The compensation for chaos synchronization error caused by the mismatch of different hardware parameters, such as frequency response, loop gain, modulator bias, and time delay, has been discussed and analyzed in simulation and experiment. Compared with other digital signal processing (DSP) algorithms including feed-forward equalization and Volterra filter, neural network shows best performance. In some occasions, the cross correlation can be improved from 0 to 0.8. Further, the performance improvement in chaotic optical communications by neural network has been verified in simulation. This technique has potential to be used in high-speed chaotic optical communications.

Duffing oscillators for secure communication

This paper introduces a new technique for using chaotic Duffing oscillators in secure communication. The secret message is encrypted using the parameters of the Duffing oscillator that indirectly affect the generated chaotic orbits. The mathematical model of the chaotic transmitter uses three parameters that can be altered between two levels, depending on the binary sequence of the digital secret message and the corresponding cipher. Consequently, a total of eight chaotic attractors are used to scramble the binary-based signal. Two different structures, for the synchronization and encryption mechanisms, between the transmitter and the receiver, are introduced. The first one uses the time series of the two chaotic signals generated by the Duffing transmitter, while implementing a cipher-less encryption mechanism. The second one uses a single time series of the Duffing transmitter, while allowing one of its parameters to act as a digital cipher. Better utilization of the communication channel is proved for the second method, while using a new adaptive Lyapunov-based technique to implement both the state synchronization and the parameters estimation at the receiver side. Both simulation and experimental case studies are presented to illustrate the proposed techniques and their applicability to securely transmit various multimedia digital signals.

Robust Polynomial Observer-Based Chaotic Synchronization for Non-ideal Channel Secure Communication: An SOS Approach

This paper proposes a novel chaotic-based secure communication scheme for non-ideal transmitting public channel. The proposed approach employs a polynomial model and sum-of-squares (SOS) decomposition technique to synchronize chaotic transmitter and receiver systems. Because of high secure communication demands and practical limitations in transforming the signals on the public channel, only limited information of the transmitter system is transformed. Therefore, at the receiver side, a robust polynomial observer-based controller is proposed to estimate the states of the transmitter and synchronize the chaotic systems. Also, since the channel is noisy and non-ideal, H∞ performance criterion is used and the sufficient design conditions of controller and observer are derived in terms of SOS decomposition such that the information is effectively recovered in the presence of external disturbances and noisy environment. In addition, to further remove the effect of the noise on the information recovery, a Savitzky–Golay polynomial filter is utilized. Finally, to show the effectiveness of the proposed approach, two chaotic and hyperchaotic case studies are considered and the obtained results are compared with the existing ones.

A Novel DWT Domain Watermarking Scheme Based On a Discrete-Time Chaotic System

Abstract In this paper, we present a novel watermarking scheme in the Discrete Wavelet Transform (DWT) domain based on a discrete-time chaotic system. A modified Henon map and a discrete step-by-step observer are, respectively, considered as transmitter and receiver of the chaotic transmission scheme, leading to an exact synchronization and therefore an exact recovery of the system states. The secret keys of the transmission scheme are the transmitter parameters. The said modified Henon map is used to encrypt an image, inserted by inclusion method in the chaotic discrete-time system’s dynamics, to then use the resulting cyphered image as a watermark to a host image. This host image is watermarked by a DWT domain watermarking function. After the extraction process, the recovered watermark is then sent through the previous chaotic channel to decrypt it. Simulation results are presented to highlight the feasibility and robustness of the proposed method.

Chaos for low probability of detection communications

Many methods for using chaos as a communications signal have been suggested, but all suffer from the difficulty in synchronizing the transmitter and receiver. Chaotic signals are broad band and unpredictable, making them potentially useful when the goal is low interference communications or even low probability of detection (LPD) communications. In this work, a set of randomly chosen chaotic sequences is used to synchronize a chaotic transmitter to a receiver. Once synchronization is achieved, two methods are presented for encoding information. Simply multiplying the chaotic signal by ±1 is used to encode the binary signals 1 or 0. The binary information is recovered by cross correlating the transmitted signal with the synchronized signal in the receiver. This encoding technique offers the same bit error performance as binary phase shift keying (BPSK). The data rate can be increased by creating orthogonal signals from different components of a multidimensional chaotic system. Cyclostationary properties of these signals and differential chaos shift keying (DCSK) are analyzed to show possible signatures that would make the signal easily detectable.

混沌光注入展宽半导体激光器混沌载波发射机带宽

混沌光注入展宽半导体激光器混沌载波发射机带宽

BI-Scale Fractional Order Statistics for Blind Channel Estimation in Chaotic STBC Systems

Space-Time Block Coding (STBC) is a MIMO based approach which achieves high reliability and diversity by transmitting multiple copies of data stream across antennas. In this paper, bi-scale based fractional order statistics for blind channel estimation in chaotic STBC systems are proposed. Accordingly, the proposed communication system contains chaotic modulator and transmitter in the transmitter section. Then, the receiver contains the channel equalizer and chaotic demodulator. In the channel equalizer, the signal is transmitted through a channel which is estimated through the proposed channel estimation algorithm. In the proposed channel estimation, the weight updating formulae will be modified based on the comparison of the estimated weighted values and its old weighted value. The analysis of the technique is carried out by finding out the evaluation metrics of BER, MSE and SER with respect to SNR and different antenna array sizeof 4, 5 and 6.

Design of a robust receiver for chaotic switching maps of DC‐DC power electronics transmitter converters for secure communication

AbstractThis paper aims to open a new vista of research in the direction of possible application of power electronics DC‐DC converters in analog chaotic communication. Most of the work reported on analog chaotic communication is based on the pioneer work of Pecora and Caroll, with synchronization between transmitter and receiver. Receiver based on synchronization, also known as coherent receiver, has a disadvantage of parameter mismatch and is sensitive to noise. In the present work, firstly, a secure transmitter using chaotic DC‐DC converters is proposed that encrypts information using chaotic switching map technique. In chaotic switching map technique, the message is encrypted by randomly switching from one chaotic converter to another. The bifurcation parameter of the randomly switched chaotic converter is modulated by the message. Secondly, an attempt has been made to design a robust non‐coherent receiver that is adaptable to the switching chaotic transmitters, even in the presence of noise. Once the receiver identifies the chaotic converter, it can decode the message as per the decryption algorithm. With the proposed non‐coherent receiver, the disadvantages of coherent receivers can be overcome. We have also devised a prototype smart meter, used in smart distribution grid for implementing the proposed communication technique. Copyright © 2016 John Wiley & Sons, Ltd.

A secure communication scheme based generalized function projective synchronization of a new 5D hyperchaotic system

In this paper, a new five-dimensional hyperchaotic system is proposed based on the Lü hyperchaotic system. Some of its basic dynamical properties, such as equilibria, Lyapunov exponents, bifurcations and various attractors are investigated. Furthermore, a new secure communication scheme based on generalized function projective synchronization (GFPS) of this hyperchaotic system with an uncertain parameter is presented. The communication scheme is composed of the modulation, the chaotic receiver, the chaotic transmitter and the demodulation. The modulation mechanism is to modulate the message signal into the system parameter. Then the chaotic signals are sent to the receiver via a public channel. In the receiver end, by designing the controllers and the parameter update rule, GFPS between the transmitter and receiver systems is achieved and the unknown parameter is estimated simultaneously. The message signal can be finally recovered by the identified parameter and the corresponding demodulation method. There is no any limitation on the message size. Numerical simulations are performed to show the validity and feasibility of the presented secure communication scheme.