Chaotic communications with correlator receivers: theory and performance limits

This paper provides a review of the principles of chaotic digital communications using correlator receivers. Modulation schemes using one and two chaotic basis functions, as well as coherent and noncoherent correlation receivers, are discussed. The performance of differential chaos shift keying (DCSK) in multipath channels is characterized. Results are presented for DCSK with multiuser capability and multiple bits per symbol

A multiple access scheme for chaos-based digital communication systems utilizing transmitted reference

Author name used in this publication: Francis C. M. LauAuthor name used in this publication: Chi K. Tse2004-2005 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Double-Stream Differential Chaos Shift Keying Communications Exploiting Chaotic Shape Forming Filter and Sequence Mapping

ACKNOWLEDGMENT This research have been supported in part by the Scientific and Technological Innovation Leading Talents Program of Shaanxi Province, China Postdoctoral Science Foundation Funded Project (2020M673349), Open Research Fund from Shaanxi Key Laboratory of Complex System Control and Intelligent Information Processing (2020CP02)Peer reviewedPostprin

Chaos-Based Communication Systems

The attractive properties of chaos signal that is generated from dynamic systems motivate the researchers to explore the advantage of using this signal type as a carrier in different communication systems. In this chapter, different types of digital chaos–based communication system are discussed; in particular, digital communications where reference signal and its modulated version are transmitted together. This type is called differential coherent systems. Brief surveys on the recently developed systems are presented

DESIGN AND PERFORMANCE ANALYSIS OF ORTHOGONAL MULTI-LEVEL CODE-SHIFTED DIFFERENTIAL CHAOS SHIFT KEYING COMMUNICATION SYSTEM

Based on Orthogonal Chaotic Vector Shift Keying (OCVSK) system and Multilevel Code-Shifted Differential Chaos Shift Keying (MCS-DCSK) system, a new Multilevel Code-Shifted Differential Chaos Shift Keying (OMCS-DCSK) modulation system is proposed and designed in this paper. New orthogonal chaotic signal sets are generated using Gram-Schmidt algorithm and Walsh code function then these signals are used for bearing information bits to achieve higher data rate and better bandwidth efficiency compared with the conventional DCSK communication system. The bit error rate (BER) analysis of the OMCS-DCSK system over additive white Gaussian noise (AWGN) and multipath Rayleigh fading channel is derived and compared with the simulation results. Also, the spectral and complexity analysis of the system are presented and compared with the conventional DCSK systems. The results show that the proposed system outperforms OCVSK and MCS-DCSK in BER performance and spectral efficienc

Advanced index modulation techniques for future wireless networks

In the research study proposed in this Ph.D Thesis, we consider Index Modulation as a novel tool to enhance energy and spectral efficiencies for upcoming 5G networks, including wireless sensor networks and internet of things. In this vein, spatial modulation was proposed to enhance the capacity of wireless systems to partially achieve the capacity of MIMO systems but at lower cost, making it a technique that has attracted significant attention over the past few years. As such, SM schemes have been regarded as possible candidates for spectrum- and energy-efficient next generation MIMO systems. However, the implementation of the SM is also challenging because of its heavy dependence on channel characteristics, channel correlation, corrupted CSI and the need to have adequate spacing between antennas. Moreover, the SM requires multiple antennas at the transmitter which adds cost to the hardware implementation. In addition, the number of mapped bits in SM is limited by the physical size of the wireless device where only small number of antennas can be used. The switching time wasted by RF antenna switches adds to the complexity of the issue. In this Thesis, we study the drawbacks of SM in the articles indicated, namely Performance Comparison of Spatial Modulation Detectors Under Channel Impairments that is placed in the Appendix at the end of Thesis as it is a conference paper, and The Impact of Antenna Switching Time on Spatial Modulation that is put in Chapter 1. In the first article, we have shown that channel impairments have serious impacts on the BER performance and on the capacity of the SM system and that the SM is too sensitive to both imperfect and correlated channels. In the second article, we have demonstrated that the switching time defined as the time needed by the system to turn off an antenna and turn on another one, which is an inherent property of RF industrial switches used in SM systems, is in the order of nanoseconds and naturally influences the transmission rate of SM systems because of introducing systematic transmission gaps or pauses. Given the speed limitation of practical RF switches in performing transitions, antenna transition-based technologies like SM schemes are capped in terms of data rate performance. In fact, the effective data rate of SM will remain hostage to developments in industrial RF switches. This brings restrictions to the implementation and operation issues when extremely high data rates become a necessity. It is shown by the assemblage of our results that the switching time Tsw which is a requirement for transitions between antennas to happen, dictates restrictions on data rate, capacity and spectral efficiency of SM systems. Furthermore, we propose baseband non-hardware-based indexing modulation schemes based on frequency-index modulation, coherent chaotic modulation and non-coherent differential chaotic modulation schemes as potential alternatives to SM, that would also fit wireless sensor networks and internet of things applications. In this regard, we have proposed three articles. The first article which represents frequency index modulation is called Frequency Index Modulation for Low Complexity Low Energy Communication Networks and is placed in Chapter 2 of this Thesis. In this article, we explore a low complexity multi-user communication system based on frequency index modulation that suits Internet of Things (IoT) applications and we show that such a system would constitute an excellent candidate for wireless sensor applications, where it represents a simpler substitution for frequency-hopping (FH) based architectures, in which the hops carry extra bits. The third article which concerns coherent chaotic modulation is called Design of an Initial-Condition Index Chaos Shift Keying Modulation and is located in Chapter 3. In this article, an initial condition index chaos shift keying modulation is proposed. This design aims to increase the spectral and energy efficiencies to unprecedented levels. The proposed scheme exploits the initial conditions to generate different chaotic sequences to convey extra bits per transmission. In comparison to rival modulation schemes, the results obtained in the proposed work show a promising data rate boost and a competitive performance. The last article employs a non-coherent differential chaotic shift-key system named Permutation Index DCSK Modulation Technique for Secure Multi-User High-Data-Rate Communication Systems that is found in the Appendix. In this original design, where each data frame is divided into two time slots in which the reference chaotic signal is sent in the first time slot and a permuted replica of the reference signal multiplied by the modulating bit is sent in the second time slot, we target enhancing data security, energy and spectral efficiencies. Overall, in light of the high demands for bandwidth and energy efficiencies of futuristic systems, the suggested soft indexing mechanisms are successful candidates with promising results

Modulation and detection schemes based on chaotic attractors properties : application to wideband transmissions

Au cours des vingt dernières années, les systèmes de communications basés sur le chaos ont été étudiés, avec pour objectif la possibilité de générer les signaux large-bande par des circuits électroniques simples, permettant une faible complexité des circuits émetteurs-récepteurs. Cette thèse concerne l’étude de systèmes de transmissions large-bande basés sur le chaos, en utilisant certaines propriétés des attracteurs chaotiques. Tout d’abord, un système dynamique a été choisi et étudié, permettant de générer des signaux chaotiques qui possèdent des composantes périodiques. L’analyse de ces attracteurs chaotiques cycliques (CCA) met en évidence des propriétés spécifiques en lien avec leur période. Ensuite, deux schémas de modulation basés sur les CCAs sont proposés. Les détections non-cohérentes associées sont réalisées par l’observation des propriétés spécifiques des signaux rec¸us. L’évaluation des performances des systèmes basés sur les CCAs dans le cas d’un canal de bruit additif Gaussien montre des performances meilleures que celles des systèmes dits ”differential chaos shift keying (DCSK)”, en bas débit de symboles. En outre, les performances dans le cas multi-trajet sont comparables dans la bande de 2,4 GHz. ------------------------------------------------------------------------------------------------------------------------------------------- In the past twenty years, chaos-based communication systems have been studied, considering the possibility of generating wideband signals by simple electronic circuits, hence low complexity in transceiver. The aim of this thesis is to study the chaos-based wideband transmission systems relying on the properties of chaotic attractors. Firstly, a dynamical system is selected and studied, allowing to generate the chaotic signals with a periodic component. The analysis of such chaotic cyclic attractors (CCA) shows the specific properties. Then, two CCA-based modulation schemes are proposed, with the simple noncoherent detections realized by observing the specific properties of the received signals. The performance evaluation of CCA-based systems in the additive white Gaussian noise (AWGN) channel shows a better noise performance with long symbol duration, compared to the one of differentially chaos shift keying (DCSK). In addition, they have a comparable multipath performance in the 2.4 GHz ISM environmen

Emulation of Narrowband Powerline Data Transmission Channels and Evaluation of PLC Systems

This work proposes advanced emulation of the physical layer behavior of NB-PLC channels and the application of a channel emulator for the evaluation of NB-PLC systems. In addition, test procedures and reference channels are proposed to improve efficiency and accuracy in the system evaluation and classification. This work shows that the channel emulator-based solution opens new ways toward flexible, reliable and technology-independent performance assessment of PLC modems