Impact of the Chaotic Synchronization’s Stability on the Performance of QCPSK Communication System
, Darja Cirjulina, Juris Grizans, Arturs Aboltins, Dmitrijs Pikulins, Maris Zeltins and Anna LitvinenkoRound 1
Reviewer 1 Report
The authors propose a model of QCPSK communication system that incorporates chaos oscillator components. They investigate the potential of applying chaos oscillators in the implementation of a communication system model. After describing the attributes of the selected Chaos oscillators used for this research, it describes in detail a comprehensive experiment involving software, hardware, and simulation. This is in addition to the abstract and the conclusion sections.
Most of the paper describes the integration of the chaos oscillators within a communication system. The integrated parts are well known but the integration between them is the added value of this research. Therefore, the paper novelty is relatively low, but the implementation is precise and very well described in detail.
Understanding the QCPSK communication system and the chaos oscillators system along with the integration between them are the real value of this paper, and professional readers will find this paper important and helpful.
Understanding the QCPSK communication system and the chaos oscillators system along of the integration between them is the real value of this paper and the profesional readers will definitely find this paper important and helpfull.
Author Response
The novelty of the paper has been risen by providing an additional experimental part on the communication system's performance in the AWGN channel using 3 different chaos oscillators- see Section 5 (the results are depicted in Fig. 12).
The novel hardware solutions for the experimental studies of the communication system in the AWGN propagation channel have been proposed- see. Fig. 10. and Fig. 11. in the revised paper.
The description of methods used in the article has been improved, including revisions of the descriptions and corresponding conclusions in Sections 4 and 5.
Reviewer 2 Report
The novelty of the paper regards two things: 1. Investigation of the noise immunity of the specific method for creating a QCPSK system, finally using one (out of three) chaotic oscillator, is presented by studying the correlation coefficient. The study seems to be performed on experimental measurements and the results are clear. 2. Investigation of the BER when the system is synchronized through a AWGN channel model. The results are this time compared for the three possible chaotic oscillators utilized in the generation of the QCPSK signals. The English are adequate. The citation is rather proper. However, there are some very important issues that the authors have to take into account: 1. They present theoretically the same system with three possible implementations differing in the chaotic oscillator utilized. But they build only one version for the experimental study for the noise immunity of the system. They have to 2. They present only simulation results for the BER calculation/estimation. The authors should present experimental results from real circuits (comprising the system) and in order to be trustworthy a real AWGN channel should be utilized. Additionally, if they are going to present the system’s realization with one chaotic oscillator, they should get away the system description with the other two.
Author Response
The English language style and spell check have been provided through all the paper. Spelling mistakes have been corrected, incorrect or repeating language constructions have been substituted and optimized.
The research design has been improved, by adding a hardware PSK modulator based on binary phase shifter circuit and use of real additive white Gaussian noise (AWGN) source for exploration of the stability of the generators. It has been decided to discard the part on the studies of the communication systems on the basis of multipath AWGN propagation channel, leaving the direct path. Wider experimental part and in-depth analysis of the results for the AWGN channel and all three chaos oscillators is provided instead. The experimental results from real circuits for the BER estimation have been measured and compared to those obtained during the simulation studies – see e.g., Fig.12 in the revised paper.
The review and corrections, provided through the paper, make the results more structured and the perception clearer.
Reviewer 3 Report
The current work presents a study of the quadrature chaos phase-shift keying communication system (QCPSK) based on the employment of chaos oscillators. The research takes two directions, with one being the study of the chaos synchronization's noise immunity for several chaos oscillators that are the potential core blocks of the QCPSK system. The correlation coefficient over time is used to estimate the synchronization noise immunity. The second direction is the evaluation of the QCPSK system's baseband model performance in the direct AWGN and multipath AWGN propagation channels using bit error ratio (BER) as the evaluation method for several chaos oscillators employed as the core of the QCPSK system's model. In paper [16], the authors proposed a model of quadrature chaos phase-shift keying based communication system (QCPSK) that employs chaos oscillators (defined by state variable differential equations). This manuscript is aimed at further investigation of the proposed system using some approaches for the study developed in [17]. However, the manuscript is not innovative enough to be published in Electronics. The results are not quite convincing and do not pose any significant advancement in the field of the QCPSK system.
Author Response
The second research direction has been extended providing additional experimental results of the BER estimation from real hardware chaotic oscillators communicating with each other over real AWGN channel. This increases the novelty of the paper.
The results obtained on the basis of the additional experimental part, as well as comparison of experimental and simulation data, pose a significant advance in the field of QCPSK systems. Detailed comparison of experimental results from LTSpice circuit simulation and hardware implementation of chaotic generators with PSK modulation capability allows drawing conclusions about the applicability and robustness of those well-known generators for use in secure low-complexity communication systems.
The review and corrections, provided through the paper, make the results more structured and the perception clearer.
Round 2
Reviewer 3 Report
The authors have satisfactorily modified their manuscript according to my previous criticisms. Therefore, I recommend the publication of this manuscript.
Author Response
The authors are grateful for the provided review and useful feedback on improving the manuscript.
