Background. Telecommunication systems with a broadband signal have undoubted advantages: increased noise immunity with narrowband and wideband interference, confidentiality of information transmission, as well as improved electromagnetic compatibility with neighboring radio-electronic devices. A broadband signal is usually formed by direct spread spectrum using well-known classical pseudo-random sequences (PRS): m-sequences, Kasami, Gold, Walsh sequences, which can be decoded and received at the receiver. Objective. The aim of the paper is creating PRS on the basis of chaos, which the subscriber is practically unable to decode, and thus ensure increased confidentiality of information transmission. Methods. Using the mathematical model of chaotic logistic mapping, which, as shown by preliminary studies, provides the best results, as well as referring to the bifurcation diagram of Feigenbaum, the parameters of 3-secret keys are defined and the PRS of the selected length is created. Based on the application of the graphical user interface developed in the MATLAB system, a correlation analysis of the resulting PRS is performed and the PRS is determined with the minimum side lobes of the autocorrelation function. Results. By empirical decision of 3 secret keys of the dynamic parameter of the Feigenbaum diagram, the initial value of the sequence and the number of the initial pulse of the PRS, as well as the study of the autocorrelation function, we obtained a PRS with a side lobe level of the autocorrelation function acceptable for practical use of no more than 0.25. Conclusions. The use of well-known pseudo-random sequence: Walsh's, Kasami's, Gold's, creating a system with a noise-like signal doesn't ensure complete confidentiality of information transmission, since they can be decoded. The most acceptable by the criterion of the side lobe minimum of the autocorrelation function-no worse than 0.25-is the use of chaos based on the Feigenbaum logistic map. When creating pseudo-random sequences based on chaos, the best results are obtained by choosing the maximum value of the dynamic parameter of the Feigenbaum diagram at the level of the boundary value equal to 4, with an accuracy of 0.05.
In telecommunications, a particular place belongs to systems with a wideband noise-free signal, the undisputed advantage of which is increased by both narrowband and wideband interference, confidentiality of information transmission, as well as electromagnetic compatibility with adjacent electronic devices. A wideband noise-free signal is formed using a number of known modulated sequences - m-, Kasam-, Gold sequences, typically by direct spreading.Systems using known pseudo-random sequences cannot be considered protected from unauthorized access.An effective way to increase the confidentiality of signal transmission in a noise-free TSC is to use a chaotic signal-based PVP.Pseudorandom sequence generators are based on one-dimensional chaotic reflections such as logistics, quadratic, and cubic. Researches have shown the undeniable advantage of logistical reflection. The construction of hidden communication systems using the deterministic chaos phenomenon is progressive issue nowadays. Several main stages should be carried out for achieving the goal. These are providing of the stability degree of synchronization between the drive and response generators of the transmitter and receiver respectively, investigation of chaotic oscillation to estimate the noise similarity and hardware design of communication system. It is known that the stable synchronization mode is needed for the quality level of data recovery. Therefore the basic conditions were computed for unidirectional coupled chaotic generators for the purpose of providing of generalized synchronization. To construct the communication system with high hiding degree first of all it is necessary to select the chaotic carrier signal the spectral and statistical characteristics of which were similar to noise. Using the obtained results the hardware prototype of hidden communication system was constructed
Background. Open multiservice network of telecommunications the Internet has become the most used source of such vital information as: scientific and technical, information, entertainment, and, especially, commercial. Today, it unites 3.36 billion users and provides high economic efficiency of human activity. However, there are many different technologies for accessing Internet services that compete with each other.Objective. The aim of the paper is to create the Internet network model and a content access model, as the main value of the network from the point of view of the end user, for building an effective network infrastructure.Methods. Analysis of all known publications on the construction and evaluation of Internet service quality parameters. Analysis of technologies for accessing the network and content. Synthesis of the model of formation and distribution of traffic between levels of the hierarchy of the Internet.Results. Enlarged indicators of Internet services provision were received. An enlarged scheme for building a global Internet network is proposed. Based on the generalized "end-to-end" scheme of user access to services and network resources, an estimate of the amount of sufficient access speed was obtained. The concepts of hierarchy level and gravitational coefficient are defined for which mathematical relations are derived.Conclusions. The main task of the providers of any level is to close the traffic as close as possible to the client, i.e. to reduce the gravity coefficient. The task of theoreticians and engineers is to determine theoretically the optimal number of levels (there were only three of them in the model in question) of closure or aggregation of traffic.
Background. Telecommunication systems with a broadband signal have improved noise immunity, the ability to receive a signal in multipath, as well as electromagnetic compatibility with neighboring radio electronic devices. The use of known pseudo-random sequences to create systems doesn't ensure their high confidentiality due to the possibility of their selection when receiving a signal. A significant increase in the confidentiality of the system can be achieved by using pseudorandom sequences based on chaos.Objective. The aim of the paper is the development of a technique for creating pseudo-random sequences based on chaos, as well as the analysis of the correlation characteristics of pseudo-random sequences formed on the basis of a chaotic signal.Methods. Chaotic signals are inherently pseudo-random, but they are generated by deterministic systems. All computer models of chaos are approximations of mathematical chaos. Any analysis of these sequences doesn't allow them to be reproduced and they can't be intercepted, so they have significant advantages when used for spreading the signal spectrum and creating a pseudo noise broadband signal. Sequence selection with an acceptable level of side lobes of the autocorrelation function is carried out by using the developed graphical interface method.Results. It is shown that, based on the chaos of pseudo-random sequences, it is possible to select sequences with side lobe level up to 0.3, suitable for practical use after analysis of their autocorrelation functions.Conclusions. Using created chaos based pseudo-random sequences is effective for building broadband single-channel telecommunication systems that have a high degree of confidentiality in the information transmission.
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