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Background. At present, the demand in tropospheric over-the-horizon communication systems determines the inherent advantages of these systems over satellite and radio-relay systems of direct visibility, especially in combat and emergency situations. Although the fundamentals of the theory of tropospheric scattering were developed as early as the middle of the last century, the development of over-the-horizon systems requires constant refinements of known theoretical positions in accordance with new data on the nature of tropospheric scattering, atmospheric inhomogeneities, capabilities of new methods for calculating and estimating radio propagation. Objective. The aim of the work is to develop a radio link model of a trans-horizon tropospheric communication to study the possibility of controlling (improving) attenuation on such a route by changing the electrophysical characteristics of the environment, in particular atmospheric turbulence, or using artificial formations in the atmosphere. Methods. The created model is based on the Ray-tracing method. Results. A model of radio link losses in the over-horizon tropospheric communication (long-range tropospheric propagation) was developed, based on the ray-tracing technique in two versions: simplified, with homogeneous layers, and full, with a combination of blocks of structures of scattering spheres in each of the layers. A study of the possibility of improving attenuation along the tropospheric scattering pathway by regulating changes in the electrophysical parameters of inhomogeneities and artificial formations in the atmosphere was conducted. Conclusions. The convergence of the results of the simulation with the data obtained by known / traditional analytical models for calculating the losses on the tropospheric scattering path confirms the adequacy of the proposed model to the statistical data of the real losses in tropospheric scattering. The obtained results indicate that, for practical purposes, the accuracy of calculations of the loss characteristics is sufficient and that they can be used to form a tropospheric dispersion route with significantly reduced loss values by artificially adding a certain liquid or solid substance to the atmospheric heterogeneity.

Mathematical models of the signals peculiar to communications using the autocorrelation reception of the shift-keyed noise signals are suggested in the present paper. System performance is investigated and the particularities of the bit error probability dependence upon the normalized signal-to-noise ratio and the bandwidth-delay product are revealed. The definition of the optimal value of the signal-to-noise ratio upon power is substantiated and the relevant values are calculated. The performed comparative analysis proved that the communication using the differential noise shift-keying, within which total time delay diversity is applied between the reference and the data signals, possesses the best system performance among the communications considered in this paper.

Background. An increase in the number of users and services with the support of the required quality of service, an increase in the coverage area of one operator's radio access network, and most importantly, the emergence of packet-switched technologies and systems, has led to a significant complication of the core mobile communications network and its nodes, an increase in the functionality and intellectualization of the network core. Gradually, it was the core network and the technologies of its functioning that became more significant than the radio access network. Hence, for the construction of mobile communication systems, more integrated information and telecommunication technologies, especially from the field of network and information technologies, became popular. Objective. The aim of the paper is to present the concept of the architecture of mobile infocommunication systems as systems whose services make a significant, even decisive, contribution to the functioning of the infrastructure of modern society, built on the constant exchange and assimilation of information. Methods. The structural and functional methods of constructing the architectures of information and telecommunication systems are investigated. Results. The signaling network of mobile infocommunications manages the maintenance of both individual wireless user terminals (telephones, smartphones, tablets), and many wireless inter-machine communication devices and the Internet of Things. In addition, the same alarm system supports various telecommunication networks of wireless subscriber access, automobile and other vehicles; creates an interface with wired / cable access networks. Thus, the core network of mobile infocommunications can fully integrate interfaces with all types of telecommunications, which are designed to transmit many low-speed data streams, as well as to transmit high-speed data streams. There is a tendency to take over traditional old services, for example, the public telephone network and radio-relay communication lines, and turn them into private services of the mobile infocommunication network, which further enhances their importance. All this creates the prerequisites for the transformation of mobile infocommunication operator systems into the main (determining) players in the telecommunications market. Confirmation of this is the high characteristics that are to be achieved in the networks of the 5th and 6th generations of mobile infocommunications. Conclusions. Mobile infocommunication systems have become a defining component of all telecommunication services provided to users and non-servicing nodes of sensor networks, and the infrastructure of core networks and access networks of mobile infocommunications has begun to determine the general technical infrastructure of telecommunications.

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