This study is devoted to radio wave propagation modeling in the urban environment. Special attention has been paid to the features of vehicular ad hoc networks (VANETs) and vehicle-to-infrastructure (V2I) communications. For the first time, the three-dimensional bidirectional parabolic equation (PE) method has been applied to the specified problem. Buildings and other obstacles are modeled by impenetrable (perfectly electric conducting) cuboids. A harmonic radiation source with an arbitrary direction pattern may be modeled. Numerical simulation is performed for various propagation scenarios. A comparison with the ray-tracing (RT) method is given. The results of the numerical simulation prove the effectiveness and reliability of the proposed method. Some recommendations for deploying VANETs are obtained based on the numerical results.

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8 ТРАНСПОРТ 05.22.01 -Транспортные и транспортно-технологические системы страны, ее регионов и городов, организация производства на транспорте; 05.22.08 -Управление процессами перевозок; 05.22.13 -Навигация и управление воздушным движением; 05.22.14 -Эксплуатация воздушного транспорта UDC 621.396.969.1The article considers the option of organizing joint processing of radar information in a multistatic rangefinder -doppler radar system. The least-squares method is used to obtain analytical expressions for oblique ranges and radial velocities of targets during joint processing of range-finding measurements of various types. The obtained expressions for inclined ranges have some similarities with the secondary processing of radar information, with the only difference being that the weighting coefficients for the evaluated parameters are updated in the case of successive measurements as data are received, and in the case of joint processing, they depend on the number of positions and the number of measurements. It is shown that the joint processing of measurements of the inclined range, the sum of the distances, the radial velocity and the rate of change of the total range allows to increase the accuracy of measuring the location of an air object and the projections of its velocity vector on the axis of a rectangular coordinate system. The physical basis for increasing the accuracy of positioning is to use redundant measurements by processing the total ranges. The considered option of processing redundant measurements in a multistatic radar system does not require time to accumulate data, and the task of increasing accuracy is solved in one measurement cycle. The potential accuracy of determining the location of an air object for different values of the standard errors of the determination of rangefinding parameters in a multistatic radar system at various distances between positions has been calculated. For an arbitrary trajectory of an air object, simulationstatistical modeling was performed, which allows to obtain the mean square errors of determining the location and velocity vector of the air object. A gain is shown in the accuracy of determining the location and velocity vector of an air object in comparison with traditional algorithms for determining coordinates in long-range multistatic radar systems.

The paper proposes a structure of self-organizing communication networks of the multi-robot system. The considered networks are organized on the basis of two radio channels: to transmit control (telemetry data) and to transmit data (video flow), which have the higher bandwidth requirements. The algorithm of self-organizing network is designed and presented based on the wideband channel quality control: data of the received signal strength indicator (RSSI), the capacity and the packet error ratio (PER).

Currently, in areas of large cities there is a steady trend towards an increase in the spatial density of telecommunications systems. Saturation of the radio spectrum with analogue and digital systems used to solve problems of radio communication and television allows on their basis improving the technologies for semi-active radar detecting and determining the coordinates of air objects. The introduction of radar surveillance using transmitters not intended for radar purpose is often called a semi-active radar using outside or “parasitic” emission sources. The advantages of the systems are the minimization of the deployment costs, low operational energy costs, a low probability of establishing distortions, stealth operation, environmental friendliness and lack of requirements for radio frequency resource allocation.  The relatively large elevations of the antennas of communication and television transmitters with the existing emitted power create favorable conditions for the detection of low altitude air objects. The digital signals of modern telecommunications systems have a spectrum width that provides acceptable resolution and accuracy for measuring the full range and angular coordinates. In general, a system of this type is a poly-static (multi-static) system consisting of one or more radiation sources and one or more receiving positions scattered in space. The promising task such systems solve along with airspace control is air traffic control. The article considers options for determining the rectangular coordinates of air objects in a system of bistatic radar stations using radio emission from external sources for target detection. The variants of the location of air objects with different composition of primary measurements of coordinates and a number of transmitting positions are considered. Analytical expressions are given for calculating the projections of the target velocity vector on the axis of the Cartesian coordinate system. The accuracy of airborne positioning for multi-static radar systems of this type is estimated.