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The results of an experiment on measuring the characteristics of a radio signal at the input of mobile base stations of local Wi-Fi networks of an electric train on the railway are presented. The analysis of the results of the experiment carried out in the laboratory of MaximaTelecom JSC using Channel Emulator CH01 (RadioGigabit) device, together with the base stations Fruidmesh 4800. The analysis of the qualitative characteristics of signals at the entrance of the train base stations in tunnels and in open areas is given. Based on the obtained graphs, it is concluded that it is necessary to study the effect of the handover on the decrease in the input signal level, an increase in the probability of error (BER), as well as the number of retransmissions and a decrease in the channel speed. Significant fluctuations of the channel velocity in open areas due to the phenomenon of multipath propagation of radio waves are noted. All these factors create time delays for transmission of information and negatively affect the efficiency of train traffic management. The methods of reducing duration of the handover and reducing the influence of multipath are offered. [ABSTRACT FROM AUTHOR]

The article substantiates the need to switch to wireless channels of the optical range for communication with mobile objects. The relevance of the topic is due to the growing need to increase the speed of information transfer. This is due to the introduction of unmanned technologies in railway transport, which involve a constant exchange of data between the rolling stock and the traffic control center. The limited capacity of radio channels does not allow remote control of trains. This problem can be solved by switching communication channels with mobile objects to the optical wavelength range. To implement projects for the introduction of wireless optical communication, it is necessary to ensure the required range and quality of communication. This problem can be solved by increasing the optical budget of the wireless optical communication channel (BOX) by increasing the sensitivity of the photodetectors and the corresponding signal-to-noise power ratio. This way is more rational than increasing the laser power. For this purpose, the article proposes to use new nanoelectronics materials based on enriched semiconductors. As evidence, the results of studies of the influence of the concentrations of heavy isotopes on the band gap of semiconductors, as well as the light absorption coefficients and quantum efficiency are presented. Calculation of the communication quality in the form of the error probability of an elementary pulse at the output of the photodetector showed that enriched materials in the form of multiple quantum wells provide the error probability by two orders of magnitude less than natural semiconductors. Thus, the obtained gain in the signal-to-noise ratio at the output of the photodetector due to new materials can be used: a) to improve the quality of communication, which is important in conditions of atmospheric interference; b) to increase the communication range, which is important for a moving object. [ABSTRACT FROM AUTHOR]