Journal of Physics: Conference Series
(2021) 042096 IOP Publishing doi:10.1088/1742-6596/2131/4/042096 3 2. Materials and methods
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railway GSM-R AVAZ
2131 (2021) 042096
IOP Publishing doi:10.1088/1742-6596/2131/4/042096 3 2. Materials and methods The assessment of the reliability of the train radio communication network can be carried out using a complex indicator - the availability factor. Since the TRC network is a system consisting of many elements, then its readiness can be found, taking into account the availability factors of all elements of this system. These elements are: – command station (CS), – stationary radio stations (SRS), – portable radio stations (PRS), – wired channel (WC), – radio channel (RC). The listed elements of the PRS system correspond to the readiness factors: – equipment (SC – K SC , SRS – K SRS , PRS – K PRS ); – wired communication channel – K WC ; – radio channel – K RC . When assessing the availability factor of a wired communication channel, all failures are taken into account: conversion equipment, linear equipment, cable, power supply devices. The availability factor of a radio channel is determined by the radio coverage readiness – the probability that the signal level at the input of the receiver of a mobile radio station at a certain point of reception will be sufficient to ensure reliable radio communication. It is possible to organize communication channels of the following types between individual subscribers of PRS networks: 1 – train driver-– train driver; 2 – train driver– train station attendant; 3 – train driver– train dispatcher; 4 – train dispatcher – train station attendant. The most important and longest channel is the third type, that is, the communication channel between the train dispatcher and the train driver. It is used to control the movement of trains with guaranteed safety of train traffic. The structure of a communication channel of this type includes the largest number of elements in comparison with channels of other types. Since the elements of the train radio communication network, forming the channel between the train dispatcher and the train driver, are located sequentially, the value of the availability factor K of this channel will be determined by the product of the availability factors of all the network elements located sequentially: 𝐾 = К 𝐶𝑆 ⋅ К 𝑊𝐶 ⋅ К 𝑆𝑅𝑆 ⋅ К 𝑅𝐶 ⋅ К 𝑃𝑅𝑆 The values of the readiness factors of individual elements of the PRS network can be either specified in the relevant regulatory documents, or estimated experimentally (according to statistical data, if any) or calculated theoretically. So, the availability factors of certain types of equipment - radio stations, command stations, can be determined on the basis of the MTBF prescribed in the documentation for the equipment, as well as the permissible recovery time. The availability factor of wired channels in railway communication networks, as a rule, has a very high standardized value. This is achieved, among other things, through the widespread use of technical diagnostics of the telecommunications network, multiple reservation of information transmission routes, the use of effective methods of protection against cyber attacks [8-15]. The availability of a radio channel, described by the coefficient of availability of the channel for radio coverage, can be found from the results of measurements of the dependence of the signal level at the input of the mobile radio station on the track coordinate, carried out using a laboratory car. The second method for determining the availability factor for radio coverage is a theoretical calculation, which can be performed using the industry-wide methodology for calculating the characteristics of a technological railway radio communication channel in force in Russia. Intelligent Information Technology and Mathematical Modeling 2021 (IITMM 2021) Journal of Physics: Conference Series 2131 (2021) 042096 IOP Publishing doi:10.1088/1742-6596/2131/4/042096 4 A feature of train radio communication networks from the point of view of calculating the availability of communication channels is the dependence of the composition of the channel elements on the location of the mobile subscriber, that is, the mobile radio station. In this case, some of the elements - a command station, a wire channel (in the general case), a mobile radio station - remain unchanged elements with constant availability factors, and some of the elements - stationary radio stations, a radio channel, change during the movement of a mobile subscriber along the railway section (Figure 3). In other words, we can assume that when the mobile radio station moves along the railway section, the virtual key switches, sequentially creating a communication channel between the mobile radio station and each next stationary radio station located along the section. Download 1.22 Mb. Do'stlaringiz bilan baham: |
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