The Model of the Communication Channel with Mobile Objects using

the Temporary Switch

I. Knyshev and D. Saprykin

Russian University of Transport, Moscow, Russia

Keywords: Telecommunication network, radio network, information, subscriber, activity, telecommunication network

structure, communication channels, fault endurance, technological process.

Abstract: The article is devoted to the consideration of the dynamic model of the train communication radio channel

(PRS). A block diagram of the model, a temporary switchboard (VC) taking in account the nature of the

movement of subscribers, expressions for reliability parameters are presented and described, comparative

calculations with the traditional calculation method are presented, ways to increase the reliability of the PRS

network are presented.

1 INTRODUCTION

During recent years, the argument that information

technologies have the most direct impact on the state

and the development of the economy has become

almost universally recognized. The computer world

became networked decades ago. The network

infrastructure makes it possible to quickly exchange

data and access information resources, both at the

local level and on a global scale. The problem is the

weakness of the telecommunications infrastructure.

In many cases, the use of wired or fiber-optic

communication lines is impossible or economically

impractical. In this situation, one of the most effective

solutions to the communication problem, and often

the only possible one, is the use of radio data

transmission networks.

2 MANUSCRIPT PREPARATION

The traditional variant of the wireless communication

is the conventional communication systems, which

are implemented by the radio stations that are not

integrated into any technical system that provides

resource management, signaling and other

coordinating procedures.

Today, a lot of conventional radio systems are in

operation around the world. The systems of this type

have been, and continue to be, the most popular type

of terrestrial mobile radio communication systems.

Due to the simplicity of implementation,

conventional systems are widely used to solve the

mobile communication problems, which are built on

the principle of "point-to-point" and "star" (with a

base radio station) without access to public telephone

networks.

GSM-R technology, described by the European

Telecommunications Standards Institute (ETSI TS)

in ("Russian Railways", 2011), makes it possible to

transfer train and manoeuvre radio communications

to a new powerful unified digital system platform and

is designed to replace a lot of different heterogeneous

radio communication systems.

GSM-R equipment allows for continuous

communication between the driver and the dispatcher

at a rolling stock speed of up to 350 km/h and

therefore allows you to remove one of the main

barriers to the creation of high-speed trains. GSM-R

integrates with GPRS to provide packet-based

switching services. Thanks to this, it is possible to

receive real-time telemetry information from any

locomotive, any station or stretch of road.

Information about the location and speed of the train

is transmitted via the GSM-R network to the control

centre, which will fully automate the process of

regulating train traffic. The use of such a system in

the passenger complex will greatly increase the safety

of passenger transportation.

Separately, it is worth noting cellular radio

communication solutions based on the DMR

standard. The first release of the standard was

released in 2005 (Digital Mobile Radio (DMR)

124

Knyshev, I. and Saprykin, D.

The Model of the Communication Channel with Mobile Objects using the Temporary Switch.

DOI: 10.5220/0011580100003527

In Proceedings of the 1st International Scientiﬁc and Practical Conference on Transport: Logistics, Construction, Maintenance, Management (TLC2M 2022), pages 124-128

ISBN: 978-989-758-606-4

 2023 by SCITEPRESS – Science and Technology Publications, Lda. Under CC license (CC BY-NC-ND 4.0)

Systems, 2019) describing the radio interface (Part 1),

as well as the voice and basic functional features of

the standard (Part 2). The third part of the DMR

standard was added, describing the packet data

transmission protocol.

Now the network of JSC "Russian Railways" is

transposed and uses equipment for various purposes:

base radios, automatic telephone stations (ATS),

multi-level multiplexers, spectral compaction

equipment, packet switching equipment, servers of

various architectures, both cable and fiber-optic

communication lines. For the security purposes,

equipment from various manufacturers has been

introduced. The combination of embedded

communication devices forms a huge communication

structure.

One of the most important parameters of

communication systems is the reliability of

information exchange channels between subscribers.

The reliability parameters become important in

communication systems with mobile subscribers,

when messages, commands and data used in the

process of controlling the movement of objects are

transmitted through the channel. In this regard, the

question of determining reliability indicators when a

subscriber moves in such a large and diverse network

arises acutely.

Previously, reliability indicators were determined

by the classical method. The most important

characteristics of the communication channel are

known: failure rate, operating time for failure,

recovery rate, etc. When determining reliability, we

relied on the prerequisites specified in (Almazyan,

2011). The radio network was a closed system, the

elements of which are homogeneous in parameters.

The reliability scheme of the PRS network shown

in Fig. 1 clearly shows the fundamental elements of

the reliability of the train dispatcher–driver

communication channel (DNC-PM). The network

structure is radio conductive. The administrative

station (AS) of the train dispatcher (DNC) is

connected to the base stations (BS) of each station

attendant (DSP) via a wired communication channel

(CC). The radio stations carried on mobile units (PS)

establish the connection of the driver (PM) with the

BS via the radio channel (RC) throughout the entire

dispatching section (circle).

The classical approach in (Almazyan, 2011;

Roenkov, 2017) to determine the reliability of the

communication channel is based on a static model,

which includes all the elements forming the

communication channel, and when the subscriber

moves and changes the elements of the model or its

parameters, this is reflected as a set of model variants.

According to (Rules of technical operation of

railways of the Russian Federation, 2010), DSP-PM

radio communication should be provided on the entire

stretch adjacent to the station. This leads to a

complete overlap of communication zones on all

stages of the dispatch circle.

Figure 1: Probabilistic model of the PRS network for

calculating the value of the traditional radio network

availability coefficient.

In (Almazyan, 2011), it is proposed to define



as one of the reliability parameters of the

DNC-PM channel as follows:



=1−

(

1−К



)

−

(

N−1

)(

1−K



)



(1)

In view of such large-scale systems, it is incorrect

to determine reliability by the traditional method due

to the movement of the subscriber, and it is necessary

to introduce an amendment for the duration of the

locomotive radio station's stay in the service area of a

particular BS and the influence of only this BS on

reliability indicators. In (Knyshev, 2021), it is

proposed to use a dynamic definition of reliability

that takes in account the subscriber's schedule.

According to the study of signal levels in the work

(Almazyan, 2011; Roenkov, 2017; Knyshev, 2021a),

it is proposed to delimit the service areas and present

them in the form of cells to simplify calculations, as

shown in Fig. 2.

Figure 2: Base station service areas.

To reflect the subscriber's transition from one BS

zone to the service zone of another BS in work

(Knyshev, 2021b), it is proposed to include a virtual

switchboard (VC) in the reliability model, which

The Model of the Communication Channel with Mobile Objects using the Temporary Switch

125

switches the BS serving the subscriber in accordance

with the subscriber's traffic schedule. The block

diagram of the PRS network using VC is shown in

Fig. 3.

Figure 3: Dynamic model of the PRS network using VC to

calculate the integral value of the radio network availability

coefficient.

The principle of time switching is to move the

subscriber from the coverage area of one BS to the

coverage area of another with the implementation of

the "handover" procedure. In other words, this is a

temporary shift of the subscriber's position. At each

moment of time, the territorial information of the

identified subscriber is transmitted. If this

information is transmitted to another BS, then this

means moving the subscriber to the area of operation

of another BS. An element of the reliability model

that implements the principle of time switching is

called a virtual switch VC. The virtual switchboard is

characterized by such parameters as: the number of

base stations, respectively, the number of radio

channels connected to the VC inputs, the number of

switched portable radio stations connected to the VC

outputs, and the subscriber traffic schedule that

determines the switching order. An example of a

traffic schedule is given in (Knyshev, 2021).

Thanks to the handover, the subscriber is not tied

to a specific BS, but is given the opportunity to move

within the coverage area of the radio network without

disconnecting the connection. When moving a

subscriber in existing conventional networks, the VC

does not have a technical implementation of such a

procedure and is due solely to the movement of the

PS.

In the case of cellular systems that implement the

handover procedure, there is a corresponding piece of

software and hardware that implements the switching

of the subscriber station to another BS.

There may be several reasons for the need to

implement a handover:

− moving the subscriber to the service areas of

different BS,

− when the current BS cell is overloaded,

subscribers are transferred in the overlap zone

to the neighboring BS, freeing up the capacity

of the current BS cell for subscribers with

whom it is possible to maintain communication

only within the boundaries of this BS,

− when the communication channel of the BS

used is noisy,

− when the subscriber's movement speed changes

(the subscriber's speed is directly proportional

to the cell of the larger area).

Depending on the reason, it is customary to

distinguish several types of handover:

− Within one BS.

− In case of failure or overload of one of the

transceivers within one sector.

− Between sectors that screw up one BS.

− Between several BS.

− If one of the BS controllers or the BS itself fails

inside one automatic telephone exchange

(ATS).

− If the ATS malfunctions, the load is transferred

to the nearest ATS with the ability to service

the necessary zones.

− With BS of various cellular communication

standards.

Depending on the reason, the type of handover

and the network standard, various analyses are

already being put forward to the reliability indicators

of load switching (subscribers). The handover

procedure can be accompanied by failures, failures

and can be characterized by a certain probability of

success or failure, which also provides for a

temporary VC switch of the model presented in Fig.

The value of the readiness coefficient of the

communication channel on the entire trajectory from

point A to point B can be determined by the weighted

sum of КrBSi for all values of i:



= К









. (2)

The weighting coefficients γ



are defined as the

fraction of the time Δt

of staying in the service area

of the total time T of moving from point A to

point B:



∆t



, (3)

where Δt

– time spent in the BS

service area;

T – full driving time from p. A in p. B.

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According to the traffic schedule, the total travel time

T is determined, and it is also possible to calculate the

time spent in the BS

service area.

As a rule, the subscriber is given a certain speed

of movement on each stage, which he must observe.

It is possible to determine the total time of movement

of the rolling stock T . The dependence v

(

)

expressed analytically.

T=

(

)







+t







, (4)

where r – the whole way of the subscriber from p. A

in p. B;

v(r) – the dependence of the subscriber's movement

speed on its trajectory;



– total time of stops in the BS

zone.

In this case, the weighting coefficients γ



will take

the following form:







v(r)

dr +









t







, (5)

where r



и r



– define the BS

service area.

As an explanation, it makes sense to consider an

example of the simplest dependence v

(

)

with

significantly different speeds of several subscribers.

On railway transport, it can be a passenger train and

an express train. We will use a hypothetical section

for the movement of trains with outdated equipment

of communication systems and equipment that is

planned to be installed on this section in the future.

For clarity, we will determine the reliability

indicators by both the traditional method and the one

proposed taking in account the subscriber's

movement.

Section A-G is equipped with RS-46MC base

stations. It is planned to modernize the section of the

RVS-1-46 radio station. Let's make calculations for

two variants of the site:

− option 1 – only RS-46MC type BS are installed

on the site, each of which has a failure time of



=7000 hours;

− option 2 – partial modernization and more

modern BS of the RVS-1-46 type have already

been installed at some stations (B, C, D),

having an operating time for failure Т



45000 hours.

As portable radio stations for both options, we

will use radio stations of the RV-1M type with a

failure time of Т



= 8000 hours. The readiness

coefficients of radio stations are shown in table 1

when the recovery time t



= 5 hours.

Table 1: The availability coefficients of the specified radio

stations.



,hours



0.999286



0.999889



0.999375

Table 2 shows the schedules of a passenger train

with all stops and a fast train (express), respectively.

For convenience, the train schedule is presented in the

form of a table.

Table 2: The train schedule.

Distillation Distance,

Driving

time, min

Parking,

min

Passenger train

A-B 7 11 3

B-C 8 11 2

C-D 11 14 2

D-E 13 17 3

E-F 9 11 1

F-G 10 12 1

Express

A-C 15 15 3

C-E 24 22 1

E-G 19 17 1

Additionally, for example, let's take a freight train

moving non-stop from the station A to the station G

with an average technical speed of 40 km/h (travel

time 1 hour 27 minutes)

The time spent in each service area is determined

as the sum of the ratio of the distance traveled in this

zone to the speed of movement along this section and

parking time. The calculation is performed in a

written program in the high-level programming

language Python. The results of the calculations of

∆𝑡



and 𝛾



are summarized in table 3 for each of the

variants, respectively, additionally К



is given for

each BS.

According to the weighted formula, the results of

the coefficients of readiness К



on the section from

st. A to st. G for passenger trains, express trains and

freight trains are summarized in table 4.

Since the radio stations carried on each train are

the same, the static reliability coefficient of the A – G

section, calculated by the method (Almazyan, 2011),

will be the same for any type of train.

For all basic radio stations of the RS-46MC type

(the first option) static К



= 0,999372 , in the

mixed case (the second option) К



= 0,999375.

The obtained values coincide with the results of

determining reliability by static (classical) methods,

The Model of the Communication Channel with Mobile Objects using the Temporary Switch

127

which is to be expected in a network with identical

parameters of all elements.

Table 3: The results of the calculations of ∆𝑡



and 𝛾



for

integral parameters

№

∆𝑡



,ч 𝛾





tion 1



tion 2

Passenger train

1 A 0,09167 0,0625 0,999286 0,999286

2 B 0,23333 0,15909 0,999286 0,999889

3 C 0,24167 0,16477 0,999286 0,999889

4 D 0,29167 0,19886 0,999286 0,999889

5 E 0,28333 0,19318 0,999286 0,999286

6 F 0,20833 0,14205 0,999286 0,999286

7 G 0,11667 0,07955 0,999286 0,999286

Express

1 A 0,05444 0,05632 0,999286 0,999286

2 B 0,11667 0,12069 0,999286 0,999889

3 C 0,19625 0,20302 0,999286 0,999889

4 D 0,18333 0,18966 0,999286 0,999889

5 E 0,18308 0,18939 0,999286 0,999286

6 F 0,14167 0,14655 0,999286 0,999286

7 G 0,09123 0,09437 0,999286 0,999286

Table 4: The availability coefficients of the specified radio

stations.

№ option Passenger

train

Express Freight

train

1 0,999286 0,999286 0,999286

2 0,999601 0,999596 0,999588

3 CONCLUSIONS

The integral values of the operating time for the

failure of Т



and К

, and, especially, the influence

of the subscriber's movement, will largely depend on

the ratio of the failure rates of the model elements in

Fig. 3. So, if the RV-1M radio station with Т



8000 hours is used as a locomotive, and the RVS-1 or

RLSM-10 with Т



= 45000 hours is used as a BS,

as well as with digital, highly reliable CP and CC

equipment, then the reliability of the train dispatcher's

communication channel will be almost completely

will be determined by the parameters of the PS radio

station. The situation seems more realistic when a

subscriber of the Russian Federation has a highly

reliable radio station, BS are implemented on

different types of radio stations (partly on RS-46MC

with Т



= 7000 hours, partly on RVS-1 or RLSM-

10). In this case, the influence of the subscriber's

movement will affect significantly.

An example of calculating the dynamic

coefficient of readiness for a different site is

presented in (Knyshev, 2021c). The qualitatively

obtained results are identical: integral reliability

parameters more accurately reflect the reliability of

communication systems.

Theoretically, by changing the subscriber's

schedule and increasing the speed of movement in

areas with low reliability of equipment (BS), it is

possible to increase the integral reliability parameters

of the system.

REFERENCES

Technical requirements for the digital system of

technological radio communication of the GSM-R

standard of the Open Joint Stock Company "Russian

Railways", 2011.

DMR - ETSI TS 102 361 v1.10.1. Electromagnetic

compatibility and Radio spectrum Matters (ERM);

Digital Mobile Radio (DMR) Systems, part 1, 2, 2019.

Almazyan, K., Verigo, A., Knyshev, I., 2011. Reliability of

train radio communication channels. Proceedings of

JSC "NIIAS" 9, pp. 175-184.

Roenkov, D., Shmatchenko, V., Yaronova, N., 2017.

Automation, communication, computer science 7, pp.

22-27.

Rules of technical operation of railways of the Russian

Federation, 2010. Order of the Ministry of Transport of

the Russian Federation.

Knyshev, I., Roenkov, D., Saprykin, D., 2021. Automation,

communication, Informatics 10, pp. 35-38.

Knyshev, I., Saprykin, D., 2021a. The reliability of

channels in communication networks with mobile

subscribers, p. 227.

Knyshev, I., Saprykin, D., 2021b. The reliability model of

a communication channel with mobile objects,

International Scientific and Practical Conference

«Railway transport and technologies, RTT 2021)».

Knyshev, I., Saprykin, D., 2021c. The reliability of

channels in communication networks.

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CONSTRUCTION, MAINTENANCE, MANAGEMENT

128