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Магистр ДонНТУ Чепак Виталий Сергеевич

Chepak Vitaliy

Faculty: "Computer Information Technologies and Automatics"

Department: Automatics and telecommunications

Speciality: The telecommunication systems and networks

Theme of master's work:

Research of mechanisms that providing reliability in transport telecommunication networks of millioneires-cities

Leader of work: associate professor Vladimir Chervinskiy

• Biography •

The abstract on a theme of final work


Introduction

Now there is an intensive growth of telecommunication services. There are the increase in number of users Internet, building of corporate networks and data storage networks, service introduction «Video on request» – demands pass-band expansion in a transport network of a city. Telecommunication systems of transfer digital hierarchy (SDH – Synchronous Digital Hierarchy) were a technical basis for construction of a transport network until recently. However the intensive way of development of the given technology practically has approached to the end, having stopped at speed 40 Gbit/with, that speaks dispersion presence in a standard optical fiber on which are constructed the majority of networks. It is essential to increase throughput the technology of multiplexing on length of a wave (WDM), at the expense of expansion of width of a strip of transfer by increase in number of channels is called.


Theme urgency. Reliability of a transport telecommunication network is the same important indicator as durability of the base of a building. Providers, service providers and operators of communication networks aspire to raise an indicator of reliability of work of a telecommunication network, that is ability of a network to carry out functions of transfer with reliability, the established norms during long time. Modern city transport telecommunication networks transfer a significant amount of the information with high speed, therefore even short-term breaks of communication conduct to loss of a considerable quantity of the information. Thus, working out of methods of increase of reliability in optical networks is actual for today.


The scientific importance of work. During work optimum methods of maintenance of reliability will be developed: efficiency of introduction of systems WDM is proved, the analysis of schemes of reservation is carried out and the algorithm of reservation on the basis of the P-cycle is offered.


Practical value of results of work consists in application of more effective methods of increase of reliability at designing new or modernisations of existing city transport networks (METRO), that will allow to use more rationally resources of a network and to minimise financial expenses for its construction and service.

The basic results

According to recommendations ITU-T G.602 as reliability understand property of a communication system to keep in time in the established limits of value of all parametres characterising ability to carry out demanded functions in set modes and conditions of application. The basic quantitative characteristic of reliability is the readiness coefficient.

                         Kr = To / (To+tв)                                (1)

Where To – an average time between failures (MTBF), and tв – average time of restoration of an efficient condition.

Reverse value is the coefficient of the compelled idle time (unavailability coefficient) Кп is a probability of that the system will not be efficient during any way chosen moment of time

                            Kп = 1 - Kr                                      (2)

It is visible from the formula (1) , that the factor of readiness of system can be improved by increase in indicator MTBF or reduction of time of restoration of working capacity. Reliability of devices can be improved by use of highly reliable devices, or redundancy of the equipment, or both that and another. However, to make an estimation of reliability of a network it is necessary taking into account all its components. In process of increase in complexity of a communication system the probability of refusal any of its components increases. Modern communication systems use a considerable quantity of elements that does necessary use of reservation and roundabout routes for increase of factor of readiness of a communication system as a whole. We will consider the basic ways of increase in an indicator of readiness of a network.

REFERENCES

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