This need is particularly pressing when businesses turn to e-commerce. However, network upgrades are generally complex and costly, and may require temporary shutdowns of existing services and reduce user productivity, incurring additional costs.

Before undertaking the modernization of the network, it must be justified. Instead of installing new gizmos every time a technology change or a vendor is offered, maybe it's better to wait until the users have a need for it or when the new system will reduce costs?

Unfortunately, there is no universal formula to justify network upgrades. "Planning a network and justifying its upgrade is more of an art than a science," said David Rinas, president of DJR Communications, a network service planning and project management consulting firm.

In this article, I will try to explain some of the techniques of this art and the methods of this science, as well as list the objective indicators of the need for modernization. Sometimes it is impossible to tell whether the business determines the technology, or vice versa. Often the process of network modernization develops under the influence of both trends. I will start by looking at technical reasons and continue with commercial considerations.

TECHNICAL REASONS

The need for increased speed is probably the most common reason for network upgrades. It can lead to equipment upgrades, such as routers or the channels themselves. If the network performance is insufficient, then the first thing to do is to find out the level of congestion of the channels.

As a rule of thumb, it is usually accepted that the capacity of a link or interface should be increased when its load level reaches 70%. If the bandwidth of the channel is sufficient, then the reason may lie in the adequate performance of the equipment.

First of all, attention should be paid to old equipment, in particular bridges between local networks. In this case, the best solution is to replace the equipment, rather than upgrading it.

However, bottlenecks are often the result of increased traffic or pressure on systems such as servers or routers that previously performed well. The answer to the question of whether it is better to upgrade or replace such systems depends on the cost of each of the solutions and its impact on the supported services. Both paths should be considered to determine which kind of upgrade is most justified.

For example, turning off the server for the weekend to increase the volume random access memory or installing another NIC will not result in noticeable downtime, will be inexpensive and almost always justified. However, when the upgrade has more significant implications for service continuity, such as moving a LAN from a compact hub/router based backbone to a switched environment, then such a decision should have a strong justification - preferably supported by an implementation plan.

In addition, inadequate performance may be due to long network latency. Delays can be caused by slow hardware or links, or inefficiencies in network protocols or application services, such as slow message processing by the SMTP server.

It is possible to solve these problems through modernization, but the process itself can be quite tortuous and time consuming. The rationale often boils down to a "whether or not it's worth doing" economic benefit analysis, taking into account both business goals and ease of use.

In other cases, the delay may be due to the need for format conversion, firewalling and access control, or even long distances between endpoints. Security functions and format conversion require hardware implementation. In this case, the cost of the upgrade will be difficult to justify without an economic benefit analysis.

Transmission delay due to geographical distance, say across the Atlantic or via satellites, cannot be eliminated unless you can find a faster-than-light network.

The need to make changes to the network can be caused by other reasons, in particular, the need to ensure the interaction between networks and systems when two companies merge. In this case, everything is determined by the requirements of the business.

Another motivation may be the need to eliminate recurrent or chronic problems in the operation or management of the network. Such an upgrade can usually be justified by improved service and reduced network maintenance and management costs.

The incentive to upgrade may also be the desire for new administrative capabilities. Simplifying network maintenance is a good reason to purchase administrative tools such as desktop inventory software. To further reinforce it, modernization can be linked to tangible benefits such as improved procurement.

The need to standardize the computing environment for the implementation of planned applications or services may also require modernization. In this situation, justification is usually not a problem: a standard environment will optimize procurement, reduce maintenance and training costs, and simplify the provision of required services.

Finally, the need to meet certification requirements or resolve contentious issues identified during a network audit may also require modernization. With the proliferation of corporate extranets, remote access services, VPNs, and inter-organizational communications, these special requirements are becoming fairly common. In such a situation, the need for modernization is caused and justified by the desire to look in the eyes of others as a “safe” and reliable partner.

“If an audit finds a problem with the network, it will need to be fixed, but this may entail the need for upgrades and further costs,” says Eric Despres, director of network services at GENet, a Canadian government network management company (see sidebar) .

Often the upgrade of one network element necessitates the upgrade of associated network infrastructure elements. For example, if the LAN is upgraded to 100 Mbps Ethernet and appropriate NICs are installed on all user systems, this may require a server upgrade as well.

One example of how this kind of coupled upgrade might be needed can be found in the proposed QoS classes for IP-based networks, Despres said. As network capacity increases enable new applications that require QoS guarantees, service providers “will need more powerful measurement and control tools to paint IP packets according to the sender's QoS expectations,” says Despres. In this case, the justification may be the need to comply with service level agreements (Service Level Agreement, SLA).

However, the implementation of QoS in existing network will result in a 20% increase in traffic overhead and a significant impact on the overall performance of the gateway devices. Moving to a modern, more efficient internetwork infrastructure can compensate for these losses while maintaining QoS and improving overall service.

FACT-FINDING

The collection, comparison and analysis of the functional parameters of the network is extremely important for making a practical justification for the modernization of the network. There are many network monitoring and data collection tools on the market. In most cases, you will need a whole set of these tools, each designed to perform a specific function or target a specific set of products.

For example, if your network contains Hewlett-Packard servers and Cisco Systems routers and switches, then you most likely have Cisco Works and HP OpenView. If the network is based on Compaq Computer and Nortel Networks equipment, then you will probably use Insight Manager and Optiivity.

In each of these examples, the collected metric reveals factors such as traffic between switches, link congestion, utilization of ports or links on switches or routers, logical data flows (from to where), and overall network load. Other parameters that can be defined may include transmission error rate, server load level, etc.

Which product to choose and which parameters to monitor will depend on the network infrastructure and what you want to find out first. For example, Chandler Pidgin, a network administrator at NAV CANADA, a private corporation that provides navigation and related services, says that if even one of the company's switches exceeds 50% per minute of port utilization, then this is a wake-up call for them.

Port traffic monitoring allows Pidgin to identify trends and determine whether an upgrade or a simple reconfiguration is needed. When an upgrade is needed, the collected statistics, including how performance changes over time, are used to plan and justify the upgrade.

One of the problems in making such decisions is the lack of knowledge. "Most people don't know how much a network costs them, so they often waste money," says Terry McMillan, a communications network management consultant.

To monitor the network and collect current and statistical data, you must do the following.

First, determine what kind of information you need and how it should be presented. For example, if you need to monitor SNMP alerts from routers and generate daily reports, then the toolkit you choose should meet these requirements and be configured to present different views.

Secondly, determine what and how you will monitor. For example, if it is important to have a detailed real-time picture of the operation of a particular switch, then you will need to install RMON probes and filters to send data to the central network management console.

Next, find and integrate the required set of tools. This advice looks trivial, but the process itself can consist of a whole range of modernization and justification measures. “Most IT departments would like to be able to determine specific costs for network elements. They need a costing tool in addition to monitoring tools,” MacMillan says.

In addition, it would be nice to compare the collected statistics with some basic indicators. This will help to distinguish random deviations from long-term problems that require intervention.

Finally, keep an eye on trends and plan ahead for necessary upgrades. For example, if a 10Mbps Ethernet hub is over 35% occupied, it's time to start planning for an upgrade. In a switched environment with 100 Mbps links, negative trends are likely to affect only certain switches or links. In such an environment, a 50% occupancy level can serve as a signal for the need for modernization.

Trend detection and proactive planning are essential to ensure the proper functioning of the network, especially for service providers. "They can't respond quickly enough to requests for service or troubleshooting," MacMillan said. “When organizing a new channel, the provision and configuration of the service can take several weeks, and this delay remains in the memory of the customer.”

DEVELOPING A PRACTICAL RATIONALE

At some point, you will definitely face the question of the advisability of upgrading from the point of view of the company's business goals. A practical rationale usually asks three questions: Will the upgrade save the company money, will it help the company make money, and will it improve the company's competitiveness?

In many organizations, especially in the high-tech industry, IT budgets are allocated according to a zero-based budgeting model. This means that any major network upgrade is justified and funded based on specific current needs. Thus, justifying the need for modernization without the involvement of a supporting business model becomes even more difficult.

The intricacies of business cost modeling are beyond the scope of this article, but understanding the basics will help you back up your modernization case with an acceptable one. pricing model. In this section, we'll talk about cost analysis, Total Cost of Ownership (TCO), productivity measurement, and return on investment (ROI).

One of the popular and relatively simple methods is a cost analysis that compares the total cost of an upgrade with the expected benefits. If the cost of upgrading looks acceptable, then you can proceed with it. In the cost analysis, it is also important to consider the consequences of abandoning the proposed upgrade model or undertaking another upgrade. Thus, you will need to simulate several scenarios and analyze for each of them.

According to Rinas, another key to successful cost analysis “is to assess and identify benefits in areas that you are familiar with.” In other words, do what you know, and if you need help, don't be afraid to ask for it.

To determine what the project costs will be, you will need to figure out the total cost of ownership, taking into account the cost of upgrades, ongoing operations and maintenance, etc. The total cost of ownership is different for each network, so you will need to collect information about the costs specific to your network. In addition, you should consider what the total cost of ownership means for your organization.

Many total cost of ownership models only consider the cost of network equipment, which can lead to misleading conclusions. For a more accurate estimate of TCO, you should also consider the initial capital cost of upgrading the network, including the cost of hiring consultants, training, and contracting.

Don't forget to factor in operating and maintenance costs. These include staff salaries, rent for premises, utilities and other services, insurance, fines for non-fulfillment of obligations and shortfall in profits.

In addition, you will need to consider how the upgrade will affect productivity. In the worst case, you will have to calculate the losses in case of an unsuccessful upgrade. Generally speaking, increasing productivity is often main goal upgrades, so you may need to find examples of performance gains from a similar upgrade.

For example, to characterize network-dependent user productivity, you could count the number of daily calls with questions about network performance. If, after the upgrade, users began to ask questions less often, then productivity has obviously increased. If, in addition, you can identify and measure several of these parameters, then this will allow you to more clearly characterize the increase in productivity.

Finally, the last criterion for the practical expediency of modernization is the return on investment. Ideally, ROI serves as a measure of capital gains resulting from network upgrades. It cannot always be accurately measured, but - as shown below - the calculation of the return on investment in technology usually takes into account the main costs compared to the main income and savings.

The basic formula is something like this: return on investment = (associated savings on operating costs + increase in revenue from services) - (initial cost of modernization + financial costs + operating costs for a given period).

Similarly, the amortization period for ROI can be calculated by dividing the total cost of the upgrade by the estimated cost per year for the existing network (see box for an example).

For example, suppose Company X needs to upgrade its network. The goal is to increase the productivity of 800 employees by 5%. Modernization will cost 500 thousand dollars. After six months, Company X finds that productivity has actually increased by 5% due to the provision of new services. Everyone is happy, but what about ROI?

With an average wages of $35,000 per year, a total 5 percent increase in productivity would give the company a total return on investment of $1.4 million.

COUNTING NUMBERS

Despite all the difficulties of financial justification for modernization, your efforts will not be in vain. The analysis should be carried out with a level of detail that can stand the test of time. With practice and familiarity with the concepts presented in this article, you can better justify an upgrade that will make your work easier and your users happier.

Barton McKinley- IT strategic planning consultant. He can be contacted at: [email protected].

Modernization in the real world

Government Enterprise Network (GENet) plans, delivers, manages and maintains WAN connections and data backhaul services for approximately 100 Canadian departments and government agencies with 220,000 users.

Served organizations have their own internal networks, and GENet is responsible for routing traffic between them. GENet's customers are such that its services must be more secure and reliable than the public network, with transfer rates ranging from typical switched telephone lines to OC-3.

To meet these requirements, GENet personnel use network performance statistics to identify performance trends and plan service or capacity upgrades. “With performance monitoring, we can detect early enough that the network is approaching saturation. For example, we set a threshold of 70 percent utilization, which usually signals the need for a link upgrade,” says Eric Despres, director of network services at GENet.

Sometimes the decision to upgrade needs to be made for the entire network. If network technology has reached its end life cycle, then GENet staff can start looking for something with better features and better price/performance ratio.

In addition, upgrades can be carried out at the request of customers. So, the purpose of one of the recent upgrades was the implementation of secure remote access (Secure Remote Access, SRA) using IPSec-compatible products. "Customers would like to have best service but they have limited resources to do so. We have to actively work with our suppliers to keep costs down to manageable levels,” says Despres.

Unfortunately, IPSec-based solutions are just emerging, so it turned out to be unique. GENet staff did not have the opportunity to preview similar implementations during project preparation. As a result, real costs were twice as high as planned, and the implementation itself took a year instead of the planned six months.

GENet operates on a cost-recovery basis, so cost overruns are a major problem for GENet. To make a decision regarding the advisability of further development of the IPSec project, the company's specialists also had to find out the potential demand for a new service. Typically, GENet planners assume that the cost of upgrading and new services should pay off within a year and a half. However, in the case of IPSec, cost recovery should have taken longer, but the demand for the service grew, so all costs had to be eventually recovered.

Most upgrades, including possible unplanned costs, are included in the GENet TCO model along with other costs such as rent, salaries, etc.

As GENet grows, upgrades continue to be an integral part of the cost of doing business. However, through the use of network statistics, service demand analysis, and formal cost modeling, GENet is able to plan upgrades in a way that makes sense both technically and commercially.

Do not count your chickens before they are hatched

"Chickens are counted in the fall" is a fictitious company with 150 employees who have 120 desktop and 25 portable systems at their disposal. The company has an Ethernet local area network with the simplest segmentation using several hubs and bridges. The desktop systems run a variety of software, and the three existing servers run two different network operating systems.

The company's network is served by two full-time administrators, and they are loaded with work beyond measure. In addition, the company employs the services of a part-time consultant. Administrators do not use any proactive monitoring tools, but manually log events.

The company's income averages $340 per day per employee. However, if there were no network downtime and transmission delays, productivity would be 2% higher and bill payments would be lower. With a 220-day operating period per year, network outages cost the company approximately $225,000 in lost revenue each year.

Administrators set out to improve network performance and reliability through upgrades that should result in increased bandwidth and improved manageability. They decided to move to one network OS, a new remote access server, and a 100 Mbps Ethernet switched environment with full monitoring.

How long does it take to count chickens in the fall for a return on investment (ROI)? (Keep in mind that these figures are estimates and do not include additional upgrade and maintenance costs for each successive year of network operation.)

The amortization period is equal to the cost of the network upgrade divided by the lost profits in the case of the existing network. Thus, the ROI for the intended network upgrade would be about 20 months ($365,500/$225,000 = 1.64 years).

Components Requiring Replacement	Unit cost (in dollars)	Total cost (in dollars)
2 new network servers	20 000	40 000
2 new licenses for SOS	500	1000
2 UPS with server boards	1500	3000
45 new desktops	1200	54 000
10 new printers	1000	10 000
130 new network cards 10/100	110	14 300
1 new control station	7000	7000
New control software and probes	10 000	10 000
130 updates of SOS software clients	25	3250
150 OS updates	60	9000
150 app package updates	100	15 000
8 new 10/100 Gigabit Ethernet switches (24 ports)	3000	24 000
1 new RAS	1000	1000
2 racks for switches/RAS	2500	5000
Consulting and installation	55 000	55 000
Training, etc. services	approx. 30,000	30 000
Unknown by "Murphy's Law"	40 000	40 000
Total for IT (excluding taxes)		321 550

Internet resources

Trellis Network Services offers a calculator on its Web site to estimate the key software and platform costs for a transition to a new desktop, mail, and network OS. Cm. http://www.trellisnet.com/migration/index1.htm .

The Gartner Group offers free and concise Research Notes on network management and capacity planning. Cm. http://gartner12.gartnerweb.com/public/static/hotc/hc00085722.html .

An extensive list of links to various network management nodes and projects is available on the Network Management All in One page at: http://alpha01.ihep.ac.cn/~caixj/netm/ .

On the web server University of Twente, Holland, has links to addresses where you can find free codes and software for network management and monitoring. Cm.

Modernization of the primary communication network

Yu.S. KACHANOVSKII, Head of the Department of Technical Management of Communication Networks of the Moscow Directorate

In the context of the dynamic development of the Russian Railways holding, the transition to a new organizational structure “by type of business”, a significant expansion of sections of high-speed and high-speed traffic, as well as the development of automation of a number of technological processes, there is a need to modernize and upgrade the entire transport infrastructure, including area of ​​telecommunication technologies. Modernization of the primary communication network makes it possible to meet not only the needs of railway transport in qualitatively new types of communication, but also, in the long term, the organization of profitable activities by providing information services to third parties.

At the test site of the Moscow Road, the first stage of upgrading the primary communication network was carried out on the basis of modern Broad Gate (BG) equipment manufactured by ECI Telecom, which combines Ethernet and SDH services. In the future, it is planned to create an optical transport platform on a network-wide scale based on dense wavelength division multiplexing - DWDM (Dense Wavelength Division Multiplexing) and non-dense wavelength division multiplexing - CWDM (Coarse Wavelength Division Multiplexing). Phased modernization will make it possible, as necessary, to multiply the throughput of optical lines without interrupting existing links.

The transition to the BG platform makes it possible to meet the requirements of railway transport in the field of providing modern means of communication. This equipment has ultra-high scalability by connecting expansion modules to standard BG modules, provides Ethernet over WAN/MAN networks. High traffic stability due to the redundancy of the main hardware and tributary protection provides an increase in the reliability and continuity of all types of communication used in freight and passenger transportation.

Upgrading the primary network through the introduction of BG equipment is justified in terms of capital cost savings, since much less equipment is used and bandwidth is optimally used. In addition, lower operating costs are achieved due to the cost-effective integration of Ethernet and SDH into one platform with a single control system. Along with data transmission, the ^G platform provides various single-port Ethernet services, Layer 2 data application functions, and EoS (Ethernet over SDH) technology.

To modernize the equipment of the primary communication network at the test site of the Moscow Road, a working group was organized by order of the head of the communications directorate. It included not only specialists from the CTU of the Moscow Directorate of Communications, but also the Moscow-Ryazan, Moscow-Kursk and Ryazan regional communication centers, in whose area of ​​responsibility the installation of BG equipment was carried out. The working group was headed by the head of the technical control center for the communication network (TsTU) and his deputy. The activities of the group were coordinated by specialists from the engineering and technical service of the CSS control apparatus and the chief engineer of the Moscow Communications Directorate.

Initially, the members of the group consisting of CTU engineers A.S. Romaniy and D.A. Cherednichenko together with the chief engineer of the Moscow-Ryazan RCS E.A. Novikov, they were engaged in obtaining equipment, accepting it on the balance sheet of the Communications Directorate, controlling the configuration according to the project, and performing full documentary support.

Then, an experimental stand was installed in the building of the Moscow Road Administration for setting up and testing equipment, and consolidating skills in its operation. The stand consisted of a line of multiplexers connected by optical fiber. After testing the equipment, multiplexers were centrally configured for each communication node. In addition, in parallel with the adjustment, the working group coordinated the installation of multiplexers by the repair and restoration team.

Much attention was paid to the training of operating personnel. It was carried out in three stages. At the first, introductory stage, technologies in the field of telecommunications were considered regarding the construction of primary communication networks, their topology and advantages. During the second session, issues of installation and initial setup of equipment produced by ECI Telecom were discussed. The third stage of the training consisted of two parts, one of which included a lesson with operational personnel on the topic "Maintenance of multiplexers", the other - classes with the personnel of the technical control center for a communication network and maintenance centers on the topic "Working in the LightSoft control system, monitoring and control upgraded communications network. The chiefs of the Central Technical Service E.A. spent a lot of effort on training. Fedorova, A.A. Slyunyaev, S.S. Prudnikova and N.V. Pole.

The final stage of work was the organization of trial operation of the upgraded section of the primary communication network. The specialists of the working group A.S. Romaniy and Yu.V. Valueva, test streams were formed, the reservation of E1 streams and the routing of segments of the primary communication network were checked. With the help of Bercut devices, special measurements of the primary digital path, parameters of the STM-16 level path were performed in accordance with the recommendations of the International Telecommunication Union for the ITU-T telecommunications group. Based on the measurement results, it was decided to transfer the load to the upgraded primary communication network.

Thus, as a result of the first stage of modernization, the capacity of fiber-optic communication lines was increased, prerequisites were created for the reconstruction of the synchronous digital hierarchy network through the use of wavelength division multiplexing (WDM) technology. At the same time, it should be noted that ECI Telecom's BG equipment also opens up new opportunities for upgrading other networks and systems. Thanks to the well-coordinated and professional work of the signalmen, the Moskva road test site has moved to a qualitatively new level of technical development in the field of telecommunication technologies.

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ANNOTATION

This graduation project is devoted to the modernization of the backbone optical communication network on the Sosnogorsk - Labytnangi section of the Northern Railway using the FlexGain A2500 Extra multiplexer. The issues of organizing a telephone communication system, the rationale for choosing the type of digital equipment and the technical data of the FlexGain A2500 Extra multiplexer are considered. Calculations of regeneration sections, the number of regenerators were made, as well as calculation and construction of a diagram of transmission levels. Plans for the placement of multiplexers and regenerators in the projected area were developed. The issue of designing a system for remote monitoring of optical fibers is considered. A scheme for organizing remote monitoring of optical fibers based on the FiberVisor (EXFO) system has been developed. The issues of labor protection on the normalization of microclimate parameters in the premises of an electromechanic are considered. Capital investments, operating costs and reduced costs of the project are calculated.

This graduation project can be accepted for implementation in other areas of railway transport.

INTRODUCTION

The world of telecommunications and data transmission is facing a dynamically growing demand for frequency resources. This trend is mainly due to the increase in the number of Internet users and also to the growing interaction international operators and an increase in the volume of transmitted information. Bandwidth per user is rapidly increasing. Therefore, providers of communications in the construction of modern information networks use fiber-optic cable systems most often. This applies to both the construction of long telecommunication backbones and local computer networks. Optical fiber (OF) is currently considered the most advanced physical medium for information transmission, as well as the most promising medium for transmitting large flows of information over long distances. Today, fiber optics is used in almost all tasks related to the transmission of information. Thanks to the advent of modern fiber-optic cables, high transmission rates in linear paths (LT) of digital transmission systems with simultaneous lengthening of regeneration sections up to 100 km or more have become possible. The performance of such LTs exceeds the performance of digital paths on cables with metal pairs by 100 or more times, which radically increases their economic efficiency. Most regenerators can be combined with terminal or transit stations.

The rapid development of telecommunications networks and the need for a significant increase in the volume, reliability and efficiency of digital signal transmission have led to fundamental changes in the practice of building and using integrated digital networks.

Telephonization is inextricably linked with the development of the primary network, changes in the topology of local public telephone networks, their digitalization and the introduction of new ATM, SDH (Synchronous Digital Hierarchy) technologies. - synchronous digital hierarchy). Prospects for the development of transport networks lie in the further digitalization of the main primary network - construction of fiber-optic transmission lines (FOTL) made using the Synchronous Digital Hierarchy (SDH) technology. SDH systems provide transmission speeds of 155 Mbps and higher and can transport both the signals of existing digital systems and new promising services, including broadband . The SDH equipment is software-controlled and integrates the means of conversion, transmission, operational switching, control, and management.

The intensive development of modern telecommunications networks, their multi-service multi-level structure and complex branched topology put forward new requirements for the principles of operation of communication networks. Most effectively, the tasks of operation are solved by automated systems for monitoring telecommunications, which provide real mode time centralized monitoring of network health, detection of faults with the possibility of their prediction and minimization of the time of elimination.

Fiber-optic communication networks (FOSN) are steadily increasing their power and, like any other complex technical system, for normal functioning require measurement and control of their parameters. At present, the solution of the problems of measuring the parameters of fiber-optic communication lines (FOCL) is provided by optical reflectometers, multimeters and other measuring instruments, which are in service with the installation and operating units.

However, in modern WOSS, automated monitoring systems are increasingly used for these purposes.

First of all, it should be noted that the amount of transmitted information is constantly increasing. Modern technology time and spectral multiplexing provides a transmission rate in the channel of more than 40 Gbit / s, and the number of transmission channels in one optical fiber (0V) can reach up to 100 spectral multiplexed channels.

The second most important consequence of the development of FOCL is an increase in the length of regeneration sections due to the development of technology for broadband optical signal amplifiers.

Improvement in technology has increased the service life of FOCL, which, with a constant high increase and minimal decommissioning, has ensured their continuous quantitative growth.

Summarizing, we note the following features state of the art VOSS:

There is a significant increase in the number of functioning FOCLs;

The topology of fiber-optic networks is becoming more complex;

The information capacity of FOCL is continuously increasing;

The share of information and the importance of traffic transmitted over FOCL are increasing;

The cost of FOCL downtime in case of accidents is growing.

FOCLs are becoming comprehensive, more and more complex, and the importance of these systems is increasing. Therefore, increasing their reliability is becoming increasingly important.

The problem of FOCL reliability covers a wide range of issues and is inherently complex. Its solution requires the use of appropriate methods for assessing, calculating and monitoring various parameters of optical cables (OC) and indicators of the reliability of FOCL. The reliability of FOCL depends on various design, production and operational factors. The former include factors associated with the development, design and manufacture of OK and other auxiliary products and devices that are part of the FOCL. To the second - all the factors affecting the reliability of OK in the process of its installation, installation and subsequent operation.

One of the main operational factors that make it possible to predict the deterioration of the characteristics of optical fibers and ensure the required level of FOCL reliability is continuous monitoring of the FOCL OK. At the same time, monitoring systems for OK FOCL should be provided already at the stage of planning and designing modern digital communication networks. This is especially important and relevant for FOCL on overhead power lines (FOCL-VL), used in the creation of large corporate communication networks by large energy companies. Such FOCL-VL have a very high reliability, but at the same time, in the event of an accident, they require a significant investment of time and material and technical resources for emergency recovery work.

That is why the systems of continuous monitoring of optical fibers in OK FOCL are of particular importance in the construction of modern digital multiservice networks.

The purpose of the diploma project is to modernize the backbone communication network on the Sosnogorsk - Labytnangi section using digital fiber-optic transmission systems.

Initially, the road data transmission network was built on analog wire communication lines using voice frequency channels and a maximum speed of 24 kbps on trunk communication channels.

1. TECHNICAL AND OPERATIONAL PART

1.1 Basic analysisdesign site security

The projected section is serviced by the Sosnogorsk branch of the Northern Railway. The length of this section with all branches is slightly less than 900 km. The scheme of the designed section with stages is shown in Figure 1.1.

Figure 1.1 - Scheme of the designed site

Today, the Sosnogorsk branch is the largest structural unit of the Northern Railway: 2588.8 kilometers of the deployed length of the main tracks connecting all the cities of the Komi Republic and the Yamalo-Nenets Autonomous Okrug with the "mainland", 2040 turnouts, 140 bridges, 108 railway crossings, 100 stations, 3 locomotive and 2 car depots, 9 track distances, 4 signaling and communication distances, 2 civil engineering, water supply and sanitation distances, 3 power supply distances, 5 recovery trains, 4 track machine stations, passenger service directorate.

In accordance with the program of economic and social development of the Republic of Komi for 2006-2010 and for the period up to 2015, it is planned to double the freight turnover at the Sosnogorsk branch of the Northern Railway. The long-term program provides for an increase in industrial production by 2015 compared to 2005 by more than 1.5 times.

At the end of 2010, the construction of a fiber-optic communication line was completed on the Vorkuta direction of the Northern Road. A fiber-optic cable and equipment for digital data transmission systems installed at each station were put into operation on the northernmost section of Sosnogorsk - Vorkuta, 700 km long. The laying of FOCL on the Sosnogorsk - Vorkuta section has been carried out since 2007. At the test site to the Inta station, a fiber-optic cable of the OKMS-A-6(2.4)Sp-24(2) type was laid in the right-of-way directly in the subgrade body. To the north, in the section Inta - Vorkuta, a cable of the type DPT-024T04-06-25.0 / 0.4-Kh was suspended on power line supports.

OKMS-A-6(2,4)Sp-24(2) - self-supporting dielectric cable with an outer sheath made of polyethylene, with strength elements made of aramid yarns, an inner sheath made of polyethylene, with 6 optical modules with a nominal outer diameter of 2.4 mm, twisted around a fiberglass rod, with 24 standard single-mode optical fibers.

DPT-024T04-06-25.0 / 0.4-X - DPT optical cable is a completely dielectric product, the main application of which is placement at electric power facilities, with an increased level of external electromagnetic influences, as well as suspension on line supports communications, contact network of railways and power lines.

Since the beginning of 2011, operational technological communication (OTS) at the Sosnogorsk-Labytnangi section has been operating via a fiber-optic communication line based on the SMK-30 multiplexer, however, trunk communication is still carried out using two symmetrical cables MCPAB - 7x4x1.05 + 5x2x0.7 + 1x0, 7 using analog transmission systems P-306 and K-60p. The organization scheme of the backbone communication network based on analog equipment is shown in Figure 1.2. For the organization of the trunk communication segment for OK, from 5 to 8 OBs are reserved, and OBs Nos. 15 and 16 are also not involved.

1.2 Modern fiber optic transmission systems

1.2.1 Standard FOTS

SDH (Synchronous Digital Hierarchy) - synchronous digital hierarchy - a technology for transmitting high-speed data over long distances using wired, optical and radio links as a physical medium. This technology came to replace PDH (Plesiochronous Digital Hierarchy), which had a significant drawback: the difficulty of separating low-speed tributary channels from high-speed streams. The reason is that the higher layer streams in PDH are obtained by serial multiplexing. Accordingly, to select a stream, it is necessary to expand the entire stream, i.e. perform the demultiplexing operation. At the same time, expensive equipment will have to be installed at each point where such a procedure is needed, which significantly increases the cost of building and operating high-speed PDH lines. SDH technology is designed to solve this problem. Speeds for SDH are no longer limited to 500 Mbps, as it was in PDH. An example of an SDH network with intermediate extraction of an E1 stream from an STM-4 stream is shown in Figure 1.3

Figure 1.3 - Scheme of building an SDH network

Consider the principles of building a synchronous digital hierarchy. The slowest bit rate in SDH, called STM-1, is 155.52 Mbps. The entire payload is carried in what is known as a virtual VC. Information can be loaded either directly into the container, or if we are talking about PDH streams, then additional intermediate containers are used, possibly with more than one level of nesting. In any case, in the end, all information must be placed within the STM-1 virtual container.

A header is added to each virtual container, which carries service information: address information, error detection information, payload data, etc. Containers always have a fixed length. To obtain a higher speed, multiplexing of 4 STM-1 streams into one STM-4 stream is used.

Thus, it is possible to obtain a speed of 622.08 Mbps. To get even more speed, another multiplexing of four STM-4s into one STM-16 stream is used, the transmission of which requires a speed of 2488.32 Mbps, etc. General speed increase scheme: four STM-Ns are multiplexed into one STM-4xN. Unlike PDH, the general multiplexing scheme is unchanged for any speeds. Table 1 below presents the first six levels of the SDH hierarchy.

Table 1.1 - Levels of the SDH hierarchy

SDH stream designation	Flow rate, Mbps

Moreover, SDH is not limited to STM-1024. At the moment, the main limitation for increasing the speed of SDH is the maximum possible speed of existing data transfer technologies. Theoretically, the digital synchronous hierarchy can go on ad infinitum. SDH is mainly used in the construction of trunk communication lines.

1.2.2 FOTS of a new generation

With development computer networks, Internet, data transfer technologies (FR, ATM, etc.) transport network infrastructure based on SDH is increasingly being used to organize digital channels data networks (i.e. building overlay networks over SDH). The disadvantages of using the "classic" SDH for data transmission became most acute when it was necessary to provide broadband communication services for local networks.

Firstly, it is the need to convert LAN (Ethernet) interfaces to SDH interfaces (E1, E3, STM-1, STM-4, etc.) using intermediate devices such as FRAD, ATM IAD, IP routers and etc. Secondly, a small number of possible data transfer rates (which is also weakly correlated with a number of LAN speeds: 10, 100, 1000 Mbps) significantly limits the possibility of efficient provision of services, or requires the use of additional schemes in the connected equipment (for example, inverse multiplexing). Thus, the typical result of adding data services to traditional SDH networks is increased hardware complexity and increased cost.

To overcome these limitations, SDH equipment manufacturers have taken the path of creating Next Generation SDH (NG SDH) systems. NG SDH equipment has integrated data transmission interfaces (in particular, Ethernet), and also uses new technologies that allow more efficient allocation of the required bandwidth for data services and ensure low cost of implementing these technologies in existing networks, since support for additional functionality is only required at the edge nodes of the network.

Ethernet over SDH (EoS) is the most common implementation of NG SDH systems. Thus, a Light Reading survey of more than 150 operators providing Ethernet services on their networks showed that the vast majority (42%) are Ethernet over SONET / SDH (Ethernet over MPLS is in second place with 16%). The use of Ethernet interfaces in NG SDH systems is natural and logical:

The same physical interface can operate in a wide range of speeds, allowing you to change the connection speed if necessary without changing the equipment;

Eliminates the need for intermediate conversion of interfaces when transferring data from one local network to another (and such traffic makes up the bulk of all data traffic);

Connection costs are significantly reduced.

Figure 1.4 shows a functional diagram of the implementation of Ethernet services within the NG SDH technology.

Figure 1.4 - Functional diagram of Ethernet over SDH

The built-in Ethernet switch is optional, but its presence expands the set of services implemented on the Ethernet network. Support for VLAN (802.1Q), Q-in-Q (802.1ad), 802.1p frame prioritization in combination with GFP, VCAT, LCAS and other SDH features allows you to build carrier-class regional Ethernet networks (Metro-Ethernet) . Additional features include network self-healing schemes and operations, administration, and maintenance tools.

Ethernet technology does not have built-in operation, administration and maintenance (OA&M) tools that provide advanced diagnostics, fault detection and localization, and performance monitoring. When implementing EoS, these functions are provided by the built-in OA&M tools in SDH. This is important and critical for those networks and those operators that provide services based on SLA. Therefore, if we compare the EoS network with Ethernet switches on top of the dark fiber, then in the latter case we have a cheap and straightforward way to support Ethernet services, leaving no doubt about what you have to pay for. And if this is a home network that provides its subscribers with broadband Internet access, then this approach is fully justified. When we need to provide reliable Ethernet transport for business applications (especially in combination with E1 leased circuit services), then EoS is often the most effective way.

Next generation SDH systems are feature-rich, multi-service platforms that deliver multiple services without the cost and complexity of overlay networks.

1. 3 Remote monitoring systems for optical fibers

It is necessary to control the state and measure the parameters of FOCL both during installation and during operation. In addition, this must be done in case of accidents - to determine their cause and place, during repair work - to determine the quality of the repair work carried out, for prevention - in order to prevent accidents and increase the reliability of FOCL.

During operation, it becomes necessary to control the total attenuation of the path and the attenuation introduced by splices. In the event of an accident, with a break in the OK or OB, it is required to quickly and accurately determine the location of the break.

To predict emergency situations, it is necessary to monitor the state of the tract and analyze the change in its state, find and analyze the heterogeneities existing in it.

At present, when measuring the parameters of the optical path, the most common is the reflectometric method. In the pulsed reflectometry (OTDR) method, a short probing optical signal is formed, which is injected into the investigated optical fiber through an optical splitter. The signal reflected on the inhomogeneities is fed to the photodetector of the reflectometer. The temporal analysis of the reflected signal ensures the fixation of the probing signal evolution along the FOCL with the subsequent determination of the path parameters.

Optical reflectometers allow measuring: total attenuation (dB) and attenuation distribution - specific attenuation in OF (dB/km); attenuation introduced by inhomogeneities (detachable and non-detachable connections, other inhomogeneities); coordinates of inhomogeneities.

The main characteristics of optical reflectometers should be noted:

Wavelength range of probing radiation lambda s: 0.85 and 1.31 µm - for multimode 0V; 1.31, 1.55 and 1.625 microns - for single-mode optical fibers;

The dynamic range of measurements, which determines the maximum attenuation in the measured 0V at a given averaging time;

Distance resolution, providing the ability to distinguish between two inhomogeneities on the OF;

Near dead zone;

Modern optical reflectometers are measuring devices with powerful personal computer and provide measurement, processing and accumulation of the primary reflected signal; processing, analysis and storage of reflectograms, as well as the possibility of information exchange and remote control using network solutions. With their help, it is possible to successfully solve the problems of measuring FOCL parameters.

Intensive development of modern telecommunication networks and the need to ensure them uptime bring to the fore the task of centralized documentation and control of network cable management with the possibility of predicting and minimizing the troubleshooting time that occurs in fiber-optic communication lines. This task is most effectively solved with the help of automated systems for the administration of fiber-optic cables, including a system for remote control of optical fibers (Remote Fiber Test System - RFTS), a program for linking the network topology to a geographic map of the area, as well as a database of optical components, criteria and control results.

Regardless of the method of control of optical fibers, the system must provide:

Remote automatic control of passive and active optical fibers of cables;

Documentation of fiber-optic cable facilities;

Automatic detection of a FOCL malfunction with an indication of its exact location based on a comparison of the current and reference results of measuring the FOCL parameters;

Carrying out measurements of the parameters of optical fibers in manual mode at the request of the system operator;

Various ways to notify personnel about damage to optical cables (visual and audible alarm, automatic sending of messages to a pager, to specified addresses Email, by fax);

Automatic analysis of changes in the parameters of optical fibers over time based on the data accumulated during monitoring;

To provide the function of managing the FOC installation process, remote access to the system via various communication channels should be provided using laptop computer or a reflectometer with a special remote access function;

Compatibility with Bellcore trace storage format. This function is designed to be able to upload to the system measurement data made on the network using reflectometers from various manufacturers.

The system must be able to be integrated into the general telecommunications management network (TMN) of the operator's communications network.

The most important function of the RFTS system is that it constantly automatically collects and statistically analyzes the results of testing the optical fibers of the network. Statistical analysis using correlation, multivariate methods, as well as modern neural network methods, makes it possible to detect and predict fiber failures long before they lead to serious problems in the network.

fiber optic communication design

2. TECHNICAL PART

2.1 Comparative analysis of equipmentNG- SDH

Currently on Russian market four RFTS systems produced by the world's leading manufacturers of such equipment are presented

Currently, NG-SDH is represented on the Russian market of equipment manufacturers by several major companies. We single out three main manufacturers.

Manufacturer: Alcatel-Lucent

Multiplexer Metropolis AMU 1655:

Modular multiplexer with Gigabit Ethernet over SDH support and cross-connect matrix protection.

Type/class: Multiplexer Metropolis AMU 1655

Main specifications: Two types of baskets (with 1 or 4 tributary slots). Support for up to 4 STM-16 interfaces, up to 8 STM-4/1 interfaces on main boards. Various types of tributary boards, 63 E1 on one tributary board, Gigabit Ethernet over SDH support. Support for CWDM interfaces and single fiber interfaces.

Scope: Universal multiplexer - Access, Main and City transport networks.

Advantages and distinctive features: Protection of the matrix of cross-connects. Main boards include matrix, controller and 4 SDH ports. Unique compactness in its class - 8 systems in a 2.2 m by 300 mm design.

63 E1 ports (120 and 75 Ohm options) 2xSTM-4 or 8xSTM-1 (SFP) tributary card

2×10/100 Base-T+ 4 x E1 (120 & 75 Ohm)

2×10/100/1000 Base-T or 2 x GBE (SX and LX based on SFP)+4 x E1 (120 & 75 Ohm)

4×10/100 Base-T + 32 x E1 (120 & 75 Ohm)

Any interface card occupies one interface slot of any shelf option. 1643AM-AMS boards are supported via an adapter.

Manufacturer: Lucent Technologies

The WaveStar ADM 16/1 multiplexer and transmission system is designed to organize STM-16 channels in urban and backbone networks. WaveStar ADM 16/1 can be used as 1+1 and 1x0 terminal multiplexer, I/O multiplexer, local WaveStar® ADM 16/1 cross-switch.

One of the key features of the WaveStar® ADM 16/1 is I/O and flexible 2 Mbps cross-connection directly at the STM-16 layer. Security mechanisms, MS-SPRing, DNI, VC-SNC/N, MSP are supported.

With the WaveStar® TransLAN™ card installed, the WaveStar ADM 16/1 multiplexer acts as a multi-service network element supporting IEEE 802.1q and IEEE 802.1p standards, providing highly efficient data and voice transport over SDH links. The multiplexer supports interfaces: DS1, E1, E3, DS3, E4, 10/100 Base-T Ethernet, STM-0, STM-1, STM-4, STM-16 and connection to DWDM systems.

Main characteristics:

The main functional element of the system is a 64 x 64 HOVC and 32 x 32 LOVC cross-connect matrix, which provides flexible line-to-line, line-to-trib, and trib-to-trib routing. The matrix supports cross-connection at the VC-12, VC-3 and VC-4(-4c) levels. A high degree of integration allows the following I/O streams to be implemented in one subrack: 504x1.5 Mbps, 504x2 Mbps, 48x34 Mbps, 96x45 Mbps, 96xSTM-0, 64x10/100 BASE-T Ethernet, 32x140 Mbps c, 32xSTM-1 and 8xSTM-4.

Single platform for use in STM-16, STM-4 and STM-1 networks.

A single network element for connecting rings STM-16, STM-4, STM-1.

Support for ETSI Synchronization Message Protocol

AU-3/TU-3 conversion.

Integrated optical amplifier and preamplifier.

Reservation of key blocks.

Network management: WaveStar® ITM-SC, Navis® Optical NMS.

Manufacturer: Natex

FlexGain A2500 is a full-featured STM-16 layer add/drop multiplexer that can be used to create ring and line networks with STM-1, STM-4/STM-4c, STM-16/STM-16c and 1000 Base SX Gigabit interfaces ethernet. The A2500 multiplexer is the "big brother" of the A155 multiplexer and is designed to build backbone networks of the STM-16 level. The multiplexer provides hardware redundancy of the main units (power supply, cross-connection) and redundancy of any interfaces with equal speed according to the 1:1 scheme. The multiplexer also has a full range of optical transceivers for various speeds and distances. The Gigabit Ethernet interface, which supports QoS VLAN functions, allows using the multiplexer to build backbone data transmission networks.

The chassis of the FlexGain A2500 Extra multiplexer is made in 19” standard and is designed to be placed in a telecommunications rack or cabinet. The main hardware modules are installed in the chassis: the control module, the cross-connect matrix module, the power supply module, and the fan assembly. Additionally, two aggregate interface cards (STM-16) and eight component interface cards can be installed.

Component stream interfaces: E1, E3, STM-1 (electrical), STM-1 (optical), STM-4/STM-4c, Gigabit Ethernet expandable to STM-16/STM-16c.

The FlexGain series multiplexers have built-in HTTP servers and SNMP agents for local and network management. Each multiplexer is equipped with a full-fledged IP router that supports RIP and OSPF protocols. The IP data is transmitted via the standard DCC bytes of the SDH headers. Multiplexers have a multi-level authorization system, which provides protection against accidental penetration of intruders into the multiplexer settings. Each multiplexer on the network has a unique IP address, eliminating the need for external software to manage the multiplexers. This multiplexer is ideal for designing backbone NG-SDH networks, which is why we choose it for designing our site's network.

2.2 Technical descriptionMultiplexer FlexGain A2500 Extra

The FlexGain A2500 Extra takes full advantage of SDH technology. This equipment is a multi-function add/drop multiplexer with multiple interfaces (including 2Mbps, 34Mbps, 45Mbps, 155Mbps and 622Mbps, which can be upgraded to 2.48Gbps /With). Using STM-4c, STM-16c and Gigabit Ethernet interfaces, FlexGain A2500 Extra allows you to combine local / corporate / global networks and provide a high level of traffic protection. The communication scheme using FlexGain A2500 Extra is shown in Figure 2.1.

In many countries of the world, the STM-16 speed is the reference for backbone networks. The FlexGain A2500 Extra equipment can be used to build this type of network. Using optical amplifiers with FlexGain A2500 Extra equipment, it is possible to transmit information over sufficiently long distances, and FlexGain A2500 Extra can also work in conjunction with equipment using DWDM (Dense Wavelength Division Multiplexing) technology.

Figure 2.1 - Scheme of application of NATEKS FlexGain A2500 Extra

Specifications are listed in tables 2.1 and 2.2

2.3 Settlement part

2.3.1 Calculation and optimization of the length of the regeneration section

The number of regenerators to be installed on the line can be found from the formula:

where: l- line length, km,

l py is the maximum length of the regeneration section for the selected equipment, km.

An elementary cable section is the entire physical transmission medium between adjacent ends of the section. The end of the section is the boundary chosen conditionally as the junction of the optical fiber with the regenerator.

Point S - the linear side of the optical cord on the optical distribution box at the end point of the section on the transmitting side.

Point R - the linear side of the optical cord on the optical distribution box at the end point of the section on the receiving side.

To calculate and optimize the length of the regeneration section, two parameters are used: the total attenuation of the regeneration section and the dispersion of the optical fiber.

Based on attenuation, taking into account all the losses that occur in the linear path, the calculation formula for the length of the regeneration section is as follows:

l ru (Ep - rs nrs - ns nns - t - B)/(+ ns /lc) (2.2)

Here: E p is the energy potential of the FOTS, dB, defined as the difference in the power of the optical signal at the output Рout = 2 dBm (table 1.3) and the input Рin = -28 dBm (table 1.3) specified in the technical characteristics of the FOTS equipment:

E p \u003d Rout - Rin \u003d - 2 - (- 28) \u003d 26 dBm,;

- attenuation coefficient of the optical fiber:\u003d 0.20 dB / km for l \u003d 1.55 μm The parameters of the optical fiber are presented in Table 2.3;

Table 2.3 -Technical specifications optical fiber SMF-28™CPC6

Parameter	Meaning
Operating wavelength, nm
Attenuation coefficient, dB/nm, not more than:
At a wavelength of 1310 nm
At a wavelength of 1550 nm
Specific chromatic dispersion:
At a wavelength of 1310 nm
At a wavelength of 1550 nm
Resulting specific bandwidth, MHz km:
At a wavelength of 1310 nm
At a wavelength of 1550 nm
Chromatic dispersion coefficient, ps/nm km, not more than:
In the wavelength range (1530-1565) nm
The slope of the dispersion characteristic in the region of the wavelength of zero dispersion, ps/nm 2 km, not more than:
In the wavelength range (1285-1330) nm
Mode field diameter, µm;
At a wavelength of 1310 nm
At a wavelength of 1550 nm
Glass geometry:
Intrinsic bending of the fiber
Reflective shell diameter Core non-concentricity	125.0±1.0 µm
Shell out-of-roundness

n rs - the number of detachable connectors (installed at the input and output of optical radiation in the optical fiber) nrs = 2;

rs- losses in the detachable connector dB (table 2.4);

n ns - the number of fixed connectors in the regeneration area,

Losses in permanent joints (table 2.5), dB Losses in permanent joints are determined from the characteristics of the welding machine, which was used to connect the fibers. Specifications of the welding machine are presented in Table 2.3.

Table 2.4 - Specifications of SC optical connectors for SMF single mode fibers

Appearance
Designation
physical characteristics
Connection type (fixed)	Latch with lock (push-pull design)
Docking	Rounded end, physical contact, floating tip, no-pull design
Optical characteristics
Insertion Loss:
Return loss:

Table 2.5 - Specifications of the Fujikura FSM-30S welding machine

Types of fibers to be welded	SMF, GI, DS, GS, ED
Average losses on the welded joint:
Splice Loss Function	Intentional loss in the range of 0.5 to 20 dB in 0.5 dB steps to create line attenuation
Reflection coefficient from a welded joint:	no more than -60dB
Stripped fiber length:
with fiber coating 0.25 mm
fiber coating 0.9 mm
Welding programs:	4 standard and 30 variable
Weld spot view method:	Camera and 4" LCD display
Checking the mechanical strength of the welding spot:	Tensile force 200 gr, additional test 450 gr
Power supply:	AC mains(85-265V) DC (10-15V) Battery FBR-5 (12V)
	210x187x173 mm
	8.0 kg (welding machine) and 4.0 kg (case)

t- tolerance for attenuation of optical fiber losses with temperature change;

AT- allowance for attenuation of losses associated with the deterioration of the characteristics of the components of the regeneration section over time;

l c - construction length of the cable.

The calculation is carried out for the entire transmission path.

Since we have multiplexers located at large stations: Sosnogorsk, Irael, Pechera, Inta, Sivaya Maska, Vorkuta, Labytnangi, our projected communication network is divided into several sections. We calculate the regeneration fate for each separately.

1) Sosnogorsk - Israel = 117.2 km

2) Israel - Pechera = 132 km

3) Pechera - Inta = 180 km

4) Inta - Gray Mask = 141 km

5) Gray Mask - Vorkuta = 130 km

6) Gray Mask - Labytnangi = 194km

Let's determine the number of fixed connectors in the areas under consideration:

where l c\u003d 4 km - construction length of the cable.

Tolerances for losses due to aging in time of elements, depending on the combination of radiation sources and receivers, we will take from Table 1.3.

Loss tolerance bv =4 dB

Let us determine the length of the regeneration section according to formula 2.2 for each section:

1) lru? (26- 0.5 2 - 29 0.04 - 4 - 4) / (0.2 + 0.04 / 4) ? 75.4 km

2) lpy? (26- 0.5 2 - 32 0.04 - 4 - 4) / (0.2 + 0.04 / 4) ? 74.9 km

3) lru? (26- 0.5 2 - 44 0.04 - 4 - 4) / (0.2 + 0.04 / 4) ? 72.5 km

4) lru? (26- 0.5 2 - 34 0.04 - 4 - 4) / (0.2 + 0.04 / 4) ? 74.4 km

5) lru? (26- 0.5 2 - 31 0.04 - 4 - 4) / (0.2 + 0.04 / 4) ? 75 km

6) lru? (26- 0.5 2 - 47 0.04 - 4 - 4) / (0.2 + 0.04 / 4) ? 72 km

Since L > l ru, then it is necessary to use regenerators (LR). We calculate the number of regenerators for each section according to formula 2.1

A total of 8 regenerators are needed.

We will check the correctness of the choice of the regeneration section, taking into account the dispersion properties of the optical fiber. The maximum length of the regeneration section, taking into account the RH dispersion, is selected from the condition:

l max 0.25/V,(2.3)

where B is the information transfer rate; B=2.488 10 9 bps;

- RMS value of the dispersion of the selected optical fiber, s/km.

For single-mode fibers, the value is found from the relationship:

= K ?l n, (2.4)

where K = 10 -12

l - bandwidth of optical radiation;

n - normalized root-mean-square variance.

= K ? l n \u003d 10 -12 0.2 3 \u003d 0.6 10 -12 s / km

l max 0.25 / 0.6 10 -12 2.488 10 9 \u003d 167.4 km

The length of the regeneration section obtained on the basis of this calculation should be:

l RU? l max? 167.4 km

previously calculated l ru satisfies this condition.

2.3. 2 Determination of the signal-to-noise ratio

The signal-to-noise ratio or error probability allocated to the length of the regeneration section for a digital fiber-optic communication system is determined by the formula:

(2.5)

where - error probability per 1 km of the optical linear path (for the backbone network 10 -11 , for the intrazonal network 1.67·10 -10 , for the local 10 -9 ). For calculations, we take the largest regeneration area l ru = 75 km

For the designed FOCL:

2 . 3. 3 System Reliability Calculation

According to the reliability theory, failures are considered as random events. The time interval from the moment of switching on to the first failure is a random variable called "uptime".

The cumulative distribution function of this random variable, which is (by definition) the probability that the uptime will be less than t, is denoted and has the meaning of the probability of failure on the interval 0…. The probability of the opposite event - failure-free operation on this interval - is equal to:

A convenient measure of the reliability of elements and systems is the failure rate, which is the conditional probability density of failures at a moment, provided that there were no failures up to this moment. There is a relationship between functions and.

During normal operation (after running in, but even before physical wear has set in), the failure rate is approximately constant. In this case:

Thus, the constant failure rate characteristic of the period of normal operation corresponds to an exponential decrease in the probability of failure-free operation over time.

The mean time of failure-free operation (time to failure) is found as the mathematical expectation of the random variable “time of failure-free operation”.

hour -1 . (2.9)

Therefore, the mean time between failures during normal operation is inversely proportional to the failure rate:

Let us estimate the reliability of some complex system consisting of many different types of elements.

Let, ... - the probability of failure-free operation of each element in the time interval 0… t, n is the number of elements in the system. If failures of individual elements occur independently, and the failure of at least one element leads to the failure of the entire system (this type of connection of elements in reliability theory is called sequential), then the probability of failure-free operation of the system as a whole is equal to the product of the probabilities of failure-free operation of its individual elements:

where - system failure rate, hour -1;

Failure rate i- th element, hour -1 .

The mean time of failure of the system is determined by:

, hour. (2.12)

Among the main characteristics of the reliability of restored systems is the availability factor, which is determined by the formula:

where is the average recovery time of the element (system), it corresponds to the probability that the element (system) will be operational at any time.

The linear path, in the general case, consists of series-connected elements (cable, NRP, ORP - serviced regeneration point), each of which is characterized by its own reliability parameters, and failures in the first approximation occur independently, therefore, the above formulas can be used to determine the reliability of the main line .

In our case, the linear path consists of serially connected cable sections and multiplexers (ORP). When designing an FOCL, its reliability should be calculated according to the following indicators:

availability rate and time between failures. At the same time, the obtained data should be compared with the reliability indicators for the corresponding type of network: local, intrazonal, backbone.

the availability factor of the linear tract equipment for the main line of maximum length = 1400 km must be greater than 0.99; MTBF should be more than 350 hours (when the recovery time of the RRP or the end point (OP) is less than 0.5 hours and the recovery time of the optical cable is less than 10 hours).

The failure rate of the linear path is defined as the sum of the failure rates of the NRP, ORP and cable:

where - failure rates of NRP and ORP;

Number of IRPs and PIUs;

Failure rate per kilometer of cable;

L- the length of the highway.

And since the cable trunk does not contain NRP, we do not take into account the failure rate of NRP.

The average Russian failure rate for 1 km of optical cable is =3.8810 -7 hour -1 . According to the technical description, the time between failures of the FlexGain A2500 Extra equipment multiplexer is 20 years or 175200 hours, from which the failure rate will be equal. We take the values ​​​​of the parameters necessary for calculating from Table 2.6

Table 2.6 - Reliability indicators

Let us determine the mean time of failure-free operation of the linear path:

Probability of non-failure operation within a day of an hour:

During the week hours:

During the month hours:

Let's calculate the readiness factor. Let us first find the average communication recovery time using the formula:

,h (2.15)

where is the recovery time, respectively, of the NRP, ORP and cable.

Now let's find the readiness factor:

Calculations of the probability of failure-free operation will be entered in Table 2.7

Table 2.7 - Data for calculating the probability of failure-free operation

As a result of the calculations, it can be concluded that the designed backbone communication network is capable of performing the specified functions with the required quality.

2. 4 Development of a scheme for organizing the backbone segment of a communication network

2.4.1 Placement of backbone equipmentnetworksconnections

Multiplexers in the projected area are located at large stations: Sosnogorsk, Irael, Pechera, Inta, Sivaya Mask, Vorkuta, Labytnangi. Let us arrange the regenerators in such a way that the length of the regeneration section does not exceed the calculated ones obtained in paragraph 2.3.1. The results will be entered in table 2.8.

Table 2.8 - Regeneration sites.

	Type of equipment	Distance of the regeneration site, km
Sosnogorsk	Multiplexer
	Regenerator
	Multiplexer
Kadzher	Regenerator
	Regenerator
	Multiplexer
	Regenerator
	Regenerator
	Multiplexer
Mounds polar	Regenerator
Gray Mask	Multiplexer
	Regenerator
	Multiplexer
	Regenerator
	Regenerator
	Regenerator
Labytnangi	Multiplexer

We are installing two regenerators at the Chum station, because there is a branch line to the Labytnangi station. Since on the sections Irael - Pechera and Chum - Labytnangi the stages do not allow us to achieve the fulfillment of inequality (2.2), we put in addition one more regenerator. The organization scheme of the backbone communication network is shown in Figure 2.1.

2.4.2 Calculating and plotting transmission levels

When designing and operating a communication system, it is necessary to know the signal levels at various points in the transmission path. To characterize changes in signal level along a communication line, a level diagram is used - a graph that shows the distribution of levels along a transmission path.

To build a level diagram, it is necessary to calculate the attenuation of all regeneration sections using the formula:

, (2.16)

where is the power level at the reception, ;

- power level of the radiation source (table 2.2), = -2;

- losses in a detachable connection (table 2.4), = 0.5;

- number of detachable connections;

- losses in permanent connections (table 2.5), = 0.04;

- number of permanent connections;

- attenuation coefficient of OF (table 2.3), = 0.2.

According to the organization scheme of the backbone communication network in Figure 2.1, there are 14 regeneration sites. The calculation results are presented in Table 2.8.

Table 2.8 - Calculation of attenuation of regeneration areas

regeneration plot	Regeneration length plot, km	Number of permanent connections	Power level at the reception, dB
Sosnogorsk - Sed-Vozh
Sed-Vozh - Israel
Irel-Kadzher
Kazhderom-Kozhva
Kozhva-Pechera
Pechera-Yanyu
Yanyu-Kozhim
Kozhim-Inta
Inta-Bugry Polar
Polar mounds - Gray Mask
Gray Mask-Chum
Chum-Vorkuta
Chum-Khorota
Khorota-Sob
Sob-Labytnangi

Based on the calculations obtained, we build a level diagram, Figure 2.2

Figure 2.2 Level diagrams for the Sosnogorsk-Vorkuta and Chum-Labytnangi sections

Based on the results obtained, we conclude that the received levels at the reception are not lower than the minimum reception level, which means that the regenerators are placed correctly.

2.5 Development of a scheme for remote monitoring of optical fibers

2.5.1 General and specific requirements for RFTS systems of large VOSS

The RFTS system should provide for the possibility of scaling up (together with the development of the network) and switching to new measurement methods using new network technologies, for example, DWDM (Dense Wave Division Multiplexing) technology. Therefore, the RFTS system must have a fully modular architecture.

The RFTS system should provide for the possibility of alternative transmission of test results of OK fibers over backup channels, for example, already existing low-speed communication channels, and the RTU modules of the system should be able to work offline, storing locally the measurement results of each fiber and transmitting information to the central server periodically independent communication channels according to a predetermined program.

Development of a scheme for organizing the infocommunication network of the railway. Calculation of parameters of fiber-optic communication lines. Selecting the type of fiber optic cable and equipment. Measures to improve the reliability of transmission lines.

term paper, added 05/28/2012

General characteristics of fiber optic communication systems. Measurement of optical power levels and attenuation. Automatic monitoring systems. Cable line equipment. Modernization of the fiber-optic network. Scheme of telecommunication equipment.

thesis, added 12/23/2011

Engineering and technical justification for the creation of a DWDM network on an existing backbone digital network communications (MCSS) JSC "Russian Railways". Calculation of the quality of transmission of digital streams in DWDM technology. Justification of the choice of fiber-optic communication lines. Equipment analysis.

thesis, added 02/26/2013

Design of fiber optic communication cables. Use of the IKM-30 transmission system. Specifications OKZ-S-8(3.0)Sp-48(2). Calculation of the length of the regeneration section. Design of the primary communication network on the railway using FOCL.

term paper, added 10/22/2014

Creation of a backbone digital communication network. The choice of cable and information transmission system. Reservation of the receive/transmit channel. Principles of division of a section into optical sections. Determining the signal strength levels required for fading protection.

term paper, added 12/05/2014

Digitization of a section of a communication network using SDH technology. Choice of fiber-optic cable route; calculation of the length of the regeneration section, multiplex plan. Development of a communication organization scheme, network synchronization. Linear hardware shop.

term paper, added 03/20/2013

Advantages of optical transmission systems over transmission systems operating over a metal cable. Design of optical communication cables. Specifications OKMS-A-6/2(2.0)Sp-12(2)/4(2). Construction of a fiber-optic communication line.

term paper, added 10/21/2014

Prospects for the development of fiber-optic transmission systems in the field of stationary fixed-line communication systems. Calculation of digital FOTS: choice of topology and block diagram, calculation of transmission speed, selection of cable, laying route and regeneration section.

The integration of telephone traffic with PD traffic has already become a reality. Private PBXs can now be used to operate in the world of networks of integrated transmission of diverse traffic. There are real possibilities for the practical implementation of this idea. Thus, already operating traditional PBXs can be gradually integrated into the STN infrastructure. A radical approach based on their complete replacement can not always be considered optimal.

The introduction of new H.323-compliant terminal equipment, so-called Ethernet telephones and other IP-oriented telephony equipment, is likely to gradually replace traditional classic PBXs. However, it will undoubtedly be years before this new technology can not only provide the same level of service, but also guarantee the same level of reliability as telephone systems.

The task of integrating two flows - telephone and PD - can currently be faced by any enterprise that has a central office and several scattered (for example, across the country) branches. Employees of branches should be able to access the central database. To do this, a geographically distributed CS covering all branches is created, which can be based on leased lines, Frame Relay or ATM virtual channels. Each branch has its own PBX. The integration of a telephone message flow and a data flow can be started with the organization of the transfer of telephone traffic between branches and the main office via SPD. The solution of this problem may make it possible to abandon the expensive services of traditional long-distance and international telephone communications. one

As carriers install more and more long-distance fiber optic links, the cost of link bandwidth is dropping rapidly. Against this background, the volume of data traffic is increasing approximately three times annually. 2

On the whole, the technology of IP-telephony justifies the hopes placed on it in terms of a significant reduction in the cost of long-distance telephone communications and the expansion of the capabilities of switching systems. However, at present, only Cisco Systems has all the necessary equipment to create an integrated 1P telephony system.

The rapid transition to an all-IP Cisco Phone System provides significant benefits in terms of increased employee productivity and reduced communication system maintenance costs.

However, there are quite a few arguments in favor of the gradual introduction of IP-telephony on VSS, which is offered by Nortel Network and Lucent Technologies.

These firms are the largest manufacturers of traditional PBX switching systems and, perhaps, that is why they consider the introduction of IP telephony as an evolutionary process. Both companies offer solutions that retain a significant amount of traditional telephone equipment. Thus, only IP interfaces are needed to connect the PBX to the enterprise backbone network. And this allows you to save for users the entire rich set of service capabilities of traditional PBXs, while maintaining high costs for their maintenance.

It is probably too early to talk about the widespread introduction of IP telephony systems in all areas, but small and medium-sized businesses may find it beneficial to completely replace office PBXs and conventional SLTs with IP systems: telephones, gateways and gatekeepers (gatekeeper).

New IP telephone systems can be a good replacement for traditional PBXs in workgroups and small offices. They can be operated in conjunction with existing telephone exchanges, which allows a gradual transition from traditional to 1P telephony.

In terms of appearance and basic service capabilities, hardware implementations of IP phones are practically no different from classic phones, but their capabilities significantly reduce the burden on personnel responsible for telephony.

1 However, one should not forget that with such a solution, the quality of message transmission is sharply reduced.

2 According to McQuillan Consulting, in 4 years only 5% of network bandwidth will be used for QC voice transmission, the remaining 95% will be used for transmission of IP data, voice and video packets.

If a traditional PBX has been installed at the enterprise, then, for example, when an employee moves to a new workplace, the administrator must make appropriate changes to linking numbers to specific ports. After the transition to IP-phones, the need for this disappears. At a new location, it is enough for an employee to simply connect his TA to the network. If at the same time, it is necessary to change any parameters (for example, forwarding or intercepting telephone calls), the employee can easily do this from his PC from a familiar Web browser.

In addition to the hardware, there are software implementations IP phones. In this case, a PC equipped with a headset or microphone and speakers turns into a multifunctional communication center. The PC user, in addition to the usual telephone service, receives additional features that increase the productivity of his work. For example, due to the presence of a standard TAPI interface to other programs, you can automatically obtain information about the caller (client), as well as use convenient interfaces for monitoring telephone calls and voice mail.

The disadvantages of IP-telephony systems include the fact that, in order to reduce the cost, the main functions of traditional PBXs are assigned to a LAN server, usually running under Windows NT. In terms of security, reliability and resilience, such server telephone systems are no different from conventional LANs. If the LAN has a reliability of 99.8%, then this means that it can be idle for 17-20 hours during the year. The reliability of traditional PBXs is guaranteed at the level of 99.999% (“five nines”), that is, their allowable downtime is only 3-5 minutes per year.

Thus, the developers of traditional PBX telephone systems consider the most reasonable and realistic strategy for enterprises that have already invested heavily in the purchase of modern digital PBXs and digital CTAs, a gradual transition to 1P telephony. At the same time, the existing telephone equipment and cable infrastructure at the initial stage are almost completely preserved, and IP-telephony is being introduced only where it can bring the greatest savings - between remote PBXs. Modules installed on such PBXs convert voice streams into IP packets and transmit them along with other traffic over VSS, bypassing the PSTN.

An IP telephony implementation strategy that maintains existing digital PBXs also allows the development of traditional telephone systems to benefit. Classic PBXs from Lucent Technologies and Nortel Networks (Definity and Meridian 1) have a wider range of service capabilities than 1P telephony solutions offered today.

Some strategies for implementing IP telephony allow for the gradual installation of new IP phones and telephony servers, first in one area of ​​the enterprise, then in another, and so on. New system, serving any department or branch of the enterprise, can be connected to a traditional digital PBX to connect department employees with other users. Such an implementation of IP telephony can take many months, but is likely to be less costly for the enterprise than the rapid replacement of one technology with a fundamentally different one everywhere.

For rate technical capabilities on the transition of an enterprise network to a new technology, a hypothetical enterprise was selected that has common problems that reflect the current state of affairs in departmental networks. The enterprise does not have a single center for receiving and processing a large number of telephone calls, its employees work through the PSTN network from various locations, including small and home offices, has a central office and a branch. The company's telephone system is based on traditional PBXs and operates independently of the Frame Relay network connecting the LANs of the two main offices (Figure 7.3).

The company intends to expand its business. An additional 8 people will be hired, living near the main offices. The task is to reduce operating costs by combining voice traffic and data traffic in one integrated network. New employees should be able to work from home and work directly in the office. It is required to provide for the possibility for employees to use their home phones, that is, to connect them in the office.

Rice. 7.3. Scheme of existing telephone network and SPD of a hypothetical enterprise To solve the problems of such an enterprise, it was proposed to 14 firms specializing in the development of equipment using IP technology.

The complete end-to-end solution was presented by Cisco. 1 Lucent Technologies and Nortel Networks offer solutions for a gradual transition to new technology without having to completely sacrifice the investment made in the development of traditional telephony infrastructure.

Artisoft, NetPhone, Nokia, Shoreline Teleworks, and Vertical Networks all offer LAN-based phone systems, but cannot fully satisfy the fictitious enterprise's requirements. AltiGen Communications and VocalTec specialize in carrier products, not business systems.

With the Cisco Communication Network (CCN) family, you can move away from classic circuit-switched PBXs and create a telephone system based on an IP network and an intelligent call processing server. In this case, proprietary phones are replaced by IP phones with Ethernet interfaces or PC-based softphones. CCN products support LDAP protocols for interacting with directory services and DHCP for automatic IP address assignment.

This solution is well suited for implementation in small and medium-sized companies where there are no full-featured PBXs, and the local network is not too busy. The Cisco-recommended 30VIP and 12SP+ IP Phones are well suited for business users, as they support call hold, call transfer, call forwarding, caller ID retrieval, and a variety of ringing tones for different types calls. However, the capabilities of Cisco products are much more modest than those provided by traditional business-class telephone systems.

To implement the fictitious Cisco-based enterprise project at the main office, branch office, and eight new home offices, all telephony is implemented over IP. Of the $70,000 project, $44,000 will be used to purchase 36 new IP phones, software for phone servers, and gateways to connect to the PSTN. Another $26,000 is recommended to be spent on routers and security systems to improve the existing enterprise network and prepare it for stable operation in the face of the emergence of a new type of traffic (IP-telephony). Significant costs should be recouped by increasing production

1 According to the company, the number of installations of its integrated IP-telephony solutions worldwide exceeded 200, and most of them are based on equipment from Selsius Systems.

efficiency of work of workers and decrease in expenses for service of communication systems. Many maintenance functions will be automated. For example, owners of 1P phones can independently change their user settings from their PC. Only one administrator is enough to maintain the entire integrated network.

One of the most interesting potential benefits of implementing 1P telephony is the ability to integrate phone and PC functionality. The new Ovso software product - Un1u-a1Phone, which imitates the operation of a 30U1P telephone set, makes it possible to initiate phone calls directly from a PC, where it can work in conjunction with the database and other applications. Obviously, the convenience of being able to call a subscriber's number found in the database with a simple mouse click on the corresponding button. The next advantage from the introduction of the Fvso 1P telephony software and hardware complex can be considered the creation of a single environment for the work of employees both at home and at the workplace in the office (see Fig. 7.4).

Rice. 7.4. Network upgrade project based on Cisco Systems equipment

The introduction of high-tech products requires certain costs for the training of personnel and their desire and willingness to work with new technology.

The Nortel Networks project is based on a fictitious enterprise having a Meridian 1 PBX and corresponding digital CTAs at every workstation in both the office and the branch office. Installing Meridian HomeOffice II devices in home offices allows employees working from home to use digital phones Meridian and get the same access to the enterprise LAN as in the case of being in the main office. Meridian Integrated IP Telephone Gateways, integrated with Meridian 1, provide load transfer between PBXs over a logical 1P channel through a virtual private network enterprises. In the case when such a method does not guarantee an acceptable quality of telephone communication, inter-office interaction will be carried out in the traditional way via PSTN channels (Fig. 7.5). For employees who are constantly on the road, using the Meridian IP Telecommuter product, it is possible to get remote access to departmental voice services and SPD from a multimedia PC or laptop computer.

If the fictitious company decides to add gateway cards to two of its Meridian 1 PBXs, install Mertidian HomeOffice II routers and Meridian digital phones for eight homeworkers, and provide them with high-speed access to LAN services, this would cost approximately $44,000.

When using gateways, the system will attempt to establish all inter-office connections through the IP network. Initially, at the same time, it will determine the time for the signal to pass through this network (that is, it will determine the correspondence of the possible delay in signal transmission to the given one). If the result is satisfactory, the voice traffic will go over the IP network, and if not (the network is congested), the PBX will route the call through the PSTN channels.

The router in each home office connects via a BRI ISDN interface and can connect to either the central office or its branch office. One BRI channel is dedicated to voice transmission and establishes telephone communication directly with the PBX. Through another channel, communication is provided with a remote access server, which, in fact, includes one or more computers of employees working at home in the office LAN.

This approach to solving the problem shows that the company believes that IP technologies are the future of telecommunications, but the transition to them should be evolutionary.

Rice. 7.5. Network modernization project based on Nortel Networks equipment

Lucent Technologies offers two solutions: 1) implement IP Exchange Systems (see Figure 7.6); 2) upgrade the Defmity PBX using 1P tools.

Rice. 7.6. A variant of solving the problem of Lucent Technologies

Installing IP Exchange Systems (IPES) enables voice, fax, and data communications over a single IP network, while still allowing employees to use low-cost analog telephones and faxes. This solution includes IP Exchange Adapters for connecting SLTs and faxes to an IP network, as well as IP ExchangeComm servers with an optional gateway for connecting to the PSTN.

Currently, one IPES system supports up to 96 1 telephone and fax machines and its resources can be used to serve several remote offices.

Implementation of the IPES system will require the replacement of a significant part of the equipment, although it remains possible to use analog SLTs. Multi-line telephones of the Partner system can also be saved. Connected to the network through adapters, they can work with a server, providing the user with a full range of business-class telephone services. Ordinary SLTs are also connected via IP Exchange Adapter, but they provide the subscriber with only a basic set of telephone services.

Lucent Technologies' two offerings based on IPES and Definity illustrate an important difference between the two approaches to implementing IP technologies in the office communications space.

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Features of the digital switching system "Kvant-E". Bandwidth of the switching field. Trunks and interactions between stations. Reliability characteristics of the equipment of CSK "Kvant". Features of the organization of subscriber access.

annotation

In this graduation project, the issues of modernizing the telephone network with. Uryupinka Akkol RTH Akmola region. The project analyzed the current state of the network, selected equipment. CSK Kvant (Russia) was chosen as the optimal equipment.

The existing local cable network was reconstructed and the problem of interstation lines was solved.

The project also calculated the main indicators of the quality of the network, as well as technical and economic indicators. Engineering solutions for life safety and ecology have been developed.

- Introduction -

It is generally accepted that the development of telephone communications in the world began in 1876, which was marked by the receipt by Alexander Graham Bell of a patent for the invention of an electromagnetic telephone. It is known from the history of the development of technology that similar inventions were made long before 1876. But for a number of reasons, these developments were not officially registered. Following the generally accepted norms of patent science, Alexander Graham Bell is considered the discoverer of telephone communications.

The term "telephone network" is interpreted as a secondary network designed for the transmission of telephone messages. The public switched telephone network (PSTN) has an unambiguous translation - Public Switched Telephone Network (PSTN). Depending on the level of the hierarchy of the VSS of the Republic of Kazakhstan, there are international, long-distance, intrazonal and local telephone networks.

Telephone exchanges and telephone exchanges are used as switching equipment on the PSTN. A telephone exchange (hereinafter only automatic telephone exchanges - PBX will be considered) is a switching station that provides connection of subscribers to the PSTN. A telephone node is a switching node designed to establish transit connections on the PSTN.

The need to develop new principles for building telecommunication networks arises, as a rule, with the appearance of each new generation of technology for the transmission and distribution of information. For telephone communications, the introduction of digital transmission and switching systems is a typical example of such a process.

The interconnected communication network (VSN) of the Republic of Kazakhstan in the early 90s entered a phase of significant qualitative changes due to the widespread introduction of digital technology for transmission and switching. Urban (GTS) and rural (STS) telephone networks are undergoing the most significant changes during the digitalization of the WSS of the Republic of Kazakhstan.

The primary and telephone networks in rural areas have a number of specific features. SPS resources are usually used for wire broadcasting, telegraph communications, organization of leased lines, and the functionality of the STS is used to build intra-industrial telephone networks (IPTS), telephone dispatcher networks (TTN) and other attributes of the management system of former collective farms and state farms. These reasons served as the basis for the creation of another guiding document - "Principles for the organization of telecommunications in rural areas".

When developing the basic principles for building a national telecommunication system, it is advisable to carefully analyze the relevant international recommendations and standards. There are several reasons that confirm the validity of this statement: firstly, only compliance with the mentioned recommendations and standards will provide reliable and high-quality international communications, which any country seeking to integrate into the international community needs; secondly, these recommendations and standards are the results of the work of international research centers, such as, for example, SSE and ETSI; it is hardly reasonable not to use the potential created by them; thirdly, neither the use of imported nor the export of domestic equipment is possible without making appropriate corrections to the hardware and software of telecommunication equipment to harmonize its main characteristics and the requirements of the national network.

In this graduation project, taking into account the above conditions and requirements, the issues of modernizing the telephone network with. Uryupinka Akkol RTH Akmola region. The KVANT-E switching system was chosen as the automatic telephone exchange.

This switching system was known in the version of quasi-electronic exchanges (they were created by the decision of the military-industrial complex in the 70s). In 1989, the second generation of `KVANT' automatic telephone exchanges was developed, already digital under the code name `KVANT-SIS' (reference and information services).

Since 1995, the production of the next automatic telephone exchange - the third generation of automatic telephone exchange KVANT - began in Euroconstruct. With each generation, the technical and operational performance of automatic telephone exchanges improved. Example: ATS KE 2048 NN - 25-30 cabinets, 1.5 W/N; ATS E SIS 2048 NN - 10-12 cabinets, 2.0 W/N; QUANT E (1996) 2048 NN - 3 cabinets, 0.6 W/N; QUANT E (1998) 2048 NN - 2 cabinets, 0.5 W/N.

At present the system is produced by the following developers: Kvant-Interkom (Riga, Latvia); Kvant - St. Petersburg (St. Petersburg, Russia). Manufacturers: GAO VEF (Riga, Latvia); AO IMPULSE (Moscow, Russia); JSC SOKOL (Belgorod, Russia); Automation Plant (Ekaterinburg, Russia); Plant TEST (Romny, Ukraine); TA plant (Lvov, Ukraine); FTA (Blagoevgrad, Bulgaria).

In addition to replacing the automatic telephone exchange during the modernization of the telephone network with. Uryupinka, the local cable network was expanded, the transmission system with interstation communication lines was replaced.

1 . Analytical researchIon the topic of the project and development on their technical implementation

1.1 Geographical and economic features of the region

Akmola region, being in the center of Eurasia, borders on several regions of Kazakhstan and today is one of the major investment-attractive regions of Northern Kazakhstan. Having unique natural resources - chromite, copper-zinc, gold-bearing, nickel-cobalt, titanium-zirconium ores, in combination with advantageous geographical location and provision with transport and communication systems, the region rightfully deserves special attention of investors. Evidence of this are foreign and joint ventures successfully operating in our region, representing the interests of companies from such countries as China, the USA, Great Britain, Germany, Turkey, Spain, etc. The level of technology and intellectual potential of the region meets modern market requirements and is able to master new types of products. An important role for the development of the region is played by the capital of the Republic of Kazakhstan, the city of Astana.

Our area offers an opportunity for investment and development of such industries as: mining, manufacturing and light industry, energy, metallurgy, mechanical engineering, agriculture.

Akmola region, occupying a favorable geographical position, has a developed network of transport communications. Railways with large junction stations connect important directions north with south, west with east.

In 2006 Akmola region achieved good rates both in the real sector of the economy and in the social sphere. In 2006, the positive nature of economic development continued, as evidenced by the increase in the production of goods and services in almost all sectors and sectors of the economy, the growth of investment in fixed assets, moderate inflation rates, and continued growth in real incomes of the population and domestic consumption. Compared to 2005 and 2004, industrial production increased by 16.2%, incl. in the mining industry, the growth was 24%, in the manufacturing industry - 2.6%. In 2006, industrial products were produced in current prices in the amount of 273.7 billion tenge. The index of the physical volume of production in comparison with 2005 amounted to 116.2%. The volume of agricultural production in all categories of farms, according to an estimate, amounted to 26.5 billion tenge and decreased by 7% compared to 2005, which is associated with a low harvest compared to last year. In 2006, 138.5 billion tenge of investments in fixed assets were used for the development of the economy and the social sphere, which is 14.7% more than in the previous year.

The Akkol district considered in the graduation project is located in the southern part of the Akmola region. Formed in 1928. The area is about 6.9 thousand km². The population is over 30 thousand. The average population density is 5.6 people.
per 1 km².

There are 9 rural and 1 urban administrations on the territory of the Akkol region. Administrative center of the district - Akkol city. The relief of the territory is flat-hilly. Soils: southern chernozems, argillaceous and loamy in combination with solonetzes. The climate is continental, arid. The average annual precipitation is 300-350 mm. The area is rich in water resources such as the rivers: Talkara, Aksuat, Koluton; lakes - Zharlykol, Itemgen, Shortankol, Balyktykol.

There are about 20 industrial enterprises, 10 construction and transport organizations on the territory of Akkkol district. The subjects of medium and small business are developing. The area of ​​agricultural land is 567.0 thousand hectares, including arable land 226.0, pastures 318.5 thousand hectares. The area mainly grows and exports wheat.

There are 39 preschool institutions, 34 secondary schools, a children's music school, a schoolchildren's home, PTSh-10, 24 clubs, 4 cultural centers, 39 medical and preventive institutions in the district. A local newspaper is published. A railway passes through the territory of the Akkol region. Astana-Kokshetau - Makinsk, Akkol-Astana highway, etc.

On the territory of the district there are: Akkol marble deposit, Akkol crushed stone plant, Akkol forestry, Granite deposit, mechanical repair plant and other organizations.

According to statistics, the population is: in the city - 16,110 people, in the villages - 15,837 people. The region is experiencing an increase in population.

1.2 a brief description of telecommunications

As of November 10, 2006, Akkol regional telecommunications networks have 4,774 UTN and STS subscribers, with an installed station capacity of 4,674 numbers. In the city telephone network, the used station capacity is 90% (2520 numbers). Since 2004, SI-2000 has been operated as a CA of the Akkol RTH.

Rural telephone networks of Akkol RTH consists of nine rural terminal stations (TS) various types, as well as the central station (CS) (Figure 1.1).

As of November 10, 2006, rural networks were used by 94.8%, with the installed station capacity for 1974 numbers, 1888 numbers were used, mainly subscribers of the apartment sector. ATSK 50/200, M-200, Kvant-E are operated as terminal stations (OS). All rural subscribers are provided with access to long-distance and international communications. At rural stations, where ATSK 50/200 is operated, modems are installed for constant monitoring of work.

Figure 1.1 - Scheme of organization of communication of the Akkol RTH

In the Akkol region, work is constantly being carried out to reconstruct and modernize the telecommunications sector. For example, work on preparing premises for a new electronic station, switching subscribers of an existing station in settlements (ATSK 50/200 to digital), analog equipment to IKM-30 equipment, telephone installation in villages where there are no automatic telephone exchanges, etc.

For 2005 - 2007 it is planned to further upgrade rural telephone exchanges АТСК-50/200 to electronic ones in other settlements. For the second and third quarters of 2007 and early 2008, it is planned to repair and reconstruct the line-cable facilities in all rural settlements in order to further increase the number of subscribers.

It is planned to prepare new premises for automatic telephone exchanges in the villages. For better operation of the connecting lines between the Central Station and the OS, it is planned to overhaul the cable lines in the villages of Priozernoye, Iskra, Trudovoye. Summary information on the state of STS telecommunications (Table 1.1).

Table 1.1 shows that in the considered area with. Uryupinka is operated by АТСК-100/2000 and -LVК-12 as channel-forming equipment. These systems are not produced by the manufacturer today, because of this there is no repair base. Along with physical wear and tear is moral wear and tear.

Table 1.1 - Summary of information on the state of telecommunications of the STS

	Name	Name locality	switching	Mounted capacity, numbers	Transmission system	guide	Distance from TsS-OS, km	Note
		Akkol	S I-2000
	OS-1					KSPP 1*4*0.9		connected to OS-1 s. Stepok with RSM-11
	OS-2	Novorybinka				KSPP 1*4*0.9		connected to OS-2 s. Kalinino and s. Kurlys with direct numbers
		Labor				KSPP 1*4*0.9		connected to OS-3 with. Podlesnoye and with. Kirovo with direct numbers
						KSPP 1*4*0.9
		Naumovka				KSPP 1*4*0.9		connected to OS-5s. Vinogradovka and s.Ornek, s. Filipovka direct numbers
		Uryupinka	ATSK100/			VLS BSA (4mm)		connected to OS-6 with. Amangeldy and the village of Erofeevka, with. Maloaleksandrivka with direct numbers
		Priozernoe				KSPP 1*4*0.9		connected to OS-7 Lidievka village with direct numbers
		Ivanovskoe				VLS BSA (4mm)
						ZKPBP 1*4*1.2

Note: Other than the above, no telephone villages (Table 1.1): Malyi Barap, Krasny Gornyak, Kzyl-tu, Kenes, Radovka, Krasny Bor are directly connected to the CA and have direct numbers.

1.3 Comparativegradecharacteristicscontemporaryswitching systems

Digital switching systems are more efficient than single-coordinate spatial type systems. The main advantages of digital automatic telephone exchanges are: reduction of overall dimensions and increase in the reliability of equipment through the use of an element base of a high level of integration; improving the quality of transmission and switching; an increase in the number of support and supplementary services; the possibility of creating integrated communication networks based on digital exchanges and digital switching systems, allowing the introduction of various types and services of telecommunications on a single methodological and technical basis; reducing the amount of work during the installation and configuration of electronic equipment in communication facilities; reduction of the serving staff due to the full automation of the control of the functioning of the equipment and the creation of unattended stations; a significant reduction in the metal consumption of the design of stations; reduction of space required for the installation of digital switching equipment. Disadvantages of digital exchanges: high energy consumption due to the continuous operation of the control complex and the need for air conditioning.

Features of digital switching devices with pulse code modulation (PCM) signals: processes at the inputs, outputs and inside the devices are coordinated in frequency and time (synchronous devices); digital switching devices are four-wire due to the peculiarities of signal transmission over digital systems.

In a digital switching system, the switching function is performed by a digital switching field. All processes in the switching system are controlled by the control complex. Digital switching fields are built according to the link principle. A link is a group (T- (time-time), S- (space-space) or S/T-) steps that implement the same digital signal coordinate transformation function. Depending on the number of links, two-, three- and multi-link digital switching fields are distinguished. (C) Information published on the website
General characteristics widespread digital exchanges are given at the end of the explanatory note in Table 1 [PA].

As rural exchanges (CS, US, OS, UPS) in our Republic, digital exchanges of Iskatel (SI-2000), MTA (M-200), Netash (DRX-4) and others have become widespread. In this graduation project, we will consider in more detail the characteristics of the DTS-3100, DRX-4 and KVANT-E systems.

Digital ATE type DTS-3100. This system is a powerful and flexible digital electronic switching system for Kazakhstan communication networks. It meets all modern requirements. Thanks to the application modern technologies microcircuits, computers, software and, above all, interconnection and services. The DTS-3100 can be applied to small capacity rural station and large capacity local or intercity hub station.

Modularity of hardware and software allows it to adapt to any network conditions. New technologies can be applied to the DTS-3100 without changing the system structure.

The design concept of the DTS-3100 switching system is an open structure, providing flexibility and modularity. With the introduction of this concept, expansion and modification of the system is facilitated, and it can be easily combined with technological development. The most important aspect is the implementation of the independent system structure technology. This means that advances in computer and semiconductor technology are having an impact on the digital switching system. This will affect not only the production of communication equipment, but also the management of use. The solution to this is the introduction of functional modularity.

All function modules in the DTS-3100 are developed on an open basis to ensure easy integration of new functions. The signaling method between function modules is standardized. A number of functional modules form a subsystem.

Key design goals for the DTS-3100: Flexibility to embrace new features; ease of expansion of the system and preservation of price lines; large capacity, applicable to big cities; adaptation to different territories (urban or metropolitan); high efficiency and reliability; facilitating the use of software.

In terms of features, the DTS-3100 system provides diverse and versatile features that meet all the requirements of a modern switching network: a wide range of applications; great opportunities; multiprocessor structure; parallel oᴨȇrational system; programming language CHILL/SDL; database management system; redundancy configuration.

Technical details. DTS-3100 found application as automatic telephone exchange: local switching; nodal switching; intercity switching; digital network of integrated services.

Capacity of the DTS-3100 system: terminating subscriber load - no more than 120,000 lines; terminal interstation load - no more than 60,480 lines; traffic capacity - maximum 27,000 Earl; call conduction - no more than 1,200,000 calls per hour.

Capacity of the switching module of remote access: traffic capacity - more than 20 Erl; terminal subscriber load - no more than 8,192 lines; call conduction - no more than 100,000 call attempts per hour.

Signaling link OKS 7 - no more than 128 links.

Interface for PCM transmission: 2.048 Mb/s (PCM-30 system) according to CCITT recommendations G. 732, G. 711; 1.544 Mb / s (PCM-24 system) according to the recommendations of the CCITT G. 733, G. 711.

Processor - MC 68030. Programming language - C++, CHILL, Assembler.

Rack size (width x depth x height): 750 5502.140 mm.

Power: 48V (42V to 57V) DC.

Power consumption - 0.85 W/line.

Working conditions environment: relative humidity - 20% - 65%.

Operating conditions. Subscriber line: line resistance: no more than - 2,000 Ohm; insulation resistance: not less than - 20,000 Ohm.

Characteristics of the transmission:

a) insertion loss (nominal loss): digital to digital - dB: 0; analog (2W) to digital - dB: 0; analog (2W) to analog (2W) - dB: 0; (Actual loss will depend on the relative national level); b) ᴨȇ crosstalk: between two lines - dB: 67 (reference to 1100 Hz, 0 dBmO); c) return loss: Four wires: 16 dB (from 300 to 500 Hz, 2500 to 3400 Hz) against mains balance; 20 dB (500 to 2500 Hz) against mains balance. Two wires: 14 dB (300 to 500 Hz, 2000 to 3400 Hz) vs. 600 ohms; 18 dB (from 500 to 2000 Hz) vs. 600 ohms; d) noise: measured noise - dBmO:< 65; неизмеренный шум - dBmO: < -40;д) уровень ошибок ᴨȇредачи: цель < на один канал.

DRX-4 system. The DRX-4 electronic station is a digital automatic system switching, intended for small settlements, urban areas and enterprises as a terminal, nodal, central rural exchange, urban substation and office and industrial exchange and complies with international ITU-T standards.

The station supports outgoing, incoming, and backhaul communications using standard local telephone network and corporate telephone network signaling systems.

Thanks to its modular architecture and taking advantage of digital switching technology, the DRX-4 based station implements the most optimal technical solution for specific conditions.

Support for many types of trunks and signaling makes it easy to fit the station into the existing environment. The communication channel with the upper-level PBX can be a digital stream transmitted via RRL, fiber-optic or copper cable, or an analog line.

At the site of the central station, DRX-4 can successfully replace the ATSK100/2000 stations by connecting directly to the ATE. At the same time, in addition to servicing communications within the district, access to the intrazonal and long-distance network is provided. In this configuration, the station can make automatic connections or connections with the participation of a long-distance operator.

The DRX-4 system is a digital PBX with distributed microprocessor control. The system has software control and a distributed structure of processor buses. Distributed control is supported by high-level data communication control protocols at speeds up to 2.048 Mbps over redundant control buses.

The microprocessors of the MHS and DTC boards operating at a frequency of 16 MHz, using the control bus, provide the performance of all the necessary functions of their module with a capacity of up to 160 analog subscriber lines and 60 digital trunk lines. These boards provide fast loading its main software into the working memory from the terminal of the workplace for control and operation.

The DRX-4 system does not require ventilation or special operating conditions. An area of ​​18 m 2 is sufficient to install a full capacity system. The power supply of the system is fully provided by a key-type KEBAN complete installation, with redundant 30 A rectifiers according to the n + 1 principle, overvoltage protection and a battery charging circuit.

The structure of the DRX-4 software is multifunctional and multitasking, enabling the parallel execution of many tasks. Real-time mode ensures activation and queuing of processes in accordance with the priority mechanism. Processes use object-oriented structures, in connection with this, any communication between processes is provided by a precisely defined data transfer method. Real-time tasks and data are processed by highly integrated 16-bit processors. The software for the control processors of the station is written in ASSEMBLY, C++, Visual Basic.

DRX-4 equipment provides operation on rural telephone networks with a closed numbering system, open without an exit index, open with an exit index, with mixed five-six-digit and six-seven-digit numbering. The characteristics of the DRX-4 system are given in Table 1.2.

ATS of the KVANT-E system. "KVANT" is a modern, reliable, cost-effective and constantly improving digital switching system (DSC) with a flexible modular structure of hardware and software (SW), developed by KVANT-INTERKOM. It is intended primarily for the development of telecommunication networks in rural administrative regions (SAR). The system can be used in a rural administrative area locally, as a district exchange (RATS), a central station (CS) or a rural-suburban node (USP) of a district center, a node (US) or terminal station (OS) of a rural area. However, a rational option is the integrated implementation of the CSK "Kvant" in the SAR, in which, due to the presence of remote switching and subscriber modules, the system simultaneously covers with its equipment all levels of the network hierarchy of a rural administrative area, forming an overlay digital network with centralized technical operation.

Table 1.2 - Characteristics of the DRX-4 system

Maximum subscriber capacity	Up to 4000 subscriber lines (ORX-4C-up to 300 subscriber lines)
Capacity per cabinet	Up to 596 subscriber lines
Maximum number of remote concentrators and their capacity	2 x 500 subscriber lines
Maximum number
Analog trunks
Digital trunks
The number of analyzed digits of the number
Maximum number of routing directions
Digital joints	2 Mbps and 8 Mbps (electrical and optical interfaces)
Analog trunks	2, 4 and 8 wire type E&M; 4-wire trunk lines with in-band signaling 2600 Hz, 2100 Hz, 600 Hz/750 Hz (in-house signaling)
up to 0.17 Earl
Number of call attempts per HNN
Power consumption	0.7W/port
Operating temperature range

Using the Kvant digital switching system, it is possible to create an overlay digital network or digital "islands" on city telephone networks (PTN), while using the system as a reference (OPS), transit (TS) and base-transit stations (OPTS) practically of any capacity and centralizing the technical operation of the corresponding network fragment. The use of remote switching modules as substations (SS) and remote units of subscriber lines (BAL) as concentrators dramatically reduces the cost of a network of subscriber lines (SL).

On departmental networks, CSK "Kvant" can be used both as autonomous office and production exchanges, and for creating branched digital networks with centralized maintenance and any required topology (fully connected, radial, tree-like, mixed), while providing departmental subscribers with a wide A wide range of specific digital services.

The possible capacity of the stations of the "Kvant-E" system is determined by the modular construction of the structure of the exchange, as well as the required ratio between the number of AL and SL. The minimum capacity station is formed from one switching module. (C) Information published on the website
Depending on the configuration of such a station with BAL units, its capacity ranges from 100 AL (one BALK) to 2048 AL and up to 420 SL of external communication.

The use of a multi-module structure makes it possible to create stations with a capacity of up to 30 thousand AL. Blocks UKS 32x32 ten KM form a digital switching field (DSC) reference-transit station containing links A and B space-time switching. Group paths (GT) ᴨȇlinks (P) in the field of link B of each UKS are evenly, by two, distributed over the rest of the UKS of link B and are used for communication between modules of link A and for transit connections between SL bundles connected to the MSC.

Connections in the digital switching field pass, depending on the direction, through a different number of links: communication of subscribers of one CM - through link A; different KM - through links A-B-A; external connections - through links A-B; transit connections of SLs of one CM - through link B, SLs of different CMs - through two links B-B.

Switching modules based on the newly developed blocks UKS-128 will make it possible to cost-effectively build medium-capacity stations compared to UKS-32, as well as create OPS (Base Station), OPTS (Base-Transit Station) and TS (Transit Station) of almost arbitrarily large containers.

The procedure for increasing the station's capacity or connecting new communication directions during operation does not require reconfiguration of existing equipment and a long interruption in call service. All necessary connections and their activation can be made between 24:00 and 05:00.

1.4 Choosing the optimal PBXand problem statement

Comparing General Specifications various systems, as well as the architecture and capabilities of three common systems (DTS-3100, DRX-4 and KVANT-E), we choose the most optimal one. The criteria in this case are affordable price, suitability in rural networks, provision of modern communication services, etc. For this graduation project, the most economical and optimal is Kvant-E from KVANT-INTERKOM.

The digital switching system "KVANT" has a modular design, geographically distributed switching, decentralized software control and the possibility of centralizing maintenance. The modular architecture of the Kvant switching system and the presence of a two-stage hierarchy of offsets (base station - remote switching module - remote subscriber module) allow distributing the system equipment throughout the city or rural administrative area, forming an overlay digital network or digital "island" of almost any required configuration and tanks with the organization of the CTE of all equipment of the Kvant system.

This project proposes the modernization of the telephone network with. Uryupinka Akkolsky district of Akmola region. Planned modernization of the telephone network with. Uryupinka Akkolsky district of Akmola region creates the preconditions for a stable growth of long-distance and international traffic, the provision of high-speed data transmission services and the provision of digital channels for rent.

Modernization of the telephone network p. Uryupinka is necessary to eliminate all the shortcomings of the telecommunications network, which will affect the increase in the number of subscribers, bring stable financial growth to the operator, further increase the markets for the provision of telecommunications services, and, accordingly, increase cash flow.

The timely replacement of the analog communication system with an electronic PBX and the expansion of the market for the provision of telecommunications services will provide a significant advantage in the competition with companies that provide similar services today.

The main goal of this project is: to meet the demand for the installation of a subscriber terminal; expansion and strengthening of the position of the speaker in the market of communication services; avoiding the loss of potential consumers of communication services; increase in the cash flow of the speaker.

The main objectives of achieving the implementation of this project are: replacement of the morally and physically obsolete station АТСК100/2000 with a total installed capacity of 500 numbers and an used capacity of 489 numbers, the utilization percentage of which is 86.2%, with a modern EATS with a capacity of 1000 numbers with the expansion of station and line capacity by 500 numbers, which will significantly improve the quality of services provided and, accordingly, increase outgoing traffic; ᴨȇconnection of existing subscribers to the new EATS, construction of a distribution network for new subscribers.

The basis of the project strategy is to meet the demand for the installation of a subscriber terminal, gain a leadership position in the provision of telecommunications services, expand the market, providing consumers with. Uryupinka is the most modern, high-quality communication services.

To achieve the set goals and objectives, in order to meet the demand for the installation of a subscriber terminal, the project proposes to carry out a timely reconstruction of the communication line in connection with the replacement of an analogue exchange with a DATS.

2 . Peculiaritiesdigital systemswitching "Kvant-E"

2.1 Architecture of the digital switching system« Quantum»

The general architecture of the Kvant system is shown in Figure 2.1. It is based on the following main elements: switching modules (CM); blocks of subscriber lines (BAL); interface modules with connecting lines (STsT, KSL); technical operation module (MTE).

The switching module KM consists of a universal switching system (UCS) and a control unit (CU). The UKS includes: a space-time switching unit with a capacity of 32 or, in the future, 128 32-channel PCM lines (UKS-32 or UKS-128) and the corresponding signal, generator and control equipment.

The UKS block performs non-blocking connections of any channels of any group paths (GT) of the PCM connected to it.

Switching modules are grouped to build a base, transit or base-transit station of the required capacity, or taken out to places of concentration of subscribers. The remote CM (VKM) can be single or multi-module and contains the CM itself, BAL units and the DCT interface module with digital SL. Such a remote switching module autonomously manages connections and is an independent station in the network structure, remaining, however, a part of the Kvant switching system due to the use of a specific internal system signaling protocol and the possibility of control from the technical operation center (TEC) of the system. Some options for grouping CMs to build a medium-capacity station or a multi-module remote switching module are given in Figure 2.1. The choice of a specific configuration is made during the design, and options with more than three links for connections within the station are immediately excluded.

Blocks of subscriber lines BAL-K - for 128 AL with a concentration of 4:1. The production of BAL-256 has already been launched. The block is included in the switching field of the CM by the group path (GT) of the PCM, does not provide for the closure of the internal message and performs the standard set of BORSCHТ functions for subscribers.

If it is necessary to connect paired telephone sets and / or payphones to the BAL, TEZs are installed in the BALK cassette with sets, respectively, for connecting paired PSAM devices and PTAM payphones. TEZ PSAM is designed for eight AL with TA paired through a blocker. TEZ PTAM serves eight AL payphones, providing them with health monitoring and voltage repolarization when the subscriber answers. All additional sets of PSAM, PTAM are included between AL and AK. Remote subscriber modules (VAM) based on BALK ATS-200 and ATS-100 can be included in the reference station or remote switching module.

ATS-100 can also be used as an independent station with a capacity of up to 128 numbers, having several directions of external communication via PCM lines or via physical or multiplexed trunk lines with a ten-day or multi-frequency code. It is possible to combine two BALK blocks in one construct into one ATS-200 up to 256 AL. The ATS-100 (ATS-200) provides internal load closure and transit connections between trunk lines.

Figure 2.1 - Architecture of the digital switching system "Kvant"

Joint modules with connecting lines:

SDT - for digital, BALK with CSL for physical lines and for lines equipped with transmission systems (SP) with frequency division channels (CHRK). Each module occupies a cassette. SDT modules allow using in external and internal (i.e. to VKM and VAM) communication lines with time division channels (TSC) - up to sixteen junctions with PCM group paths (SGT) with a transfer rate of 2048 kbit / s per one SGT. Instead of any SGT 2048, it is possible to connect SGT15 to work with PCM-15 systems with a transfer rate of 1024 kbps. Connecting analog trunk lines to a digital switching system is not recommended, but if such a need arises, then the KSL modules provide a junction with any types of trunk lines possible on the network.

The technical operation module includes one or more computers and, if necessary, additional external devices for input, output and storage of information. In the minimum configuration, the MTE is installed at each station as its control center. It is possible to use MFC as a CFC of a fragment of a digital network built on the basis of the equipment of CSK "Kvant".

The basis of the MTE is a technical operation computer (TEC) of the IBM-386 type or higher. It is connected via RS 232 interfaces to the control device of the station where the MTE is located, and to external devices - magnetic disk drives, a printer, video terminals of additional workplaces. To communicate with the control devices of remote switching modules and with an external technical operation center (TEC), KHP uses dedicated data channels and modems that provide an X.25 interface. After the implementation of SS No. 7 in the digital switching system "Kvant", it will be possible to replace X.25 channels with SS No. 7.

CHP automatically or according to the instructions of the operator manages the diagnostics and reconfiguration of equipment, measurements of load parameters, electrical measurements of the parameters of speech paths and the accumulation of relevant statistical information. In addition, KHPP charges all calls, processes data alarm and displays them on the display, printer. Using the CHP, the operator can correct the system data of different CMs. On the digital network built on the basis of TsSK "Kvant", the CHP of the main station plays the role of a technical operation center (CTE). In this case, all other stations and remote modules of the "Kvant" system are serviced by the control and corrective method, without the constant presence of personnel.

2.2 Bandwidth of the switching fieldand system performance

The digital switching system "Kvant" provides for the possibility of connecting AL and SL (channels) with an average use per hour of maximum load (HNN) from 0.2 to 0.9 Erl.

The configuration of the switching field of the station is given at the end of the explanatory note [P.B].

In this load range (PLN), there are practically no losses due to the busyness or unavailability of all possible ways to establish the required connection in the digital switching field. The high throughput of the ICT is due to the use of non-blocking UCs and large bundles of channels, multiples of thirty, between individual UCs. In particular, for the switching field of the exchange in Figure 2 [P.B.], the losses will not exceed 0.001 when switching on the AL and SL with limiting load parameters. The loss rate in the DSC due to the inability to establish a connection from a specific input (channel) to the required communication direction (in the group search mode) or to the required output (channel) in the linear search mode is set equal to 0.001 and 0.003, respectively. This corresponds to the field capacity of a single-module station or a 900 Earl remote switching module.

In CSK "Kvant" each CM has its own control device, i.e. the control system is decentralized and its performance is increased simultaneously with the increase in the capacity of the digital switching system. The control devices of individual CMs operate independently, interacting when servicing calls using intra-system signaling channels (ISCC). The performance of an individual CU (Controller) is determined mainly by the type of processor of an IBM-compatible computer.

Assuming that at the station the loads of SLs and SLs are on average approximately equally divided into outgoing and incoming ones, and the average duration of one occupation is about 100 s, the number of calls arriving at the station from one SL and SL with the maximum use of all SLs and SLs is on average 3.6 and 16.2 calls/h. Taking into account the possible uneven distribution of AL and SL loads on outgoing and incoming, as well as a possible decrease in the average duration of a session, the number of calls that should be serviced in a busy bus with a guarantee that there will be no overload of the control system is set to 5Nal + 20Nsl, where Nal and Nsl are the number of connected ALs and SL.

The computer-based control device can serve up to 100,000 calls / h, which makes it possible to guarantee the absence of overloads in any combination of the number of lines and lines.

2.3 Connectinglines and interaction between stations

The digital switching system "Kvant" provides for different types of SL. Intra-system trunk lines, as well as trunk lines to digital exchanges and other types of ATEs, can only be digital. Lines to analog stations should be digital as a rule. Their use, in comparison with analog SLs, increases the reliability and quality of transmission paths, simplifies the two-way and universal use of SLs and compliance with attenuation standards, and also reduces the range of CSC linear equipment. Joint with DSL - type A in accordance with the recommendations of G.703 and G.812 CCITT. The digital path DCT junction module allows connecting internal and external DSLs grouped into 2048 or 1024 kbit/s line paths using an AMI or HDB3 line code.

If necessary, an economically justified connection to the digital switching system "Kvant" of external analog SLs is allowed. Joints with them - type C1 (for SL with FDM) and type C2 (for FSL) in accordance with recommendations Q.517, Q.522, Q.543 and Q.544 CCITT. The BALK module with KSL junction with FSL contains sets of SL (KSL) of various types, allowing you to use:

Three-wire SL, ZSL and SLM single-acting with loop resistance up to 3000 Ohm for SL and ZSL and up to 2000 Ohm for SLM, wire resistance "s" up to 700 Ohm, insulation - at least 150 kOhm and with a capacitance up to 1.6 μF for SL and ZSL and up to 1.3 uF for SLM;

Two-wire SL single-acting and universal double-sided with loop resistance up to 2000 Ohm, insulation - over 50 kOhm and capacitance up to 1 μF.

CSL of the junction with lines sealed with SP FDM allows organizing one-sided SL, ZSL or SLM in four-wire SP channels, as well as two-sided universal SL.

TEZ joint with AL (SAL) is installed, if necessary, instead of one of the AK2 TEZs.

The maximum allowable number of external communication directions in the CSC "Kvant" is limited only by the technically possible number of connected linear paths for a specific system configuration.

Interaction of automatic telephone exchange "Kvant" with counter automatic telephone exchanges (AMTS) of external directions of communication occurs by an exchange of linear and control signals (LUS). On external DSL linear and decade address signals are transmitted in the corresponding signal timeslots (CI) of linear paths. In these CIs, depending on the method of encoding linear signals used, 1...4 VSCs can be assigned to each LT conversational channel. The conversion of the linear signals received from the VSC into the intrasystem format, their transmission to the KM control device via the intrasystem signal channel (VSSC) and the reverse actions for signals from the CU to the DSL are performed by the SGT controller of the SCR module. Any standard line signaling codes can be programmed in the SGT.

For multi-frequency signaling, the SCR module is transparent. The exchange of two-frequency combinations of the code "2 of 6" is provided by connecting through the switching field of digital multi-frequency generators (GRI) and receivers (BCA), respectively. Any method of multi-frequency exchange is possible - pulse shuttle, pulse packet and no interval packet.

When analog physical SLs are included in the TsSK Kvant, the choice of the type of CL is determined by the line conductivity, the method of their use (one or two-sided) and the method of exchanging linear control signals in the corresponding direction. Actually KSL provide an exchange of linear DC signals and battery pulses of the decade code. When the universal two-way FSL is turned on, it is possible to signal with a time code with an inductive method for transmitting control signals. Interaction of KSL with CU CM - according to VSSK. For multi-frequency signaling, the KSL module performs only analog-to-digital conversion of two-frequency code combinations.

For analog CO lines with FDM, you can use different types of CSLs that provide standard methods for exchanging LUS over CO lines, ZSL or SLM formed by SP channels. Depending on the type of SP FDM and the equipment system of the oncoming station, linear and ten-day address signals are transmitted over voice channels with a frequency of 2600 Hz, over one or two VSCs, or over one VSC and one signal channel in the conversational system. For two-way universal trunks, the use of time code is possible.

In general, the SCT and CSL modules provide for any type of SL the interaction of the CSC "Kvant" with all types of decade-step, coordinate, quasi-electronic and electronic stations available on communication networks, as well as with ᴨȇrsᴨȇactive digital switching systems of various types. Of the internationally agreed standard signaling systems, R2, R1.5 are also provided, and in 1997 signaling system No. 7 will be introduced via a common signaling channel (SCS No. 7), which will significantly expand the possibilities of interaction with any modern digital switching systems and will allow creating on the basis of the automatic telephone exchange of the "Kvant" system of the CSIO network.

2.4 Insidedancesignalingand synchronization system

Intra-system signaling in the digital switching system "Kvant" is organized according to the sixteenth CI of all internal PCM paths between the system modules (KM, VKM, BAL, SCT, KSL). In each CM, these VSSKs are constantly connected by the UKS 32x32 unit to the PCM zero path to the KVV9 input-output channel device, which temporarily stores, converts and transmits signal information from the control device to the VSSK and vice versa.

The synchronization system of ATS "Kvant" is built as follows. Each UKS is equipped with its own duplicated clock generator of the second hierarchy level (TG2) with quartz stabilization. The role of TG2 is performed by GRI UKS. Different UKS stations are connected to each other using a switching system synchronization unit (SCS) equipped with TG1 (HPP). The TG1 generator has increased stability, is the lead generator for TG2 KM and synchronizes their operation, as well as the operation of the SCT and KSL modules connected to them. If there are several TG1s, one of them is assigned as the leader. It is possible to connect to TG1 and external reference TG. Generators TG1 of different stations of the Kvant system can also mutually synchronize each other.

On the remote switching module, TGs are used, synchronized from the side of the reference station by selecting clock frequencies from the group signals of the corresponding PCM paths by the SDT VKM unit.

Synchronization of the operation of the remote subscriber module is provided by the allocation of clock frequencies from the group signals of the PCM paths from the reference station or the remote switching module. (C) Information published on the website

Any TG2 or TG1 in case of loss of the leading clock signals ᴨȇ goes into independent operation mode.

2.5 Questions about power supply andplacement of equipment

The source of energy for the stations and remote modules of the "Kvant" system is a 380/220 V AC network, the voltage of which is converted into the main reference DC supply voltage of 60 V with allowable variation limits of 54 ... 72 V. Loss or decrease in the reference DC voltage below 54 B causes the station to stop (VKM, VAM). After the voltage appears, the equipment is automatically restored in a time of no more than three minutes.

All DC equipment supply voltages, as well as temporary backup voltages for critical elements of the CSC (technical operation computer and its external devices) are formed by secondary conversion of the reference voltage of 60 V. Combined BOD and BPKM blocks are used, providing voltages + - 5 ± 0.25 V and + -12 ± 0.50 V. All secondary power supply units are protected against short circuits at the output and automatically restore the operating mode when the short circuit is eliminated. When the equipment is directly supplied with a voltage of 220 V, a BP 220-60 unit is installed in the corresponding cassettes.

Reference stations and remote modules of the system are also equipped with buffer or separate batteries that provide at least three hours for the OPS, TS or OPTS and six hours for the VKM voltage supply of 60 V in the event of a power outage. For stations with a capacity of more than 4000 AL, it is recommended to provide two independent power feeders 380/220 V. The total power consumption from a 60 V source depends on the specific composition of the equipment and averages from 0.6 to 1.0 W per depending on the composition of the equipment.

The equipment of CSK "Kvant" is installed in cabinet-type cabinets with a width of 805 mm and a depth of 325 mm. The rack accommodates up to six cassettes, which, depending on the type, have from 17 to 34 places for typical replacement elements (TEZs). The dimensions of the cassettes and TEZs correspond to the European standard. The weight of a fully equipped cabinet does not exceed 300 kg. Up to ten cabinets are installed in one row, which are attached to the floor and to each other. The height of the row with cable growth is 2800 mm (2580 mm for the row with one cabinet). Cabinet rows are serviced from both sides and placed front or back sides to each other at a distance of 925...1185 mm. The resulting load on the roof does not exceed 450 kg/m2.

The design of the system is highly durable and ensures that the equipment remains operational even during earthquakes of up to eight points on the Richter scale (up to ten - when installed in earthquake-resistant buildings).

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