Sumit's BSNL Training Report

BSNL TRAINING REPORT 2009 Sumit Kumar SPN - EL2007461/10

Govt. Polytechnic College, Kota (Raj.)

PREFACE

BSNL, SDOP I, NAYAPURA, KOTA

Practical training in an industry is an essential part of an engineering curriculum towards making a successful engineer, as in an industry only a student can realize the theory thought in classroom and it also gives an exposure to modern technology. In the field of Electronics Computer engineering there has been rapid development to support the ever increasing volume information, so Electronics students has an opportunity during Training period to knowledge about the latest technologies. The training period of 28 days is not much sufficient to take complete knowledge of technology used but one is expected to identify components, the process flow in an industry for high efficiency and about the knowledge of product technology. Practical knowledge means the visualization of the knowledge, which we read in books. For this we perform experiments and get observations. Practical knowledge is very important in every field. One must be familiar with the problems related to that field so that we may solve them and became successful person. After achieving the proper goal of life an Engineer has to enter in professional life. According to this life he has to serve an industry, may be public or private sector or self-own. For the efficient work in the field he must be well aware of practical knowledge as well as theoretical knowledge. To be a good Engineer, one must be aware of the industrial environment & must know about management, working in industry, labor problems etc., so we can tackle them successfully. Due to all the above reasons & to bridge the gap between theory and practical, our engineering curriculum provides a practical training course of 28 days. During this period a student in industry and gets all type of experience and knowledge about the working and maintenance of various types of machinery.

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Govt. Polytechnic College, Kota (Raj.) Since time immemorial, a man has tried hard to bring the world as close to himself as possible. His thirst for information is hard to quench so he has continuously tried to develop new technologies, which have helped to reach the objective.

The world we see today is a result of the continuous research in the field of communication, which started with the invention of telephone by Graham Bell to the current avatar as we see in the form INTERNET and mobile phones. All these technologies have come to existence because man continued its endeavor towards the objective. This project report of mine, STUDY OF TRENDS TECHNOLOGIES IN COMMUNICATION AND NETWORKING has been a small effort in reviewing the trends technologies prevailing. For this purpose, no organization other than BAHRAT SANCHAR NIGAM LIMITED could have been a better choice. I have undergone by 28 days of training (after II yr.) at BAHRAT SANCHAR NIGAM LIMITED, NAYAPURA, KOTA (Raj.). This report has been prepared on the basis of the knowledge which I acquired during my 28 days (15-06-2005 to 13-07-2005) training at Company.

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BSNL TRAINING REPORT 2009 Sumit Kumar SPN - EL2007461/10

Govt. Polytechnic College, Kota (Raj.)

Acknowledgement:Practical training has an important role in a shaping up an engineering student for practical knowledge how a keeping him update with latest technology. First of all, I would like to express my attitude towards Mr. S.C.Gupta (Training cum placement officer, GPC, Kota) and towards Ms. Rajul Goyal (H.O.D., Electronics department, GPC, Kota) for providing me a great opportunity to undertake training at BSNL, Kota.

I would also like to thanks to Mr. Rajkishore Sharma (TTA EWSD, Nayapura, Kota) and the co-operative management helpful staff for giving me a knowledge of their services and helping me time to time. Last but not least I would like to thanks to training incharge Mr. R.P.Manthwal (SDE SDOP1, KOTA), BSNL, Kota for arranging the training programmer for my practical training. With extremeregards and obligations.

CONTENTS: 4

BSNL TRAINING REPORT 2009 Sumit Kumar SPN - EL2007461/10

Govt. Polytechnic College, Kota (Raj.) 1) INTRODUCTION 2) COMPANY PROFILE 3) PROFILE OF THE COMPANY’S BUSINESS A. GLIMPES OF MAIN SERVICE OFFERED i. BASIC AND LIMITED MOBILE TELEPHONE SERVICES ii. CELLULAR MOBILE TELEPHONE SERVICES iii. INTERNET SERVICES iv. INTELLIGENT NETWORK v. IP TV SERVICES vi. THIRD GENERATION 3G WIRELESS TECHNOLOGY B. DEVELOPMENT OF RURAL TELECOM NETWORK i. Rural DELs ii. Village Telephones a) Village Public Telephones (VPTs) & RCPs b) Public Telephones:C. NETWORK MANAGEMENT D. Setting up KU Band VSAT network E. Policy on transmission network maintenance F. Annual Maintenance contracts for switching system & WLL G. COMPUTERISATION H. OBLIGATIONS i. Towards customers and dealers ii. Towards employees iii. Towards the Society –Corporate Social Responsibilities 4) STRUCTURE AND ABOUT THE EXCHANGES i. COMPUTER UNIT ii. POWER PLANT iii. AC Plant (CENTRAL AIR CONDITIONER) iv. MDF (MAIN DISTRIBUTION FRAME) 5) CONNECTING SYSTEM 6) EWSD EXCHANGE 1. GENERAL OVERVIEW 2. INTRODUCTION OF EWSD

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BSNL TRAINING REPORT 2009 Sumit Kumar SPN - EL2007461/10

Govt. Polytechnic College, Kota (Raj.) 3. FUNCTIONAL BLOCK DIAGRAM OF EWSD 4. GENERAL FEATURES 5. POSITION AND FUNCTIONAL STRUCTURE 6. CAPACITY STAGES 7. FUNCTIONAL UNIT OF SN 8. SWITCHING NETWORK (B) 9. RACK ASSIGNMENT 10.MODULE FRAME LAYOT 11.INTERCONECTIONS OF SWITHING MODULE 12.FUNCTIONS 13.O&M ASPECTS 14.EXCERCISES 15.SWITCHING TECHNIQUES 7) INTERNET 8) CELLULAR MOBILE SERVICES 1. WLL (WIRE LESS IN LOCAL LOOP) MOBILE 2. CODE DIVISION MULTIPLE ACCESS (CDMA) MOBILE 3. GLOBAL SYSTEM FOR MOBILE COMMUNICATION (GSM) 4. THIRD GENERATION (3G) TECHNOLOGY 9) BSNL’S IP TV 10)CONCLUSION 11)GLOSSARY OF TERMS AND ABBREVIATIONS

Introduction:Today, BSNL is the No. 1 telecommunication company and the largest public sector undertaking of India and its responsibilities includes improvement of the already impeccable quality of telecom services, expansion of telecom services in all villages and instilling confidence among its customers.

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Govt. Polytechnic College, Kota (Raj.) Apart from vast network expansions, especial emphasis has given for introducing latest technologies and new services like I-NET, INTERNET, ISDN (INTEGRATED SERVICES DIGITAL NETWORK), IN (INTELLIGENT NETWORK), CDMA, GSM and WLL (WIRELESS IN LOCAL LOOP), BROADBAND, 3G services etc. Now BSNL has also entered in mobile communication. BSNL has all the new services send technological advantages, which are available with any well, developed Telecom network anywhere else in the country. Full credit for all above achievement goes to the officers and staff of the BSNL. The administration is fully aware of the challenges lying ahead and quite committed to provide the latest and best telecom services by their continued support and active co-operation.

COMPANY PROFILE

BHARAT SANCHAR NIGAM LIMITED

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BSNL TRAINING REPORT 2009 Sumit Kumar SPN - EL2007461/10

Govt. Polytechnic College, Kota (Raj.) Bharat Sanchar Nigam Limited (BSNL) is India's leading telecommunications provider and the country's largest public-sector firm. BSNL provides local-exchange access and domestic long-distance services through a network of more than 45 million access lines covering most of India. It also offers wireless communications, data and Internet services, as well as business voice and data services. The company is still controlled by the government, as is one of India's other large phone companies, Mahanagar Telephone Nigam Limited (MTNL). Plans to merge the two companies have been discussed but seem to be on hold.

HIGHLIGHTS ➢ Bharat Sanchar Nigam Limited has a vast reservoir of highly skilled and Experienced work force of about 3,57,000 personnel. ➢ We believe that our staff, which is one of the best trained manpower in the telecom sector, is our biggest asset. ➢ To meet the technological challenges, employees are trained for technology up-gradation, modernization, computerization etc in BSNL's training Centers spread across Country. ➢ To apex training centers of BSNL i.e. Advance level Telecom Training Center (ALTTC) at Ghaziabad and Bharat Ratna Bhimrao Telecom Training Center At Jabalpur are comparable to any world class Telecom Training Center. Moreover, 43 zonal training centers and a National Academy of Telecom Finance and Management have been running for several years now. ➢ Different curriculum run in these centers to impart technology based training, Training for Attitudinal change, basic educational and skill development Program etc.

DOT: Till 31st December, 1984, the postal, telegraph and telephone services were managed by the Posts and Telegraphs Department. In January 1985, two separate Departments for the Posts and the Telecommunications were created. The accounts of the department, initially, were maintained by the Accountant General of the P&T. However, by April

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Govt. Polytechnic College, Kota (Raj.) 1972, the telecommunications accounts were separated. Simultaneously the department also started preparing the balance sheet annually. With the takeover of the accounts from the audit and delegation of larger financial powers to the field units, internal Financial Advisers were posted to all the circles and units.

DEPARTMENT OF TELECOMMUNICATIONS (DOT) The Telecommunication Board consisted of the Secretary Telecommunications, who was the Chairman with Member (Finance), Member (Operations), Member (Development), Member (Personnel) and Member (Technology). The Telecom Commission was constituted in 1989. The Commission has the DoT Secretary as its Chairman with Member (Services), Member (Technology) and Member (Finance) as its full time members. The Secretary (Finance), Secretary (DoE), Secretary (Industries) and Secretary (Planning Commission) are part time members of the Commission. The Department in 1986 reorganised the Telecommunication Circles with the Secondary Switching Areas as basic units. This was implemented in a phased manner. Bombay and Delhi Telephones were separated to create the new entity called Mahanagar Telephone Nigam Ltd. (MTNL). On 1st October 2000, Department created BSNL, a new entity to operate services in different parts of the country as a public sector unit.

PARTICULARS OF THE ORGANISATION

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Govt. Polytechnic College, Kota (Raj.) Date of incorporation

Incorporated on 15.9.2000, vide Registration No. 55107739, dated the 15th September, 2000 and became entitled to commence business with effect from 19th September, 2000.

Type of Company

The Company (BSNL) took over the .business of providing telecom services and network management throughout the country except the metro cities of Delhi and Mumbai of the erstwhile service providing departments of the Govt. of India, i.e., the Departments of Telecom Services and Telecom Operations i.e. 1.10.2000 pursuant to an MOU signed between the BSNL and the Govt. of India. Government Company under Section 617 of the Companies Act, 1956.

Administrative Ministry

Govt. of India, Ministry of Communication and Information Technology, Department of Telecommunications.

Details of Disinvestment s Shareholding pattern

The entire share capital of the Company is held by the Govt. of India

Listing with Stock Exchanges

Not applicable, as the BSNL is an unlisted company

Share Capital

Authorized Capital – Rs.17,500 crores, divided into 1,000,00,00,000[One Thousand Crores] Equity Shares of Rs.10/- each; and 750,00,00,000 [Seven Hundred and Fifty Crores] Preference Shares of Rs.10/- each

Government of India is holding 100% of the share capital of the Company

Paid Up Share Capital - Rs.5,000/- crores of Equity Shares and Rs.7,500/- crores of Preference Share Capital

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BSNL TRAINING REPORT 2009 Sumit Kumar SPN - EL2007461/10

Govt. Polytechnic College, Kota (Raj.)

VISION To become the largest telecom Service Provider in South East Asia.

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BSNL TRAINING REPORT 2009 Sumit Kumar SPN - EL2007461/10

Govt. Polytechnic College, Kota (Raj.)  It is defined as an organization’s dream, which it wants to realize in the long run say 5-10 years time frame.  A dream which a company sincerely attempts to make a reality. While it is not necessary to have a Vision statement, it makes sense to have one so that all efforts, energy and resources get directed in realizing this Vision.

MISSION - To provide world class State-of-art technology telecom services on demand at Affordable price. - To provide world class telecom infrastructure to develop country’s economy.  Mission is the path taken to realize the Vision. For example if leading a prosperous life after graduation is the vision of parents for their son, mission could be to get the son admitted in an engineering college so as to realize that vision.

PROFILE OF THE COMPANY’S BUSINESS

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Govt. Polytechnic College, Kota (Raj.) A.GLIMPSES OF MAIN SERVICES OFFERED 1. BASIC AND LIMITED MOBILE TELEPHONE SERVICES BSNL is the leading service provider in the country in the Basic Telephone Services. As of now more than 35 million Direct Exchange Lines & more than 2.2.Million telephones in the Limited Mobile telephone Services are existing. BSNL has provides a number of attractive tariff packages & Plans which shall further strengthen its subscriber base.

2. CELLULAR MOBILE TELEPHONE SERVICES BSNL’s GSM Technology based Cellular Mobile Network has reached a long way, covering more than 6400 towns, with a subscriber base of over 1.54 crore as on 31st Jan. 2006 out of which 1.16 Crore cellular telephones are in the prepaid segment.

3. INTERNET SERVICES BSNL offers Dialup and Broad Band Internet services to the customers by Post-paid service with the brand name ‘Net one’, and pre-paid service with the brand name ‘Sancharnet’. The post-paid service is a CLI based access service, currently operational in 100 cities. Sancharnet is available on local call basis throughout India to ISDN and PSTN subscribers. The Internet Dhaba scheme of the Company aims to further promote Internet usage in rural and semi urban areas. To keep pace with the latest and varied value added services to its customers, BSNL uses IP/MPLS based core to offer world class IP VPN services. MPLS based VPNs is a very useful service for Corporate, as it reduces the cost involved as well as the complexity in setting up VPNs for customers networking. As on 31.03.2005, your Company’s total Internet customer base was 17,98,089 and total Internet Dhabas were 4143. A total of 708594 dial up Internet connections have been given during 2004-2005, against a target of 7 Lakhs. BSNL plans to give 1215980 more dial up connections during the year 2005-06. As on 31.1.2006, there were 2367404 internet subscribers working in BSNL net work.

BSNL has launched its Broadband Services under the brand name ‘DataOne’ on 14/1/2005. This offers services like High Speed Internet Access with speed ranging from 256 Kbps to 8 Mbps. Other services like streaming video, Video on Demand, Bandwidth on demand etc., have also been planned. As on

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BSNL TRAINING REPORT 2009 Sumit Kumar SPN - EL2007461/10

Govt. Polytechnic College, Kota (Raj.) 31.12.2005,there were more than 356000 broad band connection provided by the BSNL. There are plans to give 2 million and 3 million connections in 2006 and 2007 respectively.

4. INTELLIGENT NETWORK Intelligent Network Services is a service that incorporates several value added facilities, thoroughly designed to save time and money, and enhance productivity. At present, your company offers Free Phone (FPH), Premium Rate Service (PRM), India Telephone Card (ITC), Account Card Calling (ACC), Virtual Private Network (VPN), Universal Access Number (UAN) and Tele voting IN services. With the commissioning of five numbers of new technology IN Platforms (Four General purpose and One Mass Calling) at Kolkata, Bangalore, Ahmadabad and Hyderabad, the India Telephone Card facility and new value added services are being provided throughout the country. Activation of these new IN platforms had increased the sale of ITC Cards taking the figure to Rs.265 crores in 2004-05 alone.

5. IP TV Service First started in Japan in 2002. Popular in France, South Korea, Germany, Hongkong etc., France is leading in IPTV having more than 1.7 million IPTV viewers, Global IPTV subscribers base will reach 14.5 million in 2007 and will be approximately 63 million by 2010.

6. Third Generation (3G) Wireless Technology Capability to support circuit and packet data at high bit rates:  144 kilobits/second or higher in high mobility (vehicular) traffic  384 kilobits/second for pedestrian traffic  2 Megabits/second or higher for indoor traffic Support of multimedia services/capabilities:  Fixed and variable rate bit traffic  Bandwidth on demand  Asymmetric data rates in the forward and reverse links  Multimedia mail store and forward  Broadband access up to 2 Megabits/second

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BSNL TRAINING REPORT 2009 Sumit Kumar SPN - EL2007461/10

Govt. Polytechnic College, Kota (Raj.)

B. DEVELOPMENT OF RURAL TELECOM NETWORK

1. Rural DELs As on 31.03.2005, in BSNL’s network, a total of 1.356 Crorerural telephone connections were working. As on 31.1.2006, there are 1.425 Crore rural telephones working in BSNL network.

2.

(a)Village Public Telephones (VPTs) & RCPs:-

BSNL, in its unstinted efforts to make the slogan ‘Connecting India’, a reality, had provided VPTs in 5,18,992 villages up to 31.03.2005. The Company entered into an agreement with USO Fund for expansion of rural telecom network by November 2007, by providing VPTs in 66,822 undisputed, undisturbed, accessible and inhabited villages having population more than 100 as per Census, 1991 in the country. BSNL provided VPTs in 5,28,886 villages up to 31.01.2006. There are plans to replace all MARR VPTs in the country . As of now total 123194 MARR VPTs already replaced in the country by BSNL. BSNL also committed to provide the Rural Community Phones as per the USO Fund agreement. As of now around 13713 RCPs already provided by BSNL.

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(b)Public Telephones:-

There are more than 2 million PCOs working in the BSNL Network out of which around 1 million PCOs are having STD/ISD.

C. NETWORK MANAGEMENT BSNL is committed to provide a robust state of the art infrastructure that will provide stable and superior services to its customers. Accordingly, the MLLN network covering more than 200 cities was made operational in May 2004. Since then, about 22000 circuits have been provided on this network. This has provided high level of stability to the leased circuits and capability to offer N X 64 Kbps circuits. Keeping in

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BSNL TRAINING REPORT 2009 Sumit Kumar SPN - EL2007461/10

Govt. Polytechnic College, Kota (Raj.) view the growing demand of leased circuits, the network is being expanded to cover about 50 more locations and additional capacity at many existing locations is also being provided.

To improve the operational efficiency of CCS 7 signaling, stand-alone signaling transfer point (SSTP) equipment is being procured. This will also enable the Company to measure signaling traffic of other operators, who are using its signaling network for exchanging messages, especially with regard to cellular services. BSNL has more than 4.7 Lakhs Route Kilometers of optical fiber network in the country & has installed capacity more than 6.4 million lines for the TAX meant for the STD/ISD network.

D.Setting up KU Band VSAT network As regards the KU Band VSAT network equipment, the hub of this network is being set up at Bangalore, The equipment has been installed and expected to be commissioned shortly. This will help your Company, to become a service provider with all types of media equipment i.e. OFC, Microwave and satellite for provision of bandwidth, this will also enable the Company to offer composite solutions to its customers. What is V-SAT? It can be defined as a class of very small aperture Intelligent Satellite Earth Station suitable for easy on-premise installation, usually operating in conjugation with a large size HUB earth station. Capable of supporting a wide range of two ways integrated Telecom Services. It has the following components: Micro Earth Station Mini Earth Station Personal Earth Station Roof Top Terminal Customer Premises Terminal

ADVANTAGES OF V-SAT Can be located in the user premises on roof top or backyard and hence eliminate last mile problem. Superior quality satellite based data services. Quick implementation time.

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Govt. Polytechnic College, Kota (Raj.) Reliable communication. Broadcast feature on satellite communication. Communication to different areas. Flexibility for network and changes. Service in distance insensitive. Low cost.

E.Policy on transmission network maintenance Telecom Circles have large transmission networks. To improve the maintenance of transmission network, guidelines for route parties and vehicles have been formalized. Telecom Territorial Circles are also being connected with computerized network for booking of transmission system faults, with a view to improve follow up and faster restoration of faults.

F. Annual

Maintenance

contracts

for

switching

system & WLL Comprehensive AMC, which includes hardware and software maintenance and upgrade, has been arranged with the respective equipment suppliers. Initial feedback suggests that, as a result of preventive and corrective maintenance support, the performance of switches is improving. Difficulties in entering into AMC with rural WLL equipments suppliers have been resolved and procedures streamlined so that adequate maintenance support becomes available. As a result, the performance of WLL network is improving. AMC arrangements have also been made with suppliers of FWTs and hand held terminals.

G.COMPUTERISATION Implementation of Inter Operator Billing and Accounting system (IOBAS) has been completed. Your Company plans to provide CDR based Customer Care and Convergent Billing system. This will help Company in providing effective and efficient billing & customer care solutions for its fixed line subscribers. It envisages building of country wide intranet to reduce the cost of operation, increase

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Govt. Polytechnic College, Kota (Raj.) realization, stop leakage of revenue and minimize frauds, besides providing round the clock best customer care services to the Company’s subscribers. Call center facility has been introduced for 71 SSAs, which is a single point approach for addressing all customer needs cum grievances. Web based Public grievance Management System has been implemented for speedy disposal and monitoring of public grievances. Web based Inventory Management package has also been introduced, through which, material management functions are being computerized gradually in different circles. Online Mobile Bill viewing facility has been made available to all Cell One Mobile Customers (all States) through Company’s Portal (http://bsnl.in). Duplicate Telephone bill viewing facility for landline telephone has also been made available at many places through Websites of respective telecom circles.

H.

OBLIGATIONS 1. Towards customers and dealers To

provide

prompt,

courteous

and

efficient

service

and

quality

of

products/services at fair and reasonable services.

2. Towards employees ✔ Develop their capability and advancement through appropriate training and career planning ✔ Expeditious redressed of grievances ✔ Fair dealings with recognized representatives of employees in pursuance of healthy trade union practices and sound personnel policies

3.Towards the Responsibilities

Society

–Corporate

Social

CORPORATE SOCIAL RESPONSIBILITIES BSNL is committed to provide quality Telecom Services at affordable price to the citizens of the remotest part of the Country. BSNL is making all effort to ensure

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Govt. Polytechnic College, Kota (Raj.) that the main objectives of the new Telecom Policy 1999 (salient points indicated below) are achieved: Access to telecommunications is of utmost importance for achievement of the country's social and economic goals. Availability of affordable and effective communications for the citizens is at the core of the vision and goal of the new Telecom policy 1999. Strive to provide a balance between the provision of universal service to all uncovered areas, including the rural areas, and the provision of high-level services capable of meeting the needs of the country's economy encourage development of telecommunication facilities in remote, hilly and tribal areas of the country; Transform in a time bound manner, the telecommunications sector to a greater competitive environment in both urban and rural areas providing equal opportunities and level playing field for all players.

STRUCTURE AND ABOUT THE EXCHANGES All telephone subscribers are served by automatic exchanges, which perform the functions the human operator. The number being dialed is stored and then passed to the exchange’s central computer, which in turns operates the switching to

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Govt. Polytechnic College, Kota (Raj.) complete the call or routes it a higher level switch for further processing. Today’s automatic exchanges uses a pair of computers, one running the program that provides services and the second monitoring the operation of the first, ready to take over in a few seconds in the event of equipment failure. Various exchanges present in BSNL are: C-DOT E-10B OCB283 (Exchange & TAX) EWSD (Exchange & TAX) All exchange has some purposes and some basic structural units, which are: 1. 2. 3. 4.

subscriber’s connection unit Switching network (CX) Control unit OMC (Operational & maintenance Control)

STRUCTURE OF THE EXCHANGE

For smooth working of an exchange following unit are very important: 1. Computer Unit: - it deals with additional services of the exchange to the customers with the help of computers. 2. Power Plant:- to feed proper power supply to exchange 3. AC Plant: - to maintain the continuous temperature + or – 2 degree Celsius to the digital switch (exchange). 4. MDF: - to connect switch (exchange) with the external environment (subscriber) i.e. it is the interface between subscribers and exchange.

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Govt. Polytechnic College, Kota (Raj.) 1.

Computer unit: -

as the name specified it is the main part of the exchange that deals with the all services provided by the exchange to the customers with the help of computer. It also provides the updated data to all other part of the exchange. The customers are using the services of the exchange by using the internet also gets connected to the main server present this room via an internet room. It mainly consists of the servers that are providing the different services. The main servers of this room are:IVRS is used for the change number services provided by the exchange. CERS are provided by the exchange to avoid the problems that the users are facing the repairing of telephone. In this system when the user enters its complained it gets directly entered to the server and user is allotted with an id number. LOCAL DIRECTORY ENQUIRY is another services provided by the exchange, by using this; subscribers calls the particular number and gets the directory enquiry. The server present in the main computer room provides this service. INTERNET DIRECTORY ENQUIRY is the latest service by the exchange. In this type of service makes it enquiry using the internet, which gets connected to the main server at the internet room in the exchange and further to the main server in the computer room. 2.

POWERPLANT: As we know that, the power is the main source or any organization. It is the case of E-10B exchange. That is the first requirement of any organization is the input. The main source of this exchange is AC supply. However, as soon as the power supply is gone off, then what is source? No one think on this that the telephone is always plays its role in the human life. Even if the power supply gone off. Thus there must be adjustment source of power. The main parts of the power room are: i. Batteries: - these are the instant sources of the power as soon as power is gone off. ii. Charging- Discharging Unit: - the batteries we are using in the power room need timely charging. As soon as the AC power supply is on, we make use of the charging unit present in the power room.

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Govt. Polytechnic College, Kota (Raj.) The slowly charging of the batteries is known as the trickle charging. But sometimes we need the BOOSTER charging. In this type of charging awe take of the batteries from the load and charge separately, until it gets fully charged. The main work of the discharging unit is to control the discharging of the batteries.

iii. Inverter and Converter Unit: - the main use of this system is to change AC mains to DC and vice versa as required by the parts of exchange.

iv. Engine Room:-we know that the batteries are the instant source of supply but we cannot use it for much larger time, thus for this, we have an engine to generate the power supply. They are of 885 KVA. Thus, this room controls the supply of the engine.

UPS OPERATING MODES: UPS system has three operating mode which can be designated as 1. Normal mode 2. Emergency mode 3. Recovery mode I. NORMAL MODE: The rectifier charger draws power from the ac mains & convert it into DC. This DC power is supplied to the inverter which converts it back into AC power to feed the critical load connected to the output of the inverter. A small amount of DC owner is also supplied to the battery which is connected to the output of the rectifier charger. The battery is thus kept in a fully charged condition by the rectifier charge. In this condition the battery is said to be on float across the rectifier charger. In this mode the battery does not supply any power to the inverter.

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Govt. Polytechnic College, Kota (Raj.)

II. EMERGENCY MODE: Emergency mode occurs when there is an interruption in the AC input to the rectifier charger. Interruption like voltage dips below the limit acceptable to the rectifier charger to fall. But the input of the inverter cannot fall because the battery is across inverter input & it maintains the voltage. AC mains is interrupted, the source of the inverter input current gets instantaneously transferred from the rectifier charger to the battery when the output voltage generated by the rectifier charger falls below the battery voltage. The battery which was earlier on float (charged) instantaneously goes into discharge & then supplies power to the inverter till the AC mains resumes or the battery gets fully discharged. During this mode current cannot flow back from the battery into the AC mains because the voltage reverse biases the diodes or THYRISTORS in the rectifier charger.

III. RECOVERY MODE: The recovery mode commences when the AC mains resumes after the interruption. When the generated voltage of the rectifier exceed the battery voltage. The input current of the inverter gets instantaneously transferred from the battery to the rectifier charger. During this mode the rectifier charger not only supplies power to the inverter but also supplies charging current to the battery to restore the charge lost by the battery during the emergency mode. When the

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BSNL TRAINING REPORT 2009 Sumit Kumar SPN - EL2007461/10

Govt. Polytechnic College, Kota (Raj.) battery gets fully charged, the charging current decreases progressively and the battery reverts to the float mode and the UPS to the normal mode. The duration of the recovery mode depends on the extent of battery discharged, approximately 10 to 20 hours depending on the battery specifications and the design of the rectifier charger.

3.

AC PLANT (CENTRAL AIR CONDITIONER) for the function of electrical equipment, cooling system is basic requirement. The basic advantages of cooling systems are followingIt provides the thermal stability so that the temperature does not reach the tolerance limit of electronic equipment. It saves equipment from dust so to avoid malfunction of equipment’s. It protects equipment from excess humidity which can caused rusting of equipment. The basic unit of measurement used in the industry is known as “ton of refrigeration” (TR) which is equivalent to the heat extracted in 24 hours for converting thousands kg of liquid to ice at zero degree. The compressor is the heart of the AC system and the costliest. It increases the pressure and temperature of the refrigerant gas coming from the evaporator coils by compressing it. Compressor comes in various types. The most widely used is simple reciprocal type a cylinder and piston arrangement. For capacity more than 120 TR, centrifugal compressors are used. The condenser liquefies the refrigerant gas by a heat exchange process. The capillary tube or the expansion valve pressurizes liquid refrigerant and meters it flows to the evaporator. The refrigerant then passes through the evaporator coils, which extract heat out of the ambience.

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Govt. Polytechnic College, Kota (Raj.)

4.

MAIN DISTRIBUTION FRAME The primary function of MDF is: The fault of telephone number is removed in the MDF; it is called as Fault Remove Section. For removing the fault of telephone number, we use the testing these testing are T.T.Y. testing, Group testing, etc. For any type of testing firstly we need the vertical no. or the live tester, printer and computer test N.E. number of that particular telephone number. The telephone numbers are also disconnected in the MDF because of some specific reason.

➢ ORGANISATION OF THE MDF

PARTS OF THE MDF Horizontal side Vertical side a. HORIZONTAL SIDE: It is again subdivided in to two parts Exchange side Line side Description of the horizontal side:RACK: - On the rack, the tags are situated. One rack is having eight tags. The courting is done from up (0) to down (7). TAG: - Each rack consists of eight tags. 1 tag = 4 core 1 core = 4 bunch 1 bunch = 2 line N.E.:- The word NE stands for the ‘NUMBER OF EQUIPMENT’. It is a 128 pair cable. The EWSD and MDF connected by NE.

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BSNL TRAINING REPORT 2009 Sumit Kumar SPN - EL2007461/10

Govt. Polytechnic College, Kota (Raj.)

WEDGE:-If we want to disconnect any two numbers then we insert a wedge between subscriber side and exchange side. Here wedge works as insulator made of plastic. a. VERTICAL SIDE: The vertical aside connected to the underground cable. This cable is having 100 pairs. These pair is distributed when we allot the telephone number to the subscriber. Vertical side is again subdivided in two parts: One part is connected with the horizontal side and another with the subscriber line by using 100 pair underground cable. This is how the present day telephone system works. Different exchanges have different architectures of switching call routing and other features.

FUNCTION OF MDF: • A fixed means of terminating the external cables. • A means for mounting the protective devices for incoming circuits. • A convenient point of interception for locating of faults. • A means for cross connecting the external circuits to the appropriate Internal circuits. The MDF is properly earthed for the protection of the equipment. The external pairs are area wise terminated on the line side of the frame, while connection from the equipment is done on the exchange side in a numerical order. By interconnections at this frame with the help of jumper wires, any subscriber in any area can be given any exchange number. This MDF mounts Delay Fuses only.

PROTECTIVE DEVICES : Comprehensive protection against effects of lightning and power line contacts, is achieved in practice by fuses, arresters and heat coils. They are not affected by normal speech and signaling voltage and current but operates when the foreign voltage or current on the line is excessive. The line is then disconnected automatically from the equipment or a connection to earth is For safety precautions fuses are used. Every subscriber line has individual fuse. These fuses are made of GD (gas discharge) tube, which are connected in parallel. These fuses have two sides, one is exchange side and other is subscriber side. Connections between the different tag blocks are made using the jumper wires of red and white colors. GD tubes are connected in parallel while electrical fuses are connected in series.

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BSNL TRAINING REPORT 2009 Sumit Kumar SPN - EL2007461/10

Govt. Polytechnic College, Kota (Raj.) In electrical fuse, when high voltage appears across it, then it will break up the Connection and thus safeguard the system. If GD tube is connected in series, then due to high voltage across any line, the whole exchange will be disconnected. Thus when GD tubes are connected in parallel, it will provide the required facility.

GASE DISCHARGE PROCTECTORS: In case of heavy lightning discharges, gas discharge protectors are used and more consistent voltage is obtained. The gas discharge protector essentially consists of two tungsten electrodes sealed in a special glass envelope containing a mixture of inert gases, mainly neon. One of the electrodes are for connections to the lines and the other is the earth electrode. If the potential difference across the electrodes rises to a certain critical value (the Striking value) the gas is ionized and becomes conducting. This condition will Continue till the potential difference across the electrodes falls to the extinction voltage value. For voltages less than striking value it will not conduct. For normal operating voltages on the lines, it offers extremely high impedance and thus does not introduce any transmission loss. For equipment side: MDF has many tag blocks of 100 and that numbered from 1 to 100. In a tag block, there are 128 pair wire theoretically. Therefore, total number of Connecting wires are 1024 theoretically. But in practical, there are only 1000 pairs. For equipment side: From ground, a single pair of 400 wires originates, which is divided In 4 pairs of 100 wires. Practically, each pair is provided with 102 wires. These Exact 2 wires are used in case of any manufacturing defect. For broadband connections, different colored tag blocks are provided. Broadband is used to provide different facilities on land-line phones with high Speed to access them. A grey colored tag block is used for line side while yellow Colored tag block is used on equipment side. These tag blocks has 0 to 47 pairs. In order to know the centre load point.: Cabinet and pillar are provided with capacity as per requirement. The D.P. box is Provided with 10 or 20 or 5 pairs. Now a days, a D.P. box of 5 pairs is used which is wall mount instead of being mounted on pole. To identify any telephone, we require the following two addresses:1. Exchange/line address 2. Equipment address Exchange address is written in given manner:

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BSNL TRAINING REPORT 2009 Sumit Kumar SPN - EL2007461/10

Govt. Polytechnic College, Kota (Raj.) Vertical number-tag block number-pair number For example 7-5-15 Here, vertical no.=7 Tag block no.=5 Pair no.=15 This gives the address of a telephone in the exchange. Equipment address is given as:Rack number-tag block number-pair number For example7-6-87 Here,rack no.=7 Tag block no.=6 Pair no.=87 This gives the information about the actual location of telephone equipment. This address is provided to lineman for repairing, in case of any fault. There is a section of fault repairing located in MDF section. When subscriber’s phone is not working, then subscriber call to exchange. For this he dial,198.

CONNECTING SYSTEM

Exchange Side

Line Side

•

Cables from all the Exchanges reach the MDF

•

From the MDF Underground Jumper Cables go to the Cabinets

* The Capacity of the Cabinets is large around 2000 pairs * If the number of subscribers is small then there is no need for the Cabinets

•

From the Cabinets the cables go to the Pillars

*the position of the pillars is chosen such that the length of the wires going to the DPs is equal in all directions

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BSNL TRAINING REPORT 2009 Sumit Kumar SPN - EL2007461/10

Govt. Polytechnic College, Kota (Raj.)

•

From the Pillars the wires go to the DPs

* the capacity of each of the Pillars is about 10 or 15

•

From the DPs the wires go to the subscribers’ homes

When a fault like Phone dead is reported then first check is made at the MDF (i)

a Phone Set is inserted on the Line Side, some number is dialed

and it is checked if the conversation takes place properly (ii)

if the conversation takes place properly then the fault is said to

be on the Line Side (Outdoors) (iii)

But if there is no Dial Tone then the fault is said to be on the

Exchange side (Indoors)



The fault in the Outdoors is checked first of all at the DP

If there is dial tone at the Pillar but not in the subscribers home then the fault is in between the DP and the subscribers phone set. 

Otherwise at the Pillar If there is dial tone at the Pillar but not at

the DP then the fault is in between the DP and the Pillar 

Otherwise the phone is checked at the Cabinet If there is dial

tone at the Cabinet but not at the Pillar then the fault is in between the Cabinet and the Pillar 

Otherwise the only option left is that the fault is in between the

MDF and the Cabinet

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EWSD

EWSD and Office Switch

1.General Overview EWSD (Elektronisches Wählsystem Digital in German, Electronic Digital Switching System/Electronic World Switch Digital in English) is one of the most widely installed telephone exchange systems in the world. EWSD can work as a local or tandem switch or combined local/tandem, and for landline or mobile phones. It is manufactured by Siemens AG, who claims that EWSD switches perform switching for over 160 million subscriber lines in more than 100 countries. DeTeWe bought its first EWSD under license in 1985 for remote switching. Bosch built its first EWSD as a local exchange in 1986. Deutsche Telekom, formerly Deutsche Bundespost, the largest German telephone company, uses EWSD and System 12 (Alcatel), the former more than the latter. In 2007, Nokia Corporation and Siemens AG formed the new company Nokia Siemens Networks, and responsibility of further development and shipments of the EWSD system is dependent on this new company.

Contents •

1 Hardware

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BSNL TRAINING REPORT 2009 Sumit Kumar SPN - EL2007461/10

Govt. Polytechnic College, Kota (Raj.) •

2 Software

•

3 Technical data

Hardware Main subsystems are: •

CP (Central Processor)

•

MB (Message Buffer)

•

CCNC (Common Channel Network Control)

•

LINE (Analog Line Group)

•

LTG (Line Trunk Group)

•

DLU (Digital Line Unit)

•

SN (Switching Network)

All system units are redundant so the inactive side can take over immediately in case of an error. DLU handles analog and ISDN lines and includes codec’s for analog lines, one of the BORSCHT functions for subscriber lines. Digital signals are assigned a time slot. DLU concentrates traffic onto a Line B unit, as well as Primary ISDN and V5.2 connections. Supervision and address signaling (dial pulse, DTMF) are also integrated in the DLU. For PCM-30 (E-1) connections to other exchanges, Line C Units are used, which also handle signaling including SS7, MFC R2 signaling, IKZ (dial pulse), and E&M. he Switching Network consists of 4 space division stages of 16x16 switches, and a time division section with 16 stages of 4x4 switches. Control is provided by the CP Co-ordination Processor. There are the following kinds of Co-ordination Processors: •

CP103 with max 22,000 call attempts in the busy hour

•

CP112 with max 60,000 call attempts in the busy hour

•

CP113D with max one million call attempts in the busy hour

•

CP113C with max six million call attempts in the busy hour

•

CP113E with max ten million call attempts in the busy hour

Software The software of EWSD is called APS (Automatic Program System). The APS is on a hard drive and includes the operating system, developed by Siemens in cooperation with Bosch. It is predominantly written in the CHILL language. Application software is switch specific and serves among other things traffic

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Govt. Polytechnic College, Kota (Raj.) management, path search, and call charging. Support software serves translating programs, binding modules as well as administration of libraries for generating data. Operating and data communication software serve for co-operation of maintenance centers and switching centers.

Technical data •

Number of access lines: to 250,000

•

Number of feeder lines: 240,000

•

Traffic connection: 25,200

•

Call attempts in busy hour: 10 million

•

Operating voltages: -48V -60V -90V

•

Rate zones: 127, for each zone of 6 tariffs

•

Tariff change-over at 15 minute intervals

•

Space requirement with 10,000 access lines: 35 square meters

•

15-25 *C Temperature

EWSD EXCHANGE KOTA EQUIPPED CAPACITY DATE OF COMISSION

32

60K

BSNL TRAINING REPORT 2009 Sumit Kumar SPN - EL2007461/10

Govt. Polytechnic College, Kota (Raj.)

MAIN (NAYAPURA)

-

6K

16.12.96

IST EXP

-

4K

10.02.97

IIND EXP

-

4.4K

18.03.97

3RD EXP

-

2K

08.06.99

RSU NGM

-

5.0 K 06-.11.97

RSUJN

-

5.0K

26.03.98

RSUANP

-

1K

20.10.98

RSUDDB

-

5.5K

16.11.98

EQUIPMENT DETAILS DLU

-

11

RSU DLU

-

65

LTG B

-

132

LTG C

-

57

CP 113A

-

1

CCNP

-

1

SNB

-

2

MBICCG

-

1

DEVO

-

1

OOF

-

1

WRKING CONNECTIONS

PBX LN

33

328

43753

BSNL TRAINING REPORT 2009 Sumit Kumar SPN - EL2007461/10

Govt. Polytechnic College, Kota (Raj.) STD PCO

1212

ISDNBRA

197

Sr.NO.

Exchange Name

Capacity

Number Scheme

DLU

1

Main

10000

232,2330,

10,150,

2331,

160,170,

2332,

180,,190,

2333,

200,210,

2340,

220,230

(Nayapura)

2341, 2342, 2450,2451

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BSNL TRAINING REPORT 2009 Sumit Kumar SPN - EL2007461/10

Govt. Polytechnic College, Kota (Raj.) 90-130,

2

NGM

6000

2360,2366

(New Grain Mandi)

250

650 260

3

JN

5000

2460,2464 270-290,

(Junction)

440-460. 4

RLY colony

2000

2465-2466

900-920

700

2410-2412

300

(Railway Colony) 5

E-10B (Road No. 2)

380-420

6

DDB (Dadbari)

6000

2500-2505 530-540

7.

KUNHARI

2500

2370-2372

350-370 800-820

8.

Ballabh Bari

3000

2390-2392 730 750-770

9.

Kaithuni Pole

2800

2385-2387 700 620-640

10.

RAMPURA

4500

2380-2384 1150

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BSNL TRAINING REPORT 2009 Sumit Kumar SPN - EL2007461/10

Govt. Polytechnic College, Kota (Raj.) 930-940 11

Keshv Pura

2800

2400-2403 780,710.

12.

BSM

1000

2490-2492

330-340

2000

2480-2481

590-610

(Bhama Shah Mandi)

13.

DCM

470-490 14

SNP

3000

2470-2473 500-510

(Shrinath Puram)

1050-1070 15

Mahaveer Nagar

2000

2475-2476 140

1000-1020 16

Talwandi

2850

2405-2407 720

17

Vigyan Nagar

18.

Kaithun

36

1000

2410-2412

1100-1110

2844

740

BSNL TRAINING REPORT 2009 Sumit Kumar SPN - EL2007461/10

Govt. Polytechnic College, Kota (Raj.)

19.

Veer Sawarkar Nagar

456

2477

6002/456-798

6001/00-356 Borkheda A(1)&(2)

912

21.

Kherali Phayak

456

LEVEL OF MAINS

6001/456-798

22

Badgaon

456

LEVEL OF KUNHARI

6002/00-356

23.

Borkhandi

500

28640-28643

6008/0/0,1,2,3, 4

24.

Thathed

6005/0/0,1,2,3, 4

25.

Alaniya

6006/0/0,1,2,3, 4

26.

Rangpur

6007/0/0,1,2,3, 4

27.

Arandkheda

20.

37

LEVEL OF MAINS

6001/12001656

BSNL TRAINING REPORT 2009 Sumit Kumar SPN - EL2007461/10

Govt. Polytechnic College, Kota (Raj.) 6011/0/0,1,2

28

29

30.

28126-28127

6012/0,1,2

28128-28129

6015/0,1,2

28150-28151

6009/0,1,2,3

28152-28153

6004/0,1,2,3

Mandana

Dara

WLL Jaipur

6000/0/0-9 CLOSED

31.

Kota CORDACT

200

22010-22011

6003

2.INTROCDUCTION OF EWSD Switching network (SN) performs the switching function for speech as well as for messages in an EWSD exchange. For this purpose it is connected to LTGs and CCNC for speech/data and to CP (through MB) for exchange of control information. Switching network with ultimate capacity up to 63 LTGs is called SN DE4. For larger

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BSNL TRAINING REPORT 2009 Sumit Kumar SPN - EL2007461/10

Govt. Polytechnic College, Kota (Raj.) exchanges SN DE5.1 is used which can connect up to 126 LTGs. Similarly SN DE5.2 can connect up to 252 and SN DE5.4 up to 504 LTGs.

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BSNL TRAINING REPORT 2009 Sumit Kumar SPN - EL2007461/10

Govt. Polytechnic College, Kota (Raj.)

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BSNL TRAINING REPORT 2009 Sumit Kumar SPN - EL2007461/10

Govt. Polytechnic College, Kota (Raj.)

3.BLOCK DIAGRAM OF EWSD EWSD switching system structure chart

DLU

•

SLM(A,D,X,I) subscriber line modules

•

DLUC - Digital line unit controller

LTG

Line trunk group

SN

Switching network

SSNC

Signaling system network control

CCNC

Common channel network control

MB

Message buffer

CP

Coordinating processor •

BAP - base processor

•

CAP - call processor

•

CMY - common memory

•

IOC- I/O controller

•

AMP - ATM bridge processor

•

B:CMY0(1) common memory access bus

CCG

Central clock generator

Net

Network management system

Manager

41

Digital line unit

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Govt. Polytechnic College, Kota (Raj.)

4.GENERAL FEATURES Switching network is provided in capacity stages SN: 63LTG to SN: 504LTG, i.e. up to 63 LTGs can be connected or, via other intermediate capacity stages, up to 504 LTGs can be connected. The modularly expandable SN has negligibly small internal blocking andcan be used in EWSD exchanges of all types and sizes.

The self monitoring switching network uses a uniform through connection format. Octets (8 bit speech samples) from the incoming time slots are switched to the outgoing time slots leading to the desired destination fully transparently. This means that each bit of all octets is transmitted to the output of the switching network in the way that it appears at the input (bit integrity). For each connection made via the switching network, the octets have the same sequence at the output as at the input (digit sequence integrity). The switching network’s full availability makes it possible for each incoming octet to be switched at any time to any outgoing highway at the output of the switching network. The time slots used in switching network for making through-connections make up a 64 Kbit/s connection path.

All of the switching network’s internal highways have a bit rate of 8192 bits/s (Secondary Digital Carriers, SDCs). 128 time slots with a transmission capacity of 64 Kbits/s each (128x64 = 8192 Kbits/s) are available on each 8192 Kbits/s highway. Separate cables each containing several (eight or sixteen) such internal highways, are used for each transmission direction. All externally connected highways also have the same uniform bit rate.

The switching network combines the numerous switching network functions in a few module types. These modules work at very high through-connection bit rates; 8192 Kbits/s and some even at 32768 Kbit/s. For example 1024 connections can be switched simultaneously through a space stage with 16 inputs and 16 outputs. Although these highly integrated switching network modules switch a large number of connections with a high degree of reliability, the EWSD switching networks are always duplicated. The amount of space needed for the switching network in the EWSD exchange is still very low despite this duplication. Two different switching network versions have been supplied in India: *

42

Switching network [SN]

supplied with first 110K order.

BSNL TRAINING REPORT 2009 Sumit Kumar SPN - EL2007461/10

Govt. Polytechnic College, Kota (Raj.) * Switching network B orders.

[SN (B)]

supplied with subsequent

5.Position and Functional Structure Switching network is connected to LTGs and CCNC for speech/data and to CP (through MB) for exchange of control information. Figure 1 shows the position of switching network in EWSD exchange with reference to other equipments. For security reasons, entire SN is duplicated. The two sides of SN (SN0 and SN1) are called planes. The external highways for both transmission directions i.e. between the switching network and one LTG or between the switching network and one Message Buffer Unit (MBU) are identified as follows as shown in figure 2. *

SDC: LTGinterface between SN and LTG: time slot 0 for message exchange between the LTG and coordination processor (CP) as well as between two LTGs, time slot 1 to 127 for subscriber connections.

*

SDC: CCNC interface between the SN and the common channel signaling network (CCNC): for common channel signaling.

*

SDC: TSG interface between SN and a message buffer unit assigned to CP (MBU: LTG) for message exchange between the CP and the LTGs as well as between the LTGs.

*

SDC: SGC between the SN and an MBU: SGC of the CP for setting up and clearing connections.

Switching network in EWSD exchanges uses time and space switching and therefore it is functionally divided into Time Stage Group (TSG) and Space Stage Group (SSG). SN DE4 with capacity stage SN: 63LTG has a TST structure and TSG/SSG division is not applicable in this case.

TSGs and SSGs are interconnected through internal 8 Mb/s interfaces called SDC:SSG. TSGs of both planes are connected to SSGs of both planes, and thus these provide further security.

Each TSG and SSG have its own Switch Group Control(SGC) that is connected to CP via MB through interfaces SDC:SGC.

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BSNL TRAINING REPORT 2009 Sumit Kumar SPN - EL2007461/10

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BSNL TRAINING REPORT 2009 Sumit Kumar SPN - EL2007461/10

Govt. Polytechnic College, Kota (Raj.)

TABLE 1: SN Capacity Stages

Capacity stages of switching network

SN:63LT G (DE 4)

Switchable traffic(E) Local Exchanges No. of lines Transit Exchanges No. of trunks Structure Connectable no. of LTGs or LTG+CCNC

SN:126LT G (DE 5.1)

SN:252LT G (DE 5.2)

SN:504LT G (DE 5.4)

3150

6300

12600

25200

30000

60000

125000

250000

7500

15000

30000

60000

TST 63 or 62+1

TSSST 126 or 125+1

TSSST 252 or 251+1

TSSST 504 or 503+1

6.Capacity Stages The present version of SN is available in capacity stages SN:63LTG, SN:126LTG, SN:252LTG and SN:504LTG. Modular structure permits partially equipped SN. Up gradation from DE5.1 to DE5.2 and from DE5.2 to DE5.4 is possible with the help of supplier. SN DE4 is not upgradable to DE5.1 as TSG and SSG are not separately identified in SN DE4. The traffic handling capacity, connect ability for various capacity stages of SN are shown in Table 1.

7.Functional Units of SN 46

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Govt. Polytechnic College, Kota (Raj.)

7.1Switching path The switching network is subdivided into time stage groups (TSG) and space stage groups (SSG). Due to its modular structure, the EWSD switching network can be partially equipped as needed and expanded step by step. The switching network uses the following switching stages:

• • •

one time stage incoming (TSI) three space stages (SS) and One time stage outgoing (TSO).

These time and space stages (functional units), shown in figure 3, are located in the following module types:

• • • • •

Link interface module between TSM and LTG (LIL) time stage module (TSM) link interface module between TSG and SSG (LIS) space stage module 8|15 (SSM8|15) space stage module 16|16 (SSM16|16)

The switching network capacity stage SN:63LTG, however has a TST structure with only one space stage as shown in figure 4. Module types LIS and SSM 8|15 are not there in SN:63 LTG. Further, the modules and the TSGs/SSGs are interconnected

A list of the various modules used in SN is given in Table 2.

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BSNL TRAINING REPORT 2009 Sumit Kumar SPN - EL2007461/10

Govt. Polytechnic College, Kota (Raj.) 7.1.1 LIL & LIS: The receiver components of the LIL and LIS compensate for differences in propagation times via connected highways. Thus, they produce phase synchronization between the incoming information on the highways. These differences in propagation times occur because an exchange’s racks are set up at varying distances to each other. Module LIL is connected on the interface to LTGs and has 4 inputs and 4 outputs while module LIS is connected on the interface to SSG and has 8 inputs and 8 outputs.

7.1.2. TSM:

The number of TSMs in a switching network is always equal to the number of LILs. Each TSM contains one time stage incoming (TSI) and one time stage outgoing (TSO) (Figure 5). The TSI and the TSO handle the incoming or outgoing information in the switching network. Between input and output, octets canchange their time slot and highway via time Stages. Octets on four incoming highways are cyclically written into the speech memory of a TSI or TSO (4x128 = 512 locations corresponding to 512 different time slots). The speech memory areas 0 and 1 are used alternately in consecutive 125- microseconds periods for writing the octets. The connections to be made determine the octet sequence during read-out. The stored octets are read-out to any one of 512 time slots and then transferred via four outgoing highways.

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BSNL TRAINING REPORT 2009 Sumit Kumar SPN - EL2007461/10

Govt. Polytechnic College, Kota (Raj.) 7.1.3. SSM8|15 and SSM 16|16: The SSM 8|15 contains two space stages as shown in figure 6. One space stage is used for transmission direction LIS  SSM 8|15  SSM 16|16 and has 8 inlets and 15 outlets while a second space stage is used for transmission direction SSM 16|16  SSM 8|15 LIS and has 15 inlets and 8 outlets. Via space stages, octets can change their highways between input and output, but they retain the same time slot. Space stages 8|15, 16|16 and 15|8 switch the received octets synchronously with the time slots and the 125-microsecond periods. The connections to be switched change in consecutive time slots. In this process, the octets arriving on incoming highways are “spatially” distributed to outgoing highways . In capacity stages with a TST structure, the SSM 16|16 Switches the octets received from the TSIs directly to the TSOs.

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TABLE 2: List of Modules used in SN

PCB

No. of No. of cards in cards in SN:63 TSG of SN:DE5 LTG

LIL

16

16

TSM

16

16

No. of Remarks cards in SSG of SN:DE5 One LIL can connect up to 4 LTGs. The cards LIL and TSM are always used in pairs

LIS

-

8

16

SSM8|15

-

-

16

SSM16|16

4

-

15

LIM

1

1

1

This PCB has 8 inlets and 8 outlets. LIS and SSM8|15 are always used in pairs Used to cross connect outlets of 16 SSM8/15 to inlets of SSM15/8

SGC

1

1

1

These two PCBs are used in the SGC

DCC(B)

2

2

2

Separate shelf is provided for the DCC(B)s in the rack

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BSNL TRAINING REPORT 2009 Sumit Kumar SPN - EL2007461/10

Govt. Polytechnic College, Kota (Raj.) 7.2Control section: Each TSG, each SSG, and with SN: 63LTG, each switching network side has its own control. These controls each consist of two modules viz. switch group control (SGC) and link interface module between SGC and MBU: SGC (LIM)

An SGC consists of a microprocessor with accompanying memory and peripheral components. The main tasks of an SGC are to handle CP commands (such as connection setup and clear down), message generation and routine test execution. Apart from the interface to the message buffer unit (MBU: SGC), an LIM has a hardware controller (HWC) and a clock generator for clock distribution.

7.3Firmware The firmware for the switching network is permanently stored in the program memory of each SGC. For this reason, it does not have to be loaded or initialized by the coordination processor (CP). SN firmware is organized in the following manner:

• • • •

53

executive control programs call processing programs maintenance programs startup and safeguarding programs

BSNL TRAINING REPORT 2009 Sumit Kumar SPN - EL2007461/10

Govt. Polytechnic College, Kota (Raj.) 8.

Switching network (B)

Switching network (B) is a special compact version of switching network wherein a number of functional units are integrated over a single module. This arrangement has the following advantages:

*

Reduction in shelf space

*

Reduction in number of PCB types

*

Utilization of available space in SN rack for accommodating LTGs

Functionally SN(B) is entirely similar to SN. However, only the following five types of modules are used in SN(B) as shown in table 3.

TSMB:

Two LILs and two time stage modules TSMs are combined to form one TSMB.

LISB:

This is formed by combining two LIS functional units in a TSG.

SSM8B: Two LIS and two SSM8|15 functional units in a SSG are combined to form one SSM8B. SSM16B: This is formed by combining eight SSM16|16 functional units. SGCB:

Functional units LIM and SGC are combined to form one SGCB.

TABLE 3:

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TSMB

No. of No. of cards in cards in SN(B) TSG of SN(B):DE :63LTG 5 8 8

No. of cards in SSG of SN(B):DE 5 -

LIS

-

4

-

2 X LIL 2 X LIS of TSG

SSM8B

-

-

8

2 X LIS of SSG +

PCB

Equivalent modules in SN 2 X TSM +

SSM16B

1

-

2

2 X SSM8|15 8 X SSM16|16

SGCB

1

1

1

LIM +

1

SGC Provided in same shelf

DCCMS

1

1

containing SN/TSG/SSG

9.Rack Assignment

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Govt. Polytechnic College, Kota (Raj.) Both planes of SN: 63LTG are accommodated in two frames of a single SN rack. In case of SN: 126 LTG, both planes of TSG or SSG occupy one rack each. Thus there are two racks for 2 TSGs and one rack for one SSG. SN: 252LTG and SN: 504LTG have rack assignment similar to SN: 126 LTG and occupy 6 and 12 racks respectively. Rack assignment for SN is shown in figure 7.

In case of SN (B) both planes of SN (B) of SN DE4 and both planes of TSG or SSG of SN DE5 are accommodated in two frames of a single SN rack. However since each such frame consists of one shelf only, the balance space in the rack is utilized for accommodating LTGs. The SSG shelf can accommodate two SSGs. The composite rack is called rack for SN (B)/LTG. Rack assignment for SN (B)/LTG is shown in figure 8.

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10.Module Frame Layout 10.1SN:63LTG One plane of SN:63LTG is accommodated in one frame consisting of two shelves. The arrangement of modules in module frame for SN:63LTG is shown in figure 9.

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10.2SN:126LTG and higher capacity stages One TSG or one SSG of SN: 126LTG or above occupies one frame consisting of two shelves. The arrangement of modules in module frame for SN: 126LTG or above is shown in figure 10 (a) and (b).

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Govt. Polytechnic College, Kota (Raj.) 10.3SN (B):126LTG and higher capacity stages

One TSG or two SSGs of SN(B):DE5 (126LTG or higher capacity) occupy one frame consisting of one shelf only. The arrangement of modules in module frame for SN:126LTG or above is shown in figure11 (a) and (b).

10.4SN (B):63LTG: - One plane of SN(B):63LTG requires

one frame consisting of only one shelf. The arrangement of modules in the module frame for SN(B):63LTG is shown in figure 12.

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11.Interconnection of Switching Modules Switching modules in EWSD switching network are connected in a manner so as to ensure nearly full availability. One module LIL, which can handle highways coming from 4 LTGs is connected to 4 inlets of a module TSM on one-to-one basis. Thus these 4 highways coming from 4 LTGs undergo a T-switching function and are then connected to inlets of 4 different LIS modules. The 8 inlets of a LIS module are connected to outlets of 8 different TSMs. Two such groups form a Time Stage Group wherein 63 LTGs can be connected. The TSG has 64 outlets coming out of 8 LIS modules. The interconnection arrangement is shown in figure 13.

Eight outlets of LIS modules in TSG are connected to 8 inlets of LIS modules in SSG on one-to-one basis. One SSG consists of 16 LIS modules and therefore two TSGs can be connected to one SSG. There is again one-to-one connection between 8 outlets of LIS modules and 8 inlets of SSM8|15 modules. Fifteen outlets of SSM8|15 and 16 inlets of SSM16|16 are cross connected. Similarly 16 outlets of SSM16|16 and 15 inlets of SSM15|8 are cross connected. The interconnection arrangement within SSG is shown in figure 14.

Fig. Time Stage group internal connections

All the TSGs of SN are connected to all the SSGs in such a manner as to ensure nearly full availability. The interconnection of TSGs with SSGs in case of SN:504 LTG is shown in figure 15, and that for SN:252 LTG and SN:126 LTG are shown in figure 16.

Interconnection of the modules in SN DE4 is simpler as there are no TSG or SSG. The TSMs are directly connected to SSM16|16 as shown in figure 17.

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Govt. Polytechnic College, Kota (Raj.) 12. Functions

Three essential functions of switching network namely speech path switching, message path switching and changeover to standby are described below: -

12.1Speech path switching The switching network switches single channel and broadcast connections with a bit rate of 64 Kbit/s and multichannel connection with nx64 Kbits/s. Two connection paths are necessary per single channel connection (e.g. from calling to called party and from called to calling party). For a multichannel connection, nx2 connection paths are necessary. In broadcast connections, the information is passed from one signal source to a number of signal sinks (no opposing direction). The coordination processor (CP) searches for free paths through the switching network according to the busy status of connection paths stored at that moment in the switching network’s memory. The path selection procedure is always the same and is independent of the capacity stage of the switching network. During path selection, the two connection paths of a call are always chosen so that they will be switched via the same space stage section. A space stage section is a quarter of the space stage arrangement; with an SN: 252 LTG, for example, this corresponds to half a space stage group SSG. After path selection, the CP causes the same connection paths to be switched through in both switching network sides of an SN. The SGCs are responsible for switching the connection paths. In a capacity stage with 63 LTGs, one switch group control participates in switching a connection path; however in a capacity stage with 504, 252, or 126 LTGs, two or three switch group controls are involved. This depends on whether or not the subscribers are connected to the same TSG. The CP gives every involved switch group control setting instructions necessary for the through-connection. These setting instructions always have the same data format. An SGC receives the setting instruction from the CP via the message buffer unit MBU: SGC, the secondary digital carrier SDC: SGC, n an SGC and the CP are exchanged via an LIM. The SGC calculates the setting data using the call processing programs and service routines. The SGC loads the data

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Govt. Polytechnic College, Kota (Raj.) into registers in the hardware controller (HWC) of the LIM and, via the HWC, controls the setting of desired connection paths in

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12.2Message path switching. Apart from the connections determined by subscribers by inputting dialing information, the switching network also makes connections between the LTG and the CP. These connections are used to exchange control information; they are setup only once, and then they are always available. For this reason, they are called semi permanent connections. Via these same connections, the LTGs also interchange message without having to burden the CP’s processing unit. In this manner, a separate line network for the exchange of messages within an exchange is not necessary. Nailed-up connections and connections for common channel signaling are made on a semi permanent basis as well.

12.3Changeover to standby All connection paths are duplicated, i.e. switched through in SN0 and SN1. This provides an alternative route for each connection in case of failure.

Figure 19 provides a simplified illustration of the various alternative routes possible in capacity stages with 504, 252, and 126 LTGs. The connection paths are switched in the same manner over both switching network sides (SN0 and SN1). The LTGs accept the incoming octets of the effective connections (subscriber/ subscriber connections) from only one switching network side. In figure 19, the effective connections lead over SN0. Of note is the duplicated routing between the time stage groups (TSG) and space stage group (SSG). This makes it possible for the TSGs and SSGs to be individually switched over to standby. Switching over to standby is implemented only if errors occur simultaneously in both switching network sides. The effective connections are then lead over routed TSGs and SSGs of both switching network sides 0 and 1. In the switching network capacity stage with 63 LTGs, it is only possible to route the connections over SN0 or SN1.

If an error occurs in the switching network, the CP initiates corresponding measures for switching over to standby and issues the corresponding messages. Changeover to standby do not interrupt existing connections. Thanks to this

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Govt. Polytechnic College, Kota (Raj.) duplication principle, all operational measures are easily carried out without impairing traffic (e.g. adding new modules or replacing defective modules).

13.O&M Aspects The following MML commands are used during operation and maintenance of switching network. Display and Modification in number of TSMs. DISP TSG

MOD TSG

Status display and Configuration commands STAT SN

CONF SN

CONF TSG

CONF SSG

Diagnosis and Test commands - SN DE4 and DE5 DIAG SN

TEST SN

Diagnosis and Test commands - SN DE5 only DIAG TSG

DIAG SSG

TEST TSG

TEST SSG

13.1Safeguarding Concept The switching network (SN) is duplicated. Normally one SN side is active (the SSG and both TSGs in ACT), and the other SN side is standby (the SSG and the TSGs in STB).

In the event of a malfunction in a switch group (SSG or TSG) in the active SN, the affected switch group is configured to UNA and the other switch groups in the previously standby SN are configured to ACT.

N the event of a malfunction in a switch group in the standby SN, only the affected switch group is configured to UNA. None of these reconfigurations affect switching traffic.

13.2Fault Printouts

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Govt. Polytechnic College, Kota (Raj.) An SN fault printout is the result report of the fault analysis program for the SN or for a switch group (SSG or TSG). It complements the more general alarm signaling with SYP etc. i.e. whenever the safeguarding system detects a malfunction in the SN, an appropriate fault printout is formulated, typically as follows: SN FAILURE WITH CONFIGURATION

MMN:SN0xx-000

SGC DEFECT FAULT LOCATION : TSG-side-tsg CONFIGURATION :

SGC

TSG-side-tsg

FROM : zzz TO : UNA

SUPPLEMENTARY INFORMATION : H ‘zzzzzzzz zzzzzzzz zzzzzzzz zzzzzzzz H ‘zzzzzzzz zzzzzzzz zzzzzzzz zzzzzzzz

Faults affecting the SN can be divided into two groups which are clearly distinguishable in terms of the system response: *

Unconditional fault

These are serious faults. The switch group in which such a fault occurs is always reconfigured to UNA. With unconditional faults, the following codeword’s may be output :

*

-

SGC/SGC FAILURE

-

SGC/HWC FAILURE

-

PATH SET/HWC-FAILURE

-

CYCLE DEFEKT

-

NO CYCLE

-

SGC CHANNEL ERROR

Conditional faults

These are not serious. If such a fault occurs in a switch group with no redundancy (i.e. where the partner switch group is in NAC, UNA or MBL), then the affected switch group is not configured to UNA. If the switch group is duplicated, then it is configured to UNA, even for a conditional fault. Codeword’s for conditional faults are : -

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SGC/PLLU-FAILURE

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SN-PLL FAILURE

-

PATH SET/TSM-FAILURE

-

PATH SET/SSM8-FAILURE

-

PATH SET/SSM16-FAILURE

-

SGC-DEFECT

-

All COC-FAILURE

-

All MCH-FAILURE

-

All MUX-FAILURE

13.3Diagnostics

Explanation: -

*

DIAG TSG

This command starts a test program, to be specified under parameter TA, for a time stage group (TSG).

*

DIAG SSG

This command starts a test program, to be specified under parameter TA, for a space stage group (SSG).

*

side

SN plane, either 0 or 1

*

tsg

Number of TSG, 0 to 7

*

TA

(test area = test program)

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*

Area

The identifier entered for the parameter TA specifies the test program to be called up. The following test programs are possible: CHALL, ALL, HWC, TSM, SSM, CSM, PLL

In test program TSM, SSM and CSM, in the diagnostic command, a subunit must also be specified.

- CHALL (check all)

- For TSG,

tests central sections, CPU with program and data memory PLL supervision circuit hardware controller tests decentralize sections : control memory of TSM modules

- For SSG,

tests central sections : CPU with program and data memory PLL supervision circuit hardware controller tests decentralize sections : control memory of SSM16|16 and SSM8|15

- ALL (check all control memories)

- For TSG,

The control memories of modules TSM are tested. Each bit in a control memory is checked for 1 and

0.

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Govt. Polytechnic College, Kota (Raj.) The addressing of each Ram chip in a control memory is also checked.

- For SSG

The control memories of modules SSM16|16 and SSM8|15 are tested. Each bit in a control memory is checked for 1 and 0.

The addressing of each RAM chip in a control memory is also checked. Whereas modules SSM8|15 are only tested according to the SN capacity stage specified in the CP command, all 15 SSM16|16 modules are tested. - HWC (HWC test)

- for TSG and SSG

The HWC registers are checked. A good or bad message gives the states of the HWC registers and the interface between SGC and HWC. The HWC interface to the switching modules is not tested.

- TSM (TSM test)

The addressing and functioning of each bit in the control memory of a TSM module are tested. - CSM (SSM16|16 test)

The addressing and functioning of each bit in the control memory of an SSM16|16 module are tested.

- SSM (SSM8|15 test)

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Govt. Polytechnic College, Kota (Raj.) The addressing and functioning of each bit in the control memory of an SSM8|15 are tested.

- PLL (PLL supervision circuit test)

*

SUBUNT

For diagnostic identifiers TSM, CSM & SSM, the subunit must be specified.

Possible subunits are:

*

X

TSM

=

functional unit TSM/LIL

SSM

=

functional unit LIS/SSM8|15

CSM

=

SSM16|16

TSM number (0 to 15) SSM8|15 number (0 to 15)

SSM16|16 number (0 to 14) 13.4Test

The SN speech path test makes a cross-office check per SN side, switch group or subunit, depending on the command.

This involves setting up connections via SN, which are then tested with a test pattern. If the SN speech path detects a COC error in such a connection path, the test is repeated with a new path setup attempt (with the same parameters). If the test again detects a COC error, it is terminated with FAILURE DETECTED. The MML command used is as follows, where symbols/parameters are same as in DIAG SN.

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14.Exercises 1.

Interrogate and find out the capacity stage of SN in your exchange. Identify its racks, frames and modules.

2.

Find out the number of LTGs and TSMs in your exchange and correlate. How many additional LTGs can be provided with the existing SN configuration?

3.

Change status of both planes of SNs, one by one, using all possible combinations of OST and tabulate the results.

4.

A fault in SN plane 0 has affected the third LTG connected to TSG1. What functional unit in SN could be faulty? Write MML commands to configure and diagnose the faulty unit.

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SWITCHING TECHNIQUES

•

SPACE DIVISION SWITCHING

•

MULTIPLE STAGE SWITCHING

•

TIME DIVISION SWITCHING

•

TWO-DIMENSIONAL SWITCHING

•

MULTI STAGE TIME AND SPACE SWITCHING

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INTERNET Introduction: The Internet is not a program, not software, not hardware or a big system. It is a group of various co-operating computers worldwide interconnected by computer based on TCP\IP communication protocols. People use it to get information over a standard communication link. The hundreds or thousands or millions of computer network are connected to each other for exchanging the information which is based on the unique identity and set of procedures. Internet is a series of interconnected networks providing global link to information. GIAS: BSNL launched the Gateway Internet Access Service (GAIS) through dial up/leased/ISDN network. Users can access GAIS from 99 cities in India by this means.

INTERNET CONNECTIVITY

INTERNET TECHNOLOGY

The basic function of Internet can be summarized as underInterconnecting of computers to form a network. Interconnecting of computers to form a network of networks. To establish a communication link between two computers within as network. To provide alternate communication link among the networks, even if one network is not working. These are based on TCP/IP communications protocol.

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Transfer of a file through Internet:-

Suppose a file is to be transmitted on Internet from one computer to other ones Break the file in to small packets Attached destination and source address in o packets Multiplexed and transmit these packets At destination de-multiplex the packets Remove address bits from the packets and assemble the data in to the original file Make source bits as destination address and send the acknowledgement in to the source Therefore, it is clear that network hardware sends the packets to specified destination and network software reassembles of communications, the computer network performs the following functionsAddressing and routing Fragmentation and error correction Data error checking Connectivity control Multiplexing and de-multiplexing Data flow control End users interface etc. The data handling

A single module cannot handle the entire process. One that adopted as a standard is an open system interconnection (OSI) model.

COMMON TERMINOLOGY USED IN INTERNET:

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Govt. Polytechnic College, Kota (Raj.) WWW: World Wide Web (WWW) is a wide area hypermedia information retrieval aiming to give universal access to a large universe of documents. HTTP: Hyper text transmission Protocol (HTTP) is the communication protocol used to transfer documents from the server to client over the WWW (http:// www). HTML: Hyper Text Markup Language (HTML) is a system of marking or tagging the various parts of web documents to tell the browser software how to display the document text, link graphics and link media. ISDN: Integrated Service Digital Network (ISDN) is a digital phone connection technology that provides both voice and data services over the same connection. ISP: Internet Service Provider (ISP) is an agency that provides Internet access and other net related services.

NATIONAL INTERNET BACKBONE (NIB)

Networking is a key component of any Internet Services Provider (ISP) operations. The networking equipments like access servers, routers and modems are critical to

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Govt. Polytechnic College, Kota (Raj.) the successful functioning of ISP. An ISP node where subscribers enter internet, consists of a set of equipments as given below. Access server Router Modem bank LAN (Local Area Network) components Security server Rack, console & power supply Network management agent. Help desk

CELLULAR MOBILE SERVICES: Cellular is one of the fastest growing and most demanding telecommunication applications. Today, it represents a continuously increasing percentage of all new telephone subscriptions around the world. Currently there are more than 45 million subscribers in worldwide and nearly 50% of those subscribers are located in USA. It is forecasted that cellular system using a digital technology will become the universal method of telecommunications. By the year 2005, forecasters predict that there will be more than 100 million cellular subscribers worldwide.

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WIRELESS IN LOCAL LOOP (WLL) MOBILE WLL is a communication system that connects customers to the Public Switch Telephone Network (PSTN) using radio frequency signals as substitutes of conventional wires for all part of connection between the subscribers and the telephone exchange. It works on CDMA technique. The local loop is access part of telecommunication network i.e. the part between PSTN switch and subscribers. WLL network application involves uses of radio to replace of the wire link between PSTN switch and subscriber. The radio technology is able to provide same quality of services as that provided by the wires line. Application of wireless loop technology has just been started in the worldwide. There is no standard for this so far. However, a number of national and international air interface standards for digital cellular mobile telephone system are available.

TECHNICAL ASPECTS: WLL is based on CDMA technique and is entirely different from GSM. The system for WLL services can be divided in two following parts:BSC (Base Switching Centre):- It provides links between BTS & BSM; it consists of different processors, in BSNL it is of SUN Polaris of LG Company. In LG 1 BSC can have 48 BTS? In BSNL we have two types of BSC:-

I.

V-5.2:- This type of BSC cannot switch by itself so it is dependent on

local exchange / PSTN for switching and keeping records of billing etc. BSNL uses this type of BSC for rural areas.

ii.

CCS-7 / R2:- These types of BSC are totally automatic it doesn’t

depend on local exchange for its functions, it is complete in itself. BSNL uses this type of BSC for urban areas.

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Govt. Polytechnic College, Kota (Raj.) BTS (Base Transreceiver System):- As it is clear from its name it transmits as well as receive signal, it works as an amplifier (router) to overcome the loss in signal in transmission.

BSM (Base Station Management):- It controls and manages the WLL services. It can troubleshoot the problem; add new users as well as capable to block service given to user. It is basically a computer system, which manages the whole process of WLL service. In BSNL BSM are two UNIX based computer system.

ADVANTAGES OF WLL: Country wide induction of WLL underway of areas than are non-feasible for the normal network Helping relieves congestion of connections in the normal cable / wire based network in urban areas Limited the mobility without any airtime charges It has improved signal and reducing the interference Greater capacity than mobile Provides ease of operation, administration & maintenance at lower cost. The telecommunication is the biggest factor in influencing the speed of life in the modern age. Today we can get connection with any corner of world through the push button of computer; with the small mobile phone we can send not only the messages but also the secret document. As we know that there is positive view behind any mention that it should be helpful in the development of society. But humans have diverted mentality some of them of positive view and some of them of negative view. Where use any invention for the welfare of society but some uses for the satisfaction their disturbed mentality and to earn more and more money whether it may be harmful for the society. They infringe the norms of society and their behavior is condemned as antisocial, immoral and sinful.

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CODE DIVISION MULTIPLE ACCESS (CDMA): CONCEPT OF MULTIPLE ACCESSES: Multiple access system allows a large number of users to share a common pool of radio telephone circuits, like sharing of trunked radio facility. Multiple access radio has similarity to the LAN in which the common channel is available to all users. The circuits are demands assigned i.e. assigned on demand first-cum-first-served basis. The provision of access to the radio circuits methods of multiple accesses are:

CDMA: - Where large number of transmission are combined on the same channel at the same time and separated by the codes.

WHAT IS CDMA? CDMA, a cellular technology originally known as IS-95, competes with GSM technology for dominance in the cellular world. There are now different variations, but the original CDMA is known as CdmaOne. Latest CDMA global subscriber & operator’s numbers As of December 2002, there were 120 million users worldwide, with 55 million of these in the USA. See other cellular technology in the world. We now have CDMA2000 and its variant like 1X EV, 1XEV-DO and MC 3X. The refer of variant of usage of a 1.25 MHz channel. 3X uses a 5 MHz channel. Wide band CDMA forms that the basis of UMTS 3G networks, developed originally by Qualcomm, high capacity and small cell radius, employing spread-spectrum technology and special coding scheme characterized by CDMA. The Telecommunication Industry Association (TIA) in 1993 adopted CDMA. May 2001 there were 35 million subscribers on cdmaOne system worldwide.

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Govt. Polytechnic College, Kota (Raj.) Over 35 countries have either commercial or trial activity ongoing. There were already 43 WLL systems in 22 countries using cdmaOne technology. Enhancing today’s data capabilities is the 1XRTT CDMA standard this next evolutionary step for cdmaOne operators will provide data rates up to 300 kbps, significant capacity increases as well as extended batteries life for handsets. Worldwide resources are being devoted to roll out third generation CDMA technology, including multi-carrier (cdmaOne2000 1xMC and HDR in 1.25 MHz bandwidth and 3xMC in 5 MHz bandwidth) and direct spread (WCDMA in 5 MHz bandwidth). This first phase of cdmaOne2000 variously called 1XRTT, 3G1X or just plain 1X is designed to double current voce capacity and support always on data transmission speed 10 times faster than typically available today, some 153.6 kbps on both the forward and reverse links.

3.

GLOBAL SYSTEM FOR MOBILE COMMUNICATION (GSM): The GSM Association is a unique organization, with a truly global reach, offering a full range of business and technical services to its members. Now as the wireless family unfolds the association is deriving forward its vision of seamless, limitless, world of wireless communication. Throughout the evolution of cellular telecommunications, various systems have been developed without the benefit of standardized specifications. This presented many problems directly related to compatibility, especially with the development of digital radio technology. The GSM standard is intended to address these problems. Global system for mobile communication (GSM) is a globally accepted standard for digital cellular communication. GSM is the name of a standardization group established in 1982 to create a common European mobile telephone standard that would formulae the specifications for a panEuropean mobile cellular radio system operating at 900 MHz it is estimated that many countries outside of Europe will join the GSM partnership.

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Govt. Polytechnic College, Kota (Raj.) OBJECTIVES OF GSM SYSTEM: One of the important objectives of GSM group is to evolve a unified standard to provide seamless roaming across Europe. Another landmark decision taken by the group is to standardize a digital radio interface for the communication between the mobile handset and the radio transmitter / receiver. The design objectives of the GSM system can be briefly states as below: • • • • • • • • • • •

Excellent speech quality High security and privacy Low module terminal cost Low service and facilities cost Design of sleek and handled mobile terminals International roaming Wide range of services and facilities Ability to adopt to new and innovative features Narrowband ISDN compatibility Digital Radio High Spectral efficiency

GSM NETWORK ELEMENTS AND ARCHITECTURE: 1. Mobile Station (MS) i. Mobile Terminal or Equipment (MT) ii. Subscriber Identity Module (SIM) Card 2. Base Station Subsystem (BSS) i. Base transceiver Station (BTS) ii. Base Station Controller (BSC) iii. Main Station Controller (MSC) iv. Transcoding and Rate Adoption Unit (XCDR/TRAU) 3. Network Switching Subsystem (NSS) i. Registration ii. Authentication and security iii. Location updating iv. Handovers and v. Routing to roaming subscribers 4. Operation and Maintenance Subsystem (OMS) i. Operation and Maintenance Centre – Switch ii. Operation and Maintenance Centre – Radio 5. Enhanced Services Subsystem (ESS) 6. Billing and Customer Care System (B&CCS)

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4.THIRD GENERATION 3G TECHNOLOGY : Introduction: Third generation (3G) networks were conceived from the Universal Mobile Telecommunications Service (UMTS) concept for high speed networks for enabling a variety of data intensive applications. 3G systems consist of the two main standards, CDMA2000 and W-CDMA, as well as other 3G variants such as NTT DoCoMo's Freedom of Mobile Multimedia Access (FOMA)

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Govt. Polytechnic College, Kota (Raj.) and Time Division Synchronous Code Division Multiple Access (TD-SCDMA) used primarily in China. Data Speed The data speed of 3G is determined based on a combination of factors including the chip rate, channel structure, power control, and synchronization. An example of calculating the theoretical 3G data speed is as follows: •

W-CDMA assigned code 400-500 Kbps/code. 6 codes X 400 > 2Mbps (UMTS target for 3G data speed in fixed location)

Actual data speeds will vary in accordance with several factors including: •

Number of users in cell/sector

•

Distance of user from cell

•

User is moving or stationary

•

Network operator capacity and network optimization requirements

1xEV-DO is a data-only solution, supporting a theoretical data speed of up to 2.457 Mbps 1xEV-DV is a data and voice solution, supporting a theoretical data speed of up to 3.072 Mbps FOMA has two operational modes, supporting a dedicated 64 Kbps connection or a 384 Kbps downlink/64 Kbps uplink best-effort connection. TD-SCDMA can operate in 1.6 MHz or 5 MHz mode for 2 Mbps or 6 Mbps respectively

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3G is the short form for third-generation technology. It is one of the popular mobile phone standards. The services utilizing 3G provide the ability to transmit

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Govt. Polytechnic College, Kota (Raj.) both voice data such as calls and non-voice data such as instant messaging, email and video telephony at the same time. Japan was the first country to introduce 3G on a wide scale commercially. In 2005, almost 40 per cent of the subscribers in Japan used 3G services. On the technical front, 3G services are wide area cellular telephone networks unlike IEEE 802.11 networks, which are short range networks meant for Internet access. Now, 3G is being used to provide various services. You have to plug in 3G Data Card into your laptop and can get the fastest available connection, with mobile broadband speeds of up to 1.8 Mbps. It’s neat, compact design makes it easy to use; you can easily swap it between laptops for use at work, home or on the move. Laptops have a PC Card slot (also known as a PCMCIA slot), or an Express Card slot. There is PCMCIA to Express Card Converter for using 3G broadband; you need 3G Data card, network SIM card, software, user

guide.

BSNL’s IPTV • •

First started in Japan in 2002. Popular in France, South Korea, Germany, Hongkong etc.

•

France is leading in IPTV having more than 1.7 million IPTV viewers

Global IPTV subscriber’s base will reach 14.5 million in 2007 and will be approximately 63 million by 2010.

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CONCLUSION: Hence in the last I can say that taking training in such an organization proved to be very beneficial for me. I learnt quite a lot about electronic exchange, Internet, Land line, WLL, Mobile GSM & 3G, and the basis of processing Exchange. I also got firsthand knowledge of how a Telephone Exchange works. The first phase of training has proved to be quite fruitful. It provides an opportunity to encounter with such huge machines. The architecture of company has various units. They are linked and working of whole plant is controlled make the student realized that engineering is not just learning the structure description and working of various machines. But the greater part is planning proper management.

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GLOSSARY OF TERMS AND ABBREVIATIONS ADM ANALOGUE

BSC BTS C-DOT CD Cabinet CDMA CKM

CLIP COAXIAL CABLE

CT BOXES DECT DEL DIGITAL EXCHANGE

DIU DLC DWDM EDX EPABX ETRP EWSD TAX

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Add/Drop Multiplexers An electrical signal which is analogous to changing physical quantity measured Base Station Controller Base Tran receiver Station Centre for Development of Telemetric Cable Distribution Cabinet Code Division Multiple Access Cable conductor kilometer – cable sheath kilometers multiplied by the number of conductor pairs in each cable Calling Line Identification Processing A cable with a single wire in the centre of cylindrical conductor forming a pair of carrying electrical signals Cable Termination Boxes Digital Enhanced Cordless Telecommunications Direct exchange lines, one each for every telephone connection The exchange having signals coded into binary pulses and having little or no moving parts DECT interface unit Digital Loop Carrier Dense Wavelength Multiplexing Terminal Electronic Data Exchange Electronic Private Automatic Branch Exchange Electronic Trunk Relay Plates Electronic Wheeler System of Digital Trunk Automatic Exchange

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Govt. Polytechnic College, Kota (Raj.) GHz GSM HDPE HDSL Hertz or Hz

IDR ISDN LDST LOI MARR MBM Mbps MCPC MDF MUX NIT NE Lines OFC Optical Fiber (OF) OLA OYT PABX PBX PCM PCO PDH PERT Chart PIJF Cable PSPDN

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Giga Hertz Global System for Mobile Communications High density polyethylene High bit rate Digital Subscriber Line Frequency (cycles per second), named after Heinrich Hertz usually in ranges of kilo 1000 KHz, mega 1,000,000 - MHz or giga 1,000,000,000 - GHz Intermediate Data Rate Integrated Services Digital Network Long Distance Satellite Telephone Letter of Intent Multi Access Rural Radio Multi Base Module Mega bits per second denoting digital frequency Multi Channel Per Carrier Main Distribution Frame Multiplex Notice Inviting Tender Non Exchange Lines Optical Fiber Cable Glass fibers using light waves for transmission of signals Optical Line Amplifiers Own your telephone Private Automatic Branch exchange Private branch exchange Pulse Code Modulation Public Call Offices Plesiochronous Digital Hierarchy Programmed Evaluation Review Technique Chart Polyethylene Insulated Jelly Filled Cable Packet Switch Public Data

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PST PSTN PVC PW RLU RSU SACFA SDH SMPS SRCs SSAs STD STM TAX TDMA

TELEX TTH UHF VHF VPT VSAT WLL

Network Progressive Stock Taking Public Switched Telephone Network Polyvinyl chloride Private Wires Remote Line Unit Remote Switching Unit Standing Advisory Committee on Radio Frequency Allocation Synchronous Digital Hierarchy Switch Mode Power Supply Subscriber Record Cards Secondary Switching Areas Subscriber trunk dialing Synchronous Transport Module Trunk automatic exchange Time Division Multiple Access – A transmission technique used in digital radio transmission in which the use of a frequency is divided into time slots that are shared amongst several users. TelePrompTer exchange Triangular Tubular Hybrid Ultra high frequency (300 to 3000 MHz) Very high frequency Village Public Telephones Very small aperture terminal Wireless-in-Local Loop

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