Industrial Training Report- I-SLT

INDUSTRIAL TRAINING REPORT - I

TRAINING ORGANIZATION SRI LANKA TELECOM PLC

PERIOD OF TRAINING FROM: 11.11.2013 TO: 17.01.2014

FIELD OF SPECIALIZATION ELECTRICAL & ELECTRONIC

ENGINEERING

THUSHAN S.

E/10/361

i

Acknowledgements

I would like to take this opportunity to express my gratitude to all ladies and gentlemen who have

given their maximum involvement to conclude the Industrial Training Session at Sri Lanka Telecom

(SLT) successfully.

I was trained 02 sections in Sri Lanka Telecom and all the staff members contributed their maximum

to me throughout the training period. Especially sectional heads guided me to extract the maximum out

of each section. The Engineering Section of SLT is highly productive and mine of knowledge for

enhancing the skills and technical knowhow of any apprentice. I would like to express my sincere

gratitude to Mr. K. Kogularanjan, Manager (OPMC-Batticaloa) and his fellow staff for guiding me to

acquire the related engineering and real life applications of the theories which were thought during the

course. In addition I am very much pleased to acknowledge Mr. Y. Kishanthan, Engineer (Network-

Esatern Province), Added to that I would like to give my regards to all other engineers, technical

officers and other staff members for the support they have given to me throughout the session. Further,

it is a must to thank the Training Planning sections of SLT, for arrange my Training and necessary

instructions to carry out our chores during the whole training period.

Finally I would like to express my sincere gratitude to National Apprentice and Industrial Training

Authority (NAITA) for providing us the facilities to undergo a well standard training session, to

Industrial Training and Career Guidance Unit (ITCGU) of Faculty of Engineering as well as the Staff

of Department of Electrical and Electronic Engineering for guiding me throughout the training period.

Thank You,

S. Thushan,

Faculty of Engineering,

University of Peradeniya.

ii

CONTENTS

Acknowledgments i

Contents ii

List of Figures iv

List of Tables v

List of Abbreviations vi

Chapter 1 INTRODUCTION 1

1.1 Introduction of my training session 1

1.2 Introduction of SLT 2

Chapter 2 OPMC (Outside Plant Maintenance Centre)-Batticaloa 6

2.1 Introduction 6

2.2 General outside plant network and key components 6

Chapter 3 NEW CONNECTIONS AND MAINTENANCE 12

3.1 Cable Development and Maintenance 12

3.2 ADSL 15

3.3 New Connection and DATA 16

3.4 PSTN Maintenance 18

3.5 MDF Section 19

Chapter 4 CDMA 21

4.1 Introduction 21

4.2 CDMA Technology 21

4.3 CDMA Architecture 21

Chapter 5 PLANNING AND DEVELOPMENT 23

5.1 Job Profile of the Section 23

5.2 Introduction 23

5.3 Objective of Rehabilitation 23

Chapter 6 OPERATION SUPPORT 24

Chapter 7 SWITCHING 25

7.1 Introduction 25

7.2 SLT Switches 25

Chapter 8 TRANSMISSION 26

8.1 Introduction 26


8.3 Some Special Practical Experiences 27

iii

Chapter 9 POWER 29

9.1 Introduction 29


Chapter 10 CONCLUSIONS 30

iv

LIST OF FIGURES

Figure.1. 1 SLT Logo 2

Figure.1. 2 Organisation Chart of SLT 3

Figure.1.3 Optical Fibre Cable 5

Figure.2.1 Outside Plant Network 6

Figure.2.2 MDF 7

Figure.2.3 Man Hole 7

Figure.2.4 Cabinet 8

Figure.2.5 Pole Mounted MSAN and MSAN Ring 8

Figure.2.6 Distribution Point 9

Figure.2.7 Discharger 9

Figure.2.8 Rosette 10

Figure.2.9 Splitter 10

Figure.2.10 ADSL Router 10

Figure.2.11 Ethernet Cable 11

Figure.2.12 Telephone 11

Figure.3.1 25-Pair Cable 12

Figure.3.2 Process Followed For a Raychem Closure Installation 14

Figure.3.3 Bicotester 15

Figure.3.4 ADSL Architecture 15

Figure.3.5 ADSL Usage Detail Repot of a Customer 16

Figure.3.6 Damaged DATA Modem and Wiring due to Lightning 18

Figure.3.7 Damaged Fuses and Rosette Box 19

Figure.3.8 Fuse Used in MDF 20

Figure.3.9 Jumbering at MDF 20

Figure.4.1 CDMA Architecture 21

Figure.4.2 CDMA Fixed Wireless Phone 22

Figure.4.3 CDMA Fixed Wireless Terminal 22

Figure.7.1 ERICSSON AXE10 Switches 25

Figure.8.1 Transmission Network Layer in SL 26

Figure.8.2 Equip Used in Loop Testing 27

Figure.8.3 Clever, Stripper and Splicer 28

Figure.9.1 Batteries 29

Figure.9.2 DETROIT Diesel Generator 29

v

LIST OF TABLES

Table 1.1 Training schedule 1

Table 3.1 Colour Codes 13

vi

LIST OF ABBERVIATIONS

ABBREVIATIONS DESCRIPTION

ADSL Asymmetric Digital Sub scribal Line

AE Assistant Engineer

CCT Cross Connection Terminal

CDM Cable Development and Maintenance

CDMA Code Division Multiple Access

CEO Chief Executive Officer

CRO Chief Regional Officer

DGM Deputy General Manager

DP Distribution Point

DSLAM Digital Subscriber Line Access Multiplexer

EP Eastern Province

FTTH Fiber To The Home

GM General Manager

HH Hand Hole

IDD International Direct Dialing

LTE Long Term Evolution

MDF Main Distribution Frame

MH Man Hole

MIMO Multi Input Multi Output

MSAN Multiple Service Access Note

NOC Network Operation Center

ODF Optical Distribution Frame

OPMC Outside Plant Maintenance Center

PSM Provincial Sales Manager

PSTN Public Switched telephone Network

RTO Regional Telecom Office

SAE Senior Assistant Engineer

SEAE Senior Executive Assistant Engineer

TDMA Time Division Multiple Access

VDSL Very high bit rate Digital Subscriber Line

1

CHAPTER 01-INTRODUCTION

1.1 INTRODUCTION OF MY TRAINING SESSION

Under the course TR400-Industrial Training I was assigned as an apprentice at Sri Lanka Telecom

PLC, Batticaloa. for a period of 10 weeks, from 11/11/2013 to 17/01/2014 by the Industrial Training

and Career Guidance Unit (ITCGU) of the Faculty of Engineering, University of Peradeniya in

collaboration with National Apprentice and Industrial Training Authority (NAITA). The training

schedule which was given to me is mentioned in Table 1.1.

Table.1.1 Training Schedule

Worksite

Period

From To

OPMC-Batticaloa 11/11/2013 29/12/2013

Cable Development and Maintenance(CDM) 11/11/2013 17/11/2013

ADSL Maintenance section 18/11/2013 24/11/2013

Code Division Multiple Access(CDMA) 25/11/2013 01/12/2013

New Connection and Data 02/12/2013 08/12/2013

PSTN Maintenance 09/12/2013 15/12/2013

Planning and Development 16/12/2013 22/12/2013

MDF 23/12/2013 29/12/2013

NETWORKING- Batticaloa 30/12/2013 17/11/2014

Switching 30/12/2013 05/01/2014

Transmission 06/01/2014 12/01/2014

Power 13/01/2014 19/01/2014

2

1.2 INTRODUCTION OF SLT

Sri Lanka Telecom PLC. (SLT) is one of Sri Lanka’s most valuable blue chip companies with a market

capitalization as at 31 December 2013 topping Rs.66 billion. Sri LankaTelecom is the national ICT

solutions provider and the leading broadband and backbone infrastructure services provider in the

country. The two main shareholders of Sri LankaTelecom as at year end were the Government of Sri

Lanka which held 49.5% through the Secretary to the Treasury and Global Telecommunication

Holdings N.V. of Netherlands, which owned a 44.98% stake. The balance shares are publicly traded.

Fig.1.1 SLT Logo

SLT- VISSION

All Sri Lankans seamlessly connected with world class information, communication and

entertainment services.

SLT- MISSION

Your trusted and proven partner for innovative and exciting communication experiences delivered

with passion, quality and commitment.

SLT- VALUES

Customer Caring - Put customers at the center of everything SLT do

Trustworthy - True to SLT promises

Innovative - Continuously invent new opportunities through creative thinking

Responsive - Ready to listen and act promptly

Teamwork - Act as one team with a common purpose to achieve common goals

Excellence - Committed to exceptional performance

Results Driven - Committed to enhancing shareholder value

3

SLT- ORGANIZATION STRUCTURE

Fig.1.2 Organization Chart of SLT

Group of CEO

CRO

GM/Region 3

DGM/EP

Accountant

EP Manager

RTO/Batticaloa

Manager

OPMC/Batticaloa

PSM

EP

Engineer

Network/EP

SEAE

Maintenance

SEAE

CDM & New

Connection

SEAE

Rehabilitation &

Development

SEAE

Switching,

Transmission & Power

SAE/PSTN SAE/ New

Connection & Data

SAE/CDM SAE/Power

& AC

AE AE

Transmission

AE

Switching

AE/MDF AE/CDMA AE/ADSL

Chairman and Board of Directors

4

SLT-SUBSIDIARIES

SLT Human Capital Solutions (Private) Limited

SLT Property Management (Private) Limited

SLT Publications (Private) Limited

SLT VisionCom (Private) Limited

Sri Lanka Telecom (Services) Limited

SKY Network (Private) Limited

Mobitel (Private) Limited

SLT-CUSTOMER PACKAGES

SLT provides various kinds of Packages to their customers. They introduce new technologies for the

satisfaction of their customers. More than this they provide 24 hours customer service for reduces the

inconvenience of telecommunication.

1. Megaline

Single play, Double play and triple play offering for telephone, Broadband and PEO TV.

Enabling the customer to choose the combination that is appropriate for envisaged usage.

Value Added service also included.

2. Broadband

Ten broadband packages available in the market to enable user to choose one that suits their

specific needs.

3. Peo TV

Platform for best of local and international news and entertainment from around the world

This offers new features such as digital quality pictures, time shifted TV, Rewind TV and

etc.

4. IDD

All SLT residential phones are now IDD enabled and 232 numbers of countries connected

with direct links to provide better quality international service.

5

SLT- FUTURE PALNS

Introducing FTTH Networks.

FTTH has obvious advantages for the consumer, both today as well as in the foreseeable future,

offering improved performance for broadband services that are delivered primarily over copper

networks. FTTH provides the highest possible speeds of internet access downstream (from the

network to the end user) as well as upstream (from the user to the network) using Optical Fiber

Cables as shown in Fig.1.3.

Fig.1.3 Optical Fiber Cable

Introducing MIMO, 4G LTE technologies with collaboration of Mobitel.

This is also for the faster internet access. With this 4G LTE technology can access internet in

mobile areas as well.

Introducing VDSL technology

This VDSL2 is also for faster access of internet for the customer. But this project going to start

after finished the FTTH project.

Microwave transmission links are replaced with of networks.

6

CHAPTER 02-OPMC (Outside Plant Maintenance Center) – Batticaloa

2.1 INTRODUCTION

OPMC means outside plant maintenance center which is place where all new connections, maintenance

and rehabilitation are done. Under the manager of the OPMC there are several groups for various activities.

They are cable develop and maintenance (CDM), ADSL, New connection and Data, PSTN maintenance,

MDF, CDMA and Planning and Development. In OPMC centers have a system to store, update and get

information where ever they want. The specific system is called clarity.

2.2 GENERAL OUTSIDE PLANT NETWORK AND KEY COMPONENTS

Fig.2.1 Outside Plant Network

2.2.1 MDF

MDF is the main Flexible place as shown in Fig.2.1 which is used to Connect, disconnect or Check

errors of the communication. Meaning of MDF is main distribution frame. MDF has two sides. One

side is to connect exchange called primary side. Another one is called Secondary side which connected

to the customer side. Primary side and secondary side are connected by jumper wires. In MDF to

power up lines used -48V DC voltage which is supplied by exchange side. And According to the

connection type color codes of the jumper wires Varied

7

Data Connections -Red and White

Voice Connections -Blue and white

ADSL Connections-Black and White

Fig.2.2 MDF

2.2.2 Man Hole and Hand Hole

Man Hole and Hand Hole are the gates to the underground cables Maintenance and repairing. The

main difference between Hand Hole and Man Hole is a person can do repairs in a man hole. But hand

hole can operate only by using hands.

Fig.2.3 Man Hole

8

2.2.3 Cross Connection Cabinet

Cabinet also a flexible points which connects MDF side and DP/CCT side through jumper wires. For a

particular DP there are 10 wires release from Cabinet. By using jumper cables, according to the

customer telephone number primary pair is connected to the DP side pair. Cabinet is used for a

protection and testing.

Fig.2.4 Cabinet

2.2.4 MSAN

Multiple Service Access Node (MSAN) is a new technology replaced for Cabinet. But here no need to

connect with MDF or Exchange. Because all the MSANs connected with Nation Ring in SriLanka.

The advantage of this new technology is however one side of the ring is disconnected MSAN works

with other side of the ring

Fig.2.5 Pole Mounted MSAN and MSAN Ring

9

2.2.5 Distribution point / Cross Connection Terminal

Distribution point (DP) is the point where drop wire connected. And underground cable from Cabinet

and aerial cables are connected at DP. DP is mounted on poles and drop wires are drawn from DP’s to

customer’s home. Normally DP has maximum 10 wire loops.

Fig.2.6 Distribution Point

2.2.6 Discharger/ Fuse Box

Discharger is used to protect telephone, Router and subscribers from the high voltage current due the

lightning .If there is a high voltage current .the fuse will be burnt and the communication path is

disconnected. After that high voltage current pass to the earth through the wire.

Fig.2.7 Discharger

10

2.2.7 Rosette

Rosette is used to connect Discharger and Telephone. Purpose of this instrument is easy to access and

change the connection pin.

Fig.2.8 Rosette

2.2.8 Splitter

Splitter is used when there is an ADSL line. Normally Data contains with high frequency range and

voice contains low frequencies. To filter them and connected to Telephone and router use Splitter. It

has a low pass filter. With is splitter we can access telephone and internet connection without

interruption.

Fig.2.9 Splitter

2.2.9 ADSL Router

ADSL Router is Provides internet service to customers through Ethernet interface.

Fig.2.10 ADSL Router

11

2.2.10 Ethernet cable

Through Ethernet cable for ADSL routers to connect them with PCs, Ethernet switches, Wireless

access Points.

Fig.2.11 Ethernet cable

2.2.11 Telephone

Telephone is used for communicate with others. It consists of 4 circuits Receiving, Transmission,

Dialing, and Ringing circuits.

Receiving circuit: - Convert electrical signal into audio signal.

Transmission circuit: - Convert audio signal into electrical signal.

Dialing circuit: - Voltages pulses generating when pressing numbers.

Ringing circuit: - Ringing when call is coming.

Fig.2.12 Telephone

12

CHAPTER 03- NEW CONNECTIONS AND MAINTENENCE

3.1 CABLE DEVELOP AND MAINTENANCE

3.1.1 JOB PROFILE OF THE SECTION

Installing and maintenance of the primary side of the telephone lines (MDF to Cabinet)

New Projects (MSAN)

3.1.2 INTRODUCTION

Cable Development and Maintenance section is responsible for the cable connect ion from the

primary side (MDF to Cabinet/ODF–Optical Distribution Frame to MSAN- Multi Service Access

Node) From the Line Side of the MDF, cables are drawn in sets of

1 0 / 2 0 / 3 0 / 5 0 / 200/300/600/../2400 pairs as underground cables through the duct lines

available/direct buried cables if the ducts are not available/aerial cables ( for small number of pairs

only) to the Cabinets through HH (Hand Ho les) and Man Holes (MH).MH and HH are found in

different sizes to suit different capacities and they are used as a access interface to the

underground cables for installation/maintenance purposes. Since the copper pairs starting from

SLT end consist of large number of pairs, therefore color codes are used to indent iffy pair

numbers. More than this there are two other types of cables used for connection through direct sand

and water. They are Varry Cables and Submarine Cables.

Fig.3.1 25-Pair Cable

13

Table.3.1 Color codes

1

White

Blue

2 Orange

3 Green

4 Brown

5 Slate

6

Red

Blue

7 Orange

8 Green

9 Brown

10 Slate

11

Black

Blue

12 Orange

13 Green

14 Brown

15 Slate

16

Yellow

Blue

17 Orange

18 Green

19 Brown

20 Slate

21

Violet

Blue

22 Orange

23 Green

24 Brown

25 Slate

3.1.3 TYPES OF FAULTS ON LINES

Disconnection

This fault occurs due to a partial or permanent disconnection in the line. Because of this fault

there is no voltage (or current) to the phone. Therefore we couldn’t hear any sound in the

telephone.

Earth

This fault occurs when A leg or B leg or both legs are connected to the earth.

Short circuits

This fault occurs when A leg and B leg are short circuited. Because of this fault the physical

length of the circuit is short circuited.

Current on line

This is an electrical contact between wires of one pair with a wire of another pair.

14

3.1.4 SOME PRACTICAL EXPERIENCES

3.1.4.1 ISTALLATION OF A RAYCHEM CLOSURE

Task: Installation of a Raychem Closure to a cable joint made inside a man hole. The cable joint had

been made in order to avoid the leakage of water due to the rainy seasons

Fig.3.2 Process Followed For a Raychem Closure Installation

3.1.4.2 CABLE FAULT LOCATING

Process Followed: All the lines of the joint were disconnected from their secondary sides and

each pair was checked using BICOTESTER for any fault in line, type of fault and the distance from

the joint to the fault location. After observing the fault location, it was concluded that there is a

discontinuity in the cable at that point due to the damages. After identify the fault, it was corrected

by technicians in SLT.

Keep Propan-2-ol

With the cable

15

Fig.3.3 Bicotester

3.2 ADSL


Install ADSL/PEO TV new connections.

Attending ADSL/PEO TV fault reported.

3.2.2 INTRODUCTION

ADSL means asymmetric digital subscriber line. This is a high speed transmission technique used to

transmit both voice and data at the same time. More than one connection can be supplied using this

technique.

Fig.3.4 ADSL Architecture

3.2.3 ADSL/PEO TV FAULTS/PROBLEMS AND SOLUTIONS

Component faults (component set up errors/ component failures)

configuration errors(Router)

16

Fault in line (fault in line may occur due to inadequate speed required for ADSL/Peo Tv)

Insufficient knowledge of the customer (Don’t know how to connect with splitter)

Interruption of hackers to the customer accounts

Fig.3.5 ADSL Usage detail report of a customer

ADSL maintenance teams visit customer premises and check on the faults and fix them. And for

hacking problems report to head office for further actions. More than this there is automatic security

system also introduced by SLT for customer safety and satisfaction.

3.3 NEW CONNECTION AND DATA


Do initial wiring and configuration for PSTN and DATA connections. Normally provide PSTN

connection for normal customers and organizations as well. But provide DATA connection only for

mainly banks and others organizations. The responsible area of the section is from DP/CCT to

customer premises.

3.3.2 PROCESS FOLLOWED

In PSTN (Public Switched Telephone Network) in order to give any service, first the physical

connection is made from MDF (Main Distribution Frame) to the customer end equipment. For a voice

connect ion, the copper pair from customer end is connected to a subscriber card in switch via

MDF and the card port is configured and relevant details are updated in the system for the

connection. And for an ADSL/PeoTv connection, Copper pair is connected to the DSLAM port and

the corresponding port is configured according to the connection type by the ADSL NOC (Network

Operation Center) in Colombo for all the connection in SriLanka. In NGN, copper pair connection in made

between a port in nearest MSAN to the customer premises equipment and the port is configured and

system is updated with relevant data for voice/ADSL/PeoTVconnection.

17

3.3.3 STANDARDS USING SLT WHILE IMPLIMENTING NEW CONNECTION

Drop wire clearance

Along the road- 4.5m, road crossing-5.0m

Power lines

o Lower than 600V-0.6m

o 600V-7000V-1.2m

o 7000V-1500V-2m

Drop wire connectors

Lower than 500m-No joints

Greater than 500m-One joint with drop wire connecter

Construction of line and clearance from foliage not less than 1m

Discharger fixed firmly at a reachable height wires without spirals

Earth wire is to be connected to the discharger without spirals and joints

Earth wire resistance should be less than 1000ohms

Internal wire stapled at 0.4m intervals

Rosette fixed on the wall 0.5m above the ground

Buried depth of the pole 1/5 of the pole height

Sag of drop wire

0.4 m for less than 40cm of pole span

0.7m for 40cm-50cm of pole span

Exchange resistance- 2 Ohms

MDF earth resistance< 5 Ohms

Cabinet earth resistance< 30 Ohms

DP earth resistance < 5 Ohms

MDF to DP maximum allowable resistance for PSTN 1500 Ohms and for ADSL 600 Ohms

3.3.4 DATA FAULTS AND SOLUTIONS

Data connection is an important part for Banks, Financial Companies and some other online

administrative offices. Therefore SLT has a responsible for continuous communication for them. And

if the brake down period has reached the particular limit for the company SLT has to pay lack of

money as compensation. Therefore SLT and there officers be always alert for prevent the

disconnection. And most of the times many DATA systems damaged due to high voltage and high

current by lightning. Replacing the damaged instrument is the common solution method.

18

Fig.3.6 Damaged DATA Modem and wiring due to lightning

3.4 PSTN MAINTENANCE


PSTN section is responsible for identify the faults through customer’s report and fix those problems

within 24 hours of reported time. More than this they do some maintenance works handovers from

CDM section as well. The working network of the PSTN maintenance is from DP/CCT to customer

premises. Working instruments of the section are DP, Fuse, Rosette box, Splitter and Telephone.

3.4.2 PSTN FAULTS, PROBLEMS AND SOLUTIONS

Cable damage

Short circuit connections

Fuse damaged due to lightning

Modem

Fuse Ethernet Cable

19

Phone damaged

Problem with Rosette code

Carbon problem with Splitter and Rosette box (In Rainy seasons)

When customers reported about their problems to SLT, then workers of the PSTN maintenance section

visit customer premises and fix them. If they couldn’t get the solution for the problem with in their

network then handover the work orders to the CDM section. Most of the above problems occurred due

to the expired. Therefore replacing is a good solution for those problems.

Fig.3.7 Damaged Fuses and Rosette box

3.5 MDF SECTION


MDF provides connection between Exchange side and outside plant.

Assign any telephone number to any loop. Because if there is any fault in the subscriber line,

MDF is the place used to assign new loop for same number. And customer can continue the

communication without any changes.

Exchange cannot replace very easily. Because of that Protecting exchange side is one of the

main functions of the MDF. For those Arresters, Proper earth connection and other protection

used in MDF.

Damaged

Fuses

Damaged Rosette box

due to Carbon

20

Updating clarity. Because all the new connection and faults are informed to MDF, MDF must

update SLT data base.

Isolation from Subscriber lines from exchange. To test conditions of the subscriber lines it is

must to isolate from exchange side.

Also the test equipment is fixed at the MDF as it is a flexible point for testing. So the loop is

disconnected and connected to their testing equipment to check the condition of lines, such as

short circuit, cross connection, disconnection. That equipment is consisting of simple circuit

diagrams.

Fig.3.8 Fused Used in MDF

Fig.3.9 Jumbering at MDF

21

CHAPTER 04-CDMA

4.1 INTRODUCTION

SLT provides many CDMA services such as voice, data, fax and payphones. SLT-CDMA (city link)

has an island wide coverage and it is a very popular and main telecommunication option especially

in the rural areas where there is no wired network or cellular mobile coverage. Some schools in

remote areas are connected to the School-Net using CDMA modems. And police offices in remote

areas using CDMA fax facility for their communication. Around 30,000 customers using CDMA

phones under the Batticaloa OPMC.

4.2 CDMA TECHNOLOGY

Cellular communication stated with AMPS (Advanced Mobile Phone System). Then it developed with

digital wireless communication. Called TDMA (Time Division Multiple Access). CDMA takes an

entirely different approach from TDMA. CDMA, after digitizing data, spreads it out over the entire

available bandwidth. Multiple calls are overlaid on each other on the channel, with each assigned a

unique sequence code. CDMA is a form of spread spectrum, which simply means that data is sent in

small pieces over a number of the discrete frequencies available for use at any time in the specified

range.

All of the users transmit in the same wide-band chunk of spectrum. Each user's signal is spread over

the entire bandwidth by a unique spreading code. At the receiver, that same unique code is used to

recover the signal. Because CDMA systems need to put an accurate time-stamp on each piece of a

signal, it references the GPS system for this information. Between eight and 10 separate calls can be

carried in the same channel space as one analog AMPS call.

4.3 CDMA ARCHITECTURE

Fig.4.1 CDMA Architecture

22

MS (Mobile Station) - Originate and receive calls and communicate with the BTS.

BTS (Base Transceiver Station) - Transmits and receives radio signals.

BSC (Base Station Controller) - Functions of BSC are BTS control and management, call

connection and disconnection, Mobility Management, Power control, Radio resource management,

Provide stable and reliable radio link.

MSC (Mobile Switching Center) - Performs the switching functions of the system.

VLR (Visitor Location Register) - Database contains temporary information about subscribers

that is needed by the mobile services switching center (MSC) in order to service visiting

subscribers

HLR (Home Location Register) - Stores permanent data about subscribers.

SMC (Short Message Center) - Responsible for handling SMS

PDSN(Packet Data Serving Node)- Acts as a router and issues IP address

Fig.4.2 CDMA Fixed Wireless Phone

Fig.4.3 CDMA Fixed Wireless Terminal

23

CHAPTER 05- PLANNING AND DEVELOPMENT

5.1 JOB PROFILE OF THE SECTION

Plans for installation of MSAN, Cabinet and DP/CCT.

Rearranging old copper connections and Rehabilitation.

Co-ordinate SLT projects with private parties and manage them.

Manage stocks of OPMC.

5.2 INTRODUCTION

Planning and Developing is the main of OPMC in SLT. Major projects of SLT depend on the report of

this division, for example when SLT install a new project, it should give profit to SLT. Therefore

achieving profit to the company and customer satisfaction this section comes into a main role of SLT.

5.3 OBJECTIVE OF REHABILITATION

MDF – Repairing of faulty or damage tag blocks, Properly earthling, Removing unwanted

wires, Updating records, Checking arrestors /fuses & replacement, Drawing of jumper wires

properly, Labeling of cables, Marking of special circuits for easy identification (Data, ADSL

etc.)

Overhead Routes - Recovery of unwanted items, Tensioning wires and cables, Installation of

stays and struts, Replacement of faulty lines, Normalization of O / H routes.

Cabinets -Cleaning inside & outside, Removing unwanted jumpers, Updating records,

Labeling & earthling, Properly sealing.

DP - Fixing properly to poles, Earthling, Replacing faulty DP, DP dressing & numbering,

Connecting through bridal rings, Fixing DP bands, Closing DP covers

Route Clearance -

Pole Recovery/Replacement - Recovering of excess, Unwanted or damaged poles,

Rearranging overhead route.

Cable Recovery - Recovering of excess or faulty cables along routes.

Internal Wiring - Fixing without joints, Fixing earth where necessary, Replacement of faulty

wires, Replacing earth wire joints, Checking earth resistance, Replacement of faulty

dischargers, Replacing of telephones which are more than 10 Years old.

Pair Gain Recovery/Rehabilitation- Recovery / Rehabilitation of DSL, Fixing earth where

necessary, Normalization of overhead wires, Recovering of Exchange Unit

MH/HH Repairs - Repairing of broken MH/HH, Labeling of cables, Raising or lowering of

MH/HH, Placing cables on brackets, Dewatering & Cleaning inside & outside , sealing duct

Removal of Drop Wire / PVC Bunches- Extending cables, Splitting DPP, Opening of

stumps.

24

CHAPTER 06-OPERATION SUPPORT

SLT is a one of the very huge organization with very wide coverage, a very large amount of staff

and with many services and products with complex and interconnected operations. In order to deliver

a good service to the customer, all these operations and all the sections and the staff must be

properly coordinated and properly guided at each and every moment. In order to s a t i s f y the

above requirements there are several mechanisms have been built around the organization and its

operations.

One such mechanism is the ‘Clarity’ - the operation support system of the SLT. Clarity is an

internet based system which is a part of the SLT intranet .It provides an interface for each and every

sect ion to look up for the duties they are been assigned or to update the system when the

duties are finished/work progress so that other sections may work on that from that point. ‘Work

Orders’ is another concept which is a part of the clarity which defines the duties assigned to each

section on some task/service order. For a one task/service order to be completed, several sub tasks

may be needed to be done by relevant sections. Therefore work orders are issued with all the

requirements and due dates etc. for a single task and they are either displayed on Clarity or posted to

relevant sections. Another supporting mechanism is the concept of call centers. It makes much

flexible and efficient connection with the customers in order to feed the system with their feedback

or requirements. In order to elaborate, how these mechanisms take place, let’s consider several

examples. When a customer needs to complain regarding a service, by just dialing ‘1212’ it connects

the customer to any of the call centers and by considering the complain/request the call center officer

enter the data to the relevant section of the clarity which then will be directed to the relevant

section of the relevant branch through clarity as a work order so that they can attend to that.

When the relevant task is done, it could be entered to the system so that system will remove the

work order after saving necessary data on the task. I think this is a very efficient way which let the

customers more clear to the operation system, but in a very responsible manner. If we consider a

situation where the network planning sect ion needs to configure new links between two switches,

then several sections (transmission, switch) in both branches as well as branches in headquarters

must incorporate to finish the task. Then all the sections are issued with a work orders containing

detailed task descript ion for each section. If we consider another situation when a new PSTN

connect ion is made, the new connect ion section enters all the relevant details including

DP(Distribution Point) number, slot number, cabinet number etc. and the MDF staff feed the

system with the relevant block and tag block numbers and the switch enters the sub card numbers.

Slot numbers etc. for a given connection. In this way, all the sect ions involved are very well

connected and well informed about the tasks done by other sections which are relevant to them too

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CHAPTER 07- SWITCHING

7.1 INTODUCTION

In telecommunication switching is defined as the on demand establishment of individual connect ion

from a desired inlet to desired outlets for the required time enabling transfer of information.

Switching is required for SLT operations for two main reasons. One is for establishment of

customers to the network and the other is for the internal communication. We need switching since

we do not have unlimited resources so that everyone is connected to everyone else or every

network link has unlimited capacity. When we consider switching, SLT has two main networks.

One is the PSTN/Legacy network which uses Time Division Multiplexing and the other is

IP/MPLS network which uses packet switching.

7.2 SLT SWITCHES

In times Cross bar technology used for switching purposes. Then semi electronic switches were

introduced to SLT called “Teletypewriter”. Manufacture was “Kitache” (Version: C23SE) in 1978.

Then “American Telephone and Telegraphy” company introduced another fully electronic switch

(Version: SESS). It can only communicate for PSTN connections. In 1996 “Erission” company

introduced a switch (Version: AXE 10) which can communicate for PSTN and ADSL as well. Recently

MSAN was introduced by SLT for all kind of telecommunications such as PSTN, ADSL, DATA, etc.

MSAN is easiest and fastest way to communication. However SLT using the old AXE 10 switches as

well. Normally MSANs working with 230V supply and working with battery power as well. However

the charging capacities of those batteries are very low. Therefore it makes many problems in practice.

Fig.7.1 ERICSSON AXE 10 Switches

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NGN Network-Packet switched network

IP/MPLS NETWORK USING O/F

LINKS

CHAPTER 8 -TRANSMISSION

8.1 INTRODUCTION

SLT provides many services to the customers all around the island and we can say that for each

service, there should be one island wide network since all the services are about communication. For

almost all the services the service providing equipment are placed in SLT premises and customers

are connected to the network through access network. The network which connects each service

providing equipment to others and to the service network can be considered as the core network

and the above connectivity is provided by transmission section. The transmission links for

connecting local service nodes and the core network is managed by transmission section. Mainly

there are two core network types in SLT and different transmission networks as well

Legacy Network-circuit switched n/w

SDH/PDH TRANSMISSION N/W

USING RADIO OR O/F LINKS

Fig.8.1 Transmission Network types in SLT

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8.2 JOB PROFILE OF THE SECTION

Maintenance of Radio and Fiber Networks

Test and provide Transmission Links

Keep and Upgrade relevant data

8.3 SOME SPECIAL PRACTICAL EXPERIENCES

8.3.1 TRANSFERING OF RADIO LINKS TO O/F NETWORK

Some Radio transmission links between Batticaloa TX room and Polanaruwa repeater station were

transferred to the Optical fiber links .First two O/F ports with minimum loss were selected from

free ports in ODF (from Batticaloa to Polanaruwa) by testing the receiving power of each link by

connecting a power meter from Polanaruwa end after sending an optical signals from an optical

source from Batticaloa end. Then the wiring was tested by sending a signal from SDH/PDH analyzer

and check for the receiving signal through SDH/PDH analyzer.

Optical Source Power Meter SDH/PDH Analyzer

Fig.8.2 Equipment used in loop testing

8.3.2 SPLICING

Optical fiber is the newest technology in SLT, when installing transmission lines there are chances

may occur for disconnection of optical fibers. Connection of optical fibers is not an easy method like

copper cables. Because for a perfect communication the optical fibers should be connect 100%

exactly.

8.3.2.1 Parts of an Optical cable

Core

Positioned at the center of the cable

As thin as human hair

Made of glass

Light travels inside the core

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Cladding

Positioned around the core

Made of glass with low reflection

Reflect light back in to the core

Jacket

Also called buffer coating

Made of plastic

Outer most covering

Protect the fiber from damage and moisture

8.3.2.1 Optical fiber splicing procedure

Stripping -Used stripper tool

Cleaning -Used alcohol

Cleaving -Used cleaver

Splicing -Used Splicing tool

Protection -Sleeve

Fig.8.3 Clever, Stripper and Splicer

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CHAPTER 9 –POWER

9.1 INTRODUCTION

Power is the main part of the telecommunication network. All the instruments used in SLT need

particular amount of power. When we consider about the usage of power are operation of Switches,

MSANs, CDMA instruments, cooling system etc. Therefore CEB provide a special and separate

connection to all Regional telecom offices. Therefore SLT have to maintenance of the power system

that CEB provide. And SLT have to maintenance their generator which are replacement of main

power and mobile generators as well for MSANs.

9.2 JOB PROFLE OF THE SECTION

Supply main power system

Installation and Maintenance of Generators

Maintenance of Rectifier and Battery

Maintenance Air conditioners

Fig.9.1 Batteries

Fig.9.2 DETROIT Diesel Generator

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CHAPTER 10- CONCLUSIONS

The industrial training program at SLT, the major telecommunication service provider for Sri Lanka

was a great experience for me where I could have industrial training experience in many

aspects of telecommunication. Other than that, it was a great experience for me where I could

learn and practice ethics and social skills for an industrial environment and as well as I could gain

the insight to appreciate even the smallest, but honest , supportive and cooperative contribution of

the staff towards the success of a company and for a better working environment.

Although I was assigned to OPMC-Batticaloa for 10 weeks, I got a chance to have my training in a

well-planned way in OPMC sect ions as well as in switching and transmission sect ions at that

period for which I am very thankful to Mr. K. Kogularanjan -the Manager at OPMC and

Mr.Y.Kishanthan- Engineer Network in Eastern Province. And I think it was better that I had the

lecture series at training center after I being exposed to the field in some level because there I

first tried to understand the technologies and the system by own with the help of the staff and some

introductory lectures from the staff and then at the training centers I could confirm what I

learned. It was actually motivated me to learn things. I really appreciate all the staff members and

the lectures at SLT who helped me to gain all these experiences and the training Planning sect ion of

SLT for coordinating my training.

I think it would be great if Trainees could have more experience on the network planning,

international switching, transmission and other engineering divisions so that they could be

more exposed to technologies and the challenges to be faced as engineers in the future.

Finally I would like to state that the training experience I had at SLT organized by the Industrial

Training Unit of University of Peradeniya in collaboration with NAITA was up to my

expectations and it was a great experience for me which would definitely help me in my future

carrier.

Industrial Training Report- I-SLT

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