STUDY OF TELECOM NETWORK – AT AT NTC An Internship report submitted in partial fulfillment fulfillment of the requirements For the award of degree of
Bachelor of Technology In
Computer Science And Engineering
Submitted by Atul Verma
14131A05B7
Lekhnath Kafle
14131A05B8
Mukesh Sah
14131A05B9
Prabin Ghimire
14131A05C3
Under the guidance of Dr.P.Krishna Subba Rao - Professor
and Head of the Department
COLLEGE OF ENGINEERING ( AUTONOMOUS)
Department of Electronics and Communicat Communication ion Engineering GAYATRI VIDYA PARISHAD COLLEGE OF ENGINEERING (AUTONOMOUS)
4
(Affiliated to J.N.T University, Kakinada, A.P) VISAKHAPATNAM- 530 048MAY, 2016
CERTIFICATE This is to certify that the Internship Training/project titled TELECOM NETWORK – at at NTC is a bonafide record of the work done by Atul Verma,Lekhnath Kafle,Mukesh Shah,Prabin Ghimire in partial fulfillment of the requirements for the award of the degree of Bachelor of Technology in Computer Science And Engineering Engineering of the Gayatri Vidya Vidya Parishad College of Engineering Engineering (Autonomous) affiliated affiliated to Jawaharlal J awaharlal Nehru Technological University, University, Kakinada during the year 2017.
(Name & Signature of the Supervisor)
(Name & Signature of the HOD)
Sri.Sagara Pandu Dr. N. Balasubramanyam
Project Viva-voce held on _____________________________
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(Affiliated to J.N.T University, Kakinada, A.P) VISAKHAPATNAM- 530 048MAY, 2016
CERTIFICATE This is to certify that the Internship Training/project titled TELECOM NETWORK – at at NTC is a bonafide record of the work done by Atul Verma,Lekhnath Kafle,Mukesh Shah,Prabin Ghimire in partial fulfillment of the requirements for the award of the degree of Bachelor of Technology in Computer Science And Engineering Engineering of the Gayatri Vidya Vidya Parishad College of Engineering Engineering (Autonomous) affiliated affiliated to Jawaharlal J awaharlal Nehru Technological University, University, Kakinada during the year 2017.
(Name & Signature of the Supervisor)
(Name & Signature of the HOD)
Sri.Sagara Pandu Dr. N. Balasubramanyam
Project Viva-voce held on _____________________________
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ACKNOWLEDGEMENT We hereby take this opportunity to express our sincere gratitude to the following eminent personalities whose aid and advice helped us to complete this training cum project work successfully successfully without any difficulty. difficulty. We express our deep gratitude to Mr. N.BALA SUBRAMANYAM, HOD of electronics and communication engineering for his constant support and encouragement. We would like to thank Sri.Sagara Pandu , ASSISTANT PROFESSOR forgiving me a chance to do the project and support during the project. We am also thankful to other faculty members of ECE department and my friends for their support during the internship in Nepal Telecom(NTC), Biratnagar,Nepal. Biratnagar,Nepal.
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ABSTRACT
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. The common man is aware of NTC (in Nepal), a giant public sector undertaking in Nepal, doing business in the telecommunication telecommunication industry. industry. NTC 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 NTC.It is the only service provider, making focused efforts and planned initiatives to bridge the rural-urban digital divide act sector. in fact there is no telecom operator in the country to beat its reach with its wide network giving services in every nook & corner of country and operates across Nepal.NTC serves serves its customers customers with its its wide bouquet of telecom services. services. In telecommunications, a broadband signaling method is one that handles a wide band of frequencies. Existing broadband is struggling to support the increasing number of Internet-capable devices in the home, which include: Mobile phones, IPads and tablets, Notebooks, e-readers (such as Kindle), Desktop PCs, Games consoles, Apple TV and media players. The term broadband commonly refers to high-speed Internet access that is always on and faster than the traditional dial-up access. Broadband includes several high-speed transmission technologies such as: Digital Subscriber Line (DSL), Cable Modem, Fiber, Wireless, Satellite, Broad band over Power lines (BPL).
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TABLE OF CONTENTS 1. INTRODUCTION TO NEPAL TELECOM 1.1 PSTN SERVICES………….…..……… SERVICES………….…..…………………………………… …………………………………...02 ……...02 1.2 CDMA………………….…………………………………………………...02 1.3 MOBILE…………………………………….……………………………...02 1.4 INTERNET AND EMAIL……………… EMAIL……………………………………………… ………………………………….03 ….03 1.5 AWARDS AND RECOGNITION………………………………………….03 RECOGNITION………………………………………….03
2. INTRODUCTION OF GSM 2.1 FREQUENCY RANGE OF GSM…………………………………….….…05 GSM…………………………………….….…05 2.2 FUNCTIONAL UNIT OF O F GSM………………..………………………..….05 2.3 ARCHITECTURE OF GSM...……………………………… GSM...………………………………………….…..05 ………….…..05 2.4 GSM NETWORK AREAS………………………… AREAS……………………………………………….…07 …………………….…07 2.5 THE MOBILE STATION(MS)…………………… STATION(MS)………………………………………….….07 …………………….….07 2.6 THE BASE STATION STAT ION SUBSYSTEM(BSS)……………………………….08 2.7 THE NETWORK SWITCHING SW ITCHING SUBSYSTEM(NSS)…………………….11 SUBSYSTEM(NSS)…………………….11 2.8 THE OPERATION SUPPORT SUPP ORT SUBSYSTEM(OSS)………………………12
3. TRANSMISSION NETWORK SYSTEM 3.1 OPTICAL FIBER CABLE………………………… CABLE…………………………………………………13 ………………………13 3.2 THE GENERAL SYSTEM………………………………… SYSTEM………………………………………………...14 ……………...14 3.3 TRANSMISSION SEQUENCE..………………………………… SEQUENCE..……………………………………….….14 …….….14 3.4 APPLICATION OF OPTICAL FIBER………….………………………....15 FIBER………….………………………....15 3.5 ROLE OF ANTENNA IN MOBILE COMMUNICATION……….………15 3.6 TELECOMMUNICATION NETWORK……..…………………… NETWORK……..……………………………17 ………17 3.7 SWITCHED COMMUNICATION NETWORK…………………… NETWORK…………………………..19 ……..19 3.8 BROADCAST NETWORK……..…………………… NETWORK……..………………………………………....19 …………………....19 3.9 NETWORK ACCESS………….………………………………………… ACCESS………….…………………………………………...19 ...19 3.10 SCHEDULE ACCESS………….…………………… ACCESS………….……………………………………….….20 ………………….….20 3.11 RANDOM ACCESS……………..……………… ACCESS……………..…………………………………………20 …………………………20
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4. INFORMATION TECHNOLOGY 4.1 CRM…………………………………………..………………………….…21 4.2 OPERATIONAL……………………………..……………………………..21 4.3 MAIN COMPONENTS…………………………………………………….22 4.4 CRM BENEFITS FOR CUSTOMER…….………………………………...23 4.5 CRTB……………………………………………………………………..…23 4.6 ADSL……………...………………………………………………………...24
5. CONCLUSION....................................................................................28 6. REFERENCES………………………………………………………29
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LIST OF FIGURES FIGURE1.0.0
NEPAL TELECOM LOGO
1
FIGURE2.3.1
ARCHITECTURE OF GSM
5
FIGURE2.3.2
GSM NETWORK ALONG WITH ADDED ELEMENTS
6
FIGURE2.6.0
BASE STATION SUBSYSTEMS
8
FIGURE2.6.1
BASE TRANSCEIVER STATION
9
FIGURE2.7.0
NETWORK SWITCHING SYSTEMS
11
FIGURE2.8.0
OPERATION AND MAINTENANCE CENTER
12
FIGURE3.1.0
OPTICAL FIBER CABEL
13
FIGURE3.3.0
FIBER OPTICS TRANSMITTER AND RECEIVER
14
FIGURE3.5.0
ANTENNA IN MOBILE COMMUNICATION
16
FIGURE3.6.3
TELECOMMUNICATION NETWORK
18
FIGURE4.6.3
FREQUENCY PLQN FOR ADSL
26
FIGURE4.6.5
FDM AND ECHO CANCELLATION
27
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1. INTRODUCTION TO NEPAL TELECOM Nepal Doorsanchar Company Ltd, popularly known as Nepal Telecomis state owned telecommunication service provider in Nepal with 85% of the government share.The company was amonopoly until 2003, when the first private sector operator UTL started providing basic telephony services. The central office of Nepal Telecom is located at Bhadrakali Plaza, Kathmandu. It has branches, exchanges and other offices in 184 locations within the country.It is the sole provider of fixed line, ISDN and leased-line services in Nepal. Following the entry of Ncell (previously called Mero Mobile) into Nepal's telecommunications industry in 2005, it is no longer the only provider of GSM mobile service. With around 5,000 employees, it is one of the largest corporations of Nepal. It has a total of 262 telephone exchanges in various part of the country serving 603,291 PSTN lines, more than 5 million GSM cellular phones and more than a million CDMA phone line as of July 2011. According to recent data, there are about 10 million users of Nepal Telecom including all those of fixed landline, GSM mobile, CDMA and internet service. As of September 2014, Nepal Telecom is planning to launch LTE by the end of 2015.
Fig: 1.0 Nepal Telecom Logo
Services provided by Nepal Telecom are as follows:11
1.1PSTN Services
Local calls
.National Trunk Calls
International Trunk Calls
International Telegram
Domestic Telex
International Telex
Leased Lines
Operator -Assisted Int'l Telephone
Packet Switching Data Communication
ISDN (Integrated services Digital Network)
Pay Phone
Intelligent Network Services
PCC Easy Call Service
HCD Service
AFS Advanced Free phone Service
Universal Access Number service
PSTN credit Limit service
1.2CDMA
Fixed Postpaid.
Fixed Prepaid.
SKY phone.
Data Services.
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1.3Mobile
Postpaid
Prepaid
Roaming (Incoming & Outgoing)
SMS
3G Service
VAS Services
1.4Internet and E-mail
Dial -up Internet /Email Access
PSTN Dial-up
Fixed hour package
Night Surfing Package
Fixed hour / month package
Unlimited Single User Package
PSTN Bills in the Internet
Post-Paid Mobile Bills
Telephone Inquiry
ISDN dialup
Leased Line Connectivity (n*64kbit/s)
Web SMS
E-mail Alert
1.5Awards and recognition
Nepal Telecom was honoured with No.1 Taxpayer' title in FY 2009-10 and FY 2010-11. 13
Best Presented Award for the best financial statements presentation awarded by Institute of Chartered Accountants of Nepal (ICAN) for consecutive three times (FY 2008-09, FY 2009-10 and FY 2010-11)
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2. INTRODUCTION OF GSM
If you are in Europe or Asia and using a mobile phone, then most probably you are using GSM technology in your mobile phone. GSM s t a n d s for Global System for Mobile Communication. It is a digital cellular technology used for transmitting mobile voice and data services. The concept of GSM emerged from a cell-based mobile radio system at Bell Laboratories in the early 1970s. GSM is the name of a standardization group established in 1982 to create a common European mobile telephone standard. GSM is the most widely accepted standard in telecommunications and it is implemented globally. GSM is a circuit-switched system that divides each 200 kHz channel into eight 25 kHz time-slots. GSM operates on the mobile communication bands 900 MHz and 1800 MHz in most parts of the world. In the US, GSM operates in the bands 850 MHz and 1900 MHz. GSM owns a market share of more than 70 percent of the world's digital cellular subscribers. GSM makes use of narrowband Time Division Multiple Access (TDMA) technique for transmitting signals. GSM was developed using digital technology. It has an ability to carry 64 kbps to 120 Mbps of data rates. Presently GSM supports more than one billion mobile subscribers in more than 210 countries throughout the world. GSM provides basic to advanced voice and data services including roaming service. Roaming is the ability to use your GSM phone number in another GSM network.
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2.1 Frequency Range of GSM GSM works on four different frequency ranges with FDMA-TDMA and FDD. They are as follows:
System
P-GSM (Primary)
E-GSM (Extended)
GSM 1800
GSM 1900
Freq Uplink
890-915MHz
880-915MHz
1710-1785Mhz
1850-1910MHz
Freq Downlink
935-960MHz
925-960MHz
1805-1880Mhz
1930-1990MHz
2.2 Functional Unit Of GSM A GSM network comprises of many functional units. These functions and interfaces are explained in this chapter. The GSM network can be broadly divided into: The Mobile Station (MS) The Base Station Subsystem (BSS) The Network Switching Subsystem (NSS) The Operation Support Subsystem (OSS)
2.3 Architecture Of GSM
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The additional components of the GSM architecture comprise of databases and messagessystems functions:
o
Home Location Register (HLR)
o
Visitor Location Register (VLR)
o
Equipment Identity Register (EIR)
o
Authentication Center (AuC)
o
SMS Serving Center (SMS SC)
o
Gateway MSC (GMSC)
o
Chargeback Center (CBC)
o
Transcoder and Adaptation Unit (TRAU)
The following diagram shows the GSM network along with the added elements:
Fig 2.3.2 GSM Network along with added elements
The MS and the BSS communicate across the Um interface. It is also known as the air interface or the radio link. The BSS communicates with the Network Service Switching (NSS) center across the A interface. 17
2.4 GSM network area
In a GSM network, the following areas are defined:
Cell : Cell is the basic service area; one BTS covers one cell. Each cell is given a Cell Global Identity (CGI), a number that uniquely identifies the cell.
Location Area : A group of cells form a Location Area (LA). This is the area that is paged when a subscriber gets an incoming call. Each LA is assigned a Location Area Identity (LAI). Each LA is served by one or more BSCs.
MSC/VLR Service Area : The area covered by one MSC is called the MSC/VLR service area.
PLMN : The area covered by one network operator is called the Public Land Mobile Network (PLMN). A PLMN can contain one or more MSCs.
2.5 The Mobile Station(MS) The MS consists of the physical equipment, such as the radio transceiver, display and digital signal processors, and the SIM card. It provides the air interface to the user in GSM networks. As such, other services are also provided, which include: Voice teleservices Data bearer services The features' supplementary services
2.5.1 The MS Functions
The MS also provides the receptor for SMS messages, enabling the user to toggle between the voice and data use. 18
Moreover, the mobile facilitates access to voice messaging systems. The MS also provides access to the various data services available in a GSM network. These data services includes
1. X.25 packet switching through a synchronous or asynchronous dial-up connection to the 2. PAD at speeds typically at 9.6 Kbps. 3. General Packet Radio Services (GPRSs) using either an X.25 or IP based data transfer method at speeds up to 115 Kbps. 4. High speed, circuit switched data at speeds up to 64 Kbps.
2.5.2SIM The SIM provides personal mobility so that the user can have access to all subscribed services irrespective of both the location of the terminal and the use of a specific terminal. You need to insert the SIM card into another GSM cellular phone to receive calls at that phone, make calls from that phone, or receive other subscribed services.
2.6 The Base Station Subsystem(BSS)
Fig 2.6.0: Base Station Subsystem
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The BSS is composed of two parts: The Base Transceiver Station (BTS) The Base Station Controller (BSC)
The BTS and the BSC communicate across the specified Abis interface, enabling operations between components that are made by different suppliers. The radio components of a BSS may consist of four to seven or nine cells. A BSS may have one or more base stations. The BSS uses the Abis interface between the BTS and the BSC. A separate high-speed line (T1 or E1) is then connected from the BSS to the Mobile MSC.
2.6.1 The Base Transceiver Station (BTS) The BTS houses the radio transceivers that define a cell and handles the radio link protocols with the MS. In a large urban area, a large number of BTSs may be deployed.
Fig 2.6.1: Base Transceiver Station 20
The BTS corresponds to the transceivers and antennas used in each cell of the network. A BTS is usually placed in the center of a cell. Its transmitting power defines the size of a cell. Each BTS has between 1 and 16 transceivers, depending on the density of users in the cell. Each BTS serves as a single cell. It also includes the following functions: Encoding, encrypting, multiplexing, modulating, and feeding the RF signals to the antenna Transcoding and rate adaptation Time and frequency synchronizing Voice through full- or half-rate services Decoding, decrypting, and equalizing received signals Random access detection Timing advances Uplink channel measurements
2.6.2 The Base Station Controller (BSC) The BSC manages the radio resources for one or more BTSs. It handles radio channel setup, frequency hopping, and handovers. The BSC is the connection between the mobile and the MSC. The BSC also translates the 13 Kbps voice channel used over the radio link to the standard 64 Kbps channel used by the Public Switched Telephone Network (PSDN) or ISDN.
21
It assigns and releases frequencies and time slots for the MS. The BSC also handles intercell handover. It controls the power transmission of the BSS and MS in its area. The function of the BSC is to allocate the necessary time slots between the BTS and the MSC. It is a switching device that handles the radio resources.
Additional functions include: Control of frequency hopping Performing traffic concentration to reduce the number of lines from the MSC Providing an interface to the Operations and Maintenance Center for the BSS Reallocation of frequencies among BTSs Time and frequency synchronization Power management Time-delay measurements of received signals from the MS
2.7 The Network Switching Subsystem(NSS) The Network switching system (NSS), the main part of which is the Mobile Switching Center (MSC), performs the switching of calls between the mobile and other fixed or mobile network users, as well as the management of mobile services such as authentication.
22
Fig 2.7: Network Switching System
2.8 The Operation Support Subsystem(OSS) Some of functions:
the
OMC
Administration and commercial operation (subscription, end terminals, charging and statistics).
Security Management.
Network configuration, Operation and Performance Management.
Maintenance Tasks.
The operation and Maintenance functions are based on the concepts of the Telecommunication Management Network (TMN), which is standardized in the ITU-T series M.30. Following is the figure, which shows how OMC system covers all the GSM elemen 23
Fig 2.8: Operation and Maintenance Center
The OSS is the functional entity from which the network operator monitors and controls the system. The purpose of OSS is to offer the customer cost-effective support for centralized, regional, and local operational and maintenance activities that are required for a GSM network. An important function of OSS is to provide a network overview and support the maintenance activities of different operation and maintenance organizations.
.
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3. Transmission Network system
3.1 Optical fiber cable The use of visible optical carrier waves or light for communication has been common for many years. Simple systems such as signal fires, reflecting mirrors and, more recently signaling lamp shave provided successful, if limited, information transfer. initially the optical fibers exhibited very high attenuation and were therefore not comparable with the coaxial cable they were to replace. There were also problems involved in jointing the fiber cables in a satisfactory manner to achieve low loss and to enable the process to be performed relatively easily and repeatedly in the field.
In microwave system if we double the distance the loss will be increased by 6db. For the shorter distance the loss is higher. In ofc system Optical wire is small size, light weight, high strength and flexibility. Its transmission benefits includes wide band width, low loss and low cost. They are suitable for both analog and digital transmission. It is not suffered by digging, electrical interference etc. problems
Figure 3.1: optical fiber cable 25
3.2 THE GENERAL SYSTEM An optical fiber communication system is similar in basic concept to
any
type of communication system. A block diagram of a general
communication system in fig.The function of which is to convey the signal from the information source over the transmission medium to the destination. In electrical communication, the information source provides an electrical signal, usually derived from a message signal which is not electrical, to a transmitter comprising electrical and electronic components which converts the signal into a suitable form for propagation over the transmission medium. The transmission medium can consists of a pair of wires, a coaxial cable or a radio link through free space down which the signal is transmitted to the receiver where it is transformed into original electrical information signal before being passed to the destination.
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3.3Transmission Sequence
Transmitter Input
Coder or
Light
Source-to-Fiber
Signal
Converter
Source
Interface
Fiber-optic
o/p Fiber-to-light
Light
Amplifier/Shaper
Interface
Detector
Decoder
Receiver
Figure 3.3: fiber optic transmitter and receiver
Information is encoded into electrical signals. Electrical signals are converted into light signals. Light travels down the fiber. A detector changes the light signals into electrical signals. Electrical signals are decoded into information
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3.4 APPLICATIONS OF OPTICAL FIBER 1. Long distance communication backbone 2. Inter exchange junctions 3. Video transmission 4. Broadband services 5. Computer data communication 6. High Emi areas 7. Non-communication application
3.5 Role of Antenna in Mobile Communication Antennas transform wire propagated waves into space propagated waves. They receive electromagnetic waves and pass them onto a receiver or they transmit electromagnetic waves which have been produced by a transmitter. As a matter of principle all the features of passive antennas can be applied for reception and transmission alike (reciprocality) . From a connection point of view the antenna appears to be a dual gate, although in reality it is a quad gate. The connection which is not made to a RF-cable is connected to the environment, therefore one must always note, that the surroundings of the antenna have a strong influence on the antennas electrical features. The principle of an antenna can be shown by bending a co-axial cable open.
.
a) A transmitter sends a high frequency wave into a co-axial cable. A pulsing electrical field is created between the wires, which cannot free itself from the cable.
28
b) The end of the cable is bent open. The field lines become longer and are orthogonal to the wires.
c) The cable is bent open at right angles. The field lines have now reached a length, which allows the wave to free itself from the cable. The apparatus radiates an electromagnetic wave, whereby the length of the two bent pieces of wire corresponds to half of the wave length. This simplified explanation describes the basic principle of almost every antenna - the λ/2-dipole. Not only is an electrical field (E) created due to the voltage potential (U) but also a magnetic field (H) which is based on the current (I) . The amplitude distribution of both fields corresponds to the voltage and current distribution on the dipole. The free propagation of the wave from the dipole is achieved by the permanent transformation from electrical into magnetic energy and vice versa. The thereby resulting electrical and magnetic fields are at right angles to the direction of propagation.
Figure 3.5: Antenna in mobile communication 29
3.6 Telecommunication Network A telecommunications network is a collection of terminal nodes, are connected so as to enable telecommunication between the terminals. The transmission links connect the nodes together. The nodes use circuit switching, message switching or package switching to pass the signal through the correct links and nodes to reach the correct destination terminal. Each terminal in the network usually has a unique address so messages or connections can be routed to the correct recipients. The collection of addresses in the network is called the address space. Examples of networks are:
telecommunications
Computer network
The internet
The telephone network
The global Telex network
The aeronautical ACARS network
3.6.1 Computer Network A computer network consists of computers and devices connected to one another. Information can be transferred from one device to the next. For example, an office filled with computers can share files together on each separate device. Computer networks can range from a local network area to a wide area network. The difference between the types of networks is the size. These types of computer networks work at certain speeds, also known as broadband. The Internet network connects computers worldwide.
. 30
3.6.2 INTERNET NETWORK: Access to the network allows users to use many resources. Over time the Internet network will replace books. This will enable users to discover information almost instantly and apply concepts to different situations. The Internet can be used for recreational, governmental, educational, and other purposes. Businesses in particular use the Internet network for research or to service customers and clients.
3.6.3 TELEPHONE NETWORK: The telephone network connects people to one another. This network can be used in a variety of ways. Many businesses use the telephone network to route calls and/or service their customers. Some businesses use a telephone network on a greater scale through a private branch exchange. It is a system where a specific business focuses on routing and servicing calls for another business. Majority of the time, the telephone network is used around the world for recreational purposes.
Fig 3.6.3: Telecommunication Network
31
3.7 SWITCHED COMMUNICATION NETWORK:
A switched communications network transfers data from source to destination through a series of network nodes. Switching can be done in one of two ways. In a circuit-switched network, a dedicated physical path is established through the network and is held for as long as communication is necessary. An example of this type of network is the traditional (analog) telephone system. A packet-switched network, on the other hand, routes digital data in small pieces called packets, each of which proceeds independently through the network. In a process called store-and-forward, each packet is temporarily stored at each intermediate
node,
then forwarded when the next link becomes
available. In a connection-oriented transmission scheme, each packet takes the same route through the network, and thus all packets usually arrive at the destination in the order in which they were sent. Conversely, each packet may take a different path through the network in a connectionless or datagram scheme. Since datagrams may not arrive at the destination in the order in which they were sent, they are numbered so that they can be properly reassembled. The latter is the method that is used for transmitting data through the Internet.
3.8 BROADCAST NETWORK: A broadcast network avoids the complex routing procedures of a switched network by ensuring that each node’s transmissions are received by all other nodes in the network. Therefore, a broadcast network has only a single communications channel. A wired local area
32
network (LAN), for example, may be set up as a broadcast network, with one user connected to each node and the nodes typically arranged in a bus, ring, or star topology, as shown in the figure. Nodes connected together in a wireless LAN may broadcast via radio or optical links. On a larger scale, many satellite radio systems are broadcast networks, since each Earth station within the system can typically hear all messages relayed by a satellite.
3.9 NETWORK ACESS: Since all nodes can hear each transmission in a broadcast network, a procedure must be established for allocating a communications channel to the node or nodes that have packets to transmit and at the same time preventing destructive interference from collisions (simultaneous transmissions). This type of communication, called multiple access, can be established either by scheduling (a technique in which nodes take turns transmitting in an orderly fashion) or by random access to the channel.
3.10 SCHEDULED ACCESS: In a scheduling method known as time-division multiple access (TDMA), a time slot is assigned in turn to each node, which uses the slot if it has something to transmit. If some nodes are much busier than others, then TDMA can be inefficient, since no data are passed during time slots allocated to silent nodes. In this case a reservation system may be implemented, in which there are fewer time slots than nodes and a node reserves a slot only when it is needed for transmission. 33
3.11 RANDOM ACCESS: Scheduled access schemes have several disadvantages, including the large overhead required for the reservation, polling, and token passing processes and the possibility of long idle periods when only a few nodes are transmitting. This can lead to extensive delays in routing information, especially when heavy traffic occurs in different parts of the network at different times —a characteristic of many practical communications networks. Random-access algorithms were designed specifically to give nodes with something to transmit quicker access to the channel. Although the channel is vulnerable to packet collisions under random access, various procedures have been developed to reduce this probability.
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4. INFORMATION TECHNOLOGY 4.1 CRM Customer relationship management (CRM) is an approach to managing a company's interaction with current and potential future Customers. The CRM approach tries to analyse data about customers' history with a company, to improve business relationships with customers, specifically focusing on customer retention, and ultimately to drive sales growth. One important aspect of the CRM approach is the systems of CRM that compile information from a range of different communication channels, including a company's website, telephone, email, live chat, marketing materials , social media, and more. Through the CRM approach and the systems used to facilitate CRM, businesses learn more about their target audiences and how to best cater to their needs. However, adopting the CRM approach may also occasionally lead to favoritism within an audience of consumers, resulting in dissatisfaction among customers and defeating the purpose of CRM.
4.2 Operational The primary goal of customer relationship management systems is to integrate and automate sales, marketing, and customer support. Therefore, these systems typically have a dashboard that gives an overall view of the three functions on a single page for each customer that a company may have. The dashboard may provide client information, past sales, previous marketing efforts, and more, summarizing all of the relationships between the customer and the firm. Operational CRM is made up of 3 main components: sales force automation, marketing automation, and service automation.
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Service automation is the part of the CRM system that focuses on direct customer service technology. Through service automation, customers are supported through multiple channels such as phone, email, knowledge bases, ticketing portals, FAQs, and more. For example, Microsoft's Dynamics CRM Software tracks call times, call resolution and more in order to improve the efficiency of customer service within a business.
Sales force automation works with all stages in the sales cycle, from initially entering contact information to converting a prospective client into an actual client. For example, in August, 2000, Oracle released a CRM software package, OracleSalesOnline.com, which makes contacts, schedules and performance tracking available online so that a customer's information is easily accessible for all employees working at the office or remotely. Sales force automationimplements Sales promotion analysis, automates the tracking of a client's account history for repeated sales or future sales and coordinates sales, marketing, call centers, and retail outlets. It prevents duplicate efforts between a salesperson and a customer and also automatically tracks all contacts and follow-ups between both parties.
36
Marketing Automation focuses on easing the overall marketing process to make it more effective and efficient. For example, by scoring customer behavior, Salesforce'sMarketing Cloud allows a business to adapt marketing
campaigns
to
how
engaged
customers
are
with
a
business. CRM tools with marketing automation capabilities can automate repeated tasks, for example, sending out automated marketing emails at certain times to customers, or posting marketing information on social media. The goal with marketing automation is to turn a sales lead into a full customer. CRM systems today also work on customer engagement through social media.
4.3 Main components The main components of CRM are building and managing customer relationships through marketing, observing relationships as they mature through distinct phases, managing these relationships at each stage and recognizing that the distribution of value of a relationship to the firm is not homogenous. When building and managing customer relationships through marketing, firms might benefit from using a variety of tools to help organizational design, incentive schemes, customer structures, and more to optimize the reach of its marketing campaigns. Through the acknowledgement of the distinct phases of CRM, businesses will be able to benefit from seeing the interaction of multiple relationships as connected transactions. The final factor of CRM highlights the importance of CRM through accounting for the profitability of customer relationships. Through studying the particular spending habits of customers, a firm may be able to dedicate different resources and amounts of attention to different types of consumers.
4.4 CRM benefits for customer With CRM systems customers are served better on day to day process and with more reliable information their demand of self service from companies will decrease. If there is less need to contact with the company for different problems, customer satisfaction level increases.These central benefits of CRM
37
will be connected hypothetically to the three kind of equity that are relationship, value and brand, and in the end to Customer equity. Seven benefits were recognized to provide value drivers:
Enhanced ability to target profitable customers .
Integrated assistance across channels
Enhanced Sales force efficiency and effectiveness
Improved pricing
Customized products and services
Improved customer service efficiency and effectiveness
Individualized marketing messages also called as campaigns
4.5
CRTB
Convergent real time billing (CRTB) system to allow its customers to conveniently pay all kinds of bills through a single billing platform.
The telecommunication service provider will be able to integrate its different services into a single account and then provide an integrated paying system to users through a common account.
The CRTB system refers to a solution used by communication service providers operating multiple services in multiple modes to integrate the services and maintain a single billing platform.
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Currently, the state-owned telecommunication service provider, which offers a number of telecom services including GSM, CDMA and landline, has been using different billing mechanisms for each of its services. CRTB uses single billing for all these services.
4.6
ADSL
Asymmetric Digital Subscriber Line (ADSL) is a form of DSL, a data communications technology that enables faster data transmission over copper telephonelines than aconventional modemcan provide.ADSL has the distinguishing characteristic that the data can flow faster in one direction (used for download streaming) than the other(used for upload streaming) i.e., asymmetrically. Asymmetric Digital Subscriber Line often referred to as ADSL Full Rate orG.dmtand now also known as G.992.1 -- supports up to 8 Mbps bandwidth downstream and up to 1 Mbps upstream.
The asymmetrical aspect of ADSL technology makes it ideal for Internet/Intranet surfing,
video-on-demand and remote local area
network (LAN) access.
Users of these applications typically download more information than they send.
ADSL requires a voice/data splitter, commonly called a POTS Splitter (Plain Old Telephone Service) to be installed at the consumer's home or business premise.
This device separates voice from data transmissions. Enables the Voice and data to travel simultaneously.
Full rate ADSL provides service up to a maximum range of 18,000 feet (about 3.4 miles, or 5.5 km) from the telecommunication provider company's central office to the end-user.
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4.6.1 Benefits of ADSL:
Always on
Simultaneous Usage of Phone and Internet.
Could connect to the Internet at up to 140 times faster than analog modems.(8Mbps vs. 56Kbps Modem)
Home has its own dedicated connection.
Connection is highly secure, compared to shared-media Cable Modem.
No telephone call charges
4.6.2 Needs of ADSL ADSL is in place due to both technical and marketing reasons. On the technical side,there is likely to be more crosstalk from other circuits at the DSLAM (Digital Subscriber Line Access Multiplex) end (where the wires from many local loops are close together) than at the customer premises. Thus the upload signal is weakest, while the download signal is strongest at the noisiest part of the local loop. It therefore makes DSLAM transmit at a higher bit rate than does the modem on the customer end. Since the typical home user in fact does prefer a higher download speed, thus telecom companies chose to make a virtue out of necessity, hence ADSL
4.6.3 Working of ADSL To obtain the asymmetrical data transfer to suit requirement of Internet and LAN access, ADSL works by firstly splitting the available bandwidth on the twisted copper wire (telephone wires) into three different channel:
A high speed downstream channel (ranges from 1.5 to 8 Mbps)
A medium speed upstream channel (ranges from 16 kbps to 1 Mbps)
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POTS (Plain Old Telephone Service) channel ADSL uses two separate frequencybands. With standard ADSL, the band from25.875 kHzto 138 kHz is used for upstream communication, while 138 kHz - 1104 kHz is used for downstreamcommunication.
4.6.4 Frequency plan for ADSL
Figure 4.6.3: frequency plan for ADSL
First the POTS channel is splits off from the digital modem by filter, thus guaranteeinguninterrupted POTS. After the POTS channel aresplittedfrom the digital data transfer bandwidth, the 26kHz to 1.1mhz data bandwidth could be further separated by using one of two ways as describe below: One band for downstream data. Time division multiplexing divides the downstream path intoone or more high speed channels and one or more low speed channels. But the upstream pathis only multiplexed into corresponding low speed.
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4.6.5 Echo cancellation :Echo cancellation assigns the upstream band to over-lap the downstream. To separate them is by local echo cancellation. This technique is common inV.32 and V.34 modems(Conventional Modems). By using either one o f the above techniques, ADSL splits off a 4khz region for POTS at the DC end of the band.
Figure 4.6.5: FDM AND ECHO CANCELLATION
4.6.6 ADSL MODULATION ADSL uses two types of Modulation Ecap (CarrierlessAmplituse Phase Modulation)&DMT(Discrete Multi Tone) & DMT is the most widely used one.
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5. SWITCHING
Switching is a process of moving data through a series of intermediate steps rather than moving from the starting point directly to the end point. A network consists of many switching devices. In order to connect multiple devices, one solution could be to have a point to point connection in between pair of devices. But this increases the number of connection. The other solution could be to have a central device and connect every device to each other via the central device which is generally known as Star Topology. Both these methods are wasteful and impractical for very large network. The other topology also can not be used at this stage. Hence a better solution for this situation is SWITCHING. A switched network is made up of a series of interconnected nodes called switches.
5.1 Types of Switching Techniques There are basically three types of switching methods are made available. Out of three methods, circuit switching and packet switching are commonly used but the message switching has been opposed out in the general communication procedure but is still used in the networking application. 1) Circuit Switching 2) Packet Switching 3) Message Switching
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Figure : Types of switching
5.1.1 Circuit Switching
Circuit Switching is generally used in the public networks. It come into existence for handling voice traffic in addition to digital data. How ever digital data handling by the use of circuit switching methods are proved to be inefficient. The network for Circuit Switching is shown in figure . Here the network connection allows the electrical current and the associated voice with it to flow in between the two respective users. The end to end communication was established during the duration of call. In circuit switching the routing decision is made when the path is set up across the given network. After the link has been sets in between the sender and the receiver then the information is forwarded continuously over the provided link. In Circuit Switching a dedicated link/path is established across the sender and the receiver which is maintained for the entire duration of conversation.
Figure : Circuit Switching Network
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5.1.2 Packet Switching
In Packet Switching, messages are broken up into packets and each of which includes a header with source, destination and intermediate node address information. Individual Packets in packet switching technique take different routes to reach their respective destination. Independent routing of packets is done in this case for following reasons: Bandwidth is reduces by the splitting of data onto different routes for a busy circuit. For a certain link in the network, the link goes down during transmission the the remaining packet can be sent through the another route. The major advantage of Packet switching is that they they are used for performing data rate conversion. When traversing the network switches, routers or the other network nodes then the packets are buffered in the queue, resulting in variable delay and throughput depending on the network’s capacity and the traffic load on network. Packet switching contrasts with another principal networking paradigm, circuit switching, a method which sets up a limited number of dedicated connections of constant bit rate and constant delay between nodes for exclusive use during the communication session. In cases where traffic fees are charged, for example in cellular communication, packet switching is characterized by a fee per unit of information transmitted.
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Figure : Packet Switching Network
5.1.3 Message Switching
In case of Message Switching it is not necessary to established a dedicated path in between any two communication devices. Here each message is treated as an independent unit and includes its own destination source address by its own. Each complete message is then transmitted from one device to another through internetwork. Each intermediate device receive the message and store it until the nest device is ready to receive it and then this message is forwarded to the next device. For this reason a message switching network is sometimes called as Store and Forward Switching.
Message switches can be programmed with the information about the most efficient route as well as information regarding to the near switches that can be used for forwarding the present message to their required destination. The storing and Forwarding introduces the concept of delay. For this reasons this switching is not recommended for real time applications like voice and video. 46
Figure : Message Switched Network
5.2 Public switched telephone network
The public switched telephone network (PSTN) is the aggregate of the world's circuit-switched telephone networks that are operated by national, regional, or local telephony operators, providing infrastructure and services for public telecommunication. The PSTN consists of telephone lines, fiber optic cables, microwave transmission links, cellular networks, communications satellites, and undersea telephone cables, all interconnected by switching centers, thus allowing most telephones to communicate with each other. Originally a network of fixed-line analog telephone systems, the PSTN is now almost entirely digital in its core network and includes mobile and other networks, as well as fixed telephones.
The technical operation of the PSTN adheres to the standards created by the ITU-T. These standards allow different networks in different countries to interconnect seamlessly. The E.163 and E.164 standards provide a single global address space for telephone numbers. The combination of the interconnected networks and
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the single numbering plan allow telephones around the world to dial each other.
Figure : PSTN Network
5.2.1 History
Commercialization of the telephone began in 1876, with instruments operated in pairs for private use between two locations. Users who wanted to communicate with persons at multiple locations had as many telephones as necessary for the purpose. Alerting another user of the desire to establish a telephone call was accomplished by whistling loudly into the transmitter until the other party heard the alert. Bells were soon added to stations for signaling, so an attendant no longer needed to wait for the whistle. Later telephones took advantage of the exchange principle already employed in telegraph networks. Each telephone was wired to a telephone exchange established for a town or area. For communications outside this exchange area, trunks were installed between exchanges. Networks were designed in a hierarchical manner until they spanned cities, countries, continents and oceans.
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Automation introduced pulse dialing between the telephone and the exchange, so that each subscriber could directly dial another subscriber connected to the same exchange, but long distance calling across multiple exchanges required manual switching by operators. Later, more sophisticated address signaling, including multi-frequency signaling methods, enabled direct-dialed long distance calls by subscribers, culminating in the Signalling System 7 (SS7) network that controlled calls between most exchanges by the end of the 20th century. The growth of the PSTN meant that teletraffic engineering techniques needed to be deployed to deliver quality of service (QoS) guarantees for the users. The work of A. K. Erlang established the mathematical foundations of methods required to determine the capacity requirements and configuration of equipment and the number of personnel required to deliver a specific level of service. In the 1970s the telecommunications industry began implementing packet-switched network data services using the X.25 protocol transported over much of the end-to-end equipment as was already in use in the PSTN. In the 1980s the industry began planning for digital services assuming they would follow much the same pattern as voice services, and conceived end-to-end circuit-switched services, known as the Broadband Integrated Services Digital Network (B-ISDN). The B-ISDN vision was overtaken by the disruptive technology of the Internet.
5.2.3Technology 5.2.3.1 Network topology
The PSTN network architecture had to evolve over the years to support increasing numbers of subscribers, calls, connections to other countries, direct dialing and so on.
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The model developed by the United States and Canada was adopted by other nations, with adaptations for local markets. The original concept was that the telephone exchanges are arranged into hierarchies, so that if a call cannot be handled in a local cluster, it is passed to one higher up for onward routing. This reduced the number of connecting trunks required between operators over long distances and also kept local traffic separate. However, in modern networks the cost of transmission and equipment is lower and, although hierarchies still exist, they are much flatter, with perhaps only two layers.
5.2.3.2 Digital channels
Most automated telephone exchanges use digital switching rather than mechanical or analog switching. The trunks connecting the exchanges are also digital, called circuits or channels. However analog two-wire circuits are still used to connect the last mile from the exchange to the telephone in the home (also called the local loop). To carry a typical phone call from a calling party to a called party, the analog audio signal is digitized at an 8 kHz sample rate with 8-bit resolution using a special type of nonlinear pulse code modulation known as G.711. The call is then transmitted from one end to another via telephone exchanges. The call is switched using a call set up protocol (usually ISUP) between the telephone exchanges under an overall routing strategy. 50
The call is carried over the PSTN using a 64 kbit/s channel, originally designed by Bell Labs. The name given to this channel is Digital Signal 0 (DS0). The DS0 circuit is the basic granularity of circuit switching in a telephone exchange. A DS0 is also known as a timeslot because DS0s are aggregated in timedivision multiplexing (TDM) equipment to form higher capacity communication links. A Digital Signal 1 (DS1) circuit carries 24 DS0s on a North American or Japanese T-carrier (T1) line, or 32 DS0s (30 for calls plus two for framing and signaling) on an E-carrier (E1) line used in most other countries. In modern networks, the multiplexing function is moved as close to the end user as possible, usually into cabinets at the roadside in residential areas, or into large business premises. These aggregated circuits are conveyed from the initial multiplexer to the exchange over a set of equipment collectively known as the access network. The access network and inter-exchange transport use synchronous optical transmission, for example, SONET and Synchronous Digital Hierarchy (SDH) technologies, although some parts still use the older PDH technology. Within the access network, there are a number of reference points defined. Most of these are of interest mainly to ISDN but one – the V reference point – is of more general interest. This is the reference point between a primary multiplexer and an exchange. The protocols at this reference point were standardized in ETSI areas as the V5 interface. At the turn of the 21st century, the oldest parts of the telephone network still use analog technology for the last mile loop to the end user.
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However, digital technologies such as DSL, ISDN, FTTx, and cable modems have become more common in this portion of the network. Several large private telephone networks are not linked to the PSTN, usually for military purposes. There are also private networks run by large companies which are linked to the PSTN only through limited gateways, such as a large private branch exchange (PBX).
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CONCLUSION
In a nutshell, this internship has been an excellent and rewarding experience. we can conclude that there have been a lot we’ve learnt from our work at NTC. Needless to say, the technical aspects of the work we’ve done are not flawless and could be improved provided enough time. As someone with no prior experience we believe our time spent this training was well worth it and contributed to finding a practical exposure. Two main things that we’ve learned the importance of time-management skills and self-motivation.
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