This document provides an overview of a summer training report completed by Avaneesh Kumar Rai at BSNL Exchange in Faizabad, Uttar Pradesh, India. The report includes acknowledgments, an introduction on BSNL and its objectives, and sections covering various telecommunication topics studied during the training, such as broadband, GSM, antennas, CDMA, wireless technologies, and fiber optics. The training aimed to provide practical exposure and understanding of technical aspects involved in the telecommunications industry.

1. A SUMMER TRAINING REPORT ON
BSNL EXCHANGE, FAIZABAD (U.P)
BY
AVANEESH KUMAR RAI
(University Roll No. 1102931035)
A report submitted in partial fulfillment
of the requirements
for the degree of
Bachelor of Technology in Electronics & Communication Engineering
Submitted to:
Dr. Padma Batra
Industrial Training Head
Department of Electronics & Communication Engineering
Krishna Institute of Engineering & Technology, Ghaziabad
2014-2015
1

2. ACKNOWLEDGEMENT
It is with profound gratitude that I express my deep indebtedness to all the
employees of B.S.N.L. without their support and guidance it would not have been
possible for this training to have materialized and taken a concrete shape. I owe my
personal thanks to my trainers in charge – Mr. N. N. Srivastav (SDE), and Mr. Vinod
Yadav (JTO) who extended full support and co-operation at every stage of my
training period. I would also like to take this opportunity to acknowledge the
guidance from Dr. Sanjay Sharma (HOD of Electronics and Communication) and Dr.
Padma Batra (Industrial Training Head of Electronics and Communication) for
undergoing training at a reputed company like B.S.N.L.
I am also indebted to my parents and friends for their constant encouragement and
helping me in my endeavor. Last, but not the least, I would like to thank everyone
who has contributed for the successful completion of my training.
AVANEESH KUMAR RAI
1102931035
(B.TECH VII SEMESTER - ECE)
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3. PREFACE
Organizations are made up of people and function through people. Without people,
organizations cannot exist. The resources of men, money, material, machinery, and
mechanism are connected, coordinated and utilized through people. Engineers need
to concentrate more on mechanism and the way in which things have been made.
The need of training arises for doing things yourself, understanding its way.
Practical exposure for doing things makes a person conversant to the technicalities
involved in any job. In view of such benefits, imparting of vocational training has
been made an integral part of any academic structure.
In B.S.N.L., training is given to Engineering Aspirants to secure future in the dynamic
world of telecommunications. Today telecommunication industry is one of the very
fastest growing industries in the world.
In this order I have taken 28 days BSNL training. In my report I try to introduce
C-DOT MAXWELL, WLL, POWER PLANT, BROAD-BAND, Leased line concepts, WIMAX,
Wi-Fi, optical fiber concepts and overview of Intranet.
3

4. Bharat Sanchar Nigam Ltd. was incorporated on 15th September 2000. It took over the business of
providing of telecom services and network management from the erstwhile Central Government
Departments of Telecom Services (DTS) and Telecom Operations (DTO), with effect from 1st
October 2000 on going concern basis. It is one of the largest & leading public sector units providing
comprehensive range of telecom services in India.
BSNL has installed Quality Telecom Network in the country & now focusing on improving it,
expanding the network, introducing new telecom services with ICT applications in villages &
winning customer's confidence. Today, it has about 43.74 million line basic telephone capacity,
8.83 million WLL capacity, 72.60 million GSM capacity, 37,885 fixed exchanges, 68,162 GSM BTSs,
12,071 CDMA Towers, 197 Satellite Stations, 6,86,644 RKm. of OFC, 50,430 RKm. of microwave
network connecting 623 districts, 7330 cities/towns & 5.8 lakhs villages .
BSNL is the only service provider, making focused efforts & planned initiatives to bridge the rural-urban
digital divide in ICT 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 the country & operates across
India except New Delhi & Mumbai. Whether it is inaccessible areas of Siachen glacier or North-
Eastern regions of the country, BSNL serves its customers with a wide bouquet of telecom services
namely Wireline, CDMA mobile, GSM mobile, Internet, Broadband, Carrier service, MPLS-VPN,
VSAT, VoIP, IN Services, FTTH, etc.
BSNL is number one of India in all services in its license area. The company offers wide ranging &
most transparent tariff schemes designed to suit every customer. BSNL has 90.09 million cellular &
5.06 million WLL customers as on 31.07.2011. 3G Facility has been given to all 2G connections of
BSNL. In basic services, BSNL is miles ahead of its rivals, with 24.58 million wireline
phone subscribers i.e. 71.93% share of the wireline subscriber base.
4
About BSNL

5. BSNL has set up a world class multi-gigabit, multi-protocol convergent IP infrastructure that
provides convergent services like voice, data & video through the same Backbone & Broadband
Access Network. At present there are 8.09 million broadband customers.
The company has vast experience in planning, installation, network integration & maintenance of
switching & transmission networks & also has a world class ISO 9000 certified Telecom Training
Institute.
During the 2010-11, turnover of BSNL is around Rs. 29,700 Crores.
VISSION:
· Be the leading telecom service provider in India with global presence.
· Create a customer focused organization with excellence in customer care, sales and
marketing.
· Leverage technology to provide affordable and innovative telecom. Services/products across
customer segments.
MISSION:
Be the leading telecom service provider in India with global presence.
· Generating value for all stakeholders - employees, shareholders, vendors & business
associates
· Maximizing return on existing assets with sustained focus on profitability
· Becoming the most trusted, preferred and admired telecom brand
· To explore International markets for Global presence
Creating a customer focused organization with excellence in customer care, sales& marketing.
· Developing a marketing and sales culture that is responsive to customer needs mere care,
sales& marketing
· Excellence in customer service-”friendly, reliable, time bound, convenient and courteous
service”
Leveraging technology to provide affordable and innovative products/ services across customer
segments
· Offering differentiated products/services tailored to different service segments
· Providing reliable telecom services that are value for money
Providing a conducive work environment with strong focus on performance
· Attracting talent and keeping them motivated
· Enhancing employees skills and utilizing them effectively
· Encouraging and rewarding individual and team/group performance
Establishing efficient business processes enabled by IT
· Changing policies and processes to enable transparent, quick and efficient decision making
· Building effective IT systems and tools
5

6. OBJECTIVES:
· To be the Leading Telecom Services provider by achieving higher rate of growth so as to
become a profitable enterprise.
· To provide quality and reliable fixed telecom service to our customer and thereby increase
customers confidence.
· To provide customer friendly mobile telephone service of high quality and play a leading
role as GSM operator in its area of operation.
Strategy for:
· Rightsizing the manpower
· Providing greater customer satisfaction>/li>
Contribute towards:
· Broadband customers base of 20 MN in India by the end of 2011-12 as per broadband policy
2004.
· Providing telephone connections in villages as per Government policy.
To leverage the existing infrastructure of BSNL for facilitating implementation of other
government programmes and initiatives particularly in the rural areas.
6

7. INDEX
1. BROADBAND
1. Introduction.............................................................9
2. Definition.................................................................9
2. GSM.......................................................................................10
3. Antenna
1. What is antenna.................................................................11
2. Types..................................................................................11
3. CELLULAR CONCEPTS.............................................................13
4. GSM ARHITECTURE................................................................14
5. Radio link ..............................................................................16
6. MOBILITY MANAGEMENT.....................................................17
7. CALL MANAGEMENT............................................................20
8. HISTORY OF WIRELESS COMMUNICATION ..........................21
9. CDMA....................................................................................24
i) WCDMA………………………………………………………………………………….25
ii) 3G MOBILE.................................................................................26
iii) IMS............................................................................................26
iv) WIRELESS LAN AND
BLUETOOTH...................................................................................27
V) BEYOND 3G INTRODUCTION.....................................................33
7

8. 10. GPRS
i).INTRODUCTION..........................................................................34
11. DSL...........................................................................................35
12. ADSL.........................................................................................36
13. NGN.........................................................................................40
14. WIRELESS
TECNOLOGY...................................................................................44
i) WIFI............................................................................................45
ii) WIMAX.......................................................................................45
15. CABLE MODEM
BASICS............................................................................................46
1. PPPOE............................................................................47
16. INTRODUCTION TO
MULTIPLAY....................................................................................49
17. FTTH.........................................................................................52
18. SMPS........................................................................................53
19. SDH..........................................................................................56
20. PROJECT on
CDOT..............................................................................................61
8

9. BROADBAND
INTRODUCTION
In 1960s people started thinking of potential value in allowing
computers to share information on research and development in scientific
and military fields. Internet was the result. Leaving what happened in
between, the next milestone was in 1965 when Lawrence Roberts
connected a computer at Massachusetts with a computer at California over
dial-up telephone lines. The feasibility of wide area networking was proved.
The Internet matured in the 70's as a result of the TCP/IP architecture
replacing the earlier Network Control Protocol (NCP) and universally
adopted by 1983.
The National Science Foundation funded NSF Net as a cross-country
56 Kbps backbone for the Internet in 1986. As the commands for e-mail,
FTP , and telnet were standardized, it became a lot easier for non-technical
people to learn to use the nets.
So people were able to make good use of the nets - to communicate
with people around the world and to share files and resources. An arc hiver
for ftp sites was created in 1989. The commands to search Archie were
UNIX commands, and it required some knowledge of UNIX to use it to its
full capability. Followed were
1. Wide Area Information Server (WAIS), which would index the full text of files in a
database and allow searches of the files
2. Gopher, which needed no knowledge of UNIX or computer architecture to use.
3. VERONICA searchable index of Gopher menus
Definition of Broadband
The definition of broadband has changed over time to time. In the 1980s and early 1990s,
broadband referred to rates greater than 45 megabits per second (Mbps), and "wideband" referred
to rates between 1.5 and 45 Mbps. In 1995, broadband commonly referred to anything 1.5 Mbps
and higher. In 2000, it was defined as a service that is at least 200 kbps in each direction.
(Reference: BROADBAND BRINGING HOME THE BITS - NATIONAL ACADEMY PRESS, Washington,
D.C.)In India, TRAI defines Broadband as:
“An ‘always-on’ data connection that is able to support interactive services including Internet
access and has the capability of the minimum download speed of 256 kilobits per second (kbps) to
an individual subscriber from the Point Of Presence (POP) of the service provider intending to
provide Broadband service where multiple such individual Broadband connections are aggregated
and the subscriber is able to access these interactive services including the Internet through this
POP. The interactive services will exclude any services for which a separate license is specifically
required, for example, real-time voice transmission, except to the extent that it is presently
permitted under ISP license with Internet Telephony.”
9

10. Applications
A question to be necessarily considered is whether "broadband" refers exclusively to Internet
service or is a more inclusive term that refers to a set of data communications services. Whether
broadband is used to bring the Internet to the home or small business at much higher speed and
with characteristics such as always-on, or is it really about delivering to the home a bundle of digital
services. Definitely, it is going to offer many services such as Video on demand, live telecast or
Interactive games in addition to a fast web browsing service.
What is GSM?
The Global System for Mobile communications (GSM: originally from Group Special
Mobile) is the most popular standard for mobile phones in the world. GSM service is used
by over 2 billion people across more than 212 countries and territories. Its ubiquity makes
international roaming very common between mobile phone operators, enabling
subscribers to use their phones in many parts of the world.
GSM differs significantly from its predecessors in that both signaling and speech channels
are digital call quality, and so is considered a second generation (2G) mobile phone
system. This has also meant that data communication was built into the system from the
3rd Generation Partnership Project (3GPP).
The main differentiator to previous mobile telephone systems, retrospectively dubbed
1G, is that the radio signals that 1G networks use are analog, while 2G networks are
digital. Note that both systems use digital signaling to connect the radio towers (which
listen to the handsets) to the rest of the telephone system.
History of GSM
GSM standard is a European standard which has addressed many problems directly related to
compatibility, especially with the development of digital radio technology.
From 1982 to 1985 discussions were held to decide between building an analog or digital system.
After multiple field tests, a digital system was adopted for GSM. The next task was to decide
between a narrow or broadband solution. In May 1987, the narrowband time division multiple
access (TDMA) solution was chosen. Although standardized in Europe, GSM is not only a European
standard. GSM networks are operational or planned in Europe, the Middle East, the Far East, Africa,
North and South America, and Australia. The acronym GSM now aptly stands for Global System for
Mobile communications
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11. WHAT IS ANTENNA?
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. All the features of passive antennas can be applied for
reception and transmission alike (reciprocally). On one side RF cable is connected and the other
side it is the environment, therefore the surroundings of the antenna have a strong influence on
the antenna's electrical features.
Principle of an antenna
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
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 wavelength. This is the basic
principle of l/2-dipole antenna.
Polarization can be defined as the direction of oscillation of the electrical field vector and
has been discussed earlier.
For Mobile communications generally vertical polarization is used.
For Broadcast systems horizontal polarization is used.
Omni directional Antennas:
The classical Omni directional lambda/2 antennas are of two types
1. Ground Plane
2. l/4-skirt Antenna
The names indicate how the antenna is decoupled from the mast. In both cases the horizontal
radiation pattern covers 360 ° and vertical half power beam width is 78 °.Hence there will be lot of
waste of energy both upwards and downwards in the desired horizontal plane.
Ground Plane Omni Directional Antenna
In this case, a conductive plane is achieved via 3 counterweighted poles. The ground plane antenna
can cover the complete frequency range because it is a wideband antenna.
11

12. Directional Antennas
Directional antennas are provided with reflectors behind the radiating element. This focuses the
energy in a desired direction avoiding transmission in the rear side of the antenna. The directional
antennas are classified into the following types:
1. Grid Parabolic Reflector antennas
2. Parabolic Reflector antennas.
3. Cassegrain antennas.
4. Array antennas.
Directional Antennas
12

13. The first two types of antennas are mainly used in fixed point-to-point
radio links and the grid types are employed up to 2GHz
whereas the solid parabolic reflector antennas are used for higher
frequencies. The connectivity between the antennas to the
equipment’s is by coaxial cable up to 2GHz and for higher
frequencies it is by hollow copper tube called wave-guide. The
beam width of these antennas depends on the diameter of the
antenna and frequency of operation. They produce very narrow
beams.
Directional Antennas
Cassegrain antennas are associated with Satellite communication are comparatively larger which
makes them to be fixed on the ground or roof tops and orient themselves towards the satellite by
operating gear arrangement either manually or using motors
Directional Antennas
Array antennas are more predominantly used in broadcasting and mobile communications. There
are two types (i) End Fire Arrays, (ii) Panel Antennas
End-fire Arrays: Yagi Antennas
Yagi antennas are very common due to their simple and cheap method of construction. The gain
and bandwidth of Yagi antennas are electrically coupled with one other which is an electrical
disadvantage, i.e. one criterion is weighed off the other. The mechanical concept is not suitable for
extreme climatic conditions.
Disadvantages of Copper Based Access Networks
13

14. Even though there is a vast and extensive copper based access network, there are several
disadvantages
1. Copper is costly and its resources are diminishing.
2. Installation of copper network is time consuming and costly affair
Advantages of wireless
1. Provisioning of connectivity is faster.
2. Since there is no physical medium, fault liability is reduced.
3. Mobility is inherent.
4. Reconfiguration is simple.
5. Cost of installation is independent of distance.
6. Connections can be at longer distances than copper based network.
Cellular Concepts - Introduction
Even though multiple access techniques allowed multiple users to share the medium
simultaneously, due to constraints in providing resources, an amount of blocking will exist. The
amount of blocking is called “Grade Of Services” (GOS).
GOS is a measure of the probability that a percentage of the offered traffic will be blocked or
delayed. It is commonly expressed as the fraction of calls or demands that fail to receive immediate
service. The aim is to achieve the GOS equal to 0
Based on GOS and resource availability (no. of carriers/no. of timeslots/both) the traffic handling
capacity of the system is calculated. If this total traffic is divided by traffic per subscriber, we get
number of subscribers supported by the system. For these purposes Erlangen B table (Blocking calls
cleared) is useful.
Cellular Concepts - What is a cell?
Cell is the basic geographic unit. They are base stations transmitting over that small area. Cells are
usually represented on paper as hexagon. In reality the shape is not so because of the landscape
and man-made structures. The base stations can be employing Omni directional or directional
antenna.
Cell size depends on sub density and demand in that given area. To start with cell can be of
maximum size 30Km radius and subsequently can be split into smaller cells. Usually in rural areas
the cells are big and in urban will be smaller.
GSM Architecture
The figure represents a GSM reference model for a PLMN (Public Land Mobile Network).
14

15. The GSM network is divided into four major systems
1. Switching system (SS)
2. Base station system (BSS)
3. Mobile station (MS)
4. Operation and maintenance Centre(OMC)
The switching system (SS) also called as Network and Switching System (NSS) is responsible for
performing call processing and Subscriber-related functions. The switching system includes the
following functional units
1. Mobile Switching Centre
2. Home Location Register
3. Visitor Location Register
4. Equipment Identity Register
5. Authentication Centre
6. GSM Architecture - The Functions Of MSC
1. Call handling that copes with the mobile nature of subscribers considering Location
Registration, Authentication of subscribers and equipment, Handover and Prepaid
service.
Home location register contains
1. The identity of mobile subscriber called IMSI (International Mobile Sub Identity)
2. ISDN directory number of mobile station.
3. Subscription information on services.
4. Service restrictions.
5. Location Information for call routing
One HLR per GSM network is recommended and it may be a distributed database. Permanent data
in HLR changed by man-machine interface. Temporary data like location information changes
15

16. It refers to the terminal equipment used by the wireless subscriber. It
consists of
1. SIM -Subscriber Identity Module
2. Mobile Equipment.
SIM is removable and with appropriate SIM, the network can be
accessed using various mobile equipment’s.
The equipment identity is not linked to the subscriber.
The equipment is validated separately with IMEI and EIR.
The SIM contains an integrated circuit chip with a microprocessor,
random access memory (RAM) and read only memory (ROM).
SIM should be valid and authenticate the validity of MS while
accessing the network.
SIM also stores subscriber related information like IMSI, cell location
identity etc.
GSM RADIO LINK
Introduction
BTS and MS are connected through radio link this air interface is
called Um. A radio wave is subject to attenuation, reflection, Doppler
shift and interference from other transmitter. These effects causes
loss of signal strength and distortion which will impact the quality of
voice or data. To cope with the harsh conditions, GSM make use of an
efficient and protective signal processing. Proper cellular design must
ensure that sufficient radio coverage is provided in the area.
Special Features of GSM
1. Authentication.
2. Encryption
3. Time Slot Staggering
4. Timing Advance
5. Discontinuous transmission
6. Power Control
7. Adoptive equalization
8. Slow Freq. Hopping
16

17. Authentication
Since the air interface is vulnerable to fraudulent access, it is
necessary to employ authentication before extending the services to
this subscriber. Authentication is built around the following notions.
1. Authentication Key (Ki) resides only in two places, SIM card and
Authentication Centre.
2. Authentication Key (Ki) is never transmitted over air.
It is virtually impossible for unauthorized individuals to obtain this
key to impersonate a given mobile subscriber.
Authentication Parameters
The MS is authenticated by the VLR with a process that uses
three parameters:
1. RAND which is completely random number
2. SRES which is an authentication signed response. It is generated by applying
an authentication algorithm (A3) to RAND and Ki
3. Kc which is cipher key. The Kc parameter generated by applying the cipher
key generation algorithm (A8) to RAND and Ki.
Encryption/Ciphering
Data is encrypted at the transmitter side in blocks of 114 bits by taking 114-bit plain text
data bursts and performing an EXOR (Exclusive OR) logical function operation with a 114-bit
cipher block.
The decryption function at the receiver side is performed by taking the encrypted data block
of 114 bits and going through the same “exclusive OR “operation using the same 114-bit
cipher block that was used at the transmitter.
The cipher block used by both ends of transmission path for a given transmission direction is
produced at the BSS and MS by an encryption algorithm called A5.The A5 algorithm uses a
64-bit cipher key (Kc), produced during the authentication process during call setup and the
22-bit TDMA frame number (COUNT) which takes decimal values from 0 through 2715647
and has a repetition time 3.48 hours (hyper frame interval).The A5 algorithm actually
produce two cipher blocks during each TDMA period. One for the uplink path and the other
for the downlink path.
Frequency Hopping
The mobile station already has to be frequency agile, meaning it can move between a
transmit, receive, and monitor time slot within one TDMA frame, which normally are on
different frequencies. GSM makes use of this inherent frequency agility to implement slow
frequency hopping, where the mobile and BTS transmit each TDMA frame on a different
carrier frequency.
MOBILITY MANAGEMENT
17

18. Network Attachment
Network attachment is a process of selecting an appropriate
cell(radio frequency)by the mobile station to provide the available
services, and making its location known to the network
The process starts when the mobile station is switched on, and
ends when the mobile station enters the idle mode. In idle mode the
mobile station does not have a traffic channel allocated to make or
receive a call, but the Public Land Mobile Network (PLMN) is aware of
the existence of the mobile station within the chosen cell.
Cell Identification
When a mobile station is switched on it attempts to make
contact with a GSM PLMN by performing the following action
1. Measures the BCCH channels.
2. Search for a suitable cell.
The mobile station measures the signal strength of the BCCH
(Broadcast Control Channel) channels received. It stores in a list of
information of about 30 of these BCCH channels, such as the signal
strength and the frequency corresponding to these BCCH channels.
Call to an active Mobile Station
As an active Mobile Station (MS) moves around in the coverage
area of a Public Land Mobile Network (PLMN), it reports its
movements so that it can be located when required using the
Locations Update procedure.
When a Mobile Services Switching Center(MSC) in the network
needs to establish a call to an MS operating in its area the following
Happens:
Location area
To eliminate the need for network-wide paging broadcasts, the
PLMN needs to know the approximate positions of the MSs that are
active within its coverage area. To enable the approximate positions
of any MS to be represented by a single parameter, the total area
covered by the network is divided into location areas.
A Location area (LA) is a cluster of one or more radio cells. The
cell cluster fulfills the following requirements:
1. The BTSs in a location area are controlled by one or more BSCs
2. BSCs that serve the same location area are always connected to the same
18

19. MSC
3. Radio cells with BTSs controlled by a common BSC can lie in different location
areas.
Location area Identity
Every radio transmitter in the PLMN broadcast, via a control channel, a Location Area
Identity (LAI) code to identify the location area that it serves.
When an MS is not engaged in a call, it automatically scans the BCCH transmitted by the
base stations in the locality and selects the channel that is delivering the strongest signal.
The LAI code broadcast by the selected channel identifies the location area in which the MS
is currently situated. This LAI code is stored in the Subscriber Identity Module (SIM) of the
mobile equipment.
.
Types of Identification Numbers
During the performance of the location update procedure and
the processing of a mobile call different types of numbers are used:
1. Mobile station ISDN Number(MSISDN)
2. Mobile Subscriber Roaming Number(MSRN)
3. International Mobile Subscriber Identity(IMSI)
4. Temporary Mobile Subscriber Identity(TMSI)
5. Local Mobile Station Identity(LMSI)
Each number is stored in the HLR and/or VLR.
Mobile Station ISDN Number
The MSISDN is the directory number allocated to the mobile subscriber. It is dialed to make a
telephone call to the mobile subscriber.
The number consists of Country Code(CC) of the country in which the mobile station is
registered(for example India 91) followed by national mobile number which consists of
Network Destination Code(NDC) and Subscriber Number(SN).A NDC is allocated to each GSM
PLMN.
The composition of the MSISDN is such that it can be used as a global title address in the
Signaling Connection Control Part(SCCP) for routing message to the HLR of the mobile
subscriber
Mobile Station Roaming Number
The MSRN is the number required by the gateway MSC to route an incoming call to a MS
that is not currently under the gateway's control
Using the MSISDN a mobile terminated call is routed to the gateway MSC. Based on this
MSISDN the gateway MSC requests for a MSRN to route the call to the current visited MSC
International Mobile Subscriber Identity
A MS is identified by its IMSI. The IMSI is embodied in the SIM of the mobile equipment. It is
provided by the MS anytime it accesses the network
Mobile Country Code (MCC): The MCC component of the IMSI is a 3-digit code that uniquely
identifies the country of the domicile of the subscriber. It is assigned by the ITU-T
Mobile Network Code (MNC): The MNC component is a 2-digit code that identifies the home
GSM PLMN of the mobile subscriber. It is assigned by the government of each country. For
19

20. GSM-1900 a 3-digit MNC is used.
Mobile Subscriber Identification Number (MSIN): The MSIN is a code that identifies the
subscriber within a GSM PLMN.I t is assigned by the operator.
Hand Over
The process of automatically switching a call in progress from
one traffic channel to another to neutralize the adverse effects of the
user movements. Hand over process will be started only if power
control is not helpful anymore.
The Hand Over process is MAHO(Mobile Assisted Hand Over).It
starts with the Down Link Measurements by the MS(Strength of the
signal from BTS, Quality of the signal from BTS).MS can measure the
Signal Strength of the 6 best neighboring BTS down link(candidate
list)
CALL MANAGEMENT
Mobile To Land Call Scenario (Mobile Origination)
Phases of Mobile To Land Call. The following table lists the
phases of a Mobile To Land Call
1. Request for services; the MS requests to setup a call
2. Authentication: the MSC/VLR requests the AUC for authentication parameters,
using these parameters the MS is authenticated.
3. Ciphering : using the parameters, which were made available earlier during
the authentication, the uplink and the downlink are ciphered
4. Equipment Validation :the MSC/VLR requests the EIR to check the IMEI for
validity
5. Call setup: the MSC establishes a connection to the MS.
6. Handover(s)
7. Call release; the speech path is released
Mobile To Land Call Scenario-Phases of Mobile To Land Call
The user enters the digits of the telephone with STD code
incase of land line or without STD code incase of mobile and presses
the "send" key after all digits have been entered
1. MS transmits a channel request message over the Random Access
Channel(RACH)
2. Once the BSS receives the Channel Request message, it allocates a Stand-alone
Dedicated Control Channel (SDCCH) and forwards this channel
assignment information to the MS over the access Grant Channel (AGCH).It is
over the SDCCH that the MS will communicate with the BSS and MSC until a
20

21. traffic channel is assigned.
3. The MS transmits a service request message to the BSS over the SDCCH.
Included in this message is the MS TMSI and Location Area Identification
(LAI).The BSS forwards the service request message to the MSC/VLR.
Mobile To Land Call Scenario-Phases of Mobile To Land Call
The IMEI code is secure and physically protected against
The Equipment Identity Register (EIR) is responsible for storing
the IMEI codes that identify the mobile-equipment deployed in the
GSM system.
History of Wireless
Communication
The idea of cell-based mobile radio systems appeared at Bell Laboratories (in USA) in the early
1970s. However, mobile cellular systems were not introduced for commercial use until the 1980s.
During the early 1980s, analog cellular telephone systems experienced a very rapid growth in
Europe, particularly in Scandinavia and the United Kingdom. Today cellular systems still represent
one of the fastest growing telecommunications systems.
But in the beginnings of cellular systems, each country developed its own system, which was an
undesirable situation for the following reasons:
1. The equipment was limited to operate only within the boundaries of each country.
2. The market for each mobile equipment was limited.
In order to overcome these problems, the Conference of European Posts and Telecommunications
(CEPT) formed, in 1982, the Group Special Mobile (GSM) in order to develop a pan-European
mobile cellular radio system (the GSM acronym became later the acronym for Global System for
Mobile communications). The standardized system had to meet certain criteria:
Cellular systems
The cellular structure
In a cellular system, the covering area of an operator is divided into cells. A cell corresponds to the
covering area of one transmitter or a small collection of transmitters. The size of a cell is
determined by the transmitter's power.
The concept of cellular systems is the use of low power transmitters in order to enable the efficient
reuse of the frequencies. In fact, if the transmitters used are very powerful, the frequencies cannot
be reused for hundreds of kilometers as they are limited to the covering area of the transmitter.
The frequency band allocated to a cellular mobile radio system is distributed over a group of cells
and this distribution is repeated in all the covering area of an operator. The whole number of radio
channels available can then be used in each group of cells that form the covering area of an
operator. Frequencies used in a cell will be reused several cells away. The distance between the
21

22. cells using the same frequency must be sufficient to avoid interference. The frequency reuse will
increase considerably the capacity in number of users.
Compatibility with other systems such as ISDN
The decision of adopting a digital technology for GSM was made in the course of developing the
standard. During the development of GSM, the telecommunications industry converted to digital
methods. The ISDN network is an example of this evolution. In order to make GSM compatible with
the services offered by ISDN, it was decide that the digital technology was the best option.
Additionally, a digital system allows, easily than an analog one, the implementation of future
improvements and the change of its own characteristics.
Architecture of the GSM network
The GSM technical specifications define the different entities that form the GSM network by
defining their functions and interface requirements.
The GSM network can be divided into four main parts:
The architecture of the GSM network is presented in figure
Mobile Station
A Mobile Station consists of two main elements:
1. The Terminal
There are different types of terminals distinguished principally by their power and application:
1. The `fixed' terminals are the ones installed in cars. Their maximum allowed output
power is 20 W.
2. The GSM portable terminals can also be installed in vehicles. Their maximum
allowed output power is 8W.
3. The handheld terminals have experienced the biggest success thanks to the weight
and volume, which are continuously decreasing. These terminals can emit up to 2 W.
The evolution of technologies allows decreasing the maximum allowed power to 0.8
W.
2. The SIM
The SIM is a smart card that identifies the terminal. By inserting the SIM card into the terminal, the
user can have access to all the subscribed services. Without the SIM card, the terminal is not
operational. The SIM card is protected by a four-digit Personal Identification Number (PIN). In order
to identify the subscriber to the system, the SIM card contains some parameters of the user such as
its International Mobile Subscriber Identity (IMSI). Another advantage of the SIM card is the
mobility of the users. In fact, the only element that personalizes a terminal is the SIM card.
Therefore, the user can have access to its subscribed services in any terminal using its SIM card.
The Base Station Subsystem
The BSS connects the Mobile Station and the NSS. It is in charge of the transmission and reception.
The BSS can be divided into two parts:
The Base Transceiver Station
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 one and sixteen transceivers depending on the density of users in the cell.
The Base Station Controller
22

23. The BSC controls a group of BTS and manages their radio resources. A BSC is principally in charge of
handovers, frequency hopping, exchange functions and control of the radio frequency power levels
of the BTSs.
The Network and Switching Subsystem
Its main role is to manage the communications between the mobile users and other users, such as
mobile users, ISDN users, fixed telephony users, etc. It also includes data bases needed in order to
store information about the subscribers and to manage their mobility. The different components of
the NSS are described below.
The Mobile services Switching Center (MSC)
It is the central component of the NSS. The MSC performs the switching functions of the network. It
also provides connection to other networks.
The Gateway Mobile services Switching Center (GMSC)
A gateway is a node interconnecting two networks. The GMSC is the interface between the mobile
cellular network and the PSTN. It is in charge of routing calls from the fixed network towards a GSM
user. The GMSC is often implemented in the same machines as the MSC.
Home Location Register (HLR)
The HLR is considered as a very important database that stores information of the subscribers
belonging to the covering area of a MSC. It also stores the current location of these subscribers and
the services to which they have access. The location of the subscriber corresponds to the SS7
address of the Visitor Location Register (VLR) associated to the terminal
Visitor Location Register (VLR)
The VLR contains information from a subscriber's HLR necessary in order to provide the subscribed
services to visiting users. When a subscriber enters the covering area of a new MSC, the VLR
associated to this MSC will request information about the new subscriber to its corresponding HLR.
The VLR will then have enough information in order to assure the subscribed services without
needing to ask the HLR each time a communication is established.
The VLR is always implemented together with a MSC; so the area under control of the MSC is also
the area under control of the VLR.
The Authentication Center (AuC)
The AuC register is used for security purposes. It provides the parameters
needed for authentication and encryption functions. These parameters help to
verify the user's identity.
The Equipment Identity Register (EIR)
The EIR is also used for security purposes. It is a register containing
information about the mobile equipments. More particularly, it contains a list of
all valid terminals. A terminal is identified by its International Mobile Equipment
Identity (IMEI). The EIR allows then to forbid calls from stolen or unauthorized
terminals (e.g., a terminal which does not respect the specifications concerning
the output RF power).
The GSM Inter-working Unit (GIWU)
23

24. The GIWU corresponds to an interface to various networks for data
communications. During these communications, the transmission of speech and
data can be alternated.
The GSM functions
In this paragraph, the description of the GSM network is focused on the different functions to fulfill
by the network and not on its physical components. In GSM, five main functions can be defined:
Mobility Management
The MM function is in charge of all the aspects related with the mobility of the user, specially the
location management and the authentication and security.
The GSM radio interface
The radio interface is the interface between the mobile stations and the fixed infrastructure. It is
one of the most important interfaces of the GSM system.
One of the main objectives of GSM is roaming. Therefore, in order to obtain a complete
compatibility between mobile stations and networks of different manufacturers and operators, the
radio interface must be completely defined.
The spectrum efficiency depends on the radio interface and the transmission, more particularly in
aspects such as the capacity of the system and the techniques used in order to decrease the
interference and to improve the frequency reuse scheme. The specification of the radio interface
has then an important influence on the spectrum efficiency.
CDMA
Introduction
Code Division Multiple Access(CDMA) is a access method in which large
number of transmissions are combined on the same RF channel at the same
time but are separated by unique assigned “codes”. This CDMA Access
method is used to provide mobile telephony and works on the cellular
principle.
Overview of CDMA System
Access network, the network between local exchange and subscriber, in the Telecom Network
accounts for a major portion of resources both in terms of capital and manpower. So far, the
subscriber loop has remained in the domain of the copper cable providing cost effective solution in
past. Quick deployment of subscriber loop, coverage of inaccessible and remote locations coupled
with modern technology has led to the emergence of new Access Technologies. The various
technological options available are as follows:
1. Multi Access Radio Relay
2. Wireless In Local Loop
3. Fiber In the Local Loop
24

25. Wireless in Local Loop (WILL)
Fixed Wireless telephony in the subscriber access network also known as Wireless in Local Loop
(WLL) is one of the hottest emerging market segments in global telecommunications today. WLL is
generally used as “the last mile solution” to deliver basic phone service expeditiously where none
has existed before. Flexibility and expediency are becoming the key driving factors behind the
deployment of WILL.
WLL shall facilitate cordless telephony for residential as well as commercial complexes where
people are highly mobile. It is also used in remote areas where it is uneconomical to lay cables and
for rapid development of telephone services. The technology employed shall depend upon various
radios accesses techniques, like FDMA, TDMA and CDMA.
Different technologies have been developed by the different countries like CT2 from France, PHS
from Japan, DECT from Europe and DAMPS & CDMA from USA. Let us discuss CDMA technology in
WILL application as it has a potential ability to tolerate a fair amount of interference as compared
to other conventional radios. This leads to a considerable advantage from a system point of view.
Advantages of CDMA System
CDMA wireless access provides the following unique advantages:
WCDMA
Background
There has been a tremendous growth in wireless communication
technology over the past decade. The significant increase in subscribers
and traffic, new bandwidth consuming applications such as gaming,
music down loading and video streaming will place new demands on
capacity. The answer to the capacity demand is the provision of new
spectrum and the development of a new technology – Wideband CDMA
or hereinafter referred to as WCDMA. WCDMA was developed in order
to create a global standard for real time multimedia services that
ensured international roaming.
With the support of ITU (International Telecommunication Union) a
specific spectrum was allocated – 2GHz for 3G telecom systems. The
work was later taken over by the 3GPP (3rd Generation Partnership
Project), which is now the WCDMA specification body with delegates
from all over the world. Ericsson has for a long time played a very active
role in both ITU and 3GPP and is a major contributor to WCDMA and
the fulfillment of the vision of a global mobile telecommunication
system.
Code Division Multiple Access and WCDMA
Code Division Multiple Access (CDMA) is a multiple access technology where the users are
separated by unique codes, which means that all users can use the same frequency and transmit at
the same time. With the fast development in signal processing, it has become feasible to use the
technology for wireless communication, also referred to as WCDMA and CDMA2000. In cdma One
and CDMA2000, a 1.25 MHz wide radio signal is multiplied by a spreading signal (which is a pseudo-noise
code sequence) with a higher rate than the data rate of the message. The resultant signal
25

26. appears as seemingly random, but if the intended recipient has the right code, this process is
reversed and the original signal is extracted. Use of unique codes means that the same frequency is
repeated in all cells, which is commonly referred to as a frequency re-use of 1.
WCDMA is a step further in the CDMA technology. It uses a 5 MHz wide radio signal and a chip rate
of 3.84 Mbps, which is about three times higher than the chip rate of CDMA2000 (1.22 Mbps). The
main benefits of a wideband carrier with a higher chiprate are:
1. Support for higher bit rates
2. Higher spectrum efficiency thanks to improved trunking efficiency (i.e. a better
statistical averaging)
3. Higher QoS
Further, experience from second-generation systems like GSM and cdmaOne has enabled
improvements to be incorporated in WCDMA. Focus has also been put on ensuring that as much as
possible of WCDMA operators’ investments in GSM equipment can be reused. Examples are the re-use
and evolution of the core network, the focus on co-sitting and the support of GSM handover. In
order to use GSM handover the subscribers need dual mode handsets.
3 G MOBILE (UMTS)
1. UMTS is the convergence of mobile communications, Information Technology (IT)
and multimedia technologies. UMTS creates new opportunities for network
operators, service providers and content providers to generate revenue and seize
market share. The benefit of UMTS is richer, more powerful communication. UMTS
is a suite of radio and network technologies that provide:
2. better spectrum efficiency,
3. high data transmission rates (up to 2 Mbit/s), worldwide roaming capability,
4. the capability to offer new multimedia applications and services,
5. Interoperability with both fixed and mobile telecommunications services.
UMTS is the natural evolution from GSM and other second generation (2G) mobile systems. It
provides interconnection with 2G networks as well as other terrestrial nd satellite-based networks.
UMTS presents a unique opportunity to cater to the needs of individuals in the Information Society.
As a multi-national, multi-sector system that supports numerous protocols and transport
technologies, UMTS eliminates barriers that one posed problems for communications and enables
the creation and delivery of fully personalized communication services to both mass
Limitations of 2G systems
The limitations of 2G mobile systems such as GSM include:
1. Congestion, There are more than 300 million wireless subscribers worldwide and
thus a need to increase system capacity.
2. limited mobility around the world,
3. There is a need for global standardization.
4. Limited services.
5. There is a need for new multimedia applications and services.
Wideband - Code Division Multiple Access (WCDMA)
26

27. WCDMA optimally divides the available radio spectrum on the air interface into a number of
channels and defines how these channels are allocated to the many users accessing the network.
WCDMA allows for variable bit rates and variable Quality of Service (QoS). WCDMA provides:
1. better spectrum efficiency,
2. wider coverage,
3. support for all types of services (circuit, packet and multimedia),
4. enhanced privacy,
IP Multimedia subsystem (IMS)
IMS (IP Multimedia Subsystem) enables and drives efficient converged service offerings. It is the key
to delivering multimedia services with telecom-grade quality of service across fixed and mobile
accesses. It creates new opportunities for operators who want to deliver attractive, easy-to-use,
reliable and profitable multimedia services – including voice, pictures, text and video, or any
combination of these –with existing services. Users benefit by being able to enjoy attractive
converged multiple services regardless of access network and device. Service success is very much
dependent on the ability of operators to create and deliver an experience that fulfills or exceeds
users’ expectations. To maintain their position as service provider, operators need to climb up the
value chain and take a more active part in service delivery. IMS is designed precisely for that
purpose. IMS is access-independent: it is the only open standardized way to deliver IP-based
consumer and enterprise services, enabled by one common core and control, to the fixed, mobile
and cable communities.
It combines the quality and interoperability of telecoms with the quick and innovative development
of the Internet. IMS does this by making the unique values of the telecom industry easily available
to the application development community. When implemented according to agreed standards,
IMS enables operators to mix and match equipment and applications from multiple vendors, and
enables mobile users to access their personal set of services wherever they roam, whichever
operator network they are connected to. IMS includes the tools and functions needed to handle
numerous non-standardized services in a standardized way – ensuring the interoperability, access
awareness, policy support, charging, security and quality of service functionality required to meet
consumer demand for attractive and convenient offerings.
Why IMS?
‘Why IMS?’ is one of the top strategic questions for any operator these days. There are many good
answers, but perhaps the key one is that IMS delivers innovative multimedia services over fixed and
mobile networks using open standards. IMS addresses key issues such as convergence, service
creation and delivery, service interconnection and open standards. IMS can allow an operator to
retain its existing business models, or evolve towards new ones.
WIRELESS LAN & Bluetooth
WIRELESS LAN INTRODUCTION
Over recent years, the market for wireless communications has enjoyed tremendous growth.
Wireless technology now reaches or is capable of reaching virtually every location on the face of
the earth. Hundreds of millions of people exchange information every day using pagers, cellular
telephones, and other wireless communication products. With tremendous success of wireless
telephony and messaging services, it is hardly surprising that wireless communication is beginning
to be applied to the realm of personal and business computing. No longer bound by the harnesses
27

28. of wired networks, people will be able to access and share information on a global scale nearly
anywhere they venture. This article will try to answer some basic questions of why and where
wireless local area networks can be used, and present a brief description of some protocols that
have been developed, with emphasis on IEEE 802.11.
Mobile IP
Mobile IP was suggested as a means to attain wireless networking. It focuses its attention at the
Network Layer, working with the current version of the Internet Protocol (IP version 4). In this
protocol, the IP address of the mobile machine does not change when it moves from a home
network to a foreign network. In order to maintain connections between the mobile node and the
rest of the network, a forwarding routine is implemented.
When a person in the physical world moves, they let their home post office know to which remote
post office their mail should be forwarded. When the person arrives at their new residence, they
register with the new post office. This same operation happens in Mobile IP. When the mobile
agent moves from its home network to a foreign (visited) network, the mobile agent tells a home
agent on the home network to which foreign agent their packets should be forwarded. In addition,
the mobile agent registers itself with that foreign agent on the foreign network. Thus the home
agent forwarded all packets, intended for the mobile agent, to the foreign agent, foreign agent
sends them to the mobile agent on the foreign network. When the mobile agent returns to its
original network, it informs both agents (home and foreign) that the original configuration has been
restored. No one on the outside networks need to know that the mobile agent moved. This
configuration works, but it has some drawbacks. Depending on how far the mobile agent moves,
there may need to be some store and forwarding of packets while the mobile agent is on neither
the home nor the foreign network. In addition, Mobile IP works only for IPv4 and does not take
advantage of the features of the newer IPv6.
BLUETOOTH
Introduction
Bluetooth is an open standard and specification for small-form factor, low-cost, short range radio
links between mobile PCs, mobile phones and other portable devices. The technology allows users
to form wireless connections between various communication devices, in order to transmit real-time
voice and data communications. It extends a new era of communication that eliminates and
replaces cables which connects mobile phones, laptops, palmtops, desktops and printers. It
provides an absolute synchronization between connecting devices.
In February 1998, five companies as Bluetooth promoters - Ericsson, IBM, Intel, Nokia and Toshiba
have organized and founded a group known as the Bluetooth SIG (Special Interest Group). The aim
of this group is to study and develop a single standard for short range radio connectivity, ensuring
interoperability between devices of different manufacturers. Since that time 3Com, Lucent,
Microsoft, Motorola and more than 2000 member (adopters) companies have joined the
organization. In July 1999 first version of the Bluetooth specification incorporating both radio
protocols and control software was published.
Concept
The Bluetooth radio is built into a small microchip and operates in the 2.4 GHz band, a globally
available frequency band ensuring communication compatibility worldwide. It uses frequency
hopping spread spectrum, which changes its signal 1600 times per second, which helps to avoid
interception by unauthorized parties. In addition software controls and identity coding built into
each microchip ensure that only those units preset by their owners can communicate.
The specification has two power levels defined; a lower power level that covers the shorter
personal area within a room, and a higher power level that can cover a medium range, such as
within a home. It supports both point-to-point and point-to-multipoint connections and provides up
to 720 Kbps data transfer within a range of 10 meters (up to 100 meters with a power boost). The
28

29. technology uses Omni directional radio waves that can transmit through walls and other non-metal
barriers. If there is interference from other devices, the transmission speed decreases but does not
stop
With the current specification, up to seven slave devices can be set to
communicate with a master radio in one device. This connection of devices
(slaves and master) is called a piconet. Several piconets can be linked together
to form scatternets, which allow communication between other device
configurations.
Bluetooth range diagram is shown in figure 1.
Frequency Hopping
Bluetooth communicates on a frequency of 2.45 GHz (starting from 2.402 GHz and stopping at
2.480 GHz), which has been set aside by international agreement for the use of industrial, scientific
and medical devices (ISM). A number of devices that you may already use take advantage of this
same radio-frequency band. Baby monitors, garage-door openers and the newest generation of
cordless phones all make use of frequencies in the ISM band. Making sure that Bluetooth and these
other devices don't interfere with one another has been a crucial part of the design process.
Bluetooth devices will coexist in the same frequency as wireless LAN and microwave oven
consequently the band has to be very robust.
Each channel is 1 MHz wide and so there are 79 different channels. Spread spectrum technologies
help to avoid interference between radio technologies. A Bluetooth device changes its frequency in
a pseudo random way 1600times per second. Interference often occurs in a small portion of
frequency band so hoping between different frequencies makes the channel insensitive. Corrupt
packets are resent on another frequency on which the same interference may not exist. Packets are
also small.
A Bluetooth channel always consists of a master and one or more slaves. Master initiates the
connection. The master decides on a hoping scheme that is related to its internal clock. The slave
calculate an offset which is the difference between master and slave clocks, and uses this
information to determine the frequency to which it will hop. This process enables the master and
its slaves to hop to the same frequencies at all times. The uplink and downlink channels for one
device are time multiplexed and use the Time Division Duplex and hence use the same frequency
hopping scheme.
Working Principle
Bluetooth uses radio medium to link devices instead of physical cable medium. Bluetooth
technology is hardware independent. For example, if a digital camera is to be connected to a
laptop/desktop, a cable system is necessary which is compatible with both devices each device
follows a different set of interface/configuration to be connected. In the Bluetooth approach, the
devices are Bluetooth enabled thus eliminating the interface/configuration conflict. This is true for
all the hand-held devices which are communicating with each other in Bluetooth mode technology.
This is possible by embedding a tiny inexpensive chip in a short-range transceiver into the mobile.
Bluetooth enabled devices are connected in two different networks ‘A’ and ‘B’ Up to eight devices
can be connected in a network. In order to communicate w with other devices, all devices should
work on the same frequency. The device, which initiates the connection, is called ‘Master Device’
and the devices, which are connected to master device, are called ‘Slave Devices’ which are
switched to the specified frequency for further communication.
29

30. If a subscriber is trying to connect his services (known device), then the
master device will send a ‘Page’ command which checks whether the device is
within the range. If so, the communication is established. However, if an
unknown device is trying to connect then the master device sends an ‘inquiry’
command and gets all the information about the unknown device and the
database is updated. Thus, the devices within the network or from other
networks talk with each other. As seen earlier, Master device sets hop sequence
for the Slave devices on the network and controls whether or not each device is
active or inactive within the network. Despite of Master/Slave designation, the
network behaves more of peer to peer relation. Instead of one device
designated to control and manage all resources. Each device has equal access
to the entire network. A slave device in a network can establish connection to
the other networks also. Thus, each slave device can participate with up to
eight different networks.
Application for End Users
Bluetooth technology supports all multimedia applications used by end users. A few applications
are as given below.
1. Provides an absolute synchronization among various digital devices (like mobile
phone, desktop, laptop and PDA).
2. Bluetooth enabled mobile phone can be used as a mobile router placed in a suit
case.
3. Internet surfing is possible from laptop from anywhere
4. Passing on print command remotely for printing jobs.
Advantages of Bluetooth
1. Bluetooth provides flexible network that allows up to eight devices to share the
information.
2. The network architecture allows one to add or remove nodes without additional
infrastructure involved.
3. The size of the implementation is small.
4. Power consumption is low.
5. It has the support of the security considerations like ‘encryption’
Conclusion
Bluetooth is going to emerge as one of the largest growing area in the field of telecommunications
in providing device to device wireless connectivity.2This standard is now available for 2G networks
and is in the process of evolution for 3G network standards tool.
Broadband through WI FI and WIMAX
WI FI Introduction
30

31. Any two computers can be directly wired to each other using a crossover cable. When number of
computer exceeds, cables must be run from each computer to another computer or to the central
device. It can be time-consuming and difficult to run cables under the floor or through walls,
especially when computers sit in different rooms. The correct cabling configuration for a wired LAN
varies depending on the mix of devices, the type of Internet connection, and whether internal or
external modems are used.
Look around us at the moment, we have our keyboard connected to the computer, as well as a
printer, mouse, monitor and so on. What (literally) joins all of these together?, they are connected
by cables. Cables have become the bane of many offices. Most of us have experienced the 'joys' of
trying to figure out what cable goes where, and getting tangled up in the details. Is there a
technology to replace cable?
Wireless is the answer.
Wireless isn't just about the freedom to stay connected as we move around the office. It's also
about the freedom to connect our mobile laptop PC to the Internet from any room in our home or
whenever we take it on the road. Going wireless used to be complicated. It meant dealing with
different wireless standards and all the resultant hardware and software. But the wireless industry
settled on 802.11b (or Wi-Fi) as the predominant standard in 1999, sending prices downward as
demand surged.
Wi-Fi (or Wi-fi, WiFi, Wifi, wifi), short for "Wireless Fidelity", is a set of product compatibility
standards for wireless local area networks (WLAN).
Wi-Fi was intended to be used for mobile devices and LANs, but is now often used for Internet and
wireless VoIP phone access. It enables a person with a wireless-enabled computer, a personal
digital assistant (PDA), or a wireless VoIP phone to connect to the Internet when in proximity of an
access point the geographical region covered by one or several access points is called a hotspot.
Wi-Fi is a trademark of the Wi-Fi Alliance (formerly the Wireless Ethernet Compatibility Alliance),
the trade organization that tests and certifies equipment compliance with the 802.11x standards.
Today WLAN technologies all follow one of the three main Wi-Fi communication standards. The
benefits of wireless networking depend on the standard employed:
802.11b was the first standard to be widely used in WLANs. The 802.11a standard is faster but
more expensive than 802.11b; 802.11a is more commonly found in business networks. The newest
standard, 802.11g, attempts to combine the best of both 802.11a and 802.11b, though it too is
more a more expensive home networking option.
Difference between WI FI and WIMAX
The main problem with WiFi access is that hot spots are very small, so coverage is sparse. Is there a
new technology that would provide high speed of broadband service, Wireless rather than wired
access, so it would be a lot less expensive than cable or DSL and much easier to extend to suburban
and rural areas and Broad coverage like the cell phone network instead of the tiny little hotspots of
WiFi. This technology is called WiMAX, short for Worldwide Interoperability for Microwave Access.
The big difference between Wi-Fi and WiMAX is that we're going to use licensed spectrum to
deliver WiMAX. To date, all Wi-Fi technology has been delivered in unlicensed spectrum. WiMAX
will use one of the unlicensed frequencies, but we're also supporting two other frequencies that are
licensed. What that means is that you can turn up the output power and broadcast longer
distances. So where Wi-Fi is something that is measured in hundreds of feet, usually WiMAX will
have a very good value proposition and bandwidth up to several miles.
Also WiMAX is designed to be a carrier-grade technology, which requires a higher level of reliability
and quality of service than are now available in typical Wi-Fi implementations.
Those fundamental differences make WiMAX more of a metropolitan area access technology versus
hotspot.
31

32. Thus WiMAX has the potential to do to broadband Internet access what cell phones have done to
phone access. In the same way that many people have given up their "land lines" in favor of cell
phones, WiMAX could replace cable and DSL services, providing universal Internet access just about
anywhere you go. WiMAX will also be as painless as WiFi -- turning your computer on will
automatically connect you to the closest available WiMAX antenna.
A WiMAX system consists of two parts: A WiMAX tower, similar in concept
to a cell-phone tower - A single WiMAX tower can provide coverage to a very
large area -- as big as 3,000 square miles (~8,000 square km). A WiMAX
receiver - The receiver and antenna could be a small box or PCMCIA card, or
they could be built into a laptop the way WiFi access is today.
A WiMAX tower station can connect directly to the Internet using a high-bandwidth,
wired connection (for example, a T3 line). It can also connect to
another WiMAX tower using a line-of-sight, microwave link. This connection to a
second tower (often referred to as a), along with the ability of a single tower to
cover up to 3,000 square miles, is what allows WiMAX to provide coverage to
remote rural areas.
What this points out is that WiMAX actually can provide two forms of
wireless service:
WiFi-style access will be limited to a 4-to-6 mile radius (perhaps 25
square miles or 65 square km of coverage, which is similar in range to a cell-phone
zone). Through the stronger line-of-sight antennas, the WiMAX
transmitting station would send data to WiMAX-enabled computers or routers
set up within the transmitter's 30-mile radius (3,600 square miles or 9,300
square km of coverage). This is what allows WiMAX to achieve its maximum
range.
WiMAX outdistances WiFi by miles. WiFi's range is about 100 feet (30 m).
WiMAX will blanket a radius of (50 km) with wireless access. The increased
range is due to the frequencies used and the power of the transmitter.
Wi-Fi kind of lives by what we call the "five minute rule". If you live in a
city, most likely you can walk five minutes and find a hotspot. Or if you're in
your car in the suburbs or a village, you can usually drive within five minutes
and find one of those. With WiMAX we're trying to offer that same type of
service without having to drive or walk five minutes. Even though it's only five
minutes, it's still five minutes. Eventually, you can just open your notebook and
get a connection, wherever you may be.
Wi-Fi is based on the IEEE 802.11 specifications. There are currently four
deployed 802.11 variations: 802.11a, 802.11b, 802.11g, and 802.11n.
Bluetooth uses Frequency Hop Spread Spectrum (FHSS) to avoid any
interference. A Bluetooth channel is divided into time slots each 625 micro
second in length. The devices hop through these timeslots making 1600 hops
per second. This trades bandwidth efficiency for reliability, integrity and
security.
32

33. The range for Bluetooth communication is 0-30 feet (10 meters) with a
power consumption of 0dBm (1mW). This distance can be increased to 100
meters by amplifying the power to 20dBm. The Bluetooth radio system is
optimized for mobility. Bluetooth communication occurs between a master radio
and a slave radio. Bluetooth radios are symmetric in that the same device may
operate as a master and also the slave. Each radio has a 48-bit unique device
address (BD_ADDR) that is fixed.
Two or more radio devices together form ad-hoc networks called
piconets. All units within a piconet share the same channel. Each piconet has
one master device and one or more slaves. There may be up to seven active
slaves at a time within a piconet. Thus, each active device within a piconet is
identifiable by a 3-bit active device address.
Beyond 3G Introduction
Introduction
New data services, interactive TV and evolving Internet behavior will influence mobile data usage.
Long sessions in always-on mode will force a re-think of radio access technology to achieve the
required but not easy to attain capacity (Gbit/s/km) at low cost. The ideas presented in this article
can increase capacity by a factor of 500 with regard to expected cellular deployments.
Coverage will be based on large umbrella cells (3G, WiMAX) and numerous Pico cells
interconnected to provide the user with seamless high data rate (several Mbs) sessions. Scalable
and progressive deployments are possible while protecting the operator’s long-term investment.
The 4G infrastructure operator will mix several technologies, each of which has its optimal usage.
The connection to one of them will result in a real-time trade-off which will offer the user the best
possible service. Some tools that genuinely improve the user’s multimedia quality of experience
(availability, response time, definition, etc.) are also presented in this article.
4G MOBILE
4G will deliver low cost multi-megabit/s sessions any time, any place, using any terminal.
Operational Excellence
Voice was the driver for second generation mobile and has been a considerable success. Today,
video and TV services are driving forward third generation (3G) deployment and in the future, low
cost, high speed data will drive forward the fourth generation (4G) as short-range communication
emerges.
Service and application ubiquity, with a high degree of personalization and synchronization
between various user appliances, will be another driver. At the same time, it is probable that the
radio access network will evolve from a centralized architecture to a distributed one.
Service Evolution
The evolution from 3G to 4G will be driven by services that offer better quality (e.g. video and
sound) thanks to greater bandwidth, more sophistication in the association of a large quantity of
information, and improved personalization. Convergence with other network (enterprise, fixed)
services will come about through the high session data rate. It will require an always-on
33

34. connection and a revenue model based on a fixed monthly fee. The impact on network capacity is
expected to be significant.
Machine-to-machine transmission will involve two basic equipment types:
1. sensors (which measure parameters)
2. tags (which are generally read/write equipment)
It is expected that users will require high data rates, similar to those on fixed networks, for data and
streaming applications. Mobile terminal usage (laptops, Personal digital assistants, hand-held) is
expected to grow rapidly as they become more user friendly. Fluid high quality video and network
reactivity are important user requirements.
4G MOBILE
Some of the key technologies required for 4G are briefly described below:
GPRS BASIC
Introduction
The General Packet Radio System (GPRS) provides actual packet
radio access for Global System for Mobile Communications (GSM)
and time-division multiple access (TDMA) users.
The main benefits of GPRS are that it reserves radio resources only
when there is data to send and it reduces reliance on traditional
circuit-switched network elements. GPRS
GPRS is a data service for GSM, the European standard digital cellular service. It is a packet-switched
mobile data service, a wireless packet based network. GPRS, further enhancing GSM
networks to carry data, is also an important component in the GSM evolution entitled GSM+. High-speed
mobile data usage is enabled with GPRS.
IF GPRS is compared to GSM data services, the following applies:
In GSM all the data that has to be sent, is sent via a circuit switched
connection. This means, that a link has to be established and is used and
maintained from setup until release. The data is sent via one physical timeslot
and has a maximum data rate of 9.6 kbps.
In GPRS all the data that has to be sent, is split into several smaller data
packets first. Those packets are then sent individually across the GPRS network
and each of those packets can travel on a different route.
34

35. The packets arrive at the right destination address and could be
reassembled in the right order, because every single packet contains the
destination address and information about the sequencing of the different
packets.
In GPRS, one user can occupy more than one timeslot or more than one
user can be on a single timeslot.
Depending on different aspects, a maximum data rate of 171.2 kbps
could be achieved.
For GPRS the ETSI Standard introduces two new elements, the Serving
GPRS Support Node (SGSN) and the Gateway GPRS Support Node (GGSN)
(Shown in the diagram below as shadowed objects) is introduced to create an
end-to-end packet transfer mode.
The HLR is enhanced with GPRS subscriber data and routing information.
Two services are provided;
Point -To-Point (PTP)
Point-To-Multipoint (PTM) (not yet specified by the Standards)
The European Telecommunications Standards Institute (ETSI) has
specified GPRS as an overlay to the existing GSM network to provide packet
data services. In order to operate a GPRS service over a GSM network, new
functionality has to be introduced into existing GSM network elements and new
network elements have to be integrated into the existing operators GSM
networks. The Base Station Subsystem (BSS) of GSM has to be upgraded to
support GPRS. The BSS works with the GPRS Support Node (GSN) to provide
GPRS service in a similar manner to its interaction with the Switching
subsystem for the circuit switched services.
DIGITAL SUBSCRIBER LOOP
The Digital Subscriber Line (DSL) technology is widely regarded as a
vehicle for offering wired broadband services to the mass market. The
services include high-speed access to the Internet, voice and telephony
services, interactive video services, e-commerce, and messaging, alerting
and other multimedia services. Success of the Internet and the World Wide
Web has created the market demand and high expectations for high-speed
data services through DSL
35

36. Twisted pair - voice
Twisted pair - voice and data
It uses the existing copper pair for providing Broadband. The
previous diagram showed how the twisted pair is used for transmitting
voice and data. The DSL technology is now mature, poised for rapid
deployment and industry growth in the near future. There are number of
DSL types available to address the various network environments and
applications in the light of trade-offs between rate and reach
1. HDSL -- High-rate DSL
2. ADSL-- Asymmetric DSL
3. SDSL – Symmetric DSL
4. RADSL – Rate Adaptive DSL
ADSL (Asymmetric Digital Subscriber Line)
Asymmetric Digital Subscriber Line (ADSL) technology was first
introduced in 1992 as a system capable of delivering Video-on-Demand
(VoD) service over telephone networks. ADSL utilizes the same twisted
two-wire facility (called the subscriber loop) as the traditional telephone
service. The traditional telephone service is often referred to as “Plain Old
Telephone Service” or POTS. With the initial system architecture and
design of ADSL, the same twisted pair could simultaneously support both
POTS and data. This is made possible due to a frequency multiplexing
technique that supports POTS in the base band and data in a high
frequency band above the telephone service.
The ADSL data service is asymmetrical, in that, it has a higher
downstream data rate (up to 6 Mbps towards the subscriber) than the
upstream data rate (up to 640 kbps towards the service provider). The
main objective is to use ADSL as a technology choice for offering VoD
service. In 1994 it was proved that ADSL technology could be used to offer
high speed data services including video. (Click to view flash movie on
36

37. speed comparison ). Mass-market success of the Internet technologies –
World Wide Web, the Internet browser, and the Universal Resource Locator
(URL) led to high residential as well as business demand for broadband
services.
SDSL (Symmetric DSL)
A variation of ADSL technology more suitable for the T1/E1 market was envisioned via a symmetric
offering of ADSL, known as SDSL. The SDSL technology was envisioned to be a 2-wire equivalent to
the 4-wire HDSL service. The market expectations were Ubiquitous and consistent high-speed data
offering, support for internet access protocols, automated provisioning, dynamic access to services
without requiring telephone company intervention, and inexpensive pricing to enable a wider
deployment of service. Note that all of these expectations have shifted from service provider
ADSL ARCHITECTURE
In POTS, with the available voice band of 3.5 kHz and allowed S/N =
30dB, the theoretical upper limit on data rate will be roughly 35Kbps.
Copper access lines can pass frequencies into the MHz region. This feature
is precisely what ADSL focuses on.
ADSL technology offers the asymmetric bandwidth characteristics
that are 1.544-8.448Mb/s in downstream and 32-768kb/s in the upstream.
This feature fits in with the requirements of client-server applications, in
which the client typically receives much more data from the server then he
is able to generate
ADSL System Architecture
The ADSL functions at the network end (central office end) are
performed by an ADSL Terminal Unit-Central office type (ATU-C) together
with a splitter function (S-C). The ATU-C interfaces with the network
switching, transport, and multiplexing functions and network operations.
The ATU-C functions are usually integrated within a higher level network
element, e.g. DSL access multiplexer (DSLAM).
Although copper pairs are widely available,
several line conditions may prevent the delivery of ADSL: first, if the
telephone line to the customer premises is longer than 5.5km, second,
existing of the load coils or an excessive number of bridged taps and third,
that some portions of the telephone line is carried to the premises on fiber
optic cable .
DSLAM contains the access interface (network termination – NT) to
the appropriate next device in the network, e.g., Tier2, Tier1 Switch etc.
ADSL functions at the customer end (remote end) are performed by an
ADSL Terminal Unit-Remote end type (ATU-R) together with a splitter
function (S-R). At the customer premises, ATU-R may present the
interfaces to the local distribution for broadband services via service
37

38. modules (SM). The SM contains necessary decoders and terminal interfaces
for the given service and customer control interfaces.
Splitters are three node devices that allow the telephony signals and
the ADSL signal to reside on the same copper loop without interfering one
with the other. The splitter provides a low pass filter to the basic voice and
control telephony signal (below 4 kHz) and a high pass filter for the ADSL
signals, starting approximately at 25 kHz or above. Most POTS splitter
designs are passive, that is without powering requirements. The
advantages of passive filters are in their reliability, because they enable
continuous telephone service even if the modem fails (for example, due to
a power outage).
The connectivity architecture of DSLAMs is as shown in figure. The
DSLAMs are connected to the Tier 2 Switches and again, the Tier2 switches
are connected to Tier1 Switch. In turn the Tier1 Switch is connected to
"Broadband Remote Access Server"(BBRAS) which is routed to core router
through which it gets access to the International Gateway.
The below diagram shows the connectivity portion of DSLAM with the
Tier2 switch. If the distance between the DSLAM and the Tier2 switch is
less than 10 Kms, then Dark Fibre could be used for connectivity. (Dark
fibre means a spare fibre). If the distance exceeds 10 Kms, then we can
use the STM medium with electrical to optical converters at both the ends,
as both DSLAM as well as Tier2 switch has optical interface whereas the
output from STM is electrical.
38

39. There are a large number of different kinds of servers that can be
accessed by an ADSL system Video on Demand service is one of the most
interesting aspect of ADSL. By using MPEG coded video it is possible to
deliver video quality movies over existing copper loops to customers. A
video quality can be achieved by only 1.5 Mbps data rate. Together with
pure VoD services there might exist combined movie information and
advertiser services in which commercial and non-commercial information
that providers and advertisers can deliver their information.
Full-rate ADSL:
The downstream uses DMT tones 7 - 255 (echo cancellation) or 32 - 255 (FDM). The upstream
channel uses tones 7 - 31. Bit loading is adaptive and varies from 2 to 15 bits per tone (sub channel)
depending on the relative noise of each carrier. When high noise levels are detected in a given sub
channel, the DMT modem can shut down a particular sub channel altogether.
ADSL MODEM
The ADSL transmission signal is modulated onto discrete multi-tones
(DMT). As already seen, there are 256 independent parallel sub channels
available in the 1.1MHz ADSL bandwidth. Each sub channel is separated by
approximately 4 kHz and has a distinct carrier frequency in the center of
this 4 kHz band. While DMT is the physical transmission level, framing and
encoding (error correction) occurs at a higher level. The modulation
technique used in each of the discrete multi-tone (DMT) channels is
Quadrature Amplitude Modulation (QAM) where both the phase angle and
the amplitude of the carrier band are modulated to represent the
information being transmitted.
In a typical ADSL modem, the main sections are
1. The Digital Interface (e.g. ATM)
2. The Framer/FEC plus Encoder/Decoder
3. The DMT Modulator
4. The AFE (Analog Front End)
The Framer multiplexes serial data into frames, generates FEC
(Forward Error Correction), and interleaves data. FEC and data interleaving
corrects for burst errors. This allows DMT-based ADSL technology to be
suitable for support of MPEG-2 and other digital video compression
techniques
For the transmit signal
The Encoder encodes frames to produce the constellation data for the DMT Modulator. It assigns
the maximum number of bits per tone (based on measured SNR of each carrier) and generates a
QAM constellation where each point represents a digital value. Each constellation point is one of N
39

40. complex numbers, x + iy, where x and y are the phase and amplitude components. The summation
of bits in all carriers, multiplied by the frame rate (4 kHz), represents the data rate
For the receive signal
The Decoder converts QAM symbols back into the data bit stream.
In the DMT Modulator, a frequency domain processor implements FFT/IFFT and associated
processing. In the transmit path, the Inverse Fast Fourier Transform (IFFT) module accepts input as
a vector of N QAM constellation points and duplicates each carrier with its conjugate counterpart
so the 2N output samples are real. The 2N time domain samples have the last 2N/16 samples
appended as a cyclic prefix, and are then delivered to the DAC (Digital to Analog converter). The set
of time domain samples represents a summation of all the modulated sub channels, for the
duration of one data frame
NGN BASIC CONCEPTS
Definition & Features of NGN
40

41. BSNL's Plan
1. Tender for 200 KC IP TAX equipment, which is Pilot Project for introduction of NGN
in transit network, has been awarded
2. Plan to introduce 6.4 million circuits capacity in 2007-2008 through IP TAX
3. Strengthen SSTP Networks
4. Trials for migration of PSTN access to NGN and for introduction of NGN in access
network underway
5. Migration to IMS expected to roll out from 2009
6. Full migration to NGN with replacement of PSTN by 2012
7. IP Multimedia Subsystems
WiMAX-Access to NGN
41

42. 8.
WHAT IS NGN?
9. NGN is a network infrastructure that will enable the provisioning of
the existing telecommunications services and innovative applications
of the next generation. It is a converged network capable of carrying
voice, data and video over the same physical network, with all traffic
carried as IP (Internet Protocol).NGN is a multi-service network,
which enables operators to implement converged and new services in
addition to POTS. From the users’ perspective, the convergence of
services will enable the “desired” services from any type of access
network.
10. NGN i.e. the Next Generation Network refers to the convergence of
different telecom services i.e. voice, data and video over a unified
packet network utilizing Internet Protocol (IP). NGN can be thought
of as a packet-based network where the packet switching and
transport elements (e.g. routers, switches and gateways) are
logically and physically separated from the service/ call control
intelligence. This control intelligence is used to support all types of
services over the packet-based transport network including
everything from the basic voice telephony services to data, video,
multimedia, advanced broadband
ARCHITECTURE OF NGN
The architecture of Next Generation Network is shown below.
42

43. It is a horizontally layered network architecture instead of the
present vertically separated networks for each service. It uses packet-based
transport for all services (including voice).The access, switching,
transport, control and service functions which are integrated in today’s
switches are separated into individual network layers, which inter-work via
interfaces based on open standards. The most significant aspect is the separation of call control
from switching and transport functions
NGN APPLICATIONS – THE KEY TO
COMPETITIVE DIFFERENTIATION
1. Voice Telephony
NGNs will likely need to support various existing voice
telephony services (e.g., Call Waiting, Call Forwarding, 3-Way
Calling, various AIN features, various Centrex features, and various
CLASS features).Note, however, that NGNs are not trying to duplicate
each and every traditional voice telephony service currently offered.
Rather, they will likely attempt to support only a small percentage of
these traditional services, with an initial focus on the most
marketable voice telephony features and the features required from a
regulatory perspective.
2. Data (Connectivity) Services
Allows for the real-time establishment of connectivity between
endpoints, along with various value-added features (e.g., bandwidth-on-
demand, connection reliability/resilient Switched Virtual
Connections [SVCs], and bandwidth management/call admission
control).
1. Multimedia Services
43

44. Allows multiple parties to interact using voice, video, and/or
data. This allows customers to converse with each other while
displaying visual information.
2. Virtual Private Networks (VPNs)
Voice VPNs improve the inter location networking capabilities of
businesses by allowing large, geographically dispersed organizations
to combine their existing private networks with portions of the PSTN,
thus providing subscribers with uniform dialing capabilities. Data
VPNs provide added security and networking features that allow
customers to use a shared IP network as a VPN.
1. Unified Messaging
Supports the delivery of voice mail, email, fax, and pages
through common interfaces. Through such interfaces, users will
access, as well as be notified of, various message types (voice mail,
email, fax, etc.), independent of the means of access (i.e., wire line
or mobile phone, computer, or wireless data device).
1. Call Center Services
A subscriber could place a call to a call center agent by clicking
on a Web page. The call could be routed to an appropriate agent,
who could be located anywhere, even at home (i.e., virtual call
centers).Voice calls and e-mail messages could be queued uniformly
for the agents. Agents would have electronic access to customer,
catalog, stock, and ordering information, which could be transmitted
back and forth between the customer and the agent.
1. Interactive gaming
Offers consumers a way to meet online and establish interactive
gaming sessions (e.g., video games).
2. Home Manager
With the advent of in-home networking and intelligent
appliances, these services could monitor and control home security
systems, energy systems, home entertainment systems, and other
home appliances
IP Multimedia subsystem (IMS)
IMS (IP Multimedia Subsystem) enables and drives efficient converged service offerings. It is the key
to delivering multimedia services with telecom-grade quality of service across fixed and mobile
44

45. accesses. It creates new opportunities for operators who want to deliver attractive, easy-to-use,
reliable and profitable multimedia services – including voice, pictures, text and video, or any
combination of these –with existing services. Users benefit by being able to enjoy attractive
converged multiple services regardless of access network and device. eService success is very much
dependent on the ability of operators to create and deliver an experience that fulfills or exceeds
users’ expectations. IMS is designed precisely for that purpose. IMS is access-independent: it is the
only open standardized way to deliver IP-based consumer and enterprise services, enabled by one
common core and control, to the fixed, mobile and cable communities.
It combines the quality and interoperability of telecoms with the quick and innovative development
of the Internet. IMS does this by making the unique values of the telecom industry easily available
to the application development community. When implemented according to agreed standards,
IMS enables operators to mix and match equipment and applications from multiple vendors, and
enables mobile users to access their personal set of services wherever they roam, whichever
operator network they are connected to. IMS includes the tools and functions needed to handle
numerous non-standardized services in a standardized way – ensuring the interoperability, access
awareness, policy support, charging, security and quality of service functionality required to meet
consumer demand for attractive and convenient offerings.
IMS offers a standardized way to deliver convenient IP-based consumer and enterprise services to
fixed, mobile and cable community – enabled by one common core and control. It is the
cornerstone of the evolution of current networks to a single, all-IP based network where all types of
services (messaging, telephony, etc.) and media (voice, video, pictures, text etc.) can be integrated
into a single user experience. For consumer, IMS opens communication options that seamlessly
combine ongoing voice sessions with multimedia elements (sharing video while talking, for
example) or enrich shared applications with voice communication (for instance, talking while
playing a multiplayer game).
WIRELESS TECHNOLOGY
Wireless broadband technology sends data over a 'wireless'
communications network, typically using radio frequency.
These technologies are a strong and popular platform for delivery of
high-speed Internet services and wireless broadband, is emerging as a
legitimate local access platform for the delivery of high-quality digital data,
video and voice services.
In many regional areas where telecommunications infrastructure
such as fibre optic or coaxial cable is limited, wireless technologies offer a
competitive broadband access solution. Rather than stringing thousands of
miles of fiber, coax or twisted-pair wiring, a wireless operator installs a
headed and transmission tower and is open for business.
Wireless technologies can provide area coverage from anywhere
between 5km to 40km depending on the local terrain and strength of the
transmitter signal.
45

46. The advantages of wireless broadband:
1. Access - a wireless network provides high-speed access to the Internet without the
need for expensive wire or cable infrastructure.
2. Flexibility - the capacity (number of customers) of a wireless network can be
expanded when required.
3. Versatility - wireless services are suitable for both lightly populated areas, but can
also be deployed to provide customized services in highly populated areas.
4. Costs - without the need for expensive equipment and/or infrastructure, the cost of
wireless broadband products can be lower than wired products.
Wi-Fi
Short for wireless fidelity, Wi-Fi technologies include the approved IEEE 802.11a, b and g
specifications, as well as the yet-to-be-ratified 802.11n specification. Wi-Fi is the first high-speed
wireless technology to enjoy broad deployment, most notably in hotspots around the world
including homes and offices, and increasingly cafes, hotels, and airports.
Wi-Fi hotspots became popular almost immediately and have been applauded by road warriors for
their ability to improve productivity. Wi-Fi is limited, however, by its range: high-speed connectivity
is possible only as long as a user remains within range of the wireless access point, which is
optimum within 300 feet.
Wi-Fi was one of the earliest high-speed wireless data technologies and now benefits from a broad
availability of supporting products and technologies. Some of the newest platforms even support
multiple Wi-Fi standards (e.g. 802.11a, b and/or g) for compatibility among several wireless
networks.
WiMAX
WiMAX is an emerging technology that will deliver last mile broadband connectivity in a larger
geographic area than Wi-Fi, enabling T1 type service to business customers and cable/DSL-equivalent
access to residential users. Providing canopies of coverage anywhere from one to six
miles wide (depending on multiple variables), WiMAX will enable greater mobility for high-speed
data applications. With such range and high throughput, WiMAX is capable of delivering backhaul
for carrier infrastructure, enterprise campuses and Wi-Fi hotspots.
WiMAX will be deployed in three phases. Phase one will see WiMAX technology using the IEEE
802.16d specification deployed via outdoor antennas that target known subscribers in a fixed
location. Phase two will roll out indoor antennas, broadening the appeal of WiMAX technology to
carriers seeking simplified installation at user sites. Phase three will launch the IEEE 802.16e
specification, in which WiMAX-Certified* hardware will be available in portable solutions for users
who want to roam within a service area, enabling more persistent connectivity akin to Wi-Fi
capabilities today.
CABLE MODEM BASICS
46

47. Current Internet access via a 28.8–, 33.6–, or 56–kbps modem is
referred to as voice band modem technology. Like voiceband modems,
cable modems modulate and demodulate data signals. However, cable
modems incorporate more functionality suitable for today's high-speed
Internet services.
Cable modem is capable of delivering up to 30 to 40 Mbps of data
this is approximately 500 times faster than a 56–kbps modem
In the conventional case the TV set receives the signal directly from
the cable operator through Co-axial cable as shown in the figure1. When
internet data combined with the TV signal is received a splitter is required
to separate the signals(figure 2).
FIGURE 1
FIGURE
CABLE MODEM BASICS
FIGURE 1
FIGURE 2
The separated data is taken through co-axial cable to the cable-modem
which in turn is connected to the PC through Ethernet/USB port
A subscriber can continue to receive cable television service while
simultaneously receiving data on cable modems to be delivered to a
personal computer (PC) with the help of a simple one-to-two splitter
A device called a cable modem termination system (CMTS), located
at the local cable operator's network hub, controls access to cable modems
on the network. It is for support of data services that integrates upstream
and downstream communication over a cable data network. The number of
47

48. upstream and downstream channels in a given CMTS can be engineered
based on serving area, number of users, data rates offered to each user,
and available spectrum
A cable headend (combiner) combines the downstream data channels
with the video, pay-per-view, audio, and local advertiser programs that are
received by television subscribers. The combined signal is then transmitted
throughout the cable distribution network.
Traffic is routed from the CMTS to the backbone of a cable Internet
service provider (ISP), such as Road Runner, which, in turn, connects to
the Internet. With newer cable modem systems, all traffic from the CMTS
to the cable modem is encrypted to ensure privacy and security for users
To try to promote cable modem rollouts, as well as relieve technological confusion, Cable Labs, an
industry trade organization, drafted a standard for cable modem products in 1996 called DOCSIS
(Data Over Cable Service Interface Specification). The standard was developed to ensure that cable
modem equipment built by a variety of manufacturers is compatible, as dial-up modems are.
Today, Cable Labs continues to manage a rigorous testing process for DOCSIS cable modems,
stamping the products that
POINT TO POINT PROTOCOL
OVER ETHERNET(PPPOE)
Point-to-Point Protocol over Ethernet is a proposal specifying how a
host personal computer (PC) interacts with a broadband modem (i.e. xDSL,
cable, wireless, etc.) to achieve access to the growing number of High-speed
data networks. Relying on two widely accepted standards, Ethernet
and the point-to-point protocol (PPP), the PPPoE implementation requires
virtually no more knowledge on the part of the end user other than that
required for standard Dial up Internet access.
In addition, PPPoE requires no major changes in the operational
model for Internet Service Providers (ISPs) and carriers. The significance
of PPP over Ethernet has to do with its far greater ease of use versus
competing approaches. By making high-speed access easier to use for end
consumers, and more seamless to integrate into the existing infrastructure
for carriers and ISPs, PPPoE could speed the widespread adoption of High-speed
access services
Also, PPP over Ethernet provides a major advantage for service providers by maximizing integration
with - and minimizing disruption of - service providers' existing dial network infrastructures.
Through tight integration with existing back office automation tools that ISPs have developed for
dial customers, PPPoE enables rapid service deployment and cost savings. From authentication,
accounting and secure access to configuration management, PPPoE supports a broad range of
existing applications and services.
48

49. Why would PPPoE be used?
PPPoE is used to allow Internet Service Providers (ISPs) the use of their existing Radius
authentication systems from their Dial-Up service on a Broadband / Ethernet based service. Dial-Up
is PPP; most broadband connections are Ethernet, hence Point to Point Protocol over Ethernet. It
also allows for ISPs to resell the same line multiple times. IE: Rated services, Broadband specific
content (movies, etc.), metered services, etc.
1. ADSL modem, splitter
Customer Premises – Connectivity
Customer Premises - Connectivity
ADSL-Configuration
49

50. 1. Unzip the zipped RASPPPoE folder to a temp directory of your choice
2. Right click on "Network Neighborhood" (in ME "My Network Places"). Choose
"Properties" Click "Add..."
3. Select "Protocol". Click "Add...”. Select "Have Disk". .Select "Browse" Then choose
the folder you unpacked the RASPPPoE programs to. Then select any one of the INF
files, it does not matter which one Click "OK“. Then "OK" again
4. In the "Select Network Protocol" window make sure "PPP over Ethernet Protocol" is
highlighted and click "OK". .Click "OK" on "Network" window. Click "Yes" to Reboot.
5. Go to your "Start" menu, and then choose "Run". Type in RASPPPoE and click "OK“
"RASPPPoE" window opens. Click Exit
6. Double click the Dial-Up short cut on your desk top
7. Enter your user id as provided by your ISP
Note: you may need to include your ISP's domain as part of your user id
INTRODUCTION TO
MULTIPLAY
The term meaning the provisioning of different telecommunication
services by Telecom Service Providers on wired and wireless networks ,
such as Broadband Internet access, TV,VOD, VPN, Telephony/VOIP and
mobile phone service.
Broadband Multi-Play network focuses on the augmentation of
Broadband Access Network supporting multi-play services like Video on
Demand, IP TV, VoIP, VPN service etc. with guaranteed control of critical
parameters like latency, throughput, jitter to ensure high grade delivery of
real time, near real time, non-real time and best effort services.
MULTIPLAY NETWORK
50

51. The Multiplay network is a three tier Architecture consisting of the
Access Network, Aggregation Network and Core & Content Delivery
Network.
BROADBAND NETWORK GATEWAY
The Redback SmartEdge 800 Multi-Service Edge Router is deployed
as Broadband Network Gateway (BNG) in BSNL Multi Play project. BNG act
as Gateway of the broadband traffic towards the MPLS core.
SmartEdge MSERs provide a comprehensive IP routing foundation
required for the evolving Multi-Play broadband services. SmartEdge 800
MSER offers a diverse range of interface options: Ethernet, Packet over
SONET (PoS) and channelized connections.
All SmartEdge MSER interface modules are hot-swappable and highly
resilient with full session and state redundancy in the event of a failure or
replacement. Support for high-performance multicast is provided, including
protocol independent multicasting (PIM), Internet group management
protocol (IGMP) and multicast routing.
1. Session level reliability: Supports Non Stop Forwarding and keeps Subscribe
Sessions running uninterrupted during a Route Processor fail-over.
2. Resilient software architecture: Modular design provides stability and protects
against crashes and protocol errors.
3. Carrier-Grade Design: Engineered to carrier standards and deployed in carrier
networks worldwide.
Network Connectivity Diagram
The network connectivity of aggregation networks of various cities are illustrated in the following
diagrams.
51

52. Broadband Multiplay – A1 & A2 Cities
The network connectivity of aggregation networks of A3 and A4 cities is shown below.
Broadband Multiplay – A3 & A4 Cities
MULTIPLAY SERVICES
The Various services offered by Multiplay are as follows:
1. Internet Services
2. Layer3 VPN Services
3. Video Services
4. IP Telephony Services
5. Data/Voice/Video Services
The network path and the traffic flow of various services are
explained in the following section.
52

53. FIBER TO THE HOME – FTTH
Fiber to the home (FTTH) is the ideal fiber-optics architecture. In this
architecture, fiber deployment is carried all the way to the customer’s
home (premises).This chapter will address the solution, which a fiber-optics
architecture is called FTTH
FTTH has been developed in response to several residential access
market drivers, including the following:
1. The Internet explosion, second line growth, the desire for higher speeds, alternative
strategies such as voice over DSL (VoDSL), voice over IP (VoIP), voice over ATM
(VoATM), and cable modems
2. The increased competition in the market due to the growing number of competitive
local-exchange carriers (CLECs), an increase in services offered by application
service providers (ASPs), and deregulation and pending Federal Communications
Commission (FCC) rulings
3. The declining costs of optical equipment Technology
Fiber To The Home – FTTH
How FTTH works
In an FTTH system, equipment at the head end or CO is interfaced into the public switched
telephone network (PSTN) and is connected to ATM or Ethernet interfaces. Video services enter the
system from the cable television (CATV) head end or from a satellite feed.
SMPS
A switched-mode power supply, switch-mode power supply, or SMPS, is an electronic
power supply unit (PSU) that incorporates a switching regulator — an internal control
circuit that switches power transistors (such as MOSFETs) rapidly on and off in order to
stabilize the output voltage or current. Switching regulators are used as replacements for
the linear regulators when higher efficiency, smaller size or lighter weight are required.
They are, however, more complicated and their switching currents can cause noise
problems if not carefully suppressed. As with any offline electronic systems employing
53

54. peak-hold AC-DC conversion, simple SMPS designs may have a poor power factor. The
power output to cost crossover point between SMPS and linear regulating alternatives has
been falling since the early 1980s as SMPS technology was developed and integrated into
dedicated silicon chips. In early 2006 even very low power linear regulators became more
expensive than SMPS when the cost of copper and iron used in the transformers increased
abruptly on world markets.
Basic Concepts
Power plant is an equipment, which gives uninterrupted DC power supply to the
telecommunication systems. Because telecommunication systems require electrical energy for
1. Conversion of speech signals to electrical signals
2. For operating switching, transmission equipments
Need of D.C. Power supply
1. Harmonics of A.C may affect the speech signals.
2. Relays used in telecom systems are more sensitive to D.C than A.C
3. Transistors and I.C.s etc. being unidirectional devices, the use of D.C has become
necessary.
4. Arranging standby source to A.C is difficult compare to D.C for which secondary cells
can be used as S/B source.
5. Not hazardous to human life
Basic Concepts
Sources of power:
Telecommunication systems need uninterrupted power supply round the clock and throughout the
year. For any uninterrupted power supply system, two sources are required.
1. Normal or Main source
Main Source is D.C derived from commercial source.
2. Secondary or standby source
Secondary cells
By name we can define Normal source is one which supplies power to the load round the clock and
secondary source is one which supplies power to the load only during the absence of power from
normal source.
Hence it is a must to convert AC from commercial mains to D.C.
Basic Concepts
A.C to D.C conversions
Previously M.G (Motor-Generator) sets were used for A.C to D.C conversion. In this A.C motor
rotates on commercial A.C. supply. To the shaft of this AC motor, D.C. Generator will be coupled
which generates D.C. Now a days static rectifiers using static electronic components like metal or
diode rectifiers are used.
Float Working
Parallel Battery Float Scheme
54

55. In this scheme two sets of Batteries (24 cells each set) are connected in parallel to the output of the
rectifier. The output of the rectifier is 51.5 V. Hence floating voltage of each cell is 51.5 divided by
24 = 2.15V/ cell. Hence always 90% of battery capacity will be available for emergency usage
For the operation of the scheme "POWER PLANT" is designed by TRC (Telecom Research Centre).
Float Working
Operating voltage:
Now a days almost all of our telecom equipment works on -48 volts D.C. supply i.e. positive lead is
earthed.
Earthing of one pole of D.C:
Reasons for earthing of one pole of D.C are as follows:
1. Switching can be single pole.
2. Cross talk and other disturbances can be avoided.
3. To make the alarm and supervisory system easy.
4. Earth return signaling can be used.
Float Working
Reasons for earthing positive pole of D.C
1. In electrolysis positive electrode will be normally corroded. If we keep our lines and
equipment at negative potential, we can minimize troubles from the corrosive effects.
2. Partial Earth faults can be definitely identified if the conductor is negative. Otherwise
fault is liable to seal up owing to oxidation.
Power plant consists of
1. Float rectifier
2. Battery Charger
3. Switching Cubicle.
Float Rectifier
The function of the Float Rectifier is to receive three phase 440 V AC and to give a constant 51.5
Volts D.C without AC ripples.
The steps involved to achieve the function are
1. Step-down
2. Rectification
3. Filtering
4. Regulation.
Step down
Transformer steps down the 3 phase A.C voltage from 440 volts to around 80 volts.
Rectification
Any unidirectional device rectifies the AC to DC. Here Diodes. SCRs are used for rectification
55

56. Float Rectifier
Filtering:
Here multi-stage L.C. Filters are used for filtering the A.C. Ripples.
Regulation:
As far as Float Rectifier is concerned, Regulation is the mechanism by which the output of a float
rectifier is kept constant at 51.5± 0.5V irrespective of input voltage variations of 12%, Output load
variations of 5% to 105% and input frequency variations of 4% or 48-52 Hz.
Why Regulation is required?
Float rectifier should not only supply power to the load but also takes care of its battery sets, which
are floated across its output. If the float rectifier output voltage is 51.5v, the cells are floated at
2.15v/cell and hence they are continuously trickle charged and this compensates losses due to self-discharge
or local action. If FR output is 49.2V, the battery set is not trickle charged, hence trickle
charging is to be given once in a fortnight.
If FR output is less than 49.0V, the battery starts discharging. If FR output is greater than 51.5V, the
floating voltage of each cell will be greater than 2.15V and the battery will be over charged.
SMPS POWER PLANT (ITI MAKE)
(Suitable for VRLA Batteries with 100A SMPS Rectifier Modules)
Introduction
The power system is intended primarily to provide uninterrupted DC power to Telecom equipments
and current for charging the batteries in the presence of AC Mains. The system works from
commercial AC mains which is rectified and regulated to -50V DC and is fed to the equipment
(exchange). The system has provision to connect three sets of VRLA batteries and facility to charge
them simultaneously to ensure that uninterrupted DC power supply is always available to the
exchange.
SMPS POWER PLANT (ITI MAKE)
Technical Specification:
For Module
1. Input Voltage
1. 320V to 480V r m s three phase (Nominal Voltage - 400V).
2. Frequency: 45 Hz. 65 Hz.
2. Output Voltage
1. Float mode
1. Nominal voltage : -54.0 + 0.5V,
2. Adjustment range : -48.0 to -56.0 V
2. Charge mode Voltage : -55.2 + 0.5 V
SMPS POWER PLANT (ITI MAKE)
1. Rated current: 100 Amps.
2. Psophometric noise :
1. Less than4 mV without battery floated.
2. Less than2 mV with battery floated.
3. Input power factor: Greater than 0.95 lag with 25% to 100% load at nominal input.
4. Efficiency: Greater than 90% at full Load and nominal input.
5. Protection :
1. Short-circuit protection.
2. Input over/under voltage protection.
3. Output over voltage protection.
4. Constant current features settable from 80 Amps. To 110 Amps. In auto
float/charge mode.
1. Alarms and indicating lamps:
1. FR/BC on Auto Float/Charge : Green LED
56

57. 2. Rectifier module over voltage : Red LED
3. DC output fail/Under voltage : Red LED
4. FR/BC Over Load (Voltage Drop) : Amber/Yellow LED
SDH
Content Snippets
Modules
 Digital Transmission
 Disadvantages of PDH
 Advantages of SDH
The objective of this session also includes
to enhance knowledge on
57

58. 1. Fundamentals
2. Multiplexing
3. Network Elements
4. Network Topology
5. Telecom Management Networks
6. Network Management
7. SDH Measurements
8. SDH Frame
And reliability of a digital network.
Standards of PDH
Disadvantages of PDH
No common Standard
1. There are different hierarchies in use around the world.
2. Specialized interface equipment is required to inter-work the two hierarchies.
3. There is no standardized definition of PDH bit rates greater than 140 Mbit/s.
1. .
Advantages of SDH
Simplified add & drop function
Compared with the older PDH system, it is much easier to extract and insert low-bit rate channels
from or into the high-speed bit streams in SDH. It is no longer necessary to de-multiplex and then
Re-multiplex the plesiochronous struct
BASIC DEFINITIONS of SDH
Synchronous Transport Module
This is the information structure used to support information pay load and over head information
field organized in a block frame structure which repeats every 125 micro seconds.
SDH NETWORK TOPOLOGY
NETWORK TOPOLOGY
The various network topologies in SDH are as follows:
1. Point-to-point link
2. Bus Topology
58

59. 3. Ring Topology
1. Collapsed ring
2. Nested ring
4. Hub Topology
5. Star Topology
6. Mesh Topology
7. Mesh and Ring Topology
Having identified and explained the current set of network building blocks, we will now look at the
various methods of constructing SDH networks in practice.
Initially, SDH technology will be deployed in new installations and then to replace or upgrade
existing systems when they reach maximum capacity. At the simplest level, new point-to-point
systems will use SDH Terminal muxes with the ability to expand to more complex SDH constructions
later. We will now examine each possible topology in turn.
SDH NETWORK TOPOLOGY
Point to Point
SDH Line Systems are natural successors to the 140 Mb/s and 565 Mb/s line systems currently
deployed in backbone networks. In new installations, these PDH capacities will commonly be
replaced by STM-4 (622 Mb/s) line systems. Increasingly, STM-16 (2.4 Gb/s) line systems will be
required to cater for the ever increasing bandwidth requirements of backbone networks.
Point to Point
Point-To-Point
Point-To-Point
Since SDH systems will begin to appear in specific routes or overlay networks within the existing
transmission network, co-existing with 140 Mb/s and 565 Mb/s systems, an issue of major
importance will be the network management. This will have to cover the whole transmission
network, including both the SDH and PDH parts.
Point to Multi Point
59

60. Point-To-Multipoint
Point-To-Multipoint
Linear Network (BUS TOPOLOGY)
SDH NEs and be joined to form the Linear network as shown. The Network has LTM which marks
the start of the SDH network and
In between there can be add drop offices. The line protection can be given with the standby line for
failure against fibre. The payload can be any of the PDH rate or the SDH line lower rate.
Bus Topology
RING TOPOLOGY
Ring Topology
60

61. Ring Topology (Contd...)
Under normal operation, a 2 Mb/s tributary is sent round the ring in both the directions. The ADM
assigned to drop the 2 Mb/s tributary monitors the two SDH signals for errors and delivers the one
with better performance. This is known as path switching.
PROJECT ON C-DOT FAMILY
BRIEF HISTORY: -
The Center for Development of Telematics (C-DOT) is the telecom technology
development center of the government, It was established in August 1984 as an
autonomous body. It was vested with full authority and total flexibility to develop
61

62. state-of-the-art telecommunication technology to meet the needs of the Indian
telecommunication network. The key objective was to build a center for excellence in
the area of telecom technology.
ACHIEVEMENTS: -
 C-DOT Technology based system from 200 lines to 40,000 lines capacity in
operation
 More than 30,000 C-DOT Exchange totaling approximately 25 million
telephone lines installed and operational in field
 Deployed telecom equipment value of Rs.7500 crore
 Significant technology transfer and royalty earnings
 Technology development with low capital investment
The C-DOT DSS FAMILY
GENERAL
C-DOT DSS MAX is a universal digital switch can be configured for different
application as local, transit or integrated local and transit switch. High traffic or
capacity of 40000 lines as local exchange or 15000 trunks as Trunk automatic
exchange.
The design of C-DOT DSS MAX has seen by a family concept because of its
advantages like standardized components, commonality in hardware, field hardware
that used minimum number of cards, standard cards, racks, frames, cabinets and
distribution frames are used which facilitated flexible system growth that make C-DOR
DSS MAX easy to maintain and highly reliable.
FLEXIBLE ARCHITECTURE
C-DOT DSS is a modular and flexible digital switching system which provides
economical means of serving metropolitan, urban and rural environments. It include
62

63. all important feature and compulsory services, required by the user with option of up
gradation to add new
Feature and services in future. The architecture for the C-DOT DSS is such that it is
possible to upgrade a working C-DOT Single Base Module.(SBM) or Multi Base
Module (MBM)exchange to provide Integrated Services Digital Network (ISDN)
service by adding minimum addition hardware modules while continue to having
existing hardware units. Another factor of architecture Remote Switching Unit (RSU).
Is support ISDN. This RSU provides switching facility locally even in case of failure of
the communication path to the parent exchange. The resources, which depend upon
the number of terminal, are provided within the basic growth unit the Base Module.
ARCHITECTURE OF C-DOT DSS MAX
C-DOT DSS MAX exchanges can be configured using four basic modules.
1. Base Module
2. Central Module
3. Administrative Module
4. Input Output Module
HARDWARE ARCHITECTURE
C-DOT MAX exchange can be configured using four basic modules:-
63

64. 1. BASE MODULE (BM)
2. CENTRAL MODULE (CM) C
3. ADMINISTRATION STRATIVE MODULE (AM)
4. INPUT OUTPUT MODULE (IOM&IOP)
(a) BASE MODULE (BM): -
The Base Module is the basic growth unit of the system. It interfaces the
external world to the switch. The interfaces may be subscriber lines, along and digital
trunks. Each Base Module can interface up to 2024 terminations. The number of Base
Modules directly corresponds to the exchange size. It carries out majority of call
processing function and in a small exchange application, it also carries out operation
and maintenance function with the help of Input-Output Module.
The Basic functions of a base modules are:-
1. Analog to digital conversion of all signals on analog lines and trunks.
2. Interface to digital trunks and digital subscriber.
3. Switching the calls between terminals connected to the same Base Module.
There are two types of Base Modules:-
1. Single Base Modules(SBM)
2. Multi Base Module (MBM)
64

65. In SBM exchange configuration, the Base Module acts as an independent
switching BM directly interface with the Input Output Module for bulk data storage,
operations and maintenance function. Clock and synchronization is provided by a
source within the BM. It is a very useful application for small urban and rural
environments.
The Base cabinet houses total 6 frames:-
· Terminal Unit (TU, Top 4 Frames) system and provides connection to 1500
lines and 128 trunks. In such a configuration, the
· Base Processor Unit (BPU, 5th frame)
· Time switch unit (TSU)
There are following four terminals units:-
1. ANALOG TERMINAL UNIT (ATU):-
The Analog Terminals Unit (ATU) is used for interfacing 128 analog termination
which may be lines or trunks and providing special circuits as
conference announcements and terminal tester. It consists of terminal cards, which
65

66. may be a combination of Analog Subscriber Line Cards, Analog Trunk card & some
Special Service Cards.
(a) Analog Subscriber Ling Cards: -
Two variants of subscriber line cards as LCC (Line Circuit Card) or CCM (Coin
Collection Monitoring) with interfaces up to 8 subscribers. Analog to digital
conversion is done by per channel CODEC according to A-Law of Pulse Code
Modulation so we can say that it for the subscriber connected for subscriber to
exchange.
A unit has 16 line cards so 16*8=128 subscribers.
There are 4 unit so 4*128= 512 subscribers.
4 cards make 1 Terminal Group (TG) so TG = 4.
(b) Analog Trunks Cards:-
Analog trunk cards interface analog inter exchange trunks which may be of
three types as TWT, EMT & EMF. These interfaces are similar to subscriber Line
Cards, with only difference that the interfaces are designed to scan/drive events on
the trunks as predefined signaling requirement.
(c) Signaling Processor Cards: -
SP Processes the signaling information received from the terminals cards. SP
processes the signaling information consists of scan/drive function like original
detection, answer detection, digit reception, reversal detection etc. The validated
events are reported to Terminal interface controller for further processing.
(d) Terminal interface controller (TIC) Cards: -
TIC controls the four terminals group (TG) of 32 channels and multiplex them
to form a duplicated 128 channels, 8 mbps link towards the Time Switch. For
Signaling information of 128 channels it communicates with signaling processor to
66

67. receive/send the signaling event on analog terminations. It also uses to communicate
with BPU.
(2) DIGITAL TERMINAL UNIT (DTU): -
Digital terminal unit is used to interface digital trunks, i.e. used between the
exchanges. One set of Digital Trunks Synchronization (DTS) Card along with the
Digital Trunk Controller (DTC) card is used to provide one E-1 interface of 2mbps.
Each interface occupies one TG of 32 channels and four such interfaces share 4
TGs in a DTU. Here Terminal Unit Controller (TUC) is used of TIC and DSP cards. Out
of 32 channels, 30 for voice communication and remaining two for Signaling and
Synchronization.
In DTU 4 TGs are there so total number of unit are 4*30 = 120 units in DTU.
(3) # 7 or Signaling Unit Module (SUM): -
It is used to support SS7 protocol handlers and some call processing function
for CCS7 calls.
SS7 capability in C_DOT DSS MAX exchanges is implemented in the form of a
SS& Signaling Unit Module (SUM).
The sum hardware is packaged into a standard equipment frame, similar to
that of terminal unit. It is a module by itself and contains global resources. It
interfaces with the Time Switch via Terminal Unit Controller (TUC) on a 128 channel
PCM link operating at 8mbps.
ISDN
67

68. To support termination of BRI/PRI interfaces and implementation of lower layers of
DSSI Signaling protocol. They are used as carriers to transport bulk volume of data.
With the increasing use of internet access, the use of ISDN interface is likely to go up
as it provides the reliable access to the user at the rate of 64/128kbps. It is of two
types i.e. circuit switched voice and data and packet switched data. In circuit switch
the traffic is routed through ISDN and is packet switched data the traffic is routed
through PSPDN.
REMOTE SWITCH UNIT: -
In this time switch card BMs are replaced by Enhanced Switch Cards (ETS). It is
used when the e exchange is at a far distance from the central module. It can
modified BM via 2 mbps digital links. Analog and Digital trunk interfaces are also
implemented in RSU to support direct perenting of small exchanges from RSU.
Instead of perenting it to the main exchange. RSU is an autonomous exchange
capable of local call completion. Only the even numbered BMs can be configured as
RSU i.e. a maximum 16 RSUs are possible in C-DOT DSS MAX-XL and 8 RSUs in MAX-L
Maintenance and operation function are handled by the host exchange.
TIME SWITCH UNIT (TSU):-
Time Switch Unit (TSU) implements three basic function as time switching with
in the Base Module, routing of control message within the Base Module and across
Base Module and support services like DTMF circuit, answering circuit, tones etc.
These functions are performed by three different functional unit, integrated as Time
Switch Unit in a single frame. i.e.
TIME SWITCH (TS): -
68

69. The Time Switch complex is implemented using three different functional cards
as multiplexer/DE multiplexer (TSM), Time Switch (TSS) and Time Switch Controller
(TSC). The Time Switch complex performs time switching with in the Base Module: -
1. Four 128 channel multiplexed link from four different terminal units which may
be any combination of ATU, DTU, #7SU AND ISTU.
2. One 128 channel multiplexes BUS from the Service Circuit interface Controller
(SCIC) in the Time Switch Unit.
3. Three 128 channel link to support on board three party conference circuit
(3*128).
BASE PROCESSOR UNIT:-
Base Processor Unit (BPU) is the master controller in the Base Module. It is
implemented as a duplicated controller with memory units. These duplicated sub-units
are realized in the form of the following cards:-
1. Base Processor Controller (BPC) Cards.
2. Base Memory Extender (BME) Card.
1. Base Processor Controller (BPC) Cards: -
BPC control time switching within the Base Module via the Base Message
Switch and the Time Switch Controller. It communicates with the Administrative
processor via Base Message Switch for operations and maintenance functions. In a
SBM configuration, BPC directly interface with the Alarm Display Panel and the input
Output Module.
To support 8,00,000 BHCA, the BC card is replaced by High performance
processor card.(HPC) i.e. Protocol Handler Card (PHC) which contain 26 slot,8slot for
the power supply, 2 for memory and remaining 10 for message switching.
69

70. 2. Base Memory Extender (BME) Card: -
It is for the storage purpose i.e. saving memory purpose. It can store up to 16
bits
CENTRAL MODULE
Central module is responsible for space switching of inter-Base Module calls,
communication between Base Module and Administrative Modules, clock
distribution and network synchronization.
The complete control conceptually is shown in following figure: -
Concept Control Scheme for Space Switch
The administrative processor communicates with the IOPs which act like a
central storage. Administrative processor is also connected to Central Message
Switches CMSA and CMSB through which AP communicates to SSC. The SSC is
connected to all the CMSs (A, B, C, D) so as to communicate with all the BMs through
these Central Message Switches (CMS_A, B, C, D).
There are two types of Central Module: -
1. CM-XL (Extra Large)
70

71. 2. CM-L (large)
CM HARDWARE DISTRIBUTION:-
CM Hardware is distributed in following frames: -
1. Bus Terminal Unit (BTU) Frame
2. Space Switch Unit (SSU) Frame
3. Space Switch Controller Unit (SCU)
4. Administrative Processor Unit (APU)
BUS TERMINATION UNIT: -
It contains Multiplexer and Demultiplexer. It is basically an Interface Unit
between the BM and Space Switch. There are two buses-Bus 0 and Bus 1.Bus 0
contain all even time slots and Bus 1 carries all odd time slots. Bus is terminated from
the Base Modulation. It controls the Space Switching between Base Modules.
BTU insert the message CMS to BMS and vice versa.
FUNCTION: -
71

72. (a) Caters to maximum 16 BMD in release one.
(b) Multiplexes the data for Space Switching.
(c) Distributed 8 MHz clock and 8 KHz sync. To BMs.
(e) Acts as a Gateway for CMS by message extraction/insertion scheme
Types of cards used: -
1. Space Switch Mux Card (SSM): - It multiplexes two BMs data.
2. Space Switch Mux Termination Card (SMT):- It is used in an unequipped. SSM slot
in the BTU frame to avoid any noise generated due to termination of a bus from BM
in BTU frame. It offer 2A load at 5V.
3. Power Supply Card: - It supplies power to the cards and unit it work as a load
sharing mode in each bus.
4. Space switch unit: Space Switch provide connectivity between two subscriber of
two different BMs on time slot basis. It is responsible for switching of cards between
various base modules
FUNCTION: -
(a) Establishes Inter Base Module Switching.
(b) Caters for 16*16 Base Module switching.
(c) Implements two 16*16 switching; one for bus 0 and other for bus 1.
(d) Provides redundancy as copy 0, copy1 (switch duplicated)
Types of cards used: -
1. Space Switch Switch Cards (SSS): -
The switch card forms the part of the space switch which is situated in the
Central Module. Each SSS Card caters for four base modules (16*4 switch in CM).
72

73. 2. Space Switch Termination Card (SST): -
It provides proper termination to the MUX data bus received from 16 space
Switch MUX Cards. The card is used if corresponding SSS slot is unequipped.
3. Space Switch CU Bus Termination Cards (SCT): -
It is used in Space Switch Unit and Space Switch Control Unit frames of CM. It
terminates CPU, address, data and control signals.
4. Power Supply Cards: -
SSU employs 4 cards for supplying power and it is used in BPU, TSU, and IOP.
3. Space Switching Controller Unit (SCU): -
It is a CPU complex and interfaces with space switch and clock for controlling
the space switch. SSC communicates with the CMSs which in turn enable the SSC to
communicate with the BMs. It contain Power Unit
FUNCTION: -
(a) Controller for the Switch
· Time slot management and allocation
· Switch monitoring for sanity
· Switch diagnosis
(b) Communication b/w the central message switch and Aps, BMs
(c) System clock generation
(d) Management of power alarms in BTU, SSU and SCU
Central Message Switch (CMS): -
It consists of four different message switches and each one of them is
implemented by using high speed 32 bit microprocessor. All Central Message
Switches (CMS 1, 2, 3 & 4) are used for routing of messages across the Base Modules.
Only CMS1 and CMS2 interface with the Administrative Module for routing control
message between Base Processors and Administrative Processor.
73

74. Type of Cards used: -
1. CPU Complex
· Space Switch Controller Card (SSC) (CPU): - This is to serve as central processing
engine for the C-DOT DSS both in the BM & the CM mode. It coordinates system
activities and perform call processing functions. It is used as Base Processor (BP) in
the BM& as administrative processor (AP) and Space Switch Controller (SSC) in
CM.
· Bus interface-CPU (BIC) Card: - It is used to access memory and space switch in
plane copy-0 & copy –1.
· Bus interface Device (BID) Card : - It along with bus interface CPU (BIC) card
provides the cross connection b/w duplicate CPU’s (controller) an duplicate
device (memory) in such a way that any one failure either at CPU or at device
does not bring down the whole processor complex.
· Memory Card (2MB): -It provides storage space and interfaces to a standard
6800 CPU bus. Both word & byte accessory are possible on the memory space.
2. Switch Interface
· BIC Card
· Bid Card
· Space Switch Controller Termination (SCT)
3. System Clock and PSU errors
· Space Switch Clock Card (SCK): - It is the source of clock signal to the space
switch switch cards & the space switch mux cards which constitute the space
74

75. switch. It is used for the control of timing and for synchronizing of the space
switches.
Administrative Processor Unit (APU): -
· Status of all module of the exchange is maintained by the AP and whenever a
problem is reported required action is initiated to clear the problem. All the global
resource like trunks. Time slots etc. are managed by the A.P. Directory to
equipment number translation for the establishment of a call is performed by AP
All global data is managed by the AP. In a multimodule exchange all the call
processing. Administration and maintenance function are supervised by the AP.
Function of APU: -
1. All administrative function in the system
2. Interaction with SSC through central message switches CMS (A, B) (SSC/BM to
IOP via AP).
3. Communication to ADP.
4. Administrative Processor (AP) somewhat similar to BP.
5. Maintain status of all modules of the exchange.
6. Initiate whenever a problem is reported required action to clear the problem.
7. Switch over of copies, diagnostic of faulty units and put in service units which
are out of service etc., are initiated and supervised by the AP.
8. Manage all the global resource (like trunks, ts etc.)
9. Perform directory to equipment no. translation for the established of a call.
10. Connects of exchange to the operator through IOP.
11. Handle the man-machine communication.
12. During initialization of the multimode exchange AP gather initialization request
from different BMs, collects code and data from IOP and send it to
corresponding BM’s.
75

76. Types of Card used: -
1. CPU Complex (APU)
· CPU Card
· BIC Card
· BID Card
· Memory Card (2MB)
2. Central Message Switch-CMS (A, B, C, D)
1. Message Switch Controller Card (MSC)
2. Message Switch Device Card (MSD)
CALL PROCESSING
GENERAL CONCEPT
There are five function steps of call processing including the location of the
originating and terminating equipment. These steps are: -
· Origination: - Origination begins when the subscriber line goes off hookor
incoming trunks seized. It receives the incoming digits, selects the digit
analysis tables, and determines the screening information for this call.
· Digit Analysis: - It interprets the digits it receives from origination, select a
destination for each call, and passes the dialed digits to routing.
· Routing/Screening: - Routing uses the destination information from digit
analysis and screening information origination to select the terminating trunk
group or line.
· charging: - It uses the charging information from routing to expand the
charging data into a format usable by call accounting process.
· Termination: - The last step in call processing is termination. Termination
Processor is different for calls destined for lines and call destined for trunks.
Trunk termination: - A trunk member of the trunks group is selected based on a
predetermined pattern. After selection the digits are out pulsed to the distant office.
76

77. Line termination: - The line identified in routing is checked to determine the line has
any special features. Ringing is applied to the line if applicable or the special feature
is activated.
SIGNALING
What is Signaling?
Signaling refers to the exchange of information between call components
required to provide and maintain service.
As users of the public Switched telephone network, we exchange signaling
with network element all the time. Examples of signaling between a telephone user
and the telephone network include. Dialing digits, providing dial tone, accessing a
voice mailbox, sending a call waiting tone, dialing *66(to retry a busy number), etc.
Signaling system 7 is means by which element of the telephone network
exchange information. Information is conveyed in the form of messages. Signaling
System 7 messages can convey information such as:
SS7 is characterized by high-speed packet data, and out-of-band signaling.
ISDN
(INTEGRATED DIGITAL SERVICE NETWORK TERMINAL UNIT)
One of the four ATUs/DTUs in a Base module be replaced by ISTU to provide
Basic Rate Interface (BRI)/Primary Rate Interface in C-DOT DSS. It is directly
connected to TSU on 8 Mbps PCM Link.
77

78. INTRODUCTION
ISDN is comprised of digital telegraphy and data transport services offered by
region telephone carries ISDN involves the digitization of the telephone network
which permits voice, data, text, graphics ,music ,video and other source material to
be transmitted over exiting telephone wires. The emergence of ISDN represent an
efforts to standardize subscriber service user/network interface and network and
inter network capabilities.
ISDN application includes high speed image application, addition telephone
lines in home to serve the telecommuting industry, high speed file transfer and video
conferencing. Voice service is also an application for ISDN.
Architecture of ISDN Terminal Unit
In C-DOT DSS architecture the ISDN interface are terminated on a new add on
terminal unit as ISTU. A maximum of 256 bearer channels are provided by integrating
one ISTU which can be configured to support any combination of BRI or PRI
interfaces. If the requirement of PRI/BRI interfaces more than 256 bearer channels,
one or more. ISTU, can be integrated in C-DOT DSS with the option of equipment
them in the same BM of distributed across different BMs in the exchange.
The architecture also support in signaling providing time slots for switching
channels, carrying data & voice.
SERVICE
There are two types of services associated with ISDN:-
1. BRI
2. PRI
78

79. 1. ISDN BRI Service
The ISDN Basic rate interface (BRI) Service offers Two B channels and one
D channels (2b+D). BRI B channels service operated at 64 Kbps and is carry user data.
BRI d channels service operates at 16 Kbps and is meant to carry control and signaling
information, although it support user data transmission under certain circumstances.
The BRP also provides for framing control and other overhead, bringing its total bit
rate to 192 Kbps.
The BRI physical layer specification is International
Telecommunication Standard Section (ITU-T). (Formerly the consultative committee
for international telegraph and telephone (CCITT)
2. ISDN PRI SERVICE
The ISDN traffic is of two distinct types:-
· Circuit switched voice & data
· Primary Rate Line (PRL)
Basic Rate Line (BRL) Card
The BRL is an interface to the switching system supporting 8 U-interface
towards the user. It interfaces with the ISDN Terminal Controller (ITC)/Switching
Network for signaling and switching of voice and packet information.
The function of the BRL card include HYBRID for 2 to 4 conversion and echo
cancellation monitoring of lines status, it’s activation and deactivation, over voltage
protection (for protect the exchange and the BRL card from high voltages),test
access.
Primary Rate Interface Line Card (PRL)
79

80. The PRL Card is an interface to terminate a 2.048 Mbps link, using symmetric
twisted pair cables with characteristic impedance of 120 ohms.
Each PRL card form a terminal group (TG) and a maximum of 8 PRL, cards can
be accommodation in each ISTU.
ISDN USER PART (ISUP)
The ISDN User Part (ISUP) defines the protocol and Procedures used to set-up.
Manage, and release trunk circuit that carry voice and data calls over the public
switched telephone network (PSTN). ISUP is used for both ISDN and non-ISDN calls.
Calls that originate and terminate at the same switch do not use ISUP signaling.
ALARM DISPLAY PANEL (ADP)
The ADP is used in the C-DOT to display the status of the system in single base
module configuration. It can also be used with a two base module system.
The status is displayed on light emitting diodes (LEDs) and seven segment LED
display. Fresh faults are reported on the panel by blinking the LEDs accompanied by
an audio alarm to draw the attention of the operator in turn is expected to
acknowledge the faults.
ADP is a microprocessor based hardware unit which is attached to the BP (in
SBM) or AP (IN MBM) by HDLC (HIGH DATA LINK CONTROLLER) link for providing
audio visual indication of system faults. a seven segment display shows the count of
lines and trunks currently faulty.
FUNCTIONAL DESCRIPTION:-
The ADP is housed on three cards:-
1. Controller card.
80

81. 2. Display card.
3. Power supply card.
1. Controller card:-
It is a subdivided into following blocks:-
(a) CPU LOGIC:-
It generates clock required by microprocessor, buffers for buffering for CPU
address and data bus, power on reset logic to generate the signal.
(b) MEMORY:-
Occupies address space RAM.
(C) DISPLAY CARD INTERFACE:-
Consist of logic which generates the various strobes for the registers on the
display card
(D) INTERRUPT AND WATCHDOG DOG:-
The sources of interrupt for the CPU are:-
(i) Real time timer
(ii) Acknowledge switch
(iii) LED test switch
(iv) The two HDLCs.
The sources for generate one interrupt line for the microprocessor.
(e) INPUT /OUTPUT PORTS AND AUDIO ALARM:-
81

82. Input port is used to determine the configuration of the system and the source
of the interrupt. Output port is used for cleaning the various interrupts & for enabling
the audio alarm. The audio alarm is implemented using a piezo-electric buzzer
(f) COMMUNICATION INTERFACE:-
Consists of clock generator for the HDLs.
.
SYSTEM CAPACITY
INTRODUCTION
The capacity of C-DOT DSS is defined in terms of the following parameters:
· The termination capacity express as the number of lines and trunks
· The amount of traffic (in erlangs) that can be switched
· The number of Busy Hour Call Attempts (BHCA) that can be processed with
a given call-mix while meeting the overall service quality requirements.
This section indicates the maximum capacity of different system element as
well as that of complete exchange, equipped to its ultimate termination capacity. It
has been ensured that the specified parameters are valid to meet overall reliability
objectives for the C-DOT DSS as specified in ITU-T recommendation.
TERMINATION CAPACITY
A terminal Card is the basic system element. It interfaces/terminates the lines
and trunks. The next higher element is a Terminal Unit. The types of terminal card
and terminal unit used in C-DOT DSS along with its function are already explained in
chapter ‘3’ &’4’. Termination capacity of BM is 488 analog lines and that of LM in 768
analog lines. A BM can be concentrated with 2 LM’s to provide maximum termination
capacity of 2024
82

83. Analog lines. Incase of BM, a maximum of 256 B channels are provided at the
cost of 512 analog lines. One to one replacement of Base channel is planned in
immediate future. Base Module and Line Module are the highest level of system
elements. Each Base Module has four Terminal Units whereas a Line Module has six
Terminal Units.
A maximum of 16 BMs can be connected in MAX-L and 32 BMS can be
connected in MAX-SL configurations.
EXCHANGE CONFIGURATION
C-DOT DSS MAX can be configured to support any combination of lines and
trunks, for different application in the network as local Exchange, Local cum Tandem
Exchange. Trunks Automatic Exchange (TAX) or Integrated Local cum Transit (ILT)
Exchange.
In this maximum configuration, up to 40,000 lines and 5,500 trunks are
supported when configured as Local/Local cum Tandem. When configured as TAX.
14,500 trunks are supported.
Termination Capacity of Exchange Configuration
Note: Out of the total equipment capacity, a maximum of 30,000 Lines may be
Remote Subscriber through RSUs in MAX-XL whereas 14000 lines.
SOFTWARE ORGANIZATION
The software is written in high level language ‘C’ & distributed over various
processors and is structured as a hierarchy of virtual machines. The software features
are implemented by communication processes. The operating system provides
communication facilities such that the processes are transparent to their physical
locations.
83

84. Resource are identified as ‘global’ or ‘local’ depending upon their distribution
in the system. The resource which depends upon the number of terminal are
provided within the basic growth module.
E.g., Processor architecture is characterized by distributed control & message based
communication in order to achieve a loosely-coupled network for a flexible system
architecture.
ROLE OF SOFTWARE IN C-DOT DSS
INTRODUCTION
The main feature of the software architecture of DSS-MAX are as:
1. Distributed architecture to ma the distributed control architecture
2. Layered architecture with loosely coupled modules & well defined message
interfaces.
3. Use of high level language
4. Modular design with each layer providing higher of abstraction
5. Time critical processes in assembly language
These feature help in to achieve the following objectives:
1. Simplicity in design
2. Increased reliability due to fault tolerant software
3. Flexibility with option of up gradation to add feature & service
4. Efficiency and strict time check
5. Ease of Maintainability
C-DOT DSS MAX Layered Software Architecture
84

85. SOFTWARE SUBSYSTEMS
The main subsystem of C-DOT DSS MAX are as:
1. C-DOT real Time operating system
2. Peripheral Processors subsystem
3. Maintenance subsystem
4. Database subsystem
5. Administration subsystem
6. IOP subsystem
7. Call Processing subsystem
These subsystem are responsible for providing the following basic services:
1. CDOS:
It is the operating system & provides the following function:
1. Process management
2. Resource management
3. Interrupt handling
4. Online & offline debugging
2. Peripheral Processor subsystem:
It controls all the telephony software. It also carries out the commands given
by the Base Processor for generating suitable telephony events. Another function is
to carry out all the maintenance related test function on hardware. It consists of 8-bit
microprocessors programmed in assembly language
3. Call processing subsystem:
It receives the information about telephony event that occur outside the
exchange. It processing this incoming information & gives commands to the
85

86. peripheral processors for interconnecting subscriber through the switching network.
A special feature is to generate Exhaustive Call Event Record for every call.
4. Maintenance subsystem:
It provides the following function:
· Initialization
· System integrity
· Switch maintenance
· Terminal interface
· Human interface
5. Administration subsystem:
It consist of traffic, billing exchange performance measurement & human
interface functions. It also provides online software patching capability. It is
responsible for maintaining a large number of traffic records on the basis of
information received by it through Call Event Records. Over 200 man-machine
commands are provided for these operations.
6. Database Subsystem:
It provides for the management of global data.
The main objectives are:
(a) Easy access
(b) Quick access
(c) Transparency
(d) Consistency
(e) Security
(f) Synchronization
BASIC SERVICE IN DSS MAX
The most important function of a DSS switch is to process subscriber calls.
Subscribers’ call can be classified as line-to-line, line-to-trunk, and trunk-to-trunk. A
86

87. lint-to-line is a call that starts on a line served by a DSS switch and terminates to
another line served by the same switch. The BMs involved in the call will perform
almost 95% of the total call processing function.
During a line-to-line call, the origination BM detects when a subscriber’s
telephone receiver as been picked up. The BM provides the dial Tone and then
removes the Dial
Tone when first digit is dialed. It then collects and analyzes the dialed digits.
Next, the BM sends a request to the AM for a call path. The terminating BM locates
the subscriber line for the line-to-line call and provides ringing.
When AM has selected an available path. It alerts the CM to set up link
between the BM’s. The CM provides call paths between BM’s and carries all internal
system communications.
The function of BM, AM, and CM in trunk-to-trunk call are basically the same
as line-to-line call described above except that the originating BM detect a trunk
seizure rather than a subscriber picking up the receiver. Also, the terminating BM
locates as available trunk instead of line.
The above scenarios may differ slightly, if the call involves both and trunk.
Lint-to-Line call can be of two types:
· INTRA_BM: When both subscriber lines connected to same BM. This
doesn’t require use of CM.
· INTER_BM: When both subscriber lines are to different BMs. This requires
use of the CM.
OTHER SERVICE PROVIDED BY MAX
87

88. The MAX provides the following features apart from processing of a telephone call:
Number identification Service:
1. Calling Line Identification Presentation (CLIP): The Calling Party’s details are
given to the user along with the incoming calls.
2. Calling Line Identification Restriction (CLIR): With this service the calling party
may restrict presentation of its number to the called party.
3. Calling Line Identification Restriction Override (CLIRO): The subscriber with this
facility receives the details of the calling party even if it has asked for its
restriction.
4. Malicious Call Identification (MCID): During conversation the subscriber can
use a procedure to identify the malicious caller.
Call offering supplementary Service:
· Call Forwarding? Unconditional (CFU) L It allows the user to forward all
incoming calls to another number.
· Call Forwarding Busy (CFB): It allows the user to forward all incoming calls
to another number if the user’s number is not free.
· Call Forwarding No Reply (CFNR): It allows user to forward all incoming calls
to another number if the user doesn’t respond in a fixed number of rings.
Call completion Services:
1. Call Waiting: A Subscriber engaged in a call, is given an indication that another
caller is trying to call him up. The user can then talk to a caller by keeping the
other holding.
88

89. 2. Call Hold: This allows the user to put the call into wait for the being and initiate
or accept a new call. The user can retrieve the call put on hold whenever
required.
Multi Party Services:
1. Three Party Conference: It enables the user to establish, participate in and
control a simultaneous communication involving the user and two other
parties. The served user can disconnect one party, disconnect the three-way
conference or communicate privately with one of the parties.
2. Multi Party Conference: It allows uses to establish and control a conference
involving at the most 6 users. The conference controller may add, drop, isolate,
and reattach parties from the conferences.
Misc. Service:
1. Hot Line (Timed): It allows the subscriber to establish calls to a pre-registered
number. After getting the dial tone, if the subscriber doesn’t dial any number
for a minimum amount of time, then he is connected to the pre-registered
number. If the subscriber dials a number, then normal connection is
established.
2. Hot line (Without Time-Out): As soon as the subscriber lift the handset, the call
to the pre –registered number is established. Normal outgoing calls can’t be
made.
POWER PLANT OF C-DOT DSS MAX
From the power supply bus bar power is tapped through cables to each suite
separately. In this there is five modules, each having 200amp. As input. In this, AC is
input and DC is output. In this input is between 340-475 V and output is 48V. There
are two batteries if one is not conduct than other is used. These are connected
89

90. together if both are disconnected than till 15-20 minutes power is supplied. From the
rectifier, which derives 48V DC from 440V AC. Power cables are terminated on the DC
distribution panel (DCDP). From the DCDP, power cables run along the cable runways
and ladders and terminated on the power distribution panel (PDP). Distribution panel
consists of two bus bars for –48V, one each for copy 0 and copy 1 equipment.
Similarly there are two bus bars for ground.
For each base module cabinet, the power i.e.-48V is tapped twice one for each
plane through a fuse. Whenever the fuse blows off the LED, which is connected in
parallel glows on the FBI card, and an audio alarm is given at a centrally located
point.
90

91. REFERENCES
1. Data Communication and Networking-
Behrouz A. Forouzan
2. Wireless Communication and
Networks-William Stallings
3. Computer Networking – Kurose & Ross
4. www.bsnl.co.in
5. www.newbsnl.co.in
6. Wikipedia, the free encyclopedia
1